Frame compliance article

[mcteague]

Interesting reading!

Here is a taste:
Riders often like to say that certain wheels ride stiffer or softer than others (and I’m sure I’m guilty of saying the same thing in the past). But the reality is that wheels, regardless of how they’re made, contribute very, very little to the overall ride quality of a bike.

https://cyclingtips.com/2018/04/jra-with-the-angry-asian-does-frame-compliance-still-matter/

Tim

[KarlC]

Interesting reading!

Here is a taste:
Riders often like to say that certain wheels ride stiffer or softer than others (and I’m sure I’m guilty of saying the same thing in the past). But the reality is that wheels, regardless of how they’re made, contribute very, very little to the overall ride quality of a bike.

https://cyclingtips.com/2018/04/jra-with-the-angry-asian-does-frame-compliance-still-matter/

Tim

Sorry I completely disagree, I dont know how they can say that with a straight face.

My Reynolds Aero 58 / 72 give a stiffer ride that my Zipp 404 Firecrest and my Mavic Cosmic CXR 80, all are tubular. This is with testing on the same roads with the same tires, same PSI and the same bike.

.

[ergott]

One interesting note about carbon. Zipp did a whole thing about the sidewalls of their rims giving some compliance. I haven't seen anything measuring that or comparing it to similarly deep rims.

In the past wheel compliance was typically ruled out since there's essentially no rim compression. If Zipp built in some compression, I'd like to see it quantified.

[Ken Robb]

If wheels flex enough for us to feel differences in ride what effect does the flexing have on the metal fatigue/life expectancy of the rim?

[El Chaba]

I'm sure that the wheels flex, but the flex is several orders of magnitude less than that of the saddle and tires....and an order of magnitude less than the bars/stem and frame....

[ergott]

If wheels flex enough for us to feel differences in ride what effect does the flexing have on the metal fatigue/life expectancy of the rim?

No less lifespan than a frame that is constantly flexing.

[Black Dog]

One interesting note about carbon. Zipp did a whole thing about the sidewalls of their rims giving some compliance. I haven't seen anything measuring that or comparing it to similarly deep rims.

In the past wheel compliance was typically ruled out since there's essentially no rim compression. If Zipp built in some compression, I'd like to see it quantified.

That compliance was measured for severe shocks, specifically for Paris Roubaix.

[Tickdoc]

Arghh...too many vaiables.

Articles like this make my brain hurt.

https://i1.wp.com/doblu.com/wp-content/uploads/2009/08/youngfrankenstein4500.jpg

[Ralph]

Not sure of the science.....but my 32 spoke light weight alloy rim wheels (IRD rims) ride softer than my Campagnolo Zonda's....same tires and approximate air pressure. Not going to argue about it, but I know the difference.

[Mark McM]

That compliance was measured for severe shocks, specifically for Paris Roubaix.

Exactly. One of the reasons that carbon rims were shunned by racers at the cobbled classics was fear that the rim would shatter if they hit something hard enough for the tire to bottom out. The compliance was added reliability to keep the rims from shattering, not for ride compliance.

[ergott]

That compliance was measured for severe shocks, specifically for Paris Roubaix.Yes and very much what I'd like to know more about. Our NE roads are aweful and we experience severe shocks like that on a regular basis.

Sent from my SM-G950U using Tapatalk

[Mark McM]

Yes and very much what I'd like to know more about. Our NE roads are aweful and we experience severe shocks like that on a regular basis.

Josh Poertner (former engineer for Zipp) talked about Zipp's work in making carbon aerowheels excepted for racers at Paris-Roubaix in his blog:

https://silca.cc/blogs/journal/115178628-road-to-roubaix-the-complete-story

[colker]

shock absorbing and flex are two different things.

[Heisenberg]

Echoing the (long/semi-tedious) article, ride quality is a reductionist argument. Start with the tires. Then the wheels. Then the frame (if tire size is a relative constant). **** tires - especially **** tires inflated to 100psi - will ruin the ride quality of any bike. I was once sent a demo bike (off-the-rack carbon race bike of decent quality) equipped with tragically cheap Kenda OE rubber, and the resulting ride was awful (unrideable?), even with pressures vastly reduced. I swapped to a set of Vittoria Corsas, and the bike's behavior changed in an enormously visceral way. That companies still send out demo/review bikes with garbage rubber is beyond me (amusingly, RKP thought the exact same bike/tire setup was the bee's knees).

Anyway, James brings up some interesting points about frame sizing and ride quality (not all sizes ride the same) that I've done a lot of pondering about. I found the idea of custom-butted Ti framesets intriguing (eg, from a builder like Baum), lending credence to the notion that the actual materials themselves are designed around an individual's riding style, preferences, weight, and power output (hence, they're $$$). Of course, manipulation of metal only goes so far, and the holy grail of ride tuning comes from carbon. Unfortunately (and this is coming from my extremely limited perspective as a total non-engineer), it seems that building a truly custom carbon frame that's tuned precisely for an individual rider (to the same level as a custom-butted metal bike) - and on the same technical level as a mass-produced Trek or Specialized - is nigh-on-impossible, from a logistical perspective. The only brand I ran across that could possibly pull it off, technically, is Festka, but methinks they still have a long way to go before getting there.

One interesting note about carbon. Zipp did a whole thing about the sidewalls of their rims giving some compliance. I haven't seen anything measuring that or comparing it to similarly deep rims.

In the past wheel compliance was typically ruled out since there's essentially no rim compression. If Zipp built in some compression, I'd like to see it quantified.

I completely disagree with James' assessment that wheels present minimal impact on ride quality/compliance. A pair of harsh/overly stiff (as I think most carbon hoops are) wheels can beat the hell out of the rider, even on a compliant frame/tire setup (Fun fact: a pair of really laterally stiff EPS wheels [Knight/Alto] can really expose the deficiencies in a frameset). I don't really think that Zipp could demonstrate improved ride quality from the damage-deterrent compression engineeered into the rims. I think that's more like high-speed compression damping vs. low-speed.

I'd still assert that Corima makes the most comfortable and well-riding rims on the market, in spite of their other faults and lack of technicality.

[Mark McM]

shock absorbing and flex are two different things.

True - but a material must flex to be able to absorb shock. This is because in order to dissipate mechanical energy, mechanical energy has to be transferred into the material (i.e., the material must be flexed). No flex, no shock absorption.

[Mark McM]

I completely disagree with James' assessment that wheels present minimal impact on ride quality/compliance. A pair of harsh/overly stiff (as I think most carbon hoops are) wheels can beat the hell out of the rider, even on a compliant frame/tire setup.

This is a common perception amongst riders. But few of these riders have actually tested this. What I mean is a real test - one in which rider perceptions are controlled for, by doing a blind test. Frequently, test subject experience what they expect to experience (whether or not there are physical justifications to support that experience). Blind testing can help remove expectation bias. When blind testing of wheel compliance has been performed, riders typically find that they can't actually distinguish between the compliance of different wheels. Here's an excerpt from an interview with Josh Poertner (https://www.slowtwitch.com/Tech/Thoughts_on_science_perception_4571.html), who conducted blind testing of wheels using professional racers:

We ran blind wheel tests a couple of times a year at Zipp to benchmark competitive wheels and our own prototypes, and we also found that blinded riders were generally unable to tell the difference between stiffness and inertia, had no reliable feedback on weight, lateral stiffness, or comfort in general, and in the end were generally only able to pick out the aero wheels because they were riding laps around a closed park environment using power, so the more observant ones would notice speed differences. In the end, we sort of determined that when riders didn't know what they 'should' feel, they really struggled to find differences in stiffness, compliance and weight between frames or wheels.

[Heisenberg]

This is a common perception amongst riders. But few of these riders have actually tested this. What I mean is a real test - one in which rider perceptions are controlled for, by doing a blind test. Frequently, test subject experience what they expect to experience (whether or not there are physical justifications to support that experience). Blind testing can help remove expectation bias. When blind testing of wheel compliance has been performed, riders typically find that they can't actually distinguish between the compliance of different wheels. Here's an excerpt from an interview with Josh Poertner (https://www.slowtwitch.com/Tech/Thoughts_on_science_perception_4571.html), who conducted blind testing of wheels using professional racers:

I don't disagree with his assessment. I should've qualified my statement - most carbon wheels pretty much ride...the same. In a straight line. There are outliers that ride particularly well and some that ride particularly terribly.

Speaking from experience, professional cyclists are usually the worst cohort to use for blind taste tests. Unfortunately, they're convenient.

[Black Dog]

This is a common perception amongst riders. But few of these riders have actually tested this. What I mean is a real test - one in which rider perceptions are controlled for, by doing a blind test. Frequently, test subject experience what they expect to experience (whether or not there are physical justifications to support that experience). Blind testing can help remove expectation bias. When blind testing of wheel compliance has been performed, riders typically find that they can't actually distinguish between the compliance of different wheels. Here's an excerpt from an interview with Josh Poertner (https://www.slowtwitch.com/Tech/Thoughts_on_science_perception_4571.html), who conducted blind testing of wheels using professional racers:

Thank you for saying this. Anecdotal evidence is only evidence of an anecdote. Perception is not reality and humans are a poor testing device. The reality is that comments like "spins up faster" and "smoother ride" are hard to accept in the complete absence of supportive evidence and under the mass of evidence to the contrary.