Since your response was defensive, and biased, let me rephrase my post simply:
Point 1: how much confidence do you have in your ideas and understandings? How about you put them to the test somehow, before jumping to conclusions.
Point 2: how about you view "contrarian" perspectives as there to not to hold you back, but to challenge you in accounting for them, while also accounting for your ideas?
Since your response was defensive, and biased, let me rephrase my post simply:
Point 1: how much confidence do you have in your ideas and understandings...
Since your response was defensive, and biased, let me rephrase my post simply:
Point 1: how much confidence do you have in your ideas and understandings? How about you put them to the test somehow, before jumping to conclusions.
Point 2: how about you view "contrarian" perspectives as there to not to hold you back, but to challenge you in accounting for them, while also accounting for your ideas?
...defensive? That's like saying "why'd you answer the question I asked you"? You posted something, I wrote back. That's how forums work.
Again dude, I started this thread, if you don't like it, go somewhere else, this isn't like a class where attendance is mandatory!
Snowmobiles, cars, dirt bikes all use scales to understand how weight is distributed throughout the vehicle. Mountain bikes are *very* interesting in that the pilot weighs more than the machine....like skis! Which (gasp) have different mount points for different size skis...and there is some wiggle room with said mount point depending on biomechanics, preference etc.
You are saying what I'm saying and not saying it all at the same time? I can't even follow what your point is. You want FC/RC to be proportional but "pros know best" and that video had bad math? Huh?
I will follow through and "prove" this, as much as anyone can prove fit. People still love driving cars with crappy weight distribution or skiing center mount skis in powder. Cool. Doesn't mean you can't do it. Just means there might be a better way.
@jeff.brines Leave if the thread you started isn't to one's liking? What's going on?
Is this a personal issue with CS length we're discussing in this thread, or a fundamental issue with the state of bike geo design?
If you're inclined to claim leadership/ownership of this thread, can I not question your authority? Let's observe your habits:
- you are excusing yourself from responsibility that calls for you to act. When you preach claims, like Steve confirming your hypothesis 100%, and jump to conclusions like "I want something closer to 50/50 than I do 45/55", the burden on proof is on you to support these when they are questioned. You try to shift this burden of proof on others.
- you state a "hypothesis" then seemingly wait for someone in agreement to do math and research for you. Follow-up conclusions are seemingly made off of such "math" with limited understanding of it. When someone else questions the math, saying it doesn't scale to work on bikes with much shorter or much longer wheelbase, they have to prove it's wrong, and not the ones promoting it, and basing conclusions off of it?
- you call to focus attention on various topics, such as bikes that go fast, with increasing CS length being center of attention. You bring up sources to justify this, but development on these ideas always seem to stop short at mere generalizations. It's like this in skiing, automobile design, or Minnaar does this. Is this some appeal to authority? If authority matters, what if Steve@Vorsprung refines his belief, do you follow the man or their idea? What if someone else came up with the idea before, is it only worth believing if Steve, Minnaar, or some celeb repeats it?
- your deflection of criticism seems to promote tribalism, bringing up the question "are you with us, or against us". You expect others to join your bandwagon through agreement based on faith/intuition, using Vorsprung's adv geo video as a "brochure".
You say you'll prove this, as much as anyone else can prove it, but are you doing anything beyond making such an empty promise? Have you picked a specific claim/topic/conclusion to prove? Any timeline on this action?
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Yes, I do want proportional CS length according to FC or WB length. I see this as a fundamental issue in bike geo. If it's not what's being discussed here, and is instead about your personal issue with wanting CS to be longer, from a perspective you dictate, then I choose not to serve some seemingly wishy-washy guy with a sensitive ego. P.S. you can buy custom, such as through Starling Cycles or Atherton/Robot Bike Co.
I, for one, just enjoy riding my bikes. These days, the bike companies are producing fantastic bikes. Are they perfect? No. Are they fast and fun? Do they bring a smile to your face? Hell yes.
But if I were to overanalyze and scrutinize every single detail like ninjichor does on the various sites, I would not enjoy riding bikes as much. It's ok that they're not perfect. Go outside, get on your bike and ride!
I, for one, just enjoy riding my bikes. These days, the bike companies are producing fantastic bikes. Are they perfect? No. Are they fast and fun...
I, for one, just enjoy riding my bikes. These days, the bike companies are producing fantastic bikes. Are they perfect? No. Are they fast and fun? Do they bring a smile to your face? Hell yes.
But if I were to overanalyze and scrutinize every single detail like ninjichor does on the various sites, I would not enjoy riding bikes as much. It's ok that they're not perfect. Go outside, get on your bike and ride!
Intensive debate isn't for everyone, but if no one was doing it, you wouldn't have modern, fantastic bikes. Please do get on your bike and ride, but rather than discourage debate, maybe give a nod to those who are trying to drive progress.
Ninjichor, you have mentioned you are buying a custom frame before. Who are you having build it?
On the topic of length adjustable dropouts I don't think sliding dropouts would work too well but you could do flip chip style dropouts and build in 20mm of adjustability with two sets of "chips" that could be reversed for positions 1,2,3,4. Rear brake mounting could be solved by moto style solution. Or just do like Norco and YT are doing and make size relevant rear ends. They need to take it a bit farther IMO but they are on the right track.
I bought a used Stumpjumper Evo in S3 size yesterday. 443mm cs to 475 reach 63.5 HA. Giddyup.
I had another thought last night while falling asleep.
Do longer cranks create a larger neutral zone when in attack position or do they mitigate it? Enduro bikes have gone from 175mm to 170 standard, Dh bikes seem to be on mostly 165-160mm. Now I realize this is mostly to prevent rock strikes but it's got affect weight balance as well. I'm thinking about trying to buy some 160 or 165mm cranks to play with, although it might hard to tease any significance out of the noise.
Ninjichor, you have mentioned you are buying a custom frame before. Who are you having build it?
On the topic of length adjustable dropouts I don't...
Ninjichor, you have mentioned you are buying a custom frame before. Who are you having build it?
On the topic of length adjustable dropouts I don't think sliding dropouts would work too well but you could do flip chip style dropouts and build in 20mm of adjustability with two sets of "chips" that could be reversed for positions 1,2,3,4. Rear brake mounting could be solved by moto style solution. Or just do like Norco and YT are doing and make size relevant rear ends. They need to take it a bit farther IMO but they are on the right track.
I bought a used Stumpjumper Evo in S3 size yesterday. 443mm cs to 475 reach 63.5 HA. Giddyup.
I had another thought last night while falling asleep.
Do longer cranks create a larger neutral zone when in attack position or do they mitigate it? Enduro bikes have gone from 175mm to 170 standard, Dh bikes seem to be on mostly 165-160mm. Now I realize this is mostly to prevent rock strikes but it's got affect weight balance as well. I'm thinking about trying to buy some 160 or 165mm cranks to play with, although it might hard to tease any significance out of the noise.
I would think that crank arm length would change your 'neutral zone' to a point, but I don't know if there would be a hugely significant difference between 2 cm of feet positioning. As a rough approximation, you could try standing with your feet at 35cm apart and see how much force (push) you could resist, and then do it at 33cm apart. You could do it with Q factor too. There is probably a point where it could be 'too long' or 'too short', but I think those are far outside of the 165-175mm crankarm lengths we deal with in MTB.
I bought 165mm cranks for my trail bike, but mostly as a fit issue (weird hips and seat tube was too long for a 150mm dropper) and secondarily for clearance.. I looked quite a bit into the 175 (stock length) vs 165 issue with regards to fit and power (since most studies are done on road bikes/athletes) and all I could find was that a) you can get a more aggressive position going shorter, b) power output doesn't change significantly, but c) cadence increases ( by about 5rpm, since it's a shorter lever). Most of what was being shown was statistically insignificant or had such a small effect as to really not be limiting (especially to a non-racer like me). I think there are such small differences here that any effects are likely to be insignificant unless you have a large sample size, and even then they probably don't have a big effect.
I don't ride MX, but those athletes seem fine with having their feet beside each other, although most of them don't have to handle World Cup Downhill terrain.
@HeatproofGenie Marino bike. They've had my money (small deposit) for a month or so. Week 1: no update, other customer orders. Week 2: front tacked, news of other orders being finished. Week 3: front welded, rear tri tacked and attached, but dropouts weren't sliding as requested. Currently on week 4. Fair warning if anyone wants to go this route.
@Masjo Cadence increases with shorter crank, because it's a smaller circle, and therefore less movement to complete a revolution. The leverage misconception is due to how crank length ties in with the chainring size. Take a 32t chainring and 175mm crank for example. Switch to 165mm only, and the gearing effectively becomes higher--if you do the same RPM, you will go the same speed, but the perceived resistance/effort is increased. The shorter total movement per crank revolution offsets the overall effort to go the same speed as before though. If you downsize to 30t at the same time, the resistance is equivalent to 175 w/32t, but going the same RPM will be slower. Since the shorter cranks require less movement per, higher RPM is more natural, which has a comparable overall effort, and you end up going the same speed. In the research reports, they explain that the foot velocity doesn't change, despite a change in RPM. In engineering, the bike drivetrain is perceived as a series of levers, including the cranks and overall wheel diameter.
I see chainring size as a way to tune anti-squat. If I want to try increased anti-squat, and get more ground clearance at the same time, I downsize the chainring by 2t and can downsize the cranks too. There's some Trailcraft cranks that apparently have no weight limit that go down to 152 and shorter, weigh similarly to XTR, and cost $150 w/chainring.
Seems to me there’s little doubt that a balanced bike is faster for racing and long gnarly, fatiguing descents. The more interesting question for me is for the non racer that wants to shred, slash turns, manual, but also ride flat turns fast and go fast generally, is a longer CS better and if so, how long. I’m 6’2” and only have short CS bikes (Demo, Process, DJ). The process (485 reach, 426 CS) is super fun. I was also just in Bellingham and rode an XL Patrol for a few days and it was rad and felt plenty stable in the steep gnar. Granted the longest descent was probably 6 - 10 mins.
Jeff, you’ve been clear your point is purely about racing and theoretically it makes sense to me. But wondering about us non racers who like to go fast but play too, are there trade offs and when do those happen. I wish i had the opportunity to try something good with longer CS to get a sense
@Allen_Gleckner Hope others forgive me for speaking for them, but I feel this question is about a general fundamental issue I can answer. I just want to clarify that a balanced bike is just easier to ride, since less effort is required to compensate for it, for the riding intended. Balanced for the kind of body position you are in for speed, vs balanced for the body position you are in for street/trials/dirt jumping.
The issue is that tall riders on short CS bikes are noticing that they have to actively weight the front end, when they've had bikes in the past that didn't require this. Newer bikes are getting even longer front ends, with longer reach and slacker HA, but the CS is not part of the marketing. The position that riders have adapted to, to make their past bikes feel balanced, is now being shifted forward. They recognize that more wheelbase helps bring stability and longer reach is a plus, but unless CS increases, it's a wash, since the lack of weight on the front results in the bike being squirrelly. If they feel that their position being even more forward is less comfortable, and requires more effort, then that means it's more demanding to ride, and this thread voices out that they think trade-off is too important to overlook.
Some may argue, isn't working hard the point of riding? Or isn't going faster more dangerous? I'd argue back that making things purposely harder is more against the point, especially when the challenge is mindless. It's like making riding braking bumps a challenge, by de-tuning your bike, and fooling yourself into thinking that's an achievement. The challenge added here is making the rider position out of their neutral position. It's like saying, here, ride with your handlebar shifted 2-3" more to the left, along with all the controls. You can adapt to it, but why? Going faster is some people's desire, and the high speed crashes are often no worse than the worst low speed crashes. Fracture your wrist, ankle, or collarbone falling off you bike at 5 mph, or get impaled by a handlebar or tree branch? Yea, that happens at 20 mph too, but you bounce, slide, spin, a bit afterwards, or make that tree flex a bit more since there's more energy still to transfer. It doesn't make your collarbone shatter beyond repair. If someone has a penchant for going fast, I'd give 'em a bike that's safer to ride, and perhaps the speed encourages them to wear protective gear that the slower riders are reluctant to use. I'd argue that's even safer...
The longer CS is merely to offset the longer front ends. Longer front ends are welcome for speed, but that's all for nothing if the CS are still short. The bikes might be getting praise, but what rides well in size M, doesn't necessarily ride well in XL. There's demand for shorter CS, and longer CS, which hints that the bike companies aren't getting things right. We're suggesting the answer is CS length being proportional to FC, and options where the CS is a bit longer or shorter than what works for the mainstream. Adapt the bike to the rider, so the demand for a rider to adapt to the bike is lower. Those who've been on many bikes, and have learned well from each bike, tend to be picky about what bike to choose. When one crosses almost every bike off their new-bike-list, you have to wonder if the mfgers have even learned...
Regarding what the trade-offs are... modern engineering is all about compromise, and what makes a modern design feel better, is making trade-offs in which the overall package feel so much better, that such trade-offs are acceptable. Trying to predict trade-offs is akin to asking someone to prejudge something. Something best off just test riding yourself. What's holding you back from trying? Fear that you'll like it? Or prejudice that fools you into be complacent, and not possibly waste your time learning something yourself first hand? Fear that all this goodness came with a very well hidden drawback, in which the frame explodes on a fireroad climb in under 2 years time?
Seems to me there’s little doubt that a balanced bike is faster for racing and long gnarly, fatiguing descents. The more interesting question for me is...
Seems to me there’s little doubt that a balanced bike is faster for racing and long gnarly, fatiguing descents. The more interesting question for me is for the non racer that wants to shred, slash turns, manual, but also ride flat turns fast and go fast generally, is a longer CS better and if so, how long. I’m 6’2” and only have short CS bikes (Demo, Process, DJ). The process (485 reach, 426 CS) is super fun. I was also just in Bellingham and rode an XL Patrol for a few days and it was rad and felt plenty stable in the steep gnar. Granted the longest descent was probably 6 - 10 mins.
Jeff, you’ve been clear your point is purely about racing and theoretically it makes sense to me. But wondering about us non racers who like to go fast but play too, are there trade offs and when do those happen. I wish i had the opportunity to try something good with longer CS to get a sense
To put it a more concisely, the concern is decreased weight on the front wheel caused by increasing the front-centre while holding steady on rear-centre. This can reduce traction.
For people who prioritize handling on extremely steep terrain, reduced weight on the front could be a good thing. For most people, it will require a change in body position, which may or may not be a bad thing. For me, the geometry of 10+ years ago forced me to hang off the back of the bike, so modern geometry allows me to stand in a neutral, relaxed position most of the time.
A flat, loose turn is the worst case scenario for a bike with an extremely long front and short rear, as this requires me to initiate a turn from a very forward stance, putting extra load on my puny arms. A partial solution is to use a front tire with a lot of traction and a rear with less.
In my opinion, steep seat tube angles and longer than traditional reaches are always good. Adding a slack head angle may be good for some, but not all. Longer chainstays are good for most, especially tall riders and when speed is the top priority, but not for everyone.
I do question if playfulness is in the geo. I think it's possible to make a bike playful through general frame and wheel feedback, and suspension tune. Progressive suspension with rebound run fairly open with progressive spring rate, tires pumped pretty firm... basically, you're after springiness, liveliness. The energy you put into the bike comes back and, if you don't catch/absorb it with your body, it'll go airborne. It's easier to make use of this energy if you're in a position that isn't forced/strained.
If you get chainstays that are too long, the front will tend to stay low off of jumps and drops. That transition, how did it feel on take offs? Did it fly naturally, nose not too high or too low? I think the Patrol in XL is on the rearward biased end of the spectrum, like your other bikes. A '19 YT Jeffsy 29 in XL is what I think would be a good experiment, to see if you'd like longer CS, and if it puts you in a more natural position for going fast, yet still meeting your desire to playful.
I do question if playfulness is in the geo. I think it's possible to make a bike playful through general frame and wheel feedback, and suspension...
I do question if playfulness is in the geo. I think it's possible to make a bike playful through general frame and wheel feedback, and suspension tune. Progressive suspension with rebound run fairly open with progressive spring rate, tires pumped pretty firm... basically, you're after springiness, liveliness. The energy you put into the bike comes back and, if you don't catch/absorb it with your body, it'll go airborne. It's easier to make use of this energy if you're in a position that isn't forced/strained.
If you get chainstays that are too long, the front will tend to stay low off of jumps and drops. That transition, how did it feel on take offs? Did it fly naturally, nose not too high or too low? I think the Patrol in XL is on the rearward biased end of the spectrum, like your other bikes. A '19 YT Jeffsy 29 in XL is what I think would be a good experiment, to see if you'd like longer CS, and if it puts you in a more natural position for going fast, yet still meeting your desire to playful.
I agree in principle, but I don't think 10 mm of chainstay length between those bikes is enough to isolate the effects of the chainstays; that difference is likely to be lost in the noise of other variables. I think we're going to have to go to something like 480 mm to really feel the difference, then bracket our way to the right value. A custom chainstay with adjustable dropouts is going to be the solution.
Another thing to consider: how much do we perceive the effect of a water bottle (or multiple bottles)? Do we notice the effect of the forward placement of a bottle on the new Guerrilla Gravity bikes or three bottles on a Pole? That probably makes more difference to weight distribution than a few millimetres of rear-centre. Water bottles, stem length, and a combination of head angle and fork offset (to maintain trail) could be ways to experiment with weight distribution without having to create custom chainstays.
Playfulness is an imprecise blanket cliche that gets used so often it means almost nothing anymore. Reminds me of "Climbs surprisingly well for a [xxx]mm travel bike." The general MTB public has been coached to believe that a short chainstay = "playful" through sheer repetition by product reviewers. That might mean the bike "manuals and kicks off of small jumps really well," or it could just mean "It doesn't feel like a boat."
My suspicion is that lots of different, unrelated qualities might result in someone using this word. A shorter wheelbase would make a bike more responsive to weight shifts, that could certainly make it "playful." Progressive suspension designs as well. A more balanced geometry that allows the rider sit neutrally would provide more opportunity to play with weight shifts without losing balance, and that could also be perceived as playful, even with the accompanying long(er) chainstays.
To put it another way: as an XL rider, will there be any drawbacks from going longer on the CS? And if not, at what point is too long? I have a hard time believing there aren’t any tradeoffs, but it’s possible things are so imbalanced on currwnt XLs that it would be only positives to a point. Take Transition, there’s definitely some tall dudes who rip there and I have to believe they’ve tried some longer CS prototypes. Either they experienced tradeoffs or the benefits didn’t outweigh the added production costs for now?
Transition’s ethos has always been “play” rather than “race” and their native trails are high in flow/berms, low in rocks/gnar. The promo videos for the Sentinel were mostly guys hitting huge, tractor made jump lines, which explains a lot. Also consider their mismatched travel design and heavily stuffed rear shocks that ramp up hard. You can juxtapose Transition with the Nukeproof lineup (275 & 290) inspired by the megavalanche. Big, matched travel, long chainstays.
I own 2 Transitions, I love them, but they’re also the bikes that convinced me the long front/short rear fad has gone too far. And I only ride mediums.
Trade-off(s) of long CS: should be balanced by longer FC, and therefore results in a long wheelbase. A long wheelbase numbs the "feedback" you get from the trail and disrupts the timing you use for pumping the trail, making it feel like you're going a bit slower, reducing the thrill. Some use this effect to go encourage themselves to go even faster.
Should easily notice this going from short travel/small wheels to longer travel/big wheels--the responsiveness and snappiness is not there. Feels like you don't have to go as fast on the smaller bike to reach your personal perception of hitting 90% of your max, in terms of reaction speed and staying in control; beyond "max" means going along for the ride and putting faith that your bike will handle things if you hold on (related to the saying that people's skill won't match the bike's capabilities). The long wheelbase would feel kind of like a cruise/tour on a limo if ridden at low speed, coming "alive" at higher speeds. People who don't have trails that give it speed, will feel like it's overkill, as they won't feel like their reaction speed and control is being challenged, and will strongly consider downsizing to a smaller bike.
It's not too unlike the middle seats of a roller coaster vs the front or back.
Go too long, without pushing the front wheel out to match, and the bike turns into a cruiser. It just forces you to plop your ass into a relaxed seated position and spin, and makes cornering and descending from a "defensive" rearward position behind the BB (hanging off the back) a viable technique. The trade off here is that using a more central standing position increases the risk of going OTB and nose diving when you try to go airborne. To adapt to jumps/drops, I've learned that you pretty much launch the bike well before your body follows, feet in front of your shoulders--some say pull back, I push the bike forward away from my body. The defensive position counters the OTB risk naturally. I've ridden plenty of these, being fairly short, and had a taste of what taller riders get from riding Kona-like aggro geo, and wanted more.
Some see these trade-offs as compromises (forced to adapt), while others see it as preferential (feels more natural). The defensive style is natural for some. The aggro style is natural for some. The neutral style is natural for some. You gotta find which you are. JFL1200 sounds like they fit well within the defensive side. R-M-R too maybe. I am looking for a mostly neutral bike. Allen sounds like they're on the aggro side, perhaps opening up to something more neutral after trying being impressed by a Patrol. Not sure what jeff's after but it definitely isn't aggro, probably more neutral-just slightly defensive, considering he liked the XL SB55. Maybe you're all of the above, and like aggro for stunting and style, defensive for aero tucking down a mountain slope at WC DH speeds, and neutral for riding unfamiliar trails (blind riding).
In my perfect world, people would choose bikes based on wheelbase length and suspension travel, according to what trails they ride and how they plan on riding it, finding that sweet spot of hitting 90% of your max, while still hitting the trail as fast as you believe is possible for mere mortals. The CS length will increase/decrease by 4-5mm for each 25mm of wheelbase change, if the bike model comes in different sizes. Brands will align themselves with 1 style: neutral, aggro, defensive, or anywhere in between. They'd further differentiate their product based on making engineering trade-offs such trading off aesthetics, water bottle mounts, future compatibility, patented technology/innovation, and versatility, low weight for performance, reliability, affordability, for maintenance-friendliness. Example: Pole Taival and Pole Stamina are what I consider to be neutrally aligned, having CS proportioned well, with different trade-offs. Stamina is high end engineering, while the Taival is what I see as a low cost test platform for perfecting geo to get the same neutral bias across the size range, made available to the public.
Also, in this perfect world, riders would do research to know better than to buy stuff that doesn't suit them, therefore driving demand for better bikes. When product managers don't get the feedback they want, sales to IBDs, since IBDs aren't buying up stuff people don't want, they gotta adapt or die. When I say riders, I mean the "media" too. Nice to see some are mechanical engineers (bturman?), but how is that qualification reflected in their reviews?
Seems like the new, but conservative, geo isnt so bad...? I do get that a lot of this discussion is on the front ends on the bigger sizes, and not on the medium/large size bikes. I just got a Cube stereo 150 29 in a size large, and it was considered a "conservative" geo by mtb-media, but from what you guys are saying, it seems to be pretty spot on - with all your number crunching.
BTW. How do you knowledgeable forumers think that bar roll effect the rindingstyle/feel of geo, or weight distribution to the front end. I came from a 435 reach, 50mm stem with pretty normal roll, to a 457mm reach with 35mm stem. And now roll my bars a lot forward so that my grips pretty much align with the end of the stem. This works great, I feel I get the weight on the front wheel, but I do wonder if I should get a longer stem(50mm) and roll the bars more back. hm...Are there any advantages/dis to roll the bars forward?
Conservative geo is just another way of saying it's similar to old school geo. Shouldn't be judged as bad, wrong, good, right, etc. It should only be judged if it suits you. To know that, you should know yourself first, and your demands (trail difficulty, goals/intentions for the bike). There's a problem with describing something old school: for some it worked great, better than new school, but, for others, new school works better. With perfect knowledge, one can give an explanation that makes it so all these people, who insist they are right, are still right, but the concept would make sense despite what seemingly is a contradiction.
The media doesn't have close to perfect knowledge. We're still piecing the bits together, cross-checking/peer-reviewing it here, to uncover more of the big picture. You just brought attention to some variable I never considered to be that big of an effect. Would like to answer, but since I don't have anything but speculation, I'll just say that it's worth keeping in mind, if it turns out to be a significant macro-issue. Some here think 10mm of CS length difference isn't a big deal, but I think it's huge, and therefore a macro-issue. The bar roll thing is just something I adapted to once set. I don't purposely put weight on the bar, only enough to guide it, and keep most of my weight on the pedals (heavy feet, light grip). I have it so my back isn't so far tilted forward, that it needs help from my arms to suspend its weight up.
When using relative terms, such as conservative, it depends on what they're comparing to. Maybe the reviewer has opened up to Pole, Geometron, Starling, etc. Others who say new school progressive geo, probably is comparing to the model that's being replaced. I could call them all of them conservative, if I think far enough forward. For example, when reach almost matches ETT, and STA is so steep, that your seated position is no different than your standing pedaling position, and the bikes are tuned for this single body CoG point, I think that's pretty much end game. This, coming from someone who has been riding bikes which seemingly were tuned for the seated position (73-74 STA), which hinders the bike from feeling naturally well balanced out-of-the-saddle; the deviation from a rearward seated CoG and a more forward standing CoG was revealing itself to be a clear compromise, forcing my standing position to shift my weight back, hovering well over half a foot (160+mm) behind the BB, which was roughly over the saddle, rather than using a more of a boxer's/fighter's stance. If I had my hips this far rearward on skiis, I'd be sliding down the hill on my ass. This end-game idea depends on finding what a person's neutral standing stance is, and designing around it, rather than making a bike based off other bikes and having the rider adapt to it. Just need to dispel prejudice, such as pedaling with a steep STA is less efficient (research says steeper, 80d, is more efficient), or fears that long wheelbase bikes can't do switchback turns (switchbacks not so much, but chicanes that you can't straight line above/over are a prob).
To put it another way: as an XL rider, will there be any drawbacks from going longer on the CS? And if not, at what point...
To put it another way: as an XL rider, will there be any drawbacks from going longer on the CS? And if not, at what point is too long? I have a hard time believing there aren’t any tradeoffs, but it’s possible things are so imbalanced on currwnt XLs that it would be only positives to a point. Take Transition, there’s definitely some tall dudes who rip there and I have to believe they’ve tried some longer CS prototypes. Either they experienced tradeoffs or the benefits didn’t outweigh the added production costs for now?
Everyone - large or small - will experience the same things with a longer rear-centre. The difference is that large riders have an inherently greater ability to shift their weight. If a rear-centre remains the same for different front-centres, either the rear-centre is too long for the short bike or it's too short for the long bike (or both).
Yes, the reason for not adjusting rear-centre in proportion to front-centre within a given model is due to cost. If riders really cared about this, they would flock to companies that vary the front- and rear-centre across the size range, such as Norco and YT, or small riders would all buy bikes with uncommonly short chainstays and tall riders would do the opposite. But they don't. A price difference of a few dollars, a minor component upgrade, or even fancy paint influence customers more than proportional chainstays - all of which cost less. So companies put their money into what sells.
Seems like the new, but conservative, geo isnt so bad...? I do get that a lot of this discussion is on the front ends on the...
Seems like the new, but conservative, geo isnt so bad...? I do get that a lot of this discussion is on the front ends on the bigger sizes, and not on the medium/large size bikes. I just got a Cube stereo 150 29 in a size large, and it was considered a "conservative" geo by mtb-media, but from what you guys are saying, it seems to be pretty spot on - with all your number crunching.
BTW. How do you knowledgeable forumers think that bar roll effect the rindingstyle/feel of geo, or weight distribution to the front end. I came from a 435 reach, 50mm stem with pretty normal roll, to a 457mm reach with 35mm stem. And now roll my bars a lot forward so that my grips pretty much align with the end of the stem. This works great, I feel I get the weight on the front wheel, but I do wonder if I should get a longer stem(50mm) and roll the bars more back. hm...Are there any advantages/dis to roll the bars forward?
For a given amount of change in cockpit length, bar roll and stem length are equivalent in terms of moving your mass around.
My hands have a narrow range of bar roll angles in which they're happy. If your hands are happy, feel free to use bar roll to adjust your position a few millimetres. If your hands would be happier with a different roll angle, set the bar at that angle and change your stem.
@R-M-R Surprised you didn't get offended at me for figuring that you were seemingly wanting something similar to JFL1200, with extremely long CS (460+mm) and more on the defensive (behind the BB by well over half a foot 160+mm) side of the positioning spectrum. If I get a e-mail notification saying JFL responded, I wouldn't be surprised if he tried to correct me. I think he said he wanted neutral handling, but with the CS #s he's giving out, I can't think of it any other way.
I urge people to look at the pics of people riding these bikes. Looking at how enduro-mtb covered the new Jeffsy 29 launch, I got the impression that it's still on the defensive spectrum of bikes, like the old one, judging by how "ass-backwards" they were in the side-perspective pics. They gave it a dose of forward geo, but it still isn't neutral. Their 27.5 bike in large is what I'd call neutral, and 29er in XL is what I'd call neutral. The RIP9 29er in L is aligned slightly defensive, based on my estimates, while the L RIP9 27.5 is neutral.
@jeff.brines Leave if the thread you started isn't to one's liking? What's going on?
Is this a personal issue with CS length we're discussing in this...
@jeff.brines Leave if the thread you started isn't to one's liking? What's going on?
Is this a personal issue with CS length we're discussing in this thread, or a fundamental issue with the state of bike geo design?
If you're inclined to claim leadership/ownership of this thread, can I not question your authority? Let's observe your habits:
- you are excusing yourself from responsibility that calls for you to act. When you preach claims, like Steve confirming your hypothesis 100%, and jump to conclusions like "I want something closer to 50/50 than I do 45/55", the burden on proof is on you to support these when they are questioned. You try to shift this burden of proof on others.
- you state a "hypothesis" then seemingly wait for someone in agreement to do math and research for you. Follow-up conclusions are seemingly made off of such "math" with limited understanding of it. When someone else questions the math, saying it doesn't scale to work on bikes with much shorter or much longer wheelbase, they have to prove it's wrong, and not the ones promoting it, and basing conclusions off of it?
- you call to focus attention on various topics, such as bikes that go fast, with increasing CS length being center of attention. You bring up sources to justify this, but development on these ideas always seem to stop short at mere generalizations. It's like this in skiing, automobile design, or Minnaar does this. Is this some appeal to authority? If authority matters, what if Steve@Vorsprung refines his belief, do you follow the man or their idea? What if someone else came up with the idea before, is it only worth believing if Steve, Minnaar, or some celeb repeats it?
- your deflection of criticism seems to promote tribalism, bringing up the question "are you with us, or against us". You expect others to join your bandwagon through agreement based on faith/intuition, using Vorsprung's adv geo video as a "brochure".
You say you'll prove this, as much as anyone else can prove it, but are you doing anything beyond making such an empty promise? Have you picked a specific claim/topic/conclusion to prove? Any timeline on this action?
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Yes, I do want proportional CS length according to FC or WB length. I see this as a fundamental issue in bike geo. If it's not what's being discussed here, and is instead about your personal issue with wanting CS to be longer, from a perspective you dictate, then I choose not to serve some seemingly wishy-washy guy with a sensitive ego. P.S. you can buy custom, such as through Starling Cycles or Atherton/Robot Bike Co.
Tribalism? Huh? You are typing a lot without saying much of anything besides calling out my character somehow? Yes, I made this thread, yes, I think if you read what I write I'm consistent with what I'm saying and utilizing objectiveness and rationality to back it up.
What is that point? For the bazillionth time I think longer bikes will be better for guys looking to go fast with rear centers that are more in proportion. That. That was my point.
I cited a few examples, though yes they are anecdotal.
I also cited a few other sports, though I guess this too is anecdotal.
This is how an idea works. It starts with "I wonder if..." then you fill in the blank with something you think might work. Maybe it does. Maybe it doesn't. Maybe it will kind of work and will need refinement. I believe I'm right, but I also believe it will take refinement to get to "perfect" (if such a thing remotely exists).
I don't know the ideal balance between front and back while I stand on a scale. I don't know the ideal length of rear center to front center (proportionally I mean). I don't know how body mechanics play into this perfectly. I do know we haven't really thought about this in mountain biking the way that road guys think about bike fit. I also know roadie style fit makes zero sense on a mountain bike. I do think there is a way to bring objectiveness to it all.
I also know that I'd like to experiment with this. I'm going to do so! I'll report back...well, maybe, not sure what my incentive is when I get called labeled for no reason besides trying to have some fun pushing bike design for the better!
Seems to me there’s little doubt that a balanced bike is faster for racing and long gnarly, fatiguing descents. The more interesting question for me is...
Seems to me there’s little doubt that a balanced bike is faster for racing and long gnarly, fatiguing descents. The more interesting question for me is for the non racer that wants to shred, slash turns, manual, but also ride flat turns fast and go fast generally, is a longer CS better and if so, how long. I’m 6’2” and only have short CS bikes (Demo, Process, DJ). The process (485 reach, 426 CS) is super fun. I was also just in Bellingham and rode an XL Patrol for a few days and it was rad and felt plenty stable in the steep gnar. Granted the longest descent was probably 6 - 10 mins.
Jeff, you’ve been clear your point is purely about racing and theoretically it makes sense to me. But wondering about us non racers who like to go fast but play too, are there trade offs and when do those happen. I wish i had the opportunity to try something good with longer CS to get a sense
There are downsides, which is why I kind of started this.
Lets go back in time before the era of long front centers. In those days, everyone was trying like hell to get the shortest chainstays possible on a bike. This actually made some sense for two reasons.
First, when you have a super short reach, super short chainstays actually matched pretty well. Second, and more importantly, it made everyone and their mom feel more Sam Hill meets Sam Blenkishop Blenkinsop on a bike. Its far easier to cutty. Its far easier to loft your front tire. Its far easier to "play" with the terrain with a compact rear end.
...all of a sudden all these intermediate level riders are doing things they never did before. And that felt fun.
So yeah, shorter chainstays do often equal "more fun". Its hard to deny that!
If your skills are higher, and strength higher, a longer rear center isn't too hard to deal with. But make no mistake about it, manualing is harder. Doing a cutty is a lot harder. The bike is just more locked in, for lack of a better word.
Ironically, back in the short chainstay, short front center era, I remember everyone trying like hell to slam their bike to the ground. Funny enough, longer bikes have a similar effect as lowering the bike, so its ironic to me we've solved this problem through different means.
Overall, a long FC with long RCs are not going to be popular as they'll be something only a few freaks (like myself) really want. Maybe slightly longer stays will become a thing, but to the point I'm thinking will have a drastic improvement on handling while racing, I doubt it. It will make the bike feel more planted, more neutral, and more...boring. Outside the race course it just won't be something a lot of dudes love. Kind of how a race ski is awesome between the gates but not so much fun...anywhere else. Maybe not that level of polarization, but I don't think these drastically longer rear ends will have the market, the same way a lot of go-fast gear kind of gets relegated to the freak show "bucket" of a sport.
Point 1: how much confidence do you have in your ideas and understandings? How about you put them to the test somehow, before jumping to conclusions.
Point 2: how about you view "contrarian" perspectives as there to not to hold you back, but to challenge you in accounting for them, while also accounting for your ideas?
Again dude, I started this thread, if you don't like it, go somewhere else, this isn't like a class where attendance is mandatory!
Snowmobiles, cars, dirt bikes all use scales to understand how weight is distributed throughout the vehicle. Mountain bikes are *very* interesting in that the pilot weighs more than the machine....like skis! Which (gasp) have different mount points for different size skis...and there is some wiggle room with said mount point depending on biomechanics, preference etc.
You are saying what I'm saying and not saying it all at the same time? I can't even follow what your point is. You want FC/RC to be proportional but "pros know best" and that video had bad math? Huh?
I will follow through and "prove" this, as much as anyone can prove fit. People still love driving cars with crappy weight distribution or skiing center mount skis in powder. Cool. Doesn't mean you can't do it. Just means there might be a better way.
Is this a personal issue with CS length we're discussing in this thread, or a fundamental issue with the state of bike geo design?
If you're inclined to claim leadership/ownership of this thread, can I not question your authority? Let's observe your habits:
- you are excusing yourself from responsibility that calls for you to act. When you preach claims, like Steve confirming your hypothesis 100%, and jump to conclusions like "I want something closer to 50/50 than I do 45/55", the burden on proof is on you to support these when they are questioned. You try to shift this burden of proof on others.
- you state a "hypothesis" then seemingly wait for someone in agreement to do math and research for you. Follow-up conclusions are seemingly made off of such "math" with limited understanding of it. When someone else questions the math, saying it doesn't scale to work on bikes with much shorter or much longer wheelbase, they have to prove it's wrong, and not the ones promoting it, and basing conclusions off of it?
- you call to focus attention on various topics, such as bikes that go fast, with increasing CS length being center of attention. You bring up sources to justify this, but development on these ideas always seem to stop short at mere generalizations. It's like this in skiing, automobile design, or Minnaar does this. Is this some appeal to authority? If authority matters, what if Steve@Vorsprung refines his belief, do you follow the man or their idea? What if someone else came up with the idea before, is it only worth believing if Steve, Minnaar, or some celeb repeats it?
- your deflection of criticism seems to promote tribalism, bringing up the question "are you with us, or against us". You expect others to join your bandwagon through agreement based on faith/intuition, using Vorsprung's adv geo video as a "brochure".
You say you'll prove this, as much as anyone else can prove it, but are you doing anything beyond making such an empty promise? Have you picked a specific claim/topic/conclusion to prove? Any timeline on this action?
---
Yes, I do want proportional CS length according to FC or WB length. I see this as a fundamental issue in bike geo. If it's not what's being discussed here, and is instead about your personal issue with wanting CS to be longer, from a perspective you dictate, then I choose not to serve some seemingly wishy-washy guy with a sensitive ego. P.S. you can buy custom, such as through Starling Cycles or Atherton/Robot Bike Co.
But if I were to overanalyze and scrutinize every single detail like ninjichor does on the various sites, I would not enjoy riding bikes as much. It's ok that they're not perfect. Go outside, get on your bike and ride!
On the topic of length adjustable dropouts I don't think sliding dropouts would work too well but you could do flip chip style dropouts and build in 20mm of adjustability with two sets of "chips" that could be reversed for positions 1,2,3,4. Rear brake mounting could be solved by moto style solution. Or just do like Norco and YT are doing and make size relevant rear ends. They need to take it a bit farther IMO but they are on the right track.
I bought a used Stumpjumper Evo in S3 size yesterday. 443mm cs to 475 reach 63.5 HA. Giddyup.
I had another thought last night while falling asleep.
Do longer cranks create a larger neutral zone when in attack position or do they mitigate it? Enduro bikes have gone from 175mm to 170 standard, Dh bikes seem to be on mostly 165-160mm. Now I realize this is mostly to prevent rock strikes but it's got affect weight balance as well. I'm thinking about trying to buy some 160 or 165mm cranks to play with, although it might hard to tease any significance out of the noise.
I bought 165mm cranks for my trail bike, but mostly as a fit issue (weird hips and seat tube was too long for a 150mm dropper) and secondarily for clearance.. I looked quite a bit into the 175 (stock length) vs 165 issue with regards to fit and power (since most studies are done on road bikes/athletes) and all I could find was that a) you can get a more aggressive position going shorter, b) power output doesn't change significantly, but c) cadence increases ( by about 5rpm, since it's a shorter lever). Most of what was being shown was statistically insignificant or had such a small effect as to really not be limiting (especially to a non-racer like me). I think there are such small differences here that any effects are likely to be insignificant unless you have a large sample size, and even then they probably don't have a big effect.
I don't ride MX, but those athletes seem fine with having their feet beside each other, although most of them don't have to handle World Cup Downhill terrain.
@Masjo Cadence increases with shorter crank, because it's a smaller circle, and therefore less movement to complete a revolution. The leverage misconception is due to how crank length ties in with the chainring size. Take a 32t chainring and 175mm crank for example. Switch to 165mm only, and the gearing effectively becomes higher--if you do the same RPM, you will go the same speed, but the perceived resistance/effort is increased. The shorter total movement per crank revolution offsets the overall effort to go the same speed as before though. If you downsize to 30t at the same time, the resistance is equivalent to 175 w/32t, but going the same RPM will be slower. Since the shorter cranks require less movement per, higher RPM is more natural, which has a comparable overall effort, and you end up going the same speed. In the research reports, they explain that the foot velocity doesn't change, despite a change in RPM. In engineering, the bike drivetrain is perceived as a series of levers, including the cranks and overall wheel diameter.
I see chainring size as a way to tune anti-squat. If I want to try increased anti-squat, and get more ground clearance at the same time, I downsize the chainring by 2t and can downsize the cranks too. There's some Trailcraft cranks that apparently have no weight limit that go down to 152 and shorter, weigh similarly to XTR, and cost $150 w/chainring.
Jeff, you’ve been clear your point is purely about racing and theoretically it makes sense to me. But wondering about us non racers who like to go fast but play too, are there trade offs and when do those happen. I wish i had the opportunity to try something good with longer CS to get a sense
The issue is that tall riders on short CS bikes are noticing that they have to actively weight the front end, when they've had bikes in the past that didn't require this. Newer bikes are getting even longer front ends, with longer reach and slacker HA, but the CS is not part of the marketing. The position that riders have adapted to, to make their past bikes feel balanced, is now being shifted forward. They recognize that more wheelbase helps bring stability and longer reach is a plus, but unless CS increases, it's a wash, since the lack of weight on the front results in the bike being squirrelly. If they feel that their position being even more forward is less comfortable, and requires more effort, then that means it's more demanding to ride, and this thread voices out that they think trade-off is too important to overlook.
Some may argue, isn't working hard the point of riding? Or isn't going faster more dangerous? I'd argue back that making things purposely harder is more against the point, especially when the challenge is mindless. It's like making riding braking bumps a challenge, by de-tuning your bike, and fooling yourself into thinking that's an achievement. The challenge added here is making the rider position out of their neutral position. It's like saying, here, ride with your handlebar shifted 2-3" more to the left, along with all the controls. You can adapt to it, but why? Going faster is some people's desire, and the high speed crashes are often no worse than the worst low speed crashes. Fracture your wrist, ankle, or collarbone falling off you bike at 5 mph, or get impaled by a handlebar or tree branch? Yea, that happens at 20 mph too, but you bounce, slide, spin, a bit afterwards, or make that tree flex a bit more since there's more energy still to transfer. It doesn't make your collarbone shatter beyond repair. If someone has a penchant for going fast, I'd give 'em a bike that's safer to ride, and perhaps the speed encourages them to wear protective gear that the slower riders are reluctant to use. I'd argue that's even safer...
The longer CS is merely to offset the longer front ends. Longer front ends are welcome for speed, but that's all for nothing if the CS are still short. The bikes might be getting praise, but what rides well in size M, doesn't necessarily ride well in XL. There's demand for shorter CS, and longer CS, which hints that the bike companies aren't getting things right. We're suggesting the answer is CS length being proportional to FC, and options where the CS is a bit longer or shorter than what works for the mainstream. Adapt the bike to the rider, so the demand for a rider to adapt to the bike is lower. Those who've been on many bikes, and have learned well from each bike, tend to be picky about what bike to choose. When one crosses almost every bike off their new-bike-list, you have to wonder if the mfgers have even learned...
Regarding what the trade-offs are... modern engineering is all about compromise, and what makes a modern design feel better, is making trade-offs in which the overall package feel so much better, that such trade-offs are acceptable. Trying to predict trade-offs is akin to asking someone to prejudge something. Something best off just test riding yourself. What's holding you back from trying? Fear that you'll like it? Or prejudice that fools you into be complacent, and not possibly waste your time learning something yourself first hand? Fear that all this goodness came with a very well hidden drawback, in which the frame explodes on a fireroad climb in under 2 years time?
For people who prioritize handling on extremely steep terrain, reduced weight on the front could be a good thing. For most people, it will require a change in body position, which may or may not be a bad thing. For me, the geometry of 10+ years ago forced me to hang off the back of the bike, so modern geometry allows me to stand in a neutral, relaxed position most of the time.
A flat, loose turn is the worst case scenario for a bike with an extremely long front and short rear, as this requires me to initiate a turn from a very forward stance, putting extra load on my puny arms. A partial solution is to use a front tire with a lot of traction and a rear with less.
In my opinion, steep seat tube angles and longer than traditional reaches are always good. Adding a slack head angle may be good for some, but not all. Longer chainstays are good for most, especially tall riders and when speed is the top priority, but not for everyone.
If you get chainstays that are too long, the front will tend to stay low off of jumps and drops. That transition, how did it feel on take offs? Did it fly naturally, nose not too high or too low? I think the Patrol in XL is on the rearward biased end of the spectrum, like your other bikes. A '19 YT Jeffsy 29 in XL is what I think would be a good experiment, to see if you'd like longer CS, and if it puts you in a more natural position for going fast, yet still meeting your desire to playful.
Another thing to consider: how much do we perceive the effect of a water bottle (or multiple bottles)? Do we notice the effect of the forward placement of a bottle on the new Guerrilla Gravity bikes or three bottles on a Pole? That probably makes more difference to weight distribution than a few millimetres of rear-centre. Water bottles, stem length, and a combination of head angle and fork offset (to maintain trail) could be ways to experiment with weight distribution without having to create custom chainstays.
My suspicion is that lots of different, unrelated qualities might result in someone using this word. A shorter wheelbase would make a bike more responsive to weight shifts, that could certainly make it "playful." Progressive suspension designs as well. A more balanced geometry that allows the rider sit neutrally would provide more opportunity to play with weight shifts without losing balance, and that could also be perceived as playful, even with the accompanying long(er) chainstays.
I own 2 Transitions, I love them, but they’re also the bikes that convinced me the long front/short rear fad has gone too far. And I only ride mediums.
Should easily notice this going from short travel/small wheels to longer travel/big wheels--the responsiveness and snappiness is not there. Feels like you don't have to go as fast on the smaller bike to reach your personal perception of hitting 90% of your max, in terms of reaction speed and staying in control; beyond "max" means going along for the ride and putting faith that your bike will handle things if you hold on (related to the saying that people's skill won't match the bike's capabilities). The long wheelbase would feel kind of like a cruise/tour on a limo if ridden at low speed, coming "alive" at higher speeds. People who don't have trails that give it speed, will feel like it's overkill, as they won't feel like their reaction speed and control is being challenged, and will strongly consider downsizing to a smaller bike.
It's not too unlike the middle seats of a roller coaster vs the front or back.
Go too long, without pushing the front wheel out to match, and the bike turns into a cruiser. It just forces you to plop your ass into a relaxed seated position and spin, and makes cornering and descending from a "defensive" rearward position behind the BB (hanging off the back) a viable technique. The trade off here is that using a more central standing position increases the risk of going OTB and nose diving when you try to go airborne. To adapt to jumps/drops, I've learned that you pretty much launch the bike well before your body follows, feet in front of your shoulders--some say pull back, I push the bike forward away from my body. The defensive position counters the OTB risk naturally. I've ridden plenty of these, being fairly short, and had a taste of what taller riders get from riding Kona-like aggro geo, and wanted more.
Some see these trade-offs as compromises (forced to adapt), while others see it as preferential (feels more natural). The defensive style is natural for some. The aggro style is natural for some. The neutral style is natural for some. You gotta find which you are. JFL1200 sounds like they fit well within the defensive side. R-M-R too maybe. I am looking for a mostly neutral bike. Allen sounds like they're on the aggro side, perhaps opening up to something more neutral after trying being impressed by a Patrol. Not sure what jeff's after but it definitely isn't aggro, probably more neutral-just slightly defensive, considering he liked the XL SB55. Maybe you're all of the above, and like aggro for stunting and style, defensive for aero tucking down a mountain slope at WC DH speeds, and neutral for riding unfamiliar trails (blind riding).
In my perfect world, people would choose bikes based on wheelbase length and suspension travel, according to what trails they ride and how they plan on riding it, finding that sweet spot of hitting 90% of your max, while still hitting the trail as fast as you believe is possible for mere mortals. The CS length will increase/decrease by 4-5mm for each 25mm of wheelbase change, if the bike model comes in different sizes. Brands will align themselves with 1 style: neutral, aggro, defensive, or anywhere in between. They'd further differentiate their product based on making engineering trade-offs such trading off aesthetics, water bottle mounts, future compatibility, patented technology/innovation, and versatility, low weight for performance, reliability, affordability, for maintenance-friendliness. Example: Pole Taival and Pole Stamina are what I consider to be neutrally aligned, having CS proportioned well, with different trade-offs. Stamina is high end engineering, while the Taival is what I see as a low cost test platform for perfecting geo to get the same neutral bias across the size range, made available to the public.
Also, in this perfect world, riders would do research to know better than to buy stuff that doesn't suit them, therefore driving demand for better bikes. When product managers don't get the feedback they want, sales to IBDs, since IBDs aren't buying up stuff people don't want, they gotta adapt or die. When I say riders, I mean the "media" too. Nice to see some are mechanical engineers (bturman?), but how is that qualification reflected in their reviews?
BTW. How do you knowledgeable forumers think that bar roll effect the rindingstyle/feel of geo, or weight distribution to the front end. I came from a 435 reach, 50mm stem with pretty normal roll, to a 457mm reach with 35mm stem. And now roll my bars a lot forward so that my grips pretty much align with the end of the stem. This works great, I feel I get the weight on the front wheel, but I do wonder if I should get a longer stem(50mm) and roll the bars more back. hm...Are there any advantages/dis to roll the bars forward?
The media doesn't have close to perfect knowledge. We're still piecing the bits together, cross-checking/peer-reviewing it here, to uncover more of the big picture. You just brought attention to some variable I never considered to be that big of an effect. Would like to answer, but since I don't have anything but speculation, I'll just say that it's worth keeping in mind, if it turns out to be a significant macro-issue. Some here think 10mm of CS length difference isn't a big deal, but I think it's huge, and therefore a macro-issue. The bar roll thing is just something I adapted to once set. I don't purposely put weight on the bar, only enough to guide it, and keep most of my weight on the pedals (heavy feet, light grip). I have it so my back isn't so far tilted forward, that it needs help from my arms to suspend its weight up.
When using relative terms, such as conservative, it depends on what they're comparing to. Maybe the reviewer has opened up to Pole, Geometron, Starling, etc. Others who say new school progressive geo, probably is comparing to the model that's being replaced. I could call them all of them conservative, if I think far enough forward. For example, when reach almost matches ETT, and STA is so steep, that your seated position is no different than your standing pedaling position, and the bikes are tuned for this single body CoG point, I think that's pretty much end game. This, coming from someone who has been riding bikes which seemingly were tuned for the seated position (73-74 STA), which hinders the bike from feeling naturally well balanced out-of-the-saddle; the deviation from a rearward seated CoG and a more forward standing CoG was revealing itself to be a clear compromise, forcing my standing position to shift my weight back, hovering well over half a foot (160+mm) behind the BB, which was roughly over the saddle, rather than using a more of a boxer's/fighter's stance. If I had my hips this far rearward on skiis, I'd be sliding down the hill on my ass. This end-game idea depends on finding what a person's neutral standing stance is, and designing around it, rather than making a bike based off other bikes and having the rider adapt to it. Just need to dispel prejudice, such as pedaling with a steep STA is less efficient (research says steeper, 80d, is more efficient), or fears that long wheelbase bikes can't do switchback turns (switchbacks not so much, but chicanes that you can't straight line above/over are a prob).
Yes, the reason for not adjusting rear-centre in proportion to front-centre within a given model is due to cost. If riders really cared about this, they would flock to companies that vary the front- and rear-centre across the size range, such as Norco and YT, or small riders would all buy bikes with uncommonly short chainstays and tall riders would do the opposite. But they don't. A price difference of a few dollars, a minor component upgrade, or even fancy paint influence customers more than proportional chainstays - all of which cost less. So companies put their money into what sells.
My hands have a narrow range of bar roll angles in which they're happy. If your hands are happy, feel free to use bar roll to adjust your position a few millimetres. If your hands would be happier with a different roll angle, set the bar at that angle and change your stem.
I urge people to look at the pics of people riding these bikes. Looking at how enduro-mtb covered the new Jeffsy 29 launch, I got the impression that it's still on the defensive spectrum of bikes, like the old one, judging by how "ass-backwards" they were in the side-perspective pics. They gave it a dose of forward geo, but it still isn't neutral. Their 27.5 bike in large is what I'd call neutral, and 29er in XL is what I'd call neutral. The RIP9 29er in L is aligned slightly defensive, based on my estimates, while the L RIP9 27.5 is neutral.
Racer or no? What level? Engineer? What kind?
What is that point? For the bazillionth time I think longer bikes will be better for guys looking to go fast with rear centers that are more in proportion. That. That was my point.
I cited a few examples, though yes they are anecdotal.
I also cited a few other sports, though I guess this too is anecdotal.
This is how an idea works. It starts with "I wonder if..." then you fill in the blank with something you think might work. Maybe it does. Maybe it doesn't. Maybe it will kind of work and will need refinement. I believe I'm right, but I also believe it will take refinement to get to "perfect" (if such a thing remotely exists).
I don't know the ideal balance between front and back while I stand on a scale. I don't know the ideal length of rear center to front center (proportionally I mean). I don't know how body mechanics play into this perfectly. I do know we haven't really thought about this in mountain biking the way that road guys think about bike fit. I also know roadie style fit makes zero sense on a mountain bike. I do think there is a way to bring objectiveness to it all.
I also know that I'd like to experiment with this. I'm going to do so! I'll report back...well, maybe, not sure what my incentive is when I get called labeled for no reason besides trying to have some fun pushing bike design for the better!
Lets go back in time before the era of long front centers. In those days, everyone was trying like hell to get the shortest chainstays possible on a bike. This actually made some sense for two reasons.
First, when you have a super short reach, super short chainstays actually matched pretty well. Second, and more importantly, it made everyone and their mom feel more Sam Hill meets Sam Blenkishop Blenkinsop on a bike. Its far easier to cutty. Its far easier to loft your front tire. Its far easier to "play" with the terrain with a compact rear end.
...all of a sudden all these intermediate level riders are doing things they never did before. And that felt fun.
So yeah, shorter chainstays do often equal "more fun". Its hard to deny that!
If your skills are higher, and strength higher, a longer rear center isn't too hard to deal with. But make no mistake about it, manualing is harder. Doing a cutty is a lot harder. The bike is just more locked in, for lack of a better word.
Ironically, back in the short chainstay, short front center era, I remember everyone trying like hell to slam their bike to the ground. Funny enough, longer bikes have a similar effect as lowering the bike, so its ironic to me we've solved this problem through different means.
Overall, a long FC with long RCs are not going to be popular as they'll be something only a few freaks (like myself) really want. Maybe slightly longer stays will become a thing, but to the point I'm thinking will have a drastic improvement on handling while racing, I doubt it. It will make the bike feel more planted, more neutral, and more...boring. Outside the race course it just won't be something a lot of dudes love. Kind of how a race ski is awesome between the gates but not so much fun...anywhere else. Maybe not that level of polarization, but I don't think these drastically longer rear ends will have the market, the same way a lot of go-fast gear kind of gets relegated to the freak show "bucket" of a sport.
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