Road Feel: Low Profile vs 45mm Depth Wheels

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RyanH
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by RyanH

So, while perusing the Lightweight thread, it was briefly derailed by a discussion on road feel between low profile vs deeper profile rims and that it was more or less a myth. Rather than derail the thread further, I wanted to open the discussion about perceived ride quality differences between different profile rims.

  • Is there a difference in the quality of the ride?
  • Follow up question: if there is a real (not imaginary) difference in road feel, could this be due to bracing angles and such with the spokes leading to a difference in ride quality?

Anecdotally, having owned Enve 25's, Reynolds 32's and Reynolds 46's and ridden them side-by-side with Continental Sprinters on all (all were DT Swiss hubs, btw), with each pumped to my usual 95 psi, the second I hit broken pavement (or chip seal), the 32's and 25's are night and day more comfortable than the 46's. I'd like to chalk it up to my imagination as some would suggest, but personally, I'd love to ditch the lower profile rims in favor of the 46's since I don't like how the lower profile rims flex on hard out of saddle sprints, but every time I put the low profile rims back on, I go "oh ya, that's why I keep these."

eric
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by eric

I find the deeper rims to ride a little rougher though not enough ti disuade me from using them. But to me there's not much of a difference between clinchers and tubulars, while other people rave about the ride of tubulars. Maybe my butt caluses are too thick. Or I am a skeptic and there's really not that much of a difference. I do notice 5psi in the tires though.

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tymon_tm
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by tymon_tm

I also find deeper rims/wheels harsher, but also stiffer, and thus - faster. I like that feeling so much, I use low-pros only for salty winter riding and really nasty rains.
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sawyer
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by sawyer

What I think can be felt is the deeper rim catching the air as it's moved side to side - for example when standing and throwing the bike a bit side to side, and it is this that gives low profile rims their light flighty feeling as though "nothing is there"
----------------------------------------
Stiff, Light, Aero - Pick Three!! :thumbup:

RyanH
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by RyanH

I skimmed through the research paper but I think their conclusion suggest otherwise:

"The present work shows that different wheel models equipped with the same tubular tire inflated at the same pressure can show different vibrational response to road roughness excitations. The ranking between comfort properties of different wheels varies with the road surface and the cruising speed considered."

Source: Department of Mechanical Engineering, University of Padova, Via Venezia 1, 35131 Padova, Italy
Procedia Engineering 01/2012; 34:409–414. DOI: 10.1016/j.proeng.2012.04.070

A method for evaluating the vibrational response of racing bicycles wheels under road roughness excitation - ResearchGate. Available from: http://www.researchgate.net/publication ... excitation [accessed Mar 24, 2015].

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by stormur

And did they need to make research for that ? Awesome ! Next week they'll reinvent the wheel :mrgreen: I wonder only how much € of EU grants went to that "project" :wink:

Higher profile - higher stiffness, less "damping" / "flexing" properties. However 2 different wheels with everything same except rims can behave different - depends on engineering ( fiber type, direction, amount , profile, resin, molding technology ).

Stuff known… 20y :?:

If someone want to check something, change spokes from bladed to double butted round ( revolution F +R NDS, Competition for DS. Tension to same specs as it was on Aero/ CXray , take a ride with sprints, up & downhill , hard cornering- and write review ;)
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by BeeSeeBee

^ stuff that's been "known" for eons that come under scrutiny has certainly been debunked before, so I welcome all research.

e.g. aerodynamics of shaving legs, the impact of rotational weight in climbing, "pulling up" with clipless pedals, etc. Now we're starting to challenge the conventions of other things like frame and wheel comfort, aerodynamics, etc. I'd rather explore things than rely on the magic and mysticism of yore this industry is rife with.

The "Higher profile - higher stiffness, less "damping" / "flexing" properties" you mentioned (I assume you're talking about radial stiffness as a function of comfort) are the very things that are being challenged. Watch the Zipp video, the rim seems to deflect more than the spokes do, and a lower profile rim simply wouldn't have the room to deflect. This is obviously an extreme example, but again, things that are "known" are often just bullshit passed between cyclists relying on imperfect perception and bias.

RyanH wrote:I skimmed through the research paper but I think their conclusion suggest otherwise:


I read that as the ranking by their comfort index, not by anything related to perceptibility, strictly by measurement results.

The plots on the 5th page don't seem to indicate to me that there's much of a difference across different rim or spoke materials, rim profiles, and spoke lacing. Their explanation of the comfort index was over my head though, so if anyone is able to better discern what it means in laymen's terms, I'd welcome it.

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kgt
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by kgt

It is true the Procedia Engineering paper is not that illuminating. OTOH the videos by Zipp or Enve do not prove anything. Zipp rims respond like that (absorb energy) while other, stiffer rims (see Enve) would respond otherwise. In fact these ''impact'' tests have nothing to do with the physics of a wheel rolling on the tarmac.
So the answer on comfort vs profile is: it depends. IME low profile wheelsets usually feel more comfortable than high profile.

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by 964Cup

I think it's mostly nonsense. The difference in feel will come from spoke lacing (radial is vertically stiffer than crossed), spoke count, rim weight and aerodynamic effects. I run Mavic R-SYS SLR and Zipp 404s on my R5, both with Pave tubs in winter. In principle the R-SYS should be *much* stiffer, with carbon spokes and an alloy rim. In practice the ride comfort is identical; there's obviously a difference in wind resistance. I'm less confident descending on the 404s because of their sensitivity (relative to the Mavics) to crosswinds, but obviously they make it easier to go fast.

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by HillRPete

stormur wrote:If someone want to check something, change spokes from bladed to double butted round ( revolution F +R NDS, Competition for DS. Tension to same specs as it was on Aero/ CXray , take a ride with sprints, up & downhill , hard cornering- and write review ;)

Because review always trumps research, right?

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by BeeSeeBee

^ :beerchug:

964Cup wrote:The difference in feel will come from spoke lacing (radial is vertically stiffer than crossed)


Look at the Reynolds link above, the difference between radial lacing and 4X was .0104mm at 1000Nm of force.

kgt wrote:It is true the Procedia Engineering paper is not that illuminating. OTOH the videos by Zipp or Enve do not prove anything. Zipp rims respond like that (absorb energy) while other, stiffer rims (see Enve) would respond otherwise. In fact these ''impact'' tests have nothing to do with the physics of a wheel rolling on the tarmac.
So the answer on comfort vs profile is: it depends. IME low profile wheelsets usually feel more comfortable than high profile.


I actually think the Procedia paper is quite enlightening because it speaks to your point about the physics of rolling on different road surfaces, in which it doesn't appear that instrumentation can measure dramatic differences in what people would consider to be very different wheels. I posted the Enve and Zipp videos not as a demonstration of what happens on the road, but to show the difference in tire deflection (which I would agree has an impact on comfort) and how little rim deflection there is relative to it.

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by RyanH

Well, one of my questions I was going to ask: how do the RZRs ride comfort-wise due to their low spoke tension, is answered by Roues Artisanales' study. They noted that the Lew's (the original RZR design) deformed 1mm per 75-80kg and have "...pleasant and unusual ride qualities."

Here's an excerpt from the study:

"As summary, a rear wheel with a shallow rim, with low tensioned spokes, will vertically be easier to deform than a deep rim wheel with high tensioned spokes. The deformation is about 1mm per 140kg (rear Lightweight, rear Sonic 50mm, rear Speedcomposites), to 1mm per 200kg (front Mavic CCU, front Corima Aéro, etc) or 1mm per 260kg (front Zipp 404, Lightweight front)."

Full report here:

http://www.rouesartisanales.com/article-23159755.html

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dmulligan
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by dmulligan

This is a great article on the topic of wheel stiffness and debunks many of the myths surrounding them. http://www.slowtwitch.com/Tech/Debunking_Wheel_Stiffness_3449.html

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