Longer reached bikes have a longer wheelbase... (obvz)... As a taller rider (2m), I found 530mm reach was so good on the S6 Stumpy Evo. I really liked the position for climbing and both wide open speed and trails. The problem was the wheelbase not fitting the trails I ride most often. So I went to S5 and love how much more nimble it is. My $0.02 from this side of the bell curve
If you put spacers under the stem it physically reduces the reach, for every 3mm of stem height spacer you add, you reduce the reach by approximately 1mm.
Also by increasing bar height, it has the same affect on body position as reducing the reach, the natural dynamic centre of gravity a rider distributes the weight will remain constant between bikes, but the rider position will adjust to suit this. I.e. if a reach is too long the rider will feel really stretched trying to get the balance of weight over the front with too much hip hinge. If the reach is too short the rider sits much further back on the bike in a more cramped position.
Generally if the reach is shorter I run the stem slammed to the forks, then on my longer reach bike I have either higher rise bars or couple of stem spacers until I feel confident & in a comfortable position loading the front up on steep trails.
No..
If you put spacers under the stem it physically reduces the reach, for every 3mm of stem height spacer you add, you reduce the reach...
No..
If you put spacers under the stem it physically reduces the reach, for every 3mm of stem height spacer you add, you reduce the reach by approximately 1mm.
Also by increasing bar height, it has the same affect on body position as reducing the reach, the natural dynamic centre of gravity a rider distributes the weight will remain constant between bikes, but the rider position will adjust to suit this. I.e. if a reach is too long the rider will feel really stretched trying to get the balance of weight over the front with too much hip hinge. If the reach is too short the rider sits much further back on the bike in a more cramped position.
Generally if the reach is shorter I run the stem slammed to the forks, then on my longer reach bike I have either higher rise bars or couple of stem spacers until I feel confident & in a comfortable position loading the front up on steep trails.
I dont think its a feel of wanting to shorten the reach, or even the intended action. More about raising the bar, going more than 35/40mm rise looks weird so alot run spacers to make up for it.
Curious, My Ebike has a really large headtube(no spacers) & one of my other bikes has a very short head tube with spacers(145ish vs 105), both have the same bar height... Can you guess which has more reach?
The Problem lies in this weird headtube trend, see the fuel Ex gen 6 for example, Long reach but a tiny ass headtube... if it had a proper size headtube, you wouldnt run spacers to 'shorten the reach' as per your explanation but infact you are just raising the bar to normal height and now theres a heap of spacers(which yes does shorten the reach) which also covers my point aswell.
My Merida has a short headtube so i have to run spacers to get the bar height up. yes the reach is long but if i bought the smaller size Id have even more spacers and Even shorter reach, if the Large had a bigger headtube the reach would be shorter by default.
No..
If you put spacers under the stem it physically reduces the reach, for every 3mm of stem height spacer you add, you reduce the reach...
No..
If you put spacers under the stem it physically reduces the reach, for every 3mm of stem height spacer you add, you reduce the reach by approximately 1mm.
Also by increasing bar height, it has the same affect on body position as reducing the reach, the natural dynamic centre of gravity a rider distributes the weight will remain constant between bikes, but the rider position will adjust to suit this. I.e. if a reach is too long the rider will feel really stretched trying to get the balance of weight over the front with too much hip hinge. If the reach is too short the rider sits much further back on the bike in a more cramped position.
Generally if the reach is shorter I run the stem slammed to the forks, then on my longer reach bike I have either higher rise bars or couple of stem spacers until I feel confident & in a comfortable position loading the front up on steep trails.
No. Sometimes adding spacers under the stem is done to raise the bars. Yes it affects the reach. But that is a side effect to the original need/reason.
Source: I have many spacers under my stem. To raise the bars. Because 55 mm rise bars with 12deg backsweep make me a praying mantis. And shorten the effective reach even more. Until I get some 55+ mm rise bars with 8deg backsweep I'll be running the spacers. And yes, I fully get what you are trying to say. I ran a 70 mm stem with the 55mm rise bars to get the grips forwards enough (due to the backsweep), but I can assure you I am NOT running the spacers to lower the reach value. I achieved that by buying a size smaller frame compared to the old one.
No..
If you put spacers under the stem it physically reduces the reach, for every 3mm of stem height spacer you add, you reduce the reach...
No..
If you put spacers under the stem it physically reduces the reach, for every 3mm of stem height spacer you add, you reduce the reach by approximately 1mm.
Also by increasing bar height, it has the same affect on body position as reducing the reach, the natural dynamic centre of gravity a rider distributes the weight will remain constant between bikes, but the rider position will adjust to suit this. I.e. if a reach is too long the rider will feel really stretched trying to get the balance of weight over the front with too much hip hinge. If the reach is too short the rider sits much further back on the bike in a more cramped position.
Generally if the reach is shorter I run the stem slammed to the forks, then on my longer reach bike I have either higher rise bars or couple of stem spacers until I feel confident & in a comfortable position loading the front up on steep trails.
I dont think its a feel of wanting to shorten the reach, or even the intended action. More about raising the bar, going more than 35/40mm...
I dont think its a feel of wanting to shorten the reach, or even the intended action. More about raising the bar, going more than 35/40mm rise looks weird so alot run spacers to make up for it.
Curious, My Ebike has a really large headtube(no spacers) & one of my other bikes has a very short head tube with spacers(145ish vs 105), both have the same bar height... Can you guess which has more reach?
The Problem lies in this weird headtube trend, see the fuel Ex gen 6 for example, Long reach but a tiny ass headtube... if it had a proper size headtube, you wouldnt run spacers to 'shorten the reach' as per your explanation but infact you are just raising the bar to normal height and now theres a heap of spacers(which yes does shorten the reach) which also covers my point aswell.
My Merida has a short headtube so i have to run spacers to get the bar height up. yes the reach is long but if i bought the smaller size Id have even more spacers and Even shorter reach, if the Large had a bigger headtube the reach would be shorter by default.
What is the correct design philosophy?
Note: all based on size large/long
Your kind of missing my point, shortening the reach, adding stem spacers or higher bars all have similar affect on the riders body position and have same affect. It's about finding a comfortable body position to enable correct weight distribution/centre of gravity.
Your headtubes notes. I suspect headtubes got shorter when 29" wheels came along to prevent too much of a height increase. Pretty sure bike companies measure reach to top of headtubes, but you could have 2 bikes with same reach value but to get them to feel right you would have different bar height or spacers because other things affect the weight distribution balance, such as chain stays length, bar width, head angle, bb height etc.
I still think reach sizing needs to grow on bikes, I'm just below average height and ride large bikes, my large trek rail is a bit too small for me but my transition patrol feels bang on. But as average height I should be fitting a medium really, maybe I have long arms or a long torso.
No..
If you put spacers under the stem it physically reduces the reach, for every 3mm of stem height spacer you add, you reduce the reach...
No..
If you put spacers under the stem it physically reduces the reach, for every 3mm of stem height spacer you add, you reduce the reach by approximately 1mm.
Also by increasing bar height, it has the same affect on body position as reducing the reach, the natural dynamic centre of gravity a rider distributes the weight will remain constant between bikes, but the rider position will adjust to suit this. I.e. if a reach is too long the rider will feel really stretched trying to get the balance of weight over the front with too much hip hinge. If the reach is too short the rider sits much further back on the bike in a more cramped position.
Generally if the reach is shorter I run the stem slammed to the forks, then on my longer reach bike I have either higher rise bars or couple of stem spacers until I feel confident & in a comfortable position loading the front up on steep trails.
No. Sometimes adding spacers under the stem is done to raise the bars. Yes it affects the reach. But that is a side effect to the...
No. Sometimes adding spacers under the stem is done to raise the bars. Yes it affects the reach. But that is a side effect to the original need/reason.
Source: I have many spacers under my stem. To raise the bars. Because 55 mm rise bars with 12deg backsweep make me a praying mantis. And shorten the effective reach even more. Until I get some 55+ mm rise bars with 8deg backsweep I'll be running the spacers. And yes, I fully get what you are trying to say. I ran a 70 mm stem with the 55mm rise bars to get the grips forwards enough (due to the backsweep), but I can assure you I am NOT running the spacers to lower the reach value. I achieved that by buying a size smaller frame compared to the old one.
If you were to look side on at a riders position
reducing reach on a top tube or raising the front up with stem spacers would both have the similar affect.
Ok higher front end also gives a bit of otb security.
So sit on a seat (currently on toilet lol) and you can visualise it
You have 2 main adjustable hinge points shoulders and hips. There'll be an optimum angle for both. With Higher bars you could just adjust the shoulder angle but it still has same affect on weight distribution moving the rider mass backwards. But to be honest not sure if my previous logic was right I used to lift the front up when I go to Alps, I think now probably made no difference to weight on my arms, maybe on cruising sections...
Look, I get it. I get it all. The point is that a lot of us adding spacers under the stem do it to raise the bars, not to shorten the reach. And I raised the bars to be more upright as previously it was like I was on all fours over the bike. Now I'm in an active position. Shortening the reach helps with that too, but the feeling of being upright with hands in the right position (high enough) is just comfortable. Which gives confidence. Which, at the end of the day, is the most important metric.
Like I said, I added spacers to be able to ride a 35 mm rise bar. Once I get a 55 mm rise bar (or more) with 8deg backsweep, I'll be removing some spacers. The 12deg bar I had with a 70 mm stem and fewer spacers put the grips in about the same position I have now. So adding spacers TECHNICALLY (including a change of bars) increased my effective reach (as I originally ran a 50 mm stem in my current bike with the 55 mm bar).
Look, I get it. I get it all. The point is that a lot of us adding spacers under the stem do it to raise the...
Look, I get it. I get it all. The point is that a lot of us adding spacers under the stem do it to raise the bars, not to shorten the reach. And I raised the bars to be more upright as previously it was like I was on all fours over the bike. Now I'm in an active position. Shortening the reach helps with that too, but the feeling of being upright with hands in the right position (high enough) is just comfortable. Which gives confidence. Which, at the end of the day, is the most important metric.
Like I said, I added spacers to be able to ride a 35 mm rise bar. Once I get a 55 mm rise bar (or more) with 8deg backsweep, I'll be removing some spacers. The 12deg bar I had with a 70 mm stem and fewer spacers put the grips in about the same position I have now. So adding spacers TECHNICALLY (including a change of bars) increased my effective reach (as I originally ran a 50 mm stem in my current bike with the 55 mm bar).
You lost me at 70mm stem
It's all interesting though and your right it's all about getting the comfortable position that inspires confidence.
I just built up a new rig, I've gone from 27.5 to 29er, both got 35mm stems.
I know I had the reach dialled on my last bike because I did quite a few experiments with different bar heights and spacers. So I wanted to replicate this feeling from my last bike. Even tho I'm running much lower bars 40mm rise Vs 19mm. What I did was measure from the bb centre to end of my bar and copied that over. It looks really low with just a 5mm spacer under stem but Just tested the bike out on my local trails and it felt bang on. Happy days.
Longer reached bikes have a longer wheelbase... (obvz)... As a taller rider (2m), I found 530mm reach was so good on the S6 Stumpy Evo. I...
Longer reached bikes have a longer wheelbase... (obvz)... As a taller rider (2m), I found 530mm reach was so good on the S6 Stumpy Evo. I really liked the position for climbing and both wide open speed and trails. The problem was the wheelbase not fitting the trails I ride most often. So I went to S5 and love how much more nimble it is. My $0.02 from this side of the bell curve
Same with me. I'm just shy of 2m and I went to an XL Geometron G1 with 535mm reach and a 79' ESTA. It was incredible to have a bike fit well finally. But it was just too long. A 1350 wheelbase is monstrous. It doesn't fit berm arcs and some climbing switchbacks are barely possible.
Last year I switched to an XXL Megatower which is a little less extreme by every measure but is a much more versatile bike. I prefer the 520 reach over 535 and the 2cm less wheelbase remains proportional yet can happily fit all berms and switchbacks. It's also lighter and prettier and I like the suspension better. It was a nice privilege to finally have a bike that was too much so I could move to a bike that was just right. That's not something 2m tall people could do previously. It's nice that there are more options.
Longer reached bikes have a longer wheelbase... (obvz)... As a taller rider (2m), I found 530mm reach was so good on the S6 Stumpy Evo. I...
Longer reached bikes have a longer wheelbase... (obvz)... As a taller rider (2m), I found 530mm reach was so good on the S6 Stumpy Evo. I really liked the position for climbing and both wide open speed and trails. The problem was the wheelbase not fitting the trails I ride most often. So I went to S5 and love how much more nimble it is. My $0.02 from this side of the bell curve
Same with me. I'm just shy of 2m and I went to an XL Geometron G1 with 535mm reach and a 79' ESTA. It was incredible...
Same with me. I'm just shy of 2m and I went to an XL Geometron G1 with 535mm reach and a 79' ESTA. It was incredible to have a bike fit well finally. But it was just too long. A 1350 wheelbase is monstrous. It doesn't fit berm arcs and some climbing switchbacks are barely possible.
Last year I switched to an XXL Megatower which is a little less extreme by every measure but is a much more versatile bike. I prefer the 520 reach over 535 and the 2cm less wheelbase remains proportional yet can happily fit all berms and switchbacks. It's also lighter and prettier and I like the suspension better. It was a nice privilege to finally have a bike that was too much so I could move to a bike that was just right. That's not something 2m tall people could do previously. It's nice that there are more options.
That's interesting, I ride with the guys at Geometron, that's where my theory came from, usually when I see people on Geometrons they have a load of spacers stacked under the stem which got me thinking. But they also gave me the idea of measuring from bb to handle bars.
TBF to them they were the originators of extending the reach and slackening out the head angle.
Seems inadequate sometimes there's only 20mm difference between sizes.
Measuring BB to handlebar (grip) length is just RAD... Add the angle of the line to the horizontal and you have RAAD. Arguably the better cockpit measurement as it takes spacer, stem and handlebar stack and reach into account as well. Hence my 70 mm stem.
when I see people on bikes that have a load of spacers stacked under the stem it makes me think......Dak. No, it makes me think......shopping bike. NO,it makes me thing bike companies don't scale stack measurements proportionally to reach to account for the increase in rider height (SC are ok).
No..
If you put spacers under the stem it physically reduces the reach, for every 3mm of stem height spacer you add, you reduce the reach...
No..
If you put spacers under the stem it physically reduces the reach, for every 3mm of stem height spacer you add, you reduce the reach by approximately 1mm.
Also by increasing bar height, it has the same affect on body position as reducing the reach, the natural dynamic centre of gravity a rider distributes the weight will remain constant between bikes, but the rider position will adjust to suit this. I.e. if a reach is too long the rider will feel really stretched trying to get the balance of weight over the front with too much hip hinge. If the reach is too short the rider sits much further back on the bike in a more cramped position.
Generally if the reach is shorter I run the stem slammed to the forks, then on my longer reach bike I have either higher rise bars or couple of stem spacers until I feel confident & in a comfortable position loading the front up on steep trails.
Well, what that means in reality? Most fork manufacturers state 30mm od stem spacers max, which means you are shortening reach by approx. 10mm according to your math. Which in turn is 2% change on 500mm reach bike. Is that significant change?
No..
If you put spacers under the stem it physically reduces the reach, for every 3mm of stem height spacer you add, you reduce the reach...
No..
If you put spacers under the stem it physically reduces the reach, for every 3mm of stem height spacer you add, you reduce the reach by approximately 1mm.
Also by increasing bar height, it has the same affect on body position as reducing the reach, the natural dynamic centre of gravity a rider distributes the weight will remain constant between bikes, but the rider position will adjust to suit this. I.e. if a reach is too long the rider will feel really stretched trying to get the balance of weight over the front with too much hip hinge. If the reach is too short the rider sits much further back on the bike in a more cramped position.
Generally if the reach is shorter I run the stem slammed to the forks, then on my longer reach bike I have either higher rise bars or couple of stem spacers until I feel confident & in a comfortable position loading the front up on steep trails.
Well, what that means in reality? Most fork manufacturers state 30mm od stem spacers max, which means you are shortening reach by approx. 10mm according to...
Well, what that means in reality? Most fork manufacturers state 30mm od stem spacers max, which means you are shortening reach by approx. 10mm according to your math. Which in turn is 2% change on 500mm reach bike. Is that significant change?
My maths wasn't great, a 45 degree head angle would be a 1:1 up Vs back
Therefore on a 67.5 ° head angle for every 2mm of spacer would be 1mm reach reduction, a slacker head angle would obviously be a bit more back, a bit of trig or just applying a ratio could work it out based on a specific head angle.
So if you had 30mm of stem spacers that's 15-18mm reduction in reach which isn't far off the difference between a large and a medium. I would say that's significant but thinking about it also makes sense to get a bike that's a bit too long and reduce it which you can't do if it's too small... love to contradict myself haha
My maths wasn't great, a 45 degree head angle would be a 1:1 up Vs back
Therefore on a 67.5 ° head angle for every 2mm...
My maths wasn't great, a 45 degree head angle would be a 1:1 up Vs back
Therefore on a 67.5 ° head angle for every 2mm of spacer would be 1mm reach reduction, a slacker head angle would obviously be a bit more back, a bit of trig or just applying a ratio could work it out based on a specific head angle.
So if you had 30mm of stem spacers that's 15-18mm reduction in reach which isn't far off the difference between a large and a medium. I would say that's significant but thinking about it also makes sense to get a bike that's a bit too long and reduce it which you can't do if it's too small... love to contradict myself haha
You can always play with Muha bike geo calculator to get precise numbers...
My maths wasn't great, a 45 degree head angle would be a 1:1 up Vs back
Therefore on a 67.5 ° head angle for every 2mm...
My maths wasn't great, a 45 degree head angle would be a 1:1 up Vs back
Therefore on a 67.5 ° head angle for every 2mm of spacer would be 1mm reach reduction, a slacker head angle would obviously be a bit more back, a bit of trig or just applying a ratio could work it out based on a specific head angle.
So if you had 30mm of stem spacers that's 15-18mm reduction in reach which isn't far off the difference between a large and a medium. I would say that's significant but thinking about it also makes sense to get a bike that's a bit too long and reduce it which you can't do if it's too small... love to contradict myself haha
You can always play with Muha bike geo calculator to get precise numbers...
I'm not sure numbers really matter, it's how it feels that matters but with that said I've made changes in the past which felt uncomfortable at first then stuck with them a bit longer to get used to it then seems really beneficial, especially moving from a medium to a large frame, I remember I didn't like it at 1st then got adjusted to it and I'm sure I ride better on it now.
Longer reached bikes have a longer wheelbase... (obvz)... As a taller rider (2m), I found 530mm reach was so good on the S6 Stumpy Evo. I...
Longer reached bikes have a longer wheelbase... (obvz)... As a taller rider (2m), I found 530mm reach was so good on the S6 Stumpy Evo. I really liked the position for climbing and both wide open speed and trails. The problem was the wheelbase not fitting the trails I ride most often. So I went to S5 and love how much more nimble it is. My $0.02 from this side of the bell curve
Same with me. I'm just shy of 2m and I went to an XL Geometron G1 with 535mm reach and a 79' ESTA. It was incredible...
Same with me. I'm just shy of 2m and I went to an XL Geometron G1 with 535mm reach and a 79' ESTA. It was incredible to have a bike fit well finally. But it was just too long. A 1350 wheelbase is monstrous. It doesn't fit berm arcs and some climbing switchbacks are barely possible.
Last year I switched to an XXL Megatower which is a little less extreme by every measure but is a much more versatile bike. I prefer the 520 reach over 535 and the 2cm less wheelbase remains proportional yet can happily fit all berms and switchbacks. It's also lighter and prettier and I like the suspension better. It was a nice privilege to finally have a bike that was too much so I could move to a bike that was just right. That's not something 2m tall people could do previously. It's nice that there are more options.
I have a L geometron with 520mm of reach but since I run the longest chainstay mutators, a DH shock and a DH fork my wheelbase currently sits at: 1352mm. I haven't felt it was too long for any corner especially berms. I find that if you lean the bike enough the backend drifts enough for you to make any corner. Slow speed hairpins can be done by nose turns.
I use this tool all the time to calculate the impact of swapping stems and spacers on stack and reach, for mountain bikes and road bikes. Super helpful: http://yojimg.net/bike/web_tools/stem.php
Longer reached bikes have a longer wheelbase... (obvz)... As a taller rider (2m), I found 530mm reach was so good on the S6 Stumpy Evo. I...
Longer reached bikes have a longer wheelbase... (obvz)... As a taller rider (2m), I found 530mm reach was so good on the S6 Stumpy Evo. I really liked the position for climbing and both wide open speed and trails. The problem was the wheelbase not fitting the trails I ride most often. So I went to S5 and love how much more nimble it is. My $0.02 from this side of the bell curve
Same with me. I'm just shy of 2m and I went to an XL Geometron G1 with 535mm reach and a 79' ESTA. It was incredible...
Same with me. I'm just shy of 2m and I went to an XL Geometron G1 with 535mm reach and a 79' ESTA. It was incredible to have a bike fit well finally. But it was just too long. A 1350 wheelbase is monstrous. It doesn't fit berm arcs and some climbing switchbacks are barely possible.
Last year I switched to an XXL Megatower which is a little less extreme by every measure but is a much more versatile bike. I prefer the 520 reach over 535 and the 2cm less wheelbase remains proportional yet can happily fit all berms and switchbacks. It's also lighter and prettier and I like the suspension better. It was a nice privilege to finally have a bike that was too much so I could move to a bike that was just right. That's not something 2m tall people could do previously. It's nice that there are more options.
I have a L geometron with 520mm of reach but since I run the longest chainstay mutators, a DH shock and a DH fork my wheelbase...
I have a L geometron with 520mm of reach but since I run the longest chainstay mutators, a DH shock and a DH fork my wheelbase currently sits at: 1352mm. I haven't felt it was too long for any corner especially berms. I find that if you lean the bike enough the backend drifts enough for you to make any corner. Slow speed hairpins can be done by nose turns.
That's entirely location-dependent. I never encountered a corner I couldn't make. Some tight double switchbacks had to be done exactly one way or the bike wouldn't fit. All berms can be ridden. All of these same features are easier and more fun to ride on my current bike with a 1330 wheelbase with no appreciable loss in stability. If anything it's remarkable that a 2cm difference in wheelbase can make such a big difference. Would I ever go back to 1350+? Absolutely not.
I use this tool all the time to calculate the impact of swapping stems and spacers on stack and reach, for mountain bikes and road bikes...
I use this tool all the time to calculate the impact of swapping stems and spacers on stack and reach, for mountain bikes and road bikes. Super helpful: http://yojimg.net/bike/web_tools/stem.php
Honestly does it even matter? Reach on it self as with all those rad and raad and whatever are useless metrics that can be modified in so many ways that as long the wheelbase is correct don't really matter. Like you can have two bikes with same reach and a 5cm of difference in wheelbase. And the same is possible in the opposite way. And guess which two bikes will ride more simmilarily?
Like seriously, once you figure out which length of bike and head tube angle you prefer, it makes choosing next bike much easier. The ony other metric that I would give a bit of tought is front/rear center ratio if you are on the extremes of sizing and that is it. Once you figure that out, everything else can be adjusted to preference with cockpit setup.
Or it's a sign of the stack being too low or handlebars with enough rise and not too much backsweep not being available...
Longer reached bikes have a longer wheelbase... (obvz)... As a taller rider (2m), I found 530mm reach was so good on the S6 Stumpy Evo. I really liked the position for climbing and both wide open speed and trails. The problem was the wheelbase not fitting the trails I ride most often. So I went to S5 and love how much more nimble it is. My $0.02 from this side of the bell curve
No, it often tells you the headtube is too short.
No..
If you put spacers under the stem it physically reduces the reach, for every 3mm of stem height spacer you add, you reduce the reach by approximately 1mm.
Also by increasing bar height, it has the same affect on body position as reducing the reach, the natural dynamic centre of gravity a rider distributes the weight will remain constant between bikes, but the rider position will adjust to suit this. I.e. if a reach is too long the rider will feel really stretched trying to get the balance of weight over the front with too much hip hinge. If the reach is too short the rider sits much further back on the bike in a more cramped position.
Generally if the reach is shorter I run the stem slammed to the forks, then on my longer reach bike I have either higher rise bars or couple of stem spacers until I feel confident & in a comfortable position loading the front up on steep trails.
I dont think its a feel of wanting to shorten the reach, or even the intended action. More about raising the bar, going more than 35/40mm rise looks weird so alot run spacers to make up for it.
Curious, My Ebike has a really large headtube(no spacers) & one of my other bikes has a very short head tube with spacers(145ish vs 105), both have the same bar height... Can you guess which has more reach?
The Problem lies in this weird headtube trend, see the fuel Ex gen 6 for example, Long reach but a tiny ass headtube... if it had a proper size headtube, you wouldnt run spacers to 'shorten the reach' as per your explanation but infact you are just raising the bar to normal height and now theres a heap of spacers(which yes does shorten the reach) which also covers my point aswell.
My Merida has a short headtube so i have to run spacers to get the bar height up. yes the reach is long but if i bought the smaller size Id have even more spacers and Even shorter reach, if the Large had a bigger headtube the reach would be shorter by default.
What is the correct design philosophy?
Note: all based on size large/long
No. Sometimes adding spacers under the stem is done to raise the bars. Yes it affects the reach. But that is a side effect to the original need/reason.
Source: I have many spacers under my stem. To raise the bars. Because 55 mm rise bars with 12deg backsweep make me a praying mantis. And shorten the effective reach even more. Until I get some 55+ mm rise bars with 8deg backsweep I'll be running the spacers. And yes, I fully get what you are trying to say. I ran a 70 mm stem with the 55mm rise bars to get the grips forwards enough (due to the backsweep), but I can assure you I am NOT running the spacers to lower the reach value. I achieved that by buying a size smaller frame compared to the old one.
Your kind of missing my point, shortening the reach, adding stem spacers or higher bars all have similar affect on the riders body position and have same affect. It's about finding a comfortable body position to enable correct weight distribution/centre of gravity.
Your headtubes notes. I suspect headtubes got shorter when 29" wheels came along to prevent too much of a height increase. Pretty sure bike companies measure reach to top of headtubes, but you could have 2 bikes with same reach value but to get them to feel right you would have different bar height or spacers because other things affect the weight distribution balance, such as chain stays length, bar width, head angle, bb height etc.
I still think reach sizing needs to grow on bikes, I'm just below average height and ride large bikes, my large trek rail is a bit too small for me but my transition patrol feels bang on. But as average height I should be fitting a medium really, maybe I have long arms or a long torso.
If you were to look side on at a riders position
reducing reach on a top tube or raising the front up with stem spacers would both have the similar affect.
Ok higher front end also gives a bit of otb security.
So sit on a seat (currently on toilet lol) and you can visualise it
You have 2 main adjustable hinge points shoulders and hips. There'll be an optimum angle for both. With Higher bars you could just adjust the shoulder angle but it still has same affect on weight distribution moving the rider mass backwards. But to be honest not sure if my previous logic was right I used to lift the front up when I go to Alps, I think now probably made no difference to weight on my arms, maybe on cruising sections...
Look, I get it. I get it all. The point is that a lot of us adding spacers under the stem do it to raise the bars, not to shorten the reach. And I raised the bars to be more upright as previously it was like I was on all fours over the bike. Now I'm in an active position. Shortening the reach helps with that too, but the feeling of being upright with hands in the right position (high enough) is just comfortable. Which gives confidence. Which, at the end of the day, is the most important metric.
Like I said, I added spacers to be able to ride a 35 mm rise bar. Once I get a 55 mm rise bar (or more) with 8deg backsweep, I'll be removing some spacers. The 12deg bar I had with a 70 mm stem and fewer spacers put the grips in about the same position I have now. So adding spacers TECHNICALLY (including a change of bars) increased my effective reach (as I originally ran a 50 mm stem in my current bike with the 55 mm bar).
You lost me at 70mm stem
It's all interesting though and your right it's all about getting the comfortable position that inspires confidence.
I just built up a new rig, I've gone from 27.5 to 29er, both got 35mm stems.
I know I had the reach dialled on my last bike because I did quite a few experiments with different bar heights and spacers. So I wanted to replicate this feeling from my last bike. Even tho I'm running much lower bars 40mm rise Vs 19mm. What I did was measure from the bb centre to end of my bar and copied that over. It looks really low with just a 5mm spacer under stem but Just tested the bike out on my local trails and it felt bang on. Happy days.
Why exactly did I lose you?
Same with me. I'm just shy of 2m and I went to an XL Geometron G1 with 535mm reach and a 79' ESTA. It was incredible to have a bike fit well finally. But it was just too long. A 1350 wheelbase is monstrous. It doesn't fit berm arcs and some climbing switchbacks are barely possible.
Last year I switched to an XXL Megatower which is a little less extreme by every measure but is a much more versatile bike. I prefer the 520 reach over 535 and the 2cm less wheelbase remains proportional yet can happily fit all berms and switchbacks. It's also lighter and prettier and I like the suspension better. It was a nice privilege to finally have a bike that was too much so I could move to a bike that was just right. That's not something 2m tall people could do previously. It's nice that there are more options.
That's interesting, I ride with the guys at Geometron, that's where my theory came from, usually when I see people on Geometrons they have a load of spacers stacked under the stem which got me thinking. But they also gave me the idea of measuring from bb to handle bars.
TBF to them they were the originators of extending the reach and slackening out the head angle.
Seems inadequate sometimes there's only 20mm difference between sizes.
You'd almost think that reach was a personal/individual Thing.............................................
Measuring BB to handlebar (grip) length is just RAD... Add the angle of the line to the horizontal and you have RAAD. Arguably the better cockpit measurement as it takes spacer, stem and handlebar stack and reach into account as well. Hence my 70 mm stem.
when I see people on bikes that have a load of spacers stacked under the stem it makes me think......Dak. No, it makes me think......shopping bike. NO,it makes me thing bike companies don't scale stack measurements proportionally to reach to account for the increase in rider height (SC are ok).
Well, what that means in reality? Most fork manufacturers state 30mm od stem spacers max, which means you are shortening reach by approx. 10mm according to your math. Which in turn is 2% change on 500mm reach bike. Is that significant change?
My maths wasn't great, a 45 degree head angle would be a 1:1 up Vs back
Therefore on a 67.5 ° head angle for every 2mm of spacer would be 1mm reach reduction, a slacker head angle would obviously be a bit more back, a bit of trig or just applying a ratio could work it out based on a specific head angle.
So if you had 30mm of stem spacers that's 15-18mm reduction in reach which isn't far off the difference between a large and a medium. I would say that's significant but thinking about it also makes sense to get a bike that's a bit too long and reduce it which you can't do if it's too small... love to contradict myself haha
You can always play with Muha bike geo calculator to get precise numbers...
I'm not sure numbers really matter, it's how it feels that matters but with that said I've made changes in the past which felt uncomfortable at first then stuck with them a bit longer to get used to it then seems really beneficial, especially moving from a medium to a large frame, I remember I didn't like it at 1st then got adjusted to it and I'm sure I ride better on it now.
On a bike with a 65degree HA.
A 10mm spacer gets you +9mm of stack and -4.2mm of reach
I have a L geometron with 520mm of reach but since I run the longest chainstay mutators, a DH shock and a DH fork my wheelbase currently sits at: 1352mm. I haven't felt it was too long for any corner especially berms. I find that if you lean the bike enough the backend drifts enough for you to make any corner. Slow speed hairpins can be done by nose turns.
I use this tool all the time to calculate the impact of swapping stems and spacers on stack and reach, for mountain bikes and road bikes. Super helpful: http://yojimg.net/bike/web_tools/stem.php
That's entirely location-dependent. I never encountered a corner I couldn't make. Some tight double switchbacks had to be done exactly one way or the bike wouldn't fit. All berms can be ridden. All of these same features are easier and more fun to ride on my current bike with a 1330 wheelbase with no appreciable loss in stability. If anything it's remarkable that a 2cm difference in wheelbase can make such a big difference. Would I ever go back to 1350+? Absolutely not.
I had a few minutes in work and was bored
Your numbers are wrong.
I just figured out why 🤦
Honestly does it even matter? Reach on it self as with all those rad and raad and whatever are useless metrics that can be modified in so many ways that as long the wheelbase is correct don't really matter. Like you can have two bikes with same reach and a 5cm of difference in wheelbase. And the same is possible in the opposite way. And guess which two bikes will ride more simmilarily?
Like seriously, once you figure out which length of bike and head tube angle you prefer, it makes choosing next bike much easier. The ony other metric that I would give a bit of tought is front/rear center ratio if you are on the extremes of sizing and that is it. Once you figure that out, everything else can be adjusted to preference with cockpit setup.
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