Not sure it would scale as equally. You need a pedal insert and, most importantly, the axle (and chainring) interface. Those parts could be fairly heavy...
Not sure it would scale as equally. You need a pedal insert and, most importantly, the axle (and chainring) interface. Those parts could be fairly heavy.
If you do the crank with a fairly big tube, you need to have it very thin to be light enough, which isn't a problem strength wise (steel can have very high tensile strength ratios). This will also give you stiffness. The thin walls will make it very dent prone (think a beverage can situation).
If you go with a smaller cross section tube to be able to make the wall thicker (to cover the issue of denting), it's possible you'll have to make it overly thick to cover the stiffness requirements.
All of this is just eyeballing and throwing out pros and cons, but I'd say there's a very good reason the vast majority of cranks, pocketed out, hollow forged or glued together, is made from aluminium (thick walls required for stiffness and strength, no issue with denting, no issue with weight due to the density of Aluminium). And when done right aluminium actually glues very well. I wonder why more companies don't do that.
How many of those are XTR cranks (hope I'm not foreshadowing)? Where's ThanksCannondale or ThanksActofive (or anyone else making two piece cranks)?
Looks like shimano is using a structural 'rear' part and a very thin cosmetic cover over it, that doesn't seem particularly structural. Plus said cover is not afixed by the spindle (though NDS cranks also have problems). Plus there are theories the main issue is moisture (looks like it's happening in Asia more than the rest of the world) possibly oxidizing aluminium. And the glued joint could possibly be designed better (it looks like it's fairly vertical currently).
I think if you made the two halves structurally similar and also strengthened them using the spindle and pedal thread insert (insert the pedal insert from the back so the pedal screwed in compresses the two halves, same for the spindle compressing the two halves once installed into the frame) and made the glued joint stout, there shouldn't be much of a problem. Cannondale has a labyrinth joint that's glued together, but I don't know how Actofive does it.
FWIW, aluminium cars are bonded together, not welded. Gluing aluminium does work when done correctly.
No pics for me either, just little question mark icons since yesterday. (Mobile site on iPhone) @sspomer feel free to delete this comment once you’ve solved the problem.
No pics for me either, just little question mark icons since yesterday. (Mobile site on iPhone) @sspomer feel free to delete this comment once you’ve solved...
No pics for me either, just little question mark icons since yesterday. (Mobile site on iPhone) @sspomer feel free to delete this comment once you’ve solved the problem.
almost no pics are showing for me on the whole vital site, doesn‘t matter if i‘m on iphone, mac or PC.
maybe those balloons north americans are shooting down last couple days…
Not sure it would scale as equally. You need a pedal insert and, most importantly, the axle (and chainring) interface. Those parts could be fairly heavy...
Not sure it would scale as equally. You need a pedal insert and, most importantly, the axle (and chainring) interface. Those parts could be fairly heavy.
If you do the crank with a fairly big tube, you need to have it very thin to be light enough, which isn't a problem strength wise (steel can have very high tensile strength ratios). This will also give you stiffness. The thin walls will make it very dent prone (think a beverage can situation).
If you go with a smaller cross section tube to be able to make the wall thicker (to cover the issue of denting), it's possible you'll have to make it overly thick to cover the stiffness requirements.
All of this is just eyeballing and throwing out pros and cons, but I'd say there's a very good reason the vast majority of cranks, pocketed out, hollow forged or glued together, is made from aluminium (thick walls required for stiffness and strength, no issue with denting, no issue with weight due to the density of Aluminium). And when done right aluminium actually glues very well. I wonder why more companies don't do that.
I had some back and forth with a steel bike manufacturer in England, it states on their website not to hang bikes over a tailgate, as it can dent the down tube. They noted they hadn’t come across this issue until they started selling bikes in Canada, where shuttling on terrible roads, with bikes on tailgate pads is pretty common. I was pretty shocked when they told me what the wall thickness was. Still want one, I’m not a shuttle pad guy, but some of my friends are.
thin walled tubes can be strong in the direction they are designed for, but can dent easily, which then becomes a real issue.
No pics for me either, just little question mark icons since yesterday. (Mobile site on iPhone) @sspomer feel free to delete this comment once you’ve solved...
No pics for me either, just little question mark icons since yesterday. (Mobile site on iPhone) @sspomer feel free to delete this comment once you’ve solved the problem.
The image server has lost it's SSL certificate it seems. I opened an image in a new tab, and told chrome that I want to proceed even though it's unsafe, and refreshed the page and i'm all good.
Just while we are on the subject of broken cranks... The only ever cranks I've had issues with were the pedal inserts coming out of Race Face carbon cranks (2 sets of SixC) and this catastrophic failure on some XX1s... luckily the step down this happened on was pretty tiny.
If you ever tried a Lefty, you will definitely appreciate the friction-"less" feeling with bearings, even under sideload. I had a Lefty Max carbon coil, and it was so sensitive!
I haven't, but I have heard about it. It makes sense. But the lefty has a steel stanchion that has 3 (or 4 in the past) flat faces ground on it. That makes it quite a bit more expensive and heavy than what we have now (leftys saving grace weight wise is the single stanchion).
If you ever tried a Lefty, you will definitely appreciate the friction-"less" feeling with bearings, even under sideload. I had a Lefty Max carbon coil, and...
If you ever tried a Lefty, you will definitely appreciate the friction-"less" feeling with bearings, even under sideload. I had a Lefty Max carbon coil, and it was so sensitive!
Nobody is doubting that roller bearings works great, everybody is doubting their (fox) ability to do anything even remotely close to that system. Even without it, with well known design/QC issues their forks cost up to 1500euro(40s actually even more than that) lol. Doing anything like this at the scale they are operating at is...Let's say highly unlikely, (even with all massive design challenges aside).
The main difference between bushings and linear bearings is bearings have significantly lower static friction particularly under side loading. The kinetic friction of bushings and bearings are roughly comparable. So a linear bearing takes less force to initiate travel (making it more sensitive) than a bushing, but once moving they're about the same (this ignores the friction from the seals). Another big benefit of bearings is under a side load or moment, the friction (both kinetic and static) of both bushings and bearings increases as the side load is increased, but the bearing increases at a lower rate than the bushing (assuming both are within their load limits of course). One downside of linear bearings is that for a given shaft size the load limit is far lower, and the OD of the bearing is of course much greater. In the article they show a 2" shaft with 3" bearing od (=~50mm and ~76mm), I'm not going to do the math, but that sounds about right, maybe even on the small side. Obviously needle bearings on flats like thelefty is better and smaller. Bushings are far more resistant to damage from shock loads than bearings (Shock loads in the engineering sense: i.e. overloading caused from unexpected impacts outside normal operation). And like Primoz said, the shaft would need to be steel. Each ball bearing point loads the shaft so it needs to be hardened, ground, and polished steel just like the races of a rotary bearing. At my old job I designed factory automation stuff and used both types, also used a lot of rail type linear bearings. Bearings were nicer and smoother when there was enough space to fit them. For a lot of reasons I'd be pretty surprised if this patent went anywhere. Even for motorcycles seems very unlikely.
Agreed, reliability/durability is the aspect where that bike needs the most improvement.
Also would be nice to see some more meaningful adjustability, like on the Canyon...
Agreed, reliability/durability is the aspect where that bike needs the most improvement.
Also would be nice to see some more meaningful adjustability, like on the Canyon Strive which has built-in reach adjust.
230x65 instead of trunnion (trash) 205x65 would be a big improvement for shock reliability.
Agreed, reliability/durability is the aspect where that bike needs the most improvement.
Also would be nice to see some more meaningful adjustability, like on the Canyon...
Agreed, reliability/durability is the aspect where that bike needs the most improvement.
Also would be nice to see some more meaningful adjustability, like on the Canyon Strive which has built-in reach adjust.
Agreed, reliability/durability is the aspect where that bike needs the most improvement.
Also would be nice to see some more meaningful adjustability, like on the Canyon...
Agreed, reliability/durability is the aspect where that bike needs the most improvement.
Also would be nice to see some more meaningful adjustability, like on the Canyon Strive which has built-in reach adjust.
The way it looks bulky at the top with the dials to adjust damping characteristics and what looks like not much there lower down in the pic, I'd say it kinda looks like a Float X (so the 'standard' air shock layout as opposed to the X2/Vivid/etc. style). That's what I see from a glimpse at the story.
How many of those are XTR cranks (hope I'm not foreshadowing)? Where's ThanksCannondale or ThanksActofive (or anyone else making two piece cranks)?
Looks like shimano is using a structural 'rear' part and a very thin cosmetic cover over it, that doesn't seem particularly structural. Plus said cover is not afixed by the spindle (though NDS cranks also have problems). Plus there are theories the main issue is moisture (looks like it's happening in Asia more than the rest of the world) possibly oxidizing aluminium. And the glued joint could possibly be designed better (it looks like it's fairly vertical currently).
I think if you made the two halves structurally similar and also strengthened them using the spindle and pedal thread insert (insert the pedal insert from the back so the pedal screwed in compresses the two halves, same for the spindle compressing the two halves once installed into the frame) and made the glued joint stout, there shouldn't be much of a problem. Cannondale has a labyrinth joint that's glued together, but I don't know how Actofive does it.
FWIW, aluminium cars are bonded together, not welded. Gluing aluminium does work when done correctly.
new Saint cranks on brendogs rig?
Second new find:
Suarez on an alloy proto dh Unno bike?
@SupremeShredder42 taking the idea of spy photos to a new level
No pics showing?
No pics for me either, just little question mark icons since yesterday. (Mobile site on iPhone) @sspomer feel free to delete this comment once you’ve solved the problem.
almost no pics are showing for me on the whole vital site, doesn‘t matter if i‘m on iphone, mac or PC.
maybe those balloons north americans are shooting down last couple days…
/JK
Even without picture I can say no, he is on dmrs and most likely always will be.
I had some back and forth with a steel bike manufacturer in England, it states on their website not to hang bikes over a tailgate, as it can dent the down tube. They noted they hadn’t come across this issue until they started selling bikes in Canada, where shuttling on terrible roads, with bikes on tailgate pads is pretty common. I was pretty shocked when they told me what the wall thickness was. Still want one, I’m not a shuttle pad guy, but some of my friends are.
thin walled tubes can be strong in the direction they are designed for, but can dent easily, which then becomes a real issue.
https://instagram.com/stories/angelsuarezdh/3037273771689986020?utm_source=ig_story_item_share&igshid=YmMyMTA2M2Y=
You are right! Just thought so because they where unbranded.
The image server has lost it's SSL certificate it seems. I opened an image in a new tab, and told chrome that I want to proceed even though it's unsafe, and refreshed the page and i'm all good.
thanks for the patience w/ image stuff, we're working on it. in the meantime here's a secret spy shot no one is allowed to see.
Aw I love you too.
https://www.dmrbikes.com/Catalogue/Components/Cranks/Axe-Crank-LE
Just while we are on the subject of broken cranks... The only ever cranks I've had issues with were the pedal inserts coming out of Race Face carbon cranks (2 sets of SixC) and this catastrophic failure on some XX1s... luckily the step down this happened on was pretty tiny.
Vital just posted a picture on Instagram with a 230 X 65 and Enduro 29. Any clues? New SpecializedEnduro on the way?
usually the new demo comes first, but maybe it‘s the other way around this time.
honestly the only thing they have to improve in the enduro is the reliability, geo is still up to date, maybe they will ad some more geo adjustments.
Some interesting patents from FOX on bike rumor, I would say good luck with those bushings but we will see I guess.https://bikerumor.com/will-future-fox-forks-have-massive-diameter-lower…
The ball bearing bushings require steel stanchions, aluminium is too soft to work. I think it's patent trolling.
If you ever tried a Lefty, you will definitely appreciate the friction-"less" feeling with bearings, even under sideload. I had a Lefty Max carbon coil, and it was so sensitive!
I haven't, but I have heard about it. It makes sense. But the lefty has a steel stanchion that has 3 (or 4 in the past) flat faces ground on it. That makes it quite a bit more expensive and heavy than what we have now (leftys saving grace weight wise is the single stanchion).
Nobody is doubting that roller bearings works great, everybody is doubting their (fox) ability to do anything even remotely close to that system. Even without it, with well known design/QC issues their forks cost up to 1500euro(40s actually even more than that) lol. Doing anything like this at the scale they are operating at is...Let's say highly unlikely, (even with all massive design challenges aside).
The main difference between bushings and linear bearings is bearings have significantly lower static friction particularly under side loading. The kinetic friction of bushings and bearings are roughly comparable. So a linear bearing takes less force to initiate travel (making it more sensitive) than a bushing, but once moving they're about the same (this ignores the friction from the seals). Another big benefit of bearings is under a side load or moment, the friction (both kinetic and static) of both bushings and bearings increases as the side load is increased, but the bearing increases at a lower rate than the bushing (assuming both are within their load limits of course). One downside of linear bearings is that for a given shaft size the load limit is far lower, and the OD of the bearing is of course much greater. In the article they show a 2" shaft with 3" bearing od (=~50mm and ~76mm), I'm not going to do the math, but that sounds about right, maybe even on the small side. Obviously needle bearings on flats like thelefty is better and smaller. Bushings are far more resistant to damage from shock loads than bearings (Shock loads in the engineering sense: i.e. overloading caused from unexpected impacts outside normal operation). And like Primoz said, the shaft would need to be steel. Each ball bearing point loads the shaft so it needs to be hardened, ground, and polished steel just like the races of a rotary bearing. At my old job I designed factory automation stuff and used both types, also used a lot of rail type linear bearings. Bearings were nicer and smoother when there was enough space to fit them. For a lot of reasons I'd be pretty surprised if this patent went anywhere. Even for motorcycles seems very unlikely.
Agreed, reliability/durability is the aspect where that bike needs the most improvement.
Also would be nice to see some more meaningful adjustability, like on the Canyon Strive which has built-in reach adjust.
Geo adjustments from kenovo and a steeper sta would be enough, maybe a taller stack aswell
230x65 instead of trunnion (trash) 205x65 would be a big improvement for shock reliability.
More likely new Fox than new Specialized.
Maybe the updated X2 platform.
it's rumored to last 4 weeks vs. the usual 2.
The way it looks bulky at the top with the dials to adjust damping characteristics and what looks like not much there lower down in the pic, I'd say it kinda looks like a Float X (so the 'standard' air shock layout as opposed to the X2/Vivid/etc. style). That's what I see from a glimpse at the story.
Post a reply to: MTB Tech Rumors and Innovation