There is a wheel review on a prominent mtb website where the reviewer attempts to educate the reader about why different wheels have different compliance. He...
There is a wheel review on a prominent mtb website where the reviewer attempts to educate the reader about why different wheels have different compliance. He uses the example that a 2X laced wheel, a 3X laced wheel, and a 3X laced wheel detensioned a small amount will all have different compliance. The rationale offered is theoretical and to put it plainly, i don’t think it’s interesting whether or not it’s good theorizing or poor.
My question is what is the technical limitation in the way of building examples of these three wheels and measuring the compliance?
Does the rig not exist? Is it prohibitively expensive? Does the test protocol not exist? Are there competing protocols where the results of one would be protested by advocates for the alternative?
Henry at PB, and many others, including very good friends of mine who are bike mechanics/wheelbuilders, all seem to think that increasing spoke tension will increase...
Henry at PB, and many others, including very good friends of mine who are bike mechanics/wheelbuilders, all seem to think that increasing spoke tension will increase the stiffness of a wheel, and vice versa. They all rely on some sort of "feel" related justification, and post hoc rationalization of why they think the tension is leading to what they think they are feeling.
I am still unconvinced. I am not sure if you have ever seen it, but Damon Rinard (who has been a lead engineer at many bike companies) designed a rig back in the 90s to test the theory. His article and results are archived on the Sheldon Brown website. Yobst Brant, the guru of wheelbuilding and author of "The Bicycle Wheel" is in agreement on the validity of these tests as far as I know. Here are links to the Rinard paper and data:
1. The Rinard tests were measuring lateral stiffness, so I suppose it is possible that lateral stiffness and radial stiffness are affected differently by spoke tension, however I find that to be unlikely.
2. As far as I know, while he compared equivalent builds with a few different spoke lacing configurations, I don't think he ever tested 1 vs 2 vs 3 cross. Three cross spoke patterns are more tangent to the hub flange, so they generally would be superior in terms of tortional loads (pedaling and braking) not that it really matters, but by virtue of their longer path to the rim they have a very slightly inferior lateral bracing angle, so that would be one reason for different flex characteristics. Henry's explanation for different crossings having different stiffnesses seemed to derive from the 3 cross being more tolerant of lower tension, so his theory was ultimately tension derived, not related to the wheel geometry.
3. Just to clarify, under loads so severe that some of the spokes go completely slack, the wheel momentarily becomes massively more flexible and weaker, both laterally and radially. Then, assuming you haven't flexed it too far and exceeded it's elastic limit, it should snap back and regain its normal strength and stiffness. Everyone is in agreement that a complete lack of tension will allow a wheel to flex more, however those de-tensioning/re-tensioning events are terrible for wheel longevity, and it is normally the goal of a wheel builder to spec the parts and build to a sufficient tension that you completely avoid those events. That is both because you run the risk of exceeding the elastic limit of the wheels, and because in the long term those massive unload/load cycles will fatigue the spoke heads/nipples/hub flanges/and spoke holes in the rim, eventually leading to fatigue failures/cracking.
When you hear about pro's running really low tension for a more compliant ride, I think they're just experiencing much more frequent de-tensioning events. You can see it clearly if you watch slow-mo videos of them getting rowdy and really loading the wheels, where you can see spokes going loose and then snapping back straight. That may be desirable in a pro-racing environment, where they are getting new wheels built for every race, but for most of us wondering about compliance for our daily drivers, and trying to get decent longevity out of the wheels, it probably isn't a good match. For compliance and longevity, I think a better match is to use a thinner/more elastic spoke, which can allow for the rim to flex more without going totally slack, while keeping the tension high enough to avoid de-tensioning events. Another alternative, I suppose, if you wanted to mess around with low spoke tension like the pros, durability be damned, is to just buy really cheap wheels and consider them to be disposable.
That Sheldon test is interesting for sure! All makes sense, along with your notes. I have tried wheels with almost no tension but it's just not sustainable to ride more than a run or 2 before it's about to fold. I think the low spoke count and thin spokes that Sapam is the way to go. At the very least, I think 28h front for comfort. Then you can run more normal tension, like in the 15 range. I just built up a rear 28-hole carbon rim that was designed for a front wheel(so slightly softer) and 1.6 butted spokes. I'm currently on a DH carbon rear rim with 1.5 butted spokes and about 10 spoke tension.
From Sheldon test- The relative contribution of the following to stiffness:
Great question! I would love to see a picture of your bike because custom builds are awesome. What suspension layout do you use? We can take...
Great question! I would love to see a picture of your bike because custom builds are awesome. What suspension layout do you use? We can take a look and get you pointed in a good direction.
I realised I didn't have any picture of my bike (after 2 seasons lol) so I took some this morning. The bike has heen welded by Egerie in France, based on a linkage file I made. The idea here is to have the chainstay length based on a front to rear center ratio. I checked that ratio at SAG on bikes I found to have good cornering characteristics. In terms of number it is 63HA, 80SA, 490mm reach, 470CS, 643stack, 15mm BB drop. The bike is full 29, 180mm front and 192mm back. The frame is atypical for a single pivot as I wanted to reduce PK to a minimum (hence the pretty rearward main pivot) and to have as much progression as possible while keeping the single pivot simplicity. It is currently in its winter guise to be pedaled (still missing the bottle and the tool holders) otherwise the dropper is removed when racing or at the park so most of summer.
I should add that the bike rides very well and is very dynamic (more than my previous GTs Force 27.5 and 29). The only moment I notice the lack of rigidity is in pretty high load type of berms, so the question is, aside from how to make it stiffer, is it worth it and could it make it worse everywhere else ?
I should add that the bike rides very well and is very dynamic (more than my previous GTs Force 27.5 and 29). The only moment I...
I should add that the bike rides very well and is very dynamic (more than my previous GTs Force 27.5 and 29). The only moment I notice the lack of rigidity is in pretty high load type of berms, so the question is, aside from how to make it stiffer, is it worth it and could it make it worse everywhere else ?
That’s a cool looking bike! How progressive did you make it?
That’s a cool looking bike! How progressive did you make it?
This much ! So slightly more than 17%.
I ride the bike with 32/33% of static SAG and a lot of compression. Makes is super dynamic and poppy (especially with the mid stroke support of a coil shock), not the best at ironing trail chater tho, and I don't have any issues with bottoming out even on big features. So far this frame has been ridden with Formula MOD (orange and green CTS), Ohlins TTX2 with all the tokens, and the VORO that a friend of mine handed to me to test. So far I am very impressed with the VORO, at least in the park, need to try to pedal with it before I settle on it or revert to another shock.
This much ! So slightly more than 17%.I ride the bike with 32/33% of static SAG and a lot of compression. Makes is super dynamic and...
This much ! So slightly more than 17%.
I ride the bike with 32/33% of static SAG and a lot of compression. Makes is super dynamic and poppy (especially with the mid stroke support of a coil shock), not the best at ironing trail chater tho, and I don't have any issues with bottoming out even on big features. So far this frame has been ridden with Formula MOD (orange and green CTS), Ohlins TTX2 with all the tokens, and the VORO that a friend of mine handed to me to test. So far I am very impressed with the VORO, at least in the park, need to try to pedal with it before I settle on it or revert to another shock.
Nice! I don’t think 17% is very progressive, so I thought you were going to say that it’s much more.
Cool project, do you think you will make a second version? Will you change anything?
So there’s evidence people have been looking at, thinking about, measuring and comparing bike component compliance for years. And there’s evidence that some component and system (for example, a wheel) makers have been doing the same.
But instead of helping to create basic language and tools riders could use to compare compliance as one more factor to consider alongside all the other bike fit and performance details, every company is mining the compliance boom in the same way. Our new gen widget is more compliant (but not too compliant!) than our previous gen widget. Start tuning your ride today!
Marketing companions, check it out: i never used your previous gen widget. So the reference is not helpful. The relative improvement isn’t meaningful. And btw, all your competitors are saying the same thing.
Imagine if companies refused to post geometry and just said 5% more reach, 1% slacker head angle, and we made our front-center to rear-center ratio 25% more proportional!
This much ! So slightly more than 17%.I ride the bike with 32/33% of static SAG and a lot of compression. Makes is super dynamic and...
This much ! So slightly more than 17%.
I ride the bike with 32/33% of static SAG and a lot of compression. Makes is super dynamic and poppy (especially with the mid stroke support of a coil shock), not the best at ironing trail chater tho, and I don't have any issues with bottoming out even on big features. So far this frame has been ridden with Formula MOD (orange and green CTS), Ohlins TTX2 with all the tokens, and the VORO that a friend of mine handed to me to test. So far I am very impressed with the VORO, at least in the park, need to try to pedal with it before I settle on it or revert to another shock.
Nice! I don’t think 17% is very progressive, so I thought you were going to say that it’s much more.Cool project, do you think you will...
Nice! I don’t think 17% is very progressive, so I thought you were going to say that it’s much more.
Cool project, do you think you will make a second version? Will you change anything?
17% isn't much but compared to most single pivot on the market that have 0 to 5% of progression this is a lot lol.
As an enduro bike I wouldn't change anything on it really.
As a DH bike I would use some slightly shorter chainstays (460 or 465mm) to help a little in the very steep stuff and add a little rear end stiffness (the whole point of this thread) as it is a bit lacking sometimes in high G scenarios. Other than that it is very capable as it is. If I was to use it as pur DH I would use an Ochain, double crown, DH transmission etc.
I might do a dedicated DH frame in the near future which is why I participated to this thread. If I can identify where my lack of stiffness comes from it could be addressed for the DH frame. The frame would be mid-pivot, fixed, non concentric idler, similar geometry, travel, progression and AR characteristics. The concept is pretty much ready in Linkage but I haven't pulled the trigger yet as I am considering other options.
So there’s evidence people have been looking at, thinking about, measuring and comparing bike component compliance for years. And there’s evidence that some component and system...
So there’s evidence people have been looking at, thinking about, measuring and comparing bike component compliance for years. And there’s evidence that some component and system (for example, a wheel) makers have been doing the same.
But instead of helping to create basic language and tools riders could use to compare compliance as one more factor to consider alongside all the other bike fit and performance details, every company is mining the compliance boom in the same way. Our new gen widget is more compliant (but not too compliant!) than our previous gen widget. Start tuning your ride today!
Marketing companions, check it out: i never used your previous gen widget. So the reference is not helpful. The relative improvement isn’t meaningful. And btw, all your competitors are saying the same thing.
Imagine if companies refused to post geometry and just said 5% more reach, 1% slacker head angle, and we made our front-center to rear-center ratio 25% more proportional!
🙃
Same goes with all the pedal kick dampers (Ochain and Rimpact, e13 new hub). For instance, did you ever see a graph, data, anything that shows in which way does pedal kick dampers actually do anything ? Yes riders tell us it does something, TEAMROBOT did an excellent video about it too. But these companies should be able to quantify what it actually does, X% less vibrations at your feet, Y% less loss of grip moments during braking situations, Z% more suspension amplitude during a given impact, etc etc.
Yet do we see any of this ? Nope, it's all "trust me bro" ... And compliance will definitely go the same route by the looks of it. Saying that, most people pick a bike based on looks and have no idea about suspension kinematics, even simple concepts like anti-squat or progression, so ... we get what we deserve I guess ?
So there’s evidence people have been looking at, thinking about, measuring and comparing bike component compliance for years. And there’s evidence that some component and system...
So there’s evidence people have been looking at, thinking about, measuring and comparing bike component compliance for years. And there’s evidence that some component and system (for example, a wheel) makers have been doing the same.
But instead of helping to create basic language and tools riders could use to compare compliance as one more factor to consider alongside all the other bike fit and performance details, every company is mining the compliance boom in the same way. Our new gen widget is more compliant (but not too compliant!) than our previous gen widget. Start tuning your ride today!
Marketing companions, check it out: i never used your previous gen widget. So the reference is not helpful. The relative improvement isn’t meaningful. And btw, all your competitors are saying the same thing.
Imagine if companies refused to post geometry and just said 5% more reach, 1% slacker head angle, and we made our front-center to rear-center ratio 25% more proportional!
🙃
Whoa whoa whoa don't go giving the marketing people any idea's like that.
Soon a 45mm stem will be marketed as 10% more compact than a 50mm stem.
So there’s evidence people have been looking at, thinking about, measuring and comparing bike component compliance for years. And there’s evidence that some component and system...
So there’s evidence people have been looking at, thinking about, measuring and comparing bike component compliance for years. And there’s evidence that some component and system (for example, a wheel) makers have been doing the same.
But instead of helping to create basic language and tools riders could use to compare compliance as one more factor to consider alongside all the other bike fit and performance details, every company is mining the compliance boom in the same way. Our new gen widget is more compliant (but not too compliant!) than our previous gen widget. Start tuning your ride today!
Marketing companions, check it out: i never used your previous gen widget. So the reference is not helpful. The relative improvement isn’t meaningful. And btw, all your competitors are saying the same thing.
Imagine if companies refused to post geometry and just said 5% more reach, 1% slacker head angle, and we made our front-center to rear-center ratio 25% more proportional!
So there’s evidence people have been looking at, thinking about, measuring and comparing bike component compliance for years. And there’s evidence that some component and system...
So there’s evidence people have been looking at, thinking about, measuring and comparing bike component compliance for years. And there’s evidence that some component and system (for example, a wheel) makers have been doing the same.
But instead of helping to create basic language and tools riders could use to compare compliance as one more factor to consider alongside all the other bike fit and performance details, every company is mining the compliance boom in the same way. Our new gen widget is more compliant (but not too compliant!) than our previous gen widget. Start tuning your ride today!
Marketing companions, check it out: i never used your previous gen widget. So the reference is not helpful. The relative improvement isn’t meaningful. And btw, all your competitors are saying the same thing.
Imagine if companies refused to post geometry and just said 5% more reach, 1% slacker head angle, and we made our front-center to rear-center ratio 25% more proportional!
Same goes with all the pedal kick dampers (Ochain and Rimpact, e13 new hub). For instance, did you ever see a graph, data, anything that shows...
Same goes with all the pedal kick dampers (Ochain and Rimpact, e13 new hub). For instance, did you ever see a graph, data, anything that shows in which way does pedal kick dampers actually do anything ? Yes riders tell us it does something, TEAMROBOT did an excellent video about it too. But these companies should be able to quantify what it actually does, X% less vibrations at your feet, Y% less loss of grip moments during braking situations, Z% more suspension amplitude during a given impact, etc etc.
Yet do we see any of this ? Nope, it's all "trust me bro" ... And compliance will definitely go the same route by the looks of it. Saying that, most people pick a bike based on looks and have no idea about suspension kinematics, even simple concepts like anti-squat or progression, so ... we get what we deserve I guess ?
To play devil's advocate a bit I think the reason Ochain and the like don't publish hard data is obvious, it's really noisy and incredibly hard to measure it well.
Also a large part of these products are psychosomatic, placebo induced often, like hand fatigue, grip levels etc. It's a feeling that can't really be measured easily.
It's not that these events can't be measured, it's just really really hard on a MTB.
I saw some F1 telemetry the other day, and they can tell when the driver is pushing too hard from gyros on the front and rear that detect sliding from steering inputs or brake steering into corners. This requires high end gyros and g-sensors at either end of the car with super high resolution all working together to detect slides which they also use their laser thermometers trained at the tyres to measure changes in tyre temp.
Good luck trying to rig a similar setup on a MTB.
I think we'll get better at it, but it's not easy, and at the end of the day, the marketing team will say what sells anyway.
So there’s evidence people have been looking at, thinking about, measuring and comparing bike component compliance for years. And there’s evidence that some component and system...
So there’s evidence people have been looking at, thinking about, measuring and comparing bike component compliance for years. And there’s evidence that some component and system (for example, a wheel) makers have been doing the same.
But instead of helping to create basic language and tools riders could use to compare compliance as one more factor to consider alongside all the other bike fit and performance details, every company is mining the compliance boom in the same way. Our new gen widget is more compliant (but not too compliant!) than our previous gen widget. Start tuning your ride today!
Marketing companions, check it out: i never used your previous gen widget. So the reference is not helpful. The relative improvement isn’t meaningful. And btw, all your competitors are saying the same thing.
Imagine if companies refused to post geometry and just said 5% more reach, 1% slacker head angle, and we made our front-center to rear-center ratio 25% more proportional!
Same goes with all the pedal kick dampers (Ochain and Rimpact, e13 new hub). For instance, did you ever see a graph, data, anything that shows...
Same goes with all the pedal kick dampers (Ochain and Rimpact, e13 new hub). For instance, did you ever see a graph, data, anything that shows in which way does pedal kick dampers actually do anything ? Yes riders tell us it does something, TEAMROBOT did an excellent video about it too. But these companies should be able to quantify what it actually does, X% less vibrations at your feet, Y% less loss of grip moments during braking situations, Z% more suspension amplitude during a given impact, etc etc.
Yet do we see any of this ? Nope, it's all "trust me bro" ... And compliance will definitely go the same route by the looks of it. Saying that, most people pick a bike based on looks and have no idea about suspension kinematics, even simple concepts like anti-squat or progression, so ... we get what we deserve I guess ?
To play devil's advocate a bit I think the reason Ochain and the like don't publish hard data is obvious, it's really noisy and incredibly hard...
To play devil's advocate a bit I think the reason Ochain and the like don't publish hard data is obvious, it's really noisy and incredibly hard to measure it well.
Also a large part of these products are psychosomatic, placebo induced often, like hand fatigue, grip levels etc. It's a feeling that can't really be measured easily.
It's not that these events can't be measured, it's just really really hard on a MTB.
I saw some F1 telemetry the other day, and they can tell when the driver is pushing too hard from gyros on the front and rear that detect sliding from steering inputs or brake steering into corners. This requires high end gyros and g-sensors at either end of the car with super high resolution all working together to detect slides which they also use their laser thermometers trained at the tyres to measure changes in tyre temp.
Good luck trying to rig a similar setup on a MTB.
I think we'll get better at it, but it's not easy, and at the end of the day, the marketing team will say what sells anyway.
There’s definitely data out there if you look deep enough. I guess there’s many consumers who don’t care about the data and just want something that’s cool? Hopefully with new technology, it will be easier for brands to gather, sort and analyze the data.
Neko Mulally had data when testing oChain and said he saw a change in dynamic sag. This was in one of his earlier videos when testing between the high and low pivot bike.
CounterShox had data showing with and out their device showing a clear difference.
So there’s evidence people have been looking at, thinking about, measuring and comparing bike component compliance for years. And there’s evidence that some component and system...
So there’s evidence people have been looking at, thinking about, measuring and comparing bike component compliance for years. And there’s evidence that some component and system (for example, a wheel) makers have been doing the same.
But instead of helping to create basic language and tools riders could use to compare compliance as one more factor to consider alongside all the other bike fit and performance details, every company is mining the compliance boom in the same way. Our new gen widget is more compliant (but not too compliant!) than our previous gen widget. Start tuning your ride today!
Marketing companions, check it out: i never used your previous gen widget. So the reference is not helpful. The relative improvement isn’t meaningful. And btw, all your competitors are saying the same thing.
Imagine if companies refused to post geometry and just said 5% more reach, 1% slacker head angle, and we made our front-center to rear-center ratio 25% more proportional!
Same goes with all the pedal kick dampers (Ochain and Rimpact, e13 new hub). For instance, did you ever see a graph, data, anything that shows...
Same goes with all the pedal kick dampers (Ochain and Rimpact, e13 new hub). For instance, did you ever see a graph, data, anything that shows in which way does pedal kick dampers actually do anything ? Yes riders tell us it does something, TEAMROBOT did an excellent video about it too. But these companies should be able to quantify what it actually does, X% less vibrations at your feet, Y% less loss of grip moments during braking situations, Z% more suspension amplitude during a given impact, etc etc.
Yet do we see any of this ? Nope, it's all "trust me bro" ... And compliance will definitely go the same route by the looks of it. Saying that, most people pick a bike based on looks and have no idea about suspension kinematics, even simple concepts like anti-squat or progression, so ... we get what we deserve I guess ?
To play devil's advocate a bit I think the reason Ochain and the like don't publish hard data is obvious, it's really noisy and incredibly hard...
To play devil's advocate a bit I think the reason Ochain and the like don't publish hard data is obvious, it's really noisy and incredibly hard to measure it well.
Also a large part of these products are psychosomatic, placebo induced often, like hand fatigue, grip levels etc. It's a feeling that can't really be measured easily.
It's not that these events can't be measured, it's just really really hard on a MTB.
I saw some F1 telemetry the other day, and they can tell when the driver is pushing too hard from gyros on the front and rear that detect sliding from steering inputs or brake steering into corners. This requires high end gyros and g-sensors at either end of the car with super high resolution all working together to detect slides which they also use their laser thermometers trained at the tyres to measure changes in tyre temp.
Good luck trying to rig a similar setup on a MTB.
I think we'll get better at it, but it's not easy, and at the end of the day, the marketing team will say what sells anyway.
Placebo effect is not too hard to prove or bust, have a double blind experiment. Put a series of riders on bikes, with or without the ochain and ask them how they liked the performance of the bike. In order to account for the pedal feedback you could tell them they are not allowed to pedal and have the bb area covered so they can't see which type or crank they are riding. Placebo effect should give you 30% of people feeling an improvement, if ochain can do better and consistently better than standard crank, voila ! you proved that your product does something. This could also be applied to compliance testing, much more easily actually.
As to quantify it, would it not be possible to use some vibration sensors at your feet and in the grips and measure if there is a change ? Todays alarm systems for cars are super compact and can mesure vibrations and such, I doubt it would be hard to find some small enough sensor that could be rigged on a bike. Run that with a GPS and a brake sensor which are now available and I don't see why you couldn't do it. My gripe here is that most likely the companies are ot bothered trying to prove what their products does and just rely on the Bro approach.
There’s definitely data out there if you look deep enough. I guess there’s many consumers who don’t care about the data and just want something that’s...
There’s definitely data out there if you look deep enough. I guess there’s many consumers who don’t care about the data and just want something that’s cool? Hopefully with new technology, it will be easier for brands to gather, sort and analyze the data.
Neko Mulally had data when testing oChain and said he saw a change in dynamic sag. This was in one of his earlier videos when testing between the high and low pivot bike.
CounterShox had data showing with and out their device showing a clear difference.
I don't remember the video from Nekko but it shouldn't be the dutty of a consumer to prove what your product does.
And yes, for some reason the mass damper products seem very data driven so for once we may get a product that is actually back-up which is cool. At least you will know what you buy, why you buy it and what it does for you.
17% isn't much but compared to most single pivot on the market that have 0 to 5% of progression this is a lot lol. As an enduro...
17% isn't much but compared to most single pivot on the market that have 0 to 5% of progression this is a lot lol.
As an enduro bike I wouldn't change anything on it really.
As a DH bike I would use some slightly shorter chainstays (460 or 465mm) to help a little in the very steep stuff and add a little rear end stiffness (the whole point of this thread) as it is a bit lacking sometimes in high G scenarios. Other than that it is very capable as it is. If I was to use it as pur DH I would use an Ochain, double crown, DH transmission etc.
I might do a dedicated DH frame in the near future which is why I participated to this thread. If I can identify where my lack of stiffness comes from it could be addressed for the DH frame. The frame would be mid-pivot, fixed, non concentric idler, similar geometry, travel, progression and AR characteristics. The concept is pretty much ready in Linkage but I haven't pulled the trigger yet as I am considering other options.
Right now, it looks like your main loss of stiffness is coming from the seat stays not being supported by anything other than the shock. The shock is essentially acting as a structural member of your bike, taking on twisting forces in corners. The biggest improvement would likely come from adding a small swing link to connect the seat stays to the front triangle. Your shock will thank you for it 😅.
From there, you could increase rear triangle rigidity by adding a seat stay bridge. If you want to take it even further, you could beef up the chain stay bridge or the bridge on the rear triangle in front of the seat tube. You asked about the downside? It might change the ride feel you currently like. And if you make the rear triangle too rigid compared to the front triangle, you could shift the flexing to the front triangle in high-G corners, potentially causing handling issues.
If you like the way your bike feels now but want just a bit more stiffness, I’d prioritize adding both a removable seat stay bridge and a small swing link. This setup would let you experiment with both independently. A swing link could introduce a little wag and reduce roll stiffness, but if you keep it light, it tiny/flexible minimize those effects.
One quick test you can try: sit on the rear wheel, grab your seat and swing you hips side to side on the wheel. Boom, you've created a test machine out of a human. Watch how things move and see what’s flexing the most. This can give you a better idea of whether a swing link would help.
Right now, it looks like your main loss of stiffness is coming from the seat stays not being supported by anything other than the shock. The...
Right now, it looks like your main loss of stiffness is coming from the seat stays not being supported by anything other than the shock. The shock is essentially acting as a structural member of your bike, taking on twisting forces in corners. The biggest improvement would likely come from adding a small swing link to connect the seat stays to the front triangle. Your shock will thank you for it 😅.
From there, you could increase rear triangle rigidity by adding a seat stay bridge. If you want to take it even further, you could beef up the chain stay bridge or the bridge on the rear triangle in front of the seat tube. You asked about the downside? It might change the ride feel you currently like. And if you make the rear triangle too rigid compared to the front triangle, you could shift the flexing to the front triangle in high-G corners, potentially causing handling issues.
If you like the way your bike feels now but want just a bit more stiffness, I’d prioritize adding both a removable seat stay bridge and a small swing link. This setup would let you experiment with both independently. A swing link could introduce a little wag and reduce roll stiffness, but if you keep it light, it tiny/flexible minimize those effects.
One quick test you can try: sit on the rear wheel, grab your seat and swing you hips side to side on the wheel. Boom, you've created a test machine out of a human. Watch how things move and see what’s flexing the most. This can give you a better idea of whether a swing link would help.
There’s a quicker way to see if you’d like what a swing link does. You could 3D print small sliders (blue) and mount them on the seat stays. These sliders would keep a small gap between the seat stays and the seat tube (or its protector, shown in red). As the bike flexes, the sliders would hit the seat tube and act like a bumper and stop the frame from continuing to flex.
You can print and bolt them onto your bike now to test if the added stiffness feels good. It might feel a little weird while riding for other reasons, but it’s a cheap and easy way to try it out and learn if you like it or not. Some bikes already use this idea... I think Joe mentioned one earlier in this thread. It has some problems but it would be fun to try.
Right now, it looks like your main loss of stiffness is coming from the seat stays not being supported by anything other than the shock. The...
Right now, it looks like your main loss of stiffness is coming from the seat stays not being supported by anything other than the shock. The shock is essentially acting as a structural member of your bike, taking on twisting forces in corners. The biggest improvement would likely come from adding a small swing link to connect the seat stays to the front triangle. Your shock will thank you for it 😅.
From there, you could increase rear triangle rigidity by adding a seat stay bridge. If you want to take it even further, you could beef up the chain stay bridge or the bridge on the rear triangle in front of the seat tube. You asked about the downside? It might change the ride feel you currently like. And if you make the rear triangle too rigid compared to the front triangle, you could shift the flexing to the front triangle in high-G corners, potentially causing handling issues.
If you like the way your bike feels now but want just a bit more stiffness, I’d prioritize adding both a removable seat stay bridge and a small swing link. This setup would let you experiment with both independently. A swing link could introduce a little wag and reduce roll stiffness, but if you keep it light, it tiny/flexible minimize those effects.
One quick test you can try: sit on the rear wheel, grab your seat and swing you hips side to side on the wheel. Boom, you've created a test machine out of a human. Watch how things move and see what’s flexing the most. This can give you a better idea of whether a swing link would help.
There’s a quicker way to see if you’d like what a swing link does. You could 3D print small sliders (blue) and mount them on the...
There’s a quicker way to see if you’d like what a swing link does. You could 3D print small sliders (blue) and mount them on the seat stays. These sliders would keep a small gap between the seat stays and the seat tube (or its protector, shown in red). As the bike flexes, the sliders would hit the seat tube and act like a bumper and stop the frame from continuing to flex.
You can print and bolt them onto your bike now to test if the added stiffness feels good. It might feel a little weird while riding for other reasons, but it’s a cheap and easy way to try it out and learn if you like it or not. Some bikes already use this idea... I think Joe mentioned one earlier in this thread. It has some problems but it would be fun to try.
Ryan, those sliders are a cool idea!
Erwan, if you interested or need, I could help you print some and send them over
I don't think the slider is the best approach. If anything it will just kill your shock quicker as it prys off your seattube. Just add a brace between the pivot and shock mount to make that stiff.
My frame has a pretty tight gap from rear end to seattube (1/4") and it has never touched, even with spherical bearings on the shock. Most movement or flex is rotation behind the pivot point.
A bridge behind the seattube will help and a stiffer axle interface.
I run a BMX style bolt on 135 hub with right washers to remove axle gap.
Before we ran the tighter tolerance washers, there was noticable more flex, so don't underestimate the rear axle/hub/frame interface.
There’s a quicker way to see if you’d like what a swing link does. You could 3D print small sliders (blue) and mount them on the...
There’s a quicker way to see if you’d like what a swing link does. You could 3D print small sliders (blue) and mount them on the seat stays. These sliders would keep a small gap between the seat stays and the seat tube (or its protector, shown in red). As the bike flexes, the sliders would hit the seat tube and act like a bumper and stop the frame from continuing to flex.
You can print and bolt them onto your bike now to test if the added stiffness feels good. It might feel a little weird while riding for other reasons, but it’s a cheap and easy way to try it out and learn if you like it or not. Some bikes already use this idea... I think Joe mentioned one earlier in this thread. It has some problems but it would be fun to try.
There was a bike with sliders that came up recently, but also the 1st gen Intense M1, which had a strut rather than linkage activated single pivot design, used sliders. Having said that, the M1 suddenly became a lot more successful in racing when they switched to the 2nd gen without sliders, although there are other variables involved.
Same goes with all the pedal kick dampers (Ochain and Rimpact, e13 new hub). For instance, did you ever see a graph, data, anything that shows...
Same goes with all the pedal kick dampers (Ochain and Rimpact, e13 new hub). For instance, did you ever see a graph, data, anything that shows in which way does pedal kick dampers actually do anything ? Yes riders tell us it does something, TEAMROBOT did an excellent video about it too. But these companies should be able to quantify what it actually does, X% less vibrations at your feet, Y% less loss of grip moments during braking situations, Z% more suspension amplitude during a given impact, etc etc.
Yet do we see any of this ? Nope, it's all "trust me bro" ... And compliance will definitely go the same route by the looks of it. Saying that, most people pick a bike based on looks and have no idea about suspension kinematics, even simple concepts like anti-squat or progression, so ... we get what we deserve I guess ?
To play devil's advocate a bit I think the reason Ochain and the like don't publish hard data is obvious, it's really noisy and incredibly hard...
To play devil's advocate a bit I think the reason Ochain and the like don't publish hard data is obvious, it's really noisy and incredibly hard to measure it well.
Also a large part of these products are psychosomatic, placebo induced often, like hand fatigue, grip levels etc. It's a feeling that can't really be measured easily.
It's not that these events can't be measured, it's just really really hard on a MTB.
I saw some F1 telemetry the other day, and they can tell when the driver is pushing too hard from gyros on the front and rear that detect sliding from steering inputs or brake steering into corners. This requires high end gyros and g-sensors at either end of the car with super high resolution all working together to detect slides which they also use their laser thermometers trained at the tyres to measure changes in tyre temp.
Good luck trying to rig a similar setup on a MTB.
I think we'll get better at it, but it's not easy, and at the end of the day, the marketing team will say what sells anyway.
There’s definitely data out there if you look deep enough. I guess there’s many consumers who don’t care about the data and just want something that’s...
There’s definitely data out there if you look deep enough. I guess there’s many consumers who don’t care about the data and just want something that’s cool? Hopefully with new technology, it will be easier for brands to gather, sort and analyze the data.
Neko Mulally had data when testing oChain and said he saw a change in dynamic sag. This was in one of his earlier videos when testing between the high and low pivot bike.
CounterShox had data showing with and out their device showing a clear difference.
Yeah I agree with this and with @Erwan_Ghesquiere views, the companies can definitely test, but I do understand if they don't publish the data.
I think an interesting point is there isn't really an engineering or rider based objective standard of what is good or bad flex yet, we are still at the stage of figuring out whats good, let alone specifically designing for it.
In the broadest sense, everyone can agree that "wind-up" flex from a frame is undesirable, i.e the frame can wind up in a corner and spring back aggressively losing traction and control exiting corners. Also that noodling isn't wanted, where a frame flexes so you cant load it up through corners or compressions as it just deviates during the loading.
But aside from that, the jury is out. Lots of riders like stiff rides, lots like steel like muted feeling, some love hard carbon rims, stiff dual crowns, others swear by "flexy" USD forks and alloy rims for off-camber traction.
It'll be interesting as we can collect data and actually start narrowing in on desirable compliance traits
I wouldn't say it's doing weird things here, but it does look weird. It's "just" flexing. But it does look a bit hectic.
It's a perfect illustration as to why frame compliance and wheel flex is important.
The way I think about it is this (could be totally wrong), he's pushed aggressively hard into the corner, the front is tracking perfectly as it has an axle to pivot on (the fork) and thus flex isn't really an issue up front.
The rear wheel of a bike/motorbike will always understeer in a corner, which is an issue in berms, as it means the rear wheel always takes a lower line in a berm with less support (if the bike is only angled and the front wheel not turned there won't be understeer fyi, it's the act of the front wheel being turned creates understeer). He pushes into the corner to generate grip and speed and starts to exceed to limit of grip on the rear and it will slide up the berm until it can grip enough to stop sliding (a schralp as we say). On the more angled part of the berm the tyre gets more support (grip) and stops sliding, but the sideways moment of the slide has to go somewhere now, the tyre stops moving but the force hasn't gone, so we see the frame (imagine it from the axles perspective) continue to move past the contact point of the tyre from this momentum. Now we have a few options, either the rear triangle flexes to absorb this, or the spokes do. Both are good, as it means the tyre can stay happily stuck to berm, the issue is if when this flex occurs, since it's a spring, on corner exit when the load is gone, it violently whips back and forces the tyre to ping to the riders right-hand side and lose grip.
Imagine the counterfactual, if the frame and wheel don't flex here, his sideways momentum will continue to drag the rear tyre up the berm, even though the tyre has enough grip now. Because the energy has to go somewhere. If it's not absorbed by the spokes and rim and rear triangle it will be translated into the tyre and cause a slide. You probably won't crash, but you will schralp harder and destabilize the front of the bike by pivoting so much and probably have to counter steer the front tyre to account for now large amounts of oversteer, which is slower, and harder.
It's this harmony between wheel flex and frame flex that makes a nice tracking bike, some rear triangle flex allows a more skateboard like approach to cornering where the rear can track closer to the front tyre path. A few high end cars have rear wheel steering to achieve this.
It goes to far when you get crabbing however, particularly from g-outs the rear triangle can want to move sideways and kinda spear you off trail.
How to engineer this all? Well that's for Ryan to figure out haha. I know a bit about wheel building though to help it.
That Sheldon test is interesting for sure! All makes sense, along with your notes. I have tried wheels with almost no tension but it's just not sustainable to ride more than a run or 2 before it's about to fold. I think the low spoke count and thin spokes that Sapam is the way to go. At the very least, I think 28h front for comfort. Then you can run more normal tension, like in the 15 range. I just built up a rear 28-hole carbon rim that was designed for a front wheel(so slightly softer) and 1.6 butted spokes. I'm currently on a DH carbon rear rim with 1.5 butted spokes and about 10 spoke tension.
From Sheldon test- The relative contribution of the following to stiffness:
I realised I didn't have any picture of my bike (after 2 seasons lol) so I took some this morning. The bike has heen welded by Egerie in France, based on a linkage file I made. The idea here is to have the chainstay length based on a front to rear center ratio. I checked that ratio at SAG on bikes I found to have good cornering characteristics. In terms of number it is 63HA, 80SA, 490mm reach, 470CS, 643stack, 15mm BB drop. The bike is full 29, 180mm front and 192mm back. The frame is atypical for a single pivot as I wanted to reduce PK to a minimum (hence the pretty rearward main pivot) and to have as much progression as possible while keeping the single pivot simplicity. It is currently in its winter guise to be pedaled (still missing the bottle and the tool holders) otherwise the dropper is removed when racing or at the park so most of summer.
I should add that the bike rides very well and is very dynamic (more than my previous GTs Force 27.5 and 29). The only moment I notice the lack of rigidity is in pretty high load type of berms, so the question is, aside from how to make it stiffer, is it worth it and could it make it worse everywhere else ?
That’s a cool looking bike! How progressive did you make it?
This much ! So slightly more than 17%.
I ride the bike with 32/33% of static SAG and a lot of compression. Makes is super dynamic and poppy (especially with the mid stroke support of a coil shock), not the best at ironing trail chater tho, and I don't have any issues with bottoming out even on big features. So far this frame has been ridden with Formula MOD (orange and green CTS), Ohlins TTX2 with all the tokens, and the VORO that a friend of mine handed to me to test. So far I am very impressed with the VORO, at least in the park, need to try to pedal with it before I settle on it or revert to another shock.
Nice! I don’t think 17% is very progressive, so I thought you were going to say that it’s much more.
Cool project, do you think you will make a second version? Will you change anything?
So there’s evidence people have been looking at, thinking about, measuring and comparing bike component compliance for years. And there’s evidence that some component and system (for example, a wheel) makers have been doing the same.
But instead of helping to create basic language and tools riders could use to compare compliance as one more factor to consider alongside all the other bike fit and performance details, every company is mining the compliance boom in the same way. Our new gen widget is more compliant (but not too compliant!) than our previous gen widget. Start tuning your ride today!
Marketing companions, check it out: i never used your previous gen widget. So the reference is not helpful. The relative improvement isn’t meaningful. And btw, all your competitors are saying the same thing.
Imagine if companies refused to post geometry and just said 5% more reach, 1% slacker head angle, and we made our front-center to rear-center ratio 25% more proportional!
🙃
17% isn't much but compared to most single pivot on the market that have 0 to 5% of progression this is a lot lol.
As an enduro bike I wouldn't change anything on it really.
As a DH bike I would use some slightly shorter chainstays (460 or 465mm) to help a little in the very steep stuff and add a little rear end stiffness (the whole point of this thread) as it is a bit lacking sometimes in high G scenarios. Other than that it is very capable as it is. If I was to use it as pur DH I would use an Ochain, double crown, DH transmission etc.
I might do a dedicated DH frame in the near future which is why I participated to this thread. If I can identify where my lack of stiffness comes from it could be addressed for the DH frame. The frame would be mid-pivot, fixed, non concentric idler, similar geometry, travel, progression and AR characteristics. The concept is pretty much ready in Linkage but I haven't pulled the trigger yet as I am considering other options.
Same goes with all the pedal kick dampers (Ochain and Rimpact, e13 new hub). For instance, did you ever see a graph, data, anything that shows in which way does pedal kick dampers actually do anything ? Yes riders tell us it does something, TEAMROBOT did an excellent video about it too. But these companies should be able to quantify what it actually does, X% less vibrations at your feet, Y% less loss of grip moments during braking situations, Z% more suspension amplitude during a given impact, etc etc.
Yet do we see any of this ? Nope, it's all "trust me bro" ... And compliance will definitely go the same route by the looks of it. Saying that, most people pick a bike based on looks and have no idea about suspension kinematics, even simple concepts like anti-squat or progression, so ... we get what we deserve I guess ?
Whoa whoa whoa don't go giving the marketing people any idea's like that.
Soon a 45mm stem will be marketed as 10% more compact than a 50mm stem.
"Now 50% wigglier steering!"
To play devil's advocate a bit I think the reason Ochain and the like don't publish hard data is obvious, it's really noisy and incredibly hard to measure it well.
Also a large part of these products are psychosomatic, placebo induced often, like hand fatigue, grip levels etc. It's a feeling that can't really be measured easily.
It's not that these events can't be measured, it's just really really hard on a MTB.
I saw some F1 telemetry the other day, and they can tell when the driver is pushing too hard from gyros on the front and rear that detect sliding from steering inputs or brake steering into corners. This requires high end gyros and g-sensors at either end of the car with super high resolution all working together to detect slides which they also use their laser thermometers trained at the tyres to measure changes in tyre temp.
Good luck trying to rig a similar setup on a MTB.
I think we'll get better at it, but it's not easy, and at the end of the day, the marketing team will say what sells anyway.
There’s definitely data out there if you look deep enough. I guess there’s many consumers who don’t care about the data and just want something that’s cool? Hopefully with new technology, it will be easier for brands to gather, sort and analyze the data.
Neko Mulally had data when testing oChain and said he saw a change in dynamic sag. This was in one of his earlier videos when testing between the high and low pivot bike.
CounterShox had data showing with and out their device showing a clear difference.
Placebo effect is not too hard to prove or bust, have a double blind experiment. Put a series of riders on bikes, with or without the ochain and ask them how they liked the performance of the bike. In order to account for the pedal feedback you could tell them they are not allowed to pedal and have the bb area covered so they can't see which type or crank they are riding. Placebo effect should give you 30% of people feeling an improvement, if ochain can do better and consistently better than standard crank, voila ! you proved that your product does something. This could also be applied to compliance testing, much more easily actually.
As to quantify it, would it not be possible to use some vibration sensors at your feet and in the grips and measure if there is a change ? Todays alarm systems for cars are super compact and can mesure vibrations and such, I doubt it would be hard to find some small enough sensor that could be rigged on a bike. Run that with a GPS and a brake sensor which are now available and I don't see why you couldn't do it. My gripe here is that most likely the companies are ot bothered trying to prove what their products does and just rely on the Bro approach.
I don't remember the video from Nekko but it shouldn't be the dutty of a consumer to prove what your product does.
And yes, for some reason the mass damper products seem very data driven so for once we may get a product that is actually back-up which is cool. At least you will know what you buy, why you buy it and what it does for you.
Right now, it looks like your main loss of stiffness is coming from the seat stays not being supported by anything other than the shock. The shock is essentially acting as a structural member of your bike, taking on twisting forces in corners. The biggest improvement would likely come from adding a small swing link to connect the seat stays to the front triangle. Your shock will thank you for it 😅.
From there, you could increase rear triangle rigidity by adding a seat stay bridge. If you want to take it even further, you could beef up the chain stay bridge or the bridge on the rear triangle in front of the seat tube. You asked about the downside? It might change the ride feel you currently like. And if you make the rear triangle too rigid compared to the front triangle, you could shift the flexing to the front triangle in high-G corners, potentially causing handling issues.
If you like the way your bike feels now but want just a bit more stiffness, I’d prioritize adding both a removable seat stay bridge and a small swing link. This setup would let you experiment with both independently. A swing link could introduce a little wag and reduce roll stiffness, but if you keep it light, it tiny/flexible minimize those effects.
One quick test you can try: sit on the rear wheel, grab your seat and swing you hips side to side on the wheel. Boom, you've created a test machine out of a human. Watch how things move and see what’s flexing the most. This can give you a better idea of whether a swing link would help.
There’s a quicker way to see if you’d like what a swing link does. You could 3D print small sliders (blue) and mount them on the seat stays. These sliders would keep a small gap between the seat stays and the seat tube (or its protector, shown in red). As the bike flexes, the sliders would hit the seat tube and act like a bumper and stop the frame from continuing to flex.
You can print and bolt them onto your bike now to test if the added stiffness feels good. It might feel a little weird while riding for other reasons, but it’s a cheap and easy way to try it out and learn if you like it or not. Some bikes already use this idea... I think Joe mentioned one earlier in this thread. It has some problems but it would be fun to try.
Ryan, those sliders are a cool idea!
Erwan, if you interested or need, I could help you print some and send them over
Someone built a steel frame incorporating the slider idea I to it. I can't recall off the top of my head who the builder is to find the IG link.
Igus sells a filament that would work well for this, now sure difficult it is to print on a consumer FDM printer.
I don't think the slider is the best approach. If anything it will just kill your shock quicker as it prys off your seattube. Just add a brace between the pivot and shock mount to make that stiff.
My frame has a pretty tight gap from rear end to seattube (1/4") and it has never touched, even with spherical bearings on the shock. Most movement or flex is rotation behind the pivot point.
A bridge behind the seattube will help and a stiffer axle interface.
I run a BMX style bolt on 135 hub with right washers to remove axle gap.
Before we ran the tighter tolerance washers, there was noticable more flex, so don't underestimate the rear axle/hub/frame interface.
There was a bike with sliders that came up recently, but also the 1st gen Intense M1, which had a strut rather than linkage activated single pivot design, used sliders. Having said that, the M1 suddenly became a lot more successful in racing when they switched to the 2nd gen without sliders, although there are other variables involved.
Im sorry I am late to this discussion, I missed where anyone brought up the topic of spoke tension and how that plays into the frame Roll and Wag.
OOOOO and rim material.
Yeah I agree with this and with @Erwan_Ghesquiere views, the companies can definitely test, but I do understand if they don't publish the data.
I think an interesting point is there isn't really an engineering or rider based objective standard of what is good or bad flex yet, we are still at the stage of figuring out whats good, let alone specifically designing for it.
In the broadest sense, everyone can agree that "wind-up" flex from a frame is undesirable, i.e the frame can wind up in a corner and spring back aggressively losing traction and control exiting corners. Also that noodling isn't wanted, where a frame flexes so you cant load it up through corners or compressions as it just deviates during the loading.
But aside from that, the jury is out. Lots of riders like stiff rides, lots like steel like muted feeling, some love hard carbon rims, stiff dual crowns, others swear by "flexy" USD forks and alloy rims for off-camber traction.
It'll be interesting as we can collect data and actually start narrowing in on desirable compliance traits
I'm not a wheel expert but I think this image can tell us something from the awesome Let's Go Racing Series. The wheel is doing a lot of weird things here. I'd need to spend some time looking into it. It's definitely doing something funky. https://www.vitalmtb.com/videos/features/Wheel-Testing-Lets-Go-Racing-Season-2-Episode-2,40149/sspomer,2
I have nothing of value to contribute but keep it coming nerds, this is so interesting to read
Road bike frame flex test. Some good images here of BB torsional movement.
World Cup DH frame modifications
I wouldn't say it's doing weird things here, but it does look weird. It's "just" flexing. But it does look a bit hectic.
It's a perfect illustration as to why frame compliance and wheel flex is important.
The way I think about it is this (could be totally wrong), he's pushed aggressively hard into the corner, the front is tracking perfectly as it has an axle to pivot on (the fork) and thus flex isn't really an issue up front.
The rear wheel of a bike/motorbike will always understeer in a corner, which is an issue in berms, as it means the rear wheel always takes a lower line in a berm with less support (if the bike is only angled and the front wheel not turned there won't be understeer fyi, it's the act of the front wheel being turned creates understeer). He pushes into the corner to generate grip and speed and starts to exceed to limit of grip on the rear and it will slide up the berm until it can grip enough to stop sliding (a schralp as we say). On the more angled part of the berm the tyre gets more support (grip) and stops sliding, but the sideways moment of the slide has to go somewhere now, the tyre stops moving but the force hasn't gone, so we see the frame (imagine it from the axles perspective) continue to move past the contact point of the tyre from this momentum. Now we have a few options, either the rear triangle flexes to absorb this, or the spokes do. Both are good, as it means the tyre can stay happily stuck to berm, the issue is if when this flex occurs, since it's a spring, on corner exit when the load is gone, it violently whips back and forces the tyre to ping to the riders right-hand side and lose grip.
Imagine the counterfactual, if the frame and wheel don't flex here, his sideways momentum will continue to drag the rear tyre up the berm, even though the tyre has enough grip now. Because the energy has to go somewhere. If it's not absorbed by the spokes and rim and rear triangle it will be translated into the tyre and cause a slide. You probably won't crash, but you will schralp harder and destabilize the front of the bike by pivoting so much and probably have to counter steer the front tyre to account for now large amounts of oversteer, which is slower, and harder.
It's this harmony between wheel flex and frame flex that makes a nice tracking bike, some rear triangle flex allows a more skateboard like approach to cornering where the rear can track closer to the front tyre path. A few high end cars have rear wheel steering to achieve this.
It goes to far when you get crabbing however, particularly from g-outs the rear triangle can want to move sideways and kinda spear you off trail.
How to engineer this all? Well that's for Ryan to figure out haha. I know a bit about wheel building though to help it.
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