Wheel Cornering Performance

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ft_critical
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Wheel Cornering Performance

Postby ft_critical » Sat Jul 14, 2018 10:54 am

Hi gang,

Any good articles on wheel cornering performance that you could refer me to? Most of the focus is aero, weight, durability....

Great to get opinions too?

I have had all sorts of wheels, but my current race wheels are Campagnolo Neutrons (low profile, 1450g for the set, 22/24 spokes, clincher, running Michelin Pro tyres) and TWE Carbon Clinchers (45mm, ~1550g, sapim spokes 28/32, clincher, Michelin Pro tyres). I am 73-76kg depending and run the tyres at between 90 and 105psi.

So my comparisons are:
Crit hotdog corner and fast downhill corners.

- I find the aluminium Neutrons flex and grip better, enable more precise cornering.
- The Carbon TWE are so stiff that they tend to skate, indeed I have slipped them in a crit twice.

Overall, for both road racing and crits I would rate the Neutrons better. I truly don't notice the aero impact. In a sprint I can feel the Neutron flex, but to be honest, that keeps it on the road more, whereas the TWE wheel skips more.

Thoughts? Love to hear others experiences with other wheels, carbon low-profile. I read a review of the Mavic SLR wheel which said it was a poor handling wheel relative to newer wheels - not sure what that means. Are there any super handling wheels out there on the market?

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foo on patrol
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Re: Wheel Cornering Performance

Postby foo on patrol » Sun Jul 15, 2018 9:41 am

ft_critical wrote:Hi gang,

Any good articles on wheel cornering performance that you could refer me to? Most of the focus is aero, weight, durability....

Great to get opinions too?

I have had all sorts of wheels, but my current race wheels are Campagnolo Neutrons (low profile, 1450g for the set, 22/24 spokes, clincher, running Michelin Pro tyres) and TWE Carbon Clinchers (45mm, ~1550g, sapim spokes 28/32, clincher, Michelin Pro tyres). I am 73-76kg depending and run the tyres at between 90 and 105psi.

So my comparisons are:
Crit hotdog corner and fast downhill corners.

- I find the aluminium Neutrons flex and grip better, enable more precise cornering.
- The Carbon TWE are so stiff that they tend to skate, indeed I have slipped them in a crit twice
.

Overall, for both road racing and crits I would rate the Neutrons better. I truly don't notice the aero impact. In a sprint I can feel the Neutron flex, but to be honest, that keeps it on the road more, whereas the TWE wheel skips more.

Thoughts? Love to hear others experiences with other wheels, carbon low-profile. I read a review of the Mavic SLR wheel which said it was a poor handling wheel relative to newer wheels - not sure what that means. Are there any super handling wheels out there on the market?


I find this part of your statement odd? :? Grip in the road is governed by tyres and how you corner. If, you are riding a a course where the surface is rough, then you should be dropping the pressure a little to compensate for chatter. :wink:

Frame geometry would have more impact on how your bike behaves on these surfaces = a nervous geometry would be more twitchy than a less so one. Me personally I prefer a tight frame to a lazy one for racing due to reaction to powering up when kicking but that's me. :wink:

Foo
Last edited by foo on patrol on Sun Jul 15, 2018 10:12 am, edited 1 time in total.
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10speedsemiracer
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Re: Wheel Cornering Performance

Postby 10speedsemiracer » Sun Jul 15, 2018 9:53 am

I'm with foo on this, but from a different perspective. A stiff wheel is less likely to flex under load/climbing etc thereby avoiding the likelihood of brake rub (at the worst possible time i.e. while accelerating or climbing).

I'm also guessing you're mainly concerned with lateral stiffness, or the amount of sideways deflection in the wheel. Radial stiffness etc isn't going to result in what you're describing.

If the TWE's skate with Michelin Pro's, I'd be looking at a softer compound tyre. But then I could be misinterpreting what you're experiencing or describing, and also I still think the Mavic CXP30 was one of the best wheelsets I ever had, so don't worry about me I'm going slightly senile..
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madmacca
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Re: Wheel Cornering Performance

Postby madmacca » Sun Jul 15, 2018 6:34 pm

One possibility is that the internal rim width is different between the wheels.

This will affect the shape of the contact patch and tyre volume, which will affect handling.

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Re: Wheel Cornering Performance

Postby Derny Driver » Sun Jul 15, 2018 6:50 pm

Wheels that are too stiff eg Zipp 808s or too flexible eg 16- 24 spokes are both terrible for criterium racing.
Crit races require traditional aluminium spoked wheels with 32-36 spokes.
A 180 degree turn in a hotdog crit can be ridden with whatever wheel you like. A fast 90 degree turn is a different matter.
But you are asking for data on wheel performance ...errr, what a silly question. The data only exists for weight, appearance, aerodynamics. Manufacturers (and buyers) dont give a rats about performance.

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Re: Wheel Cornering Performance

Postby trailgumby » Sun Jul 15, 2018 9:13 pm

I hear what you're saying on flex. Given that you have no suspension, flex has to take its place.

There are similarities to karting and - back in my uni days - racing 1/12th scale RC model cars before lightweight suspension designs became a thing. Back then, we all relied on flex in the thin plate epoxy fibreglass chassis for compliance and grip. Once, one of the quick guys turned up with a (then) new-fangled CF chassis thinking he'd cream everybody with his lightweight missile. Much to everyone's amusement, the thing was way too stiff and had no compliance, even on the relatively smooth carpark surface on which we were racing. It wouldn't go around corners.

Now that's not to say that means CF is a bad thing for your purposes for bike wheels, merely to point out it is possible to have too much of a good thing (stiffness). Depending on the alloy, aluminium can be stiffer than CF.

You could try lowering pressures. At your weight they seem excessively high to me. At 80kg, I top out at 85psi on the rear and 80 at the front with 700x25. Anything over that and it starts to feel harsh for no improvement in rolling resistance and a dramatic loss of cornering confidence. Whether the lower pressures will compensate for loss of wheel flex will depend on how well things like flex amplitudes, harmonics, and response speeds match to the irregularites in the track surface.

You could also try carbon wheels with a lower spoke count. The challenge is that trial and error to find the right combination is expensive and time consuming unless you can borrow lots of different gear to try out.

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ft_critical
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Re: Wheel Cornering Performance

Postby ft_critical » Tue Jul 17, 2018 6:03 pm

Thanks. DD of course picked up the issue, there is no reporting on performance beyond weight and aero. Indeed I am talking about cornering under high load, a 90 degree Crit corner - exactly.

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Re: Wheel Cornering Performance

Postby ironhanglider » Wed Jul 18, 2018 10:40 pm

I've experienced differences in cornering performance that I've put down to stiffness, but it wasn't grip that suffered, but tracking.

I inherited some CX-ray spokes that a shop was virtually giving away because they were really long (300+mm) and the people that need spokes of that length usually don't want high performance aero spokes. A combination of some work with a spoke calculator, and a decent collection of spares etc and I was able to use them in a 36 spoke really shallow tubular rim laced 4x. This was my spare wheel, compared to my 2x spoked Mach 2 rim on my race wheel. One day I needed to use my spare in a crit and I could not believe the difference in cornering. I had no problems with absolute grip, but I did have issues with keeping the wheel on line. It would just walk off the line I had picked for the corner, similar to the effect when your tyre pressure is too low. I didn't have any fear of sliding out, but I did find myself in the gutter a couple of times.

I am more familiar with cornering performance degradation with increased tyre pressure, which scares me much more.

Cheers,

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Duck!
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Re: Wheel Cornering Performance

Postby Duck! » Thu Jul 19, 2018 9:54 pm

What I have found, with both road and MTB use, is that aluminium rims are typically softer against relatively low-frequency forces such as direction changes and large bumps, so depending on how you're perceiving the situation can feel either vague or stable and compliant, because the rims as well as the tyres are providing some degree of suspension.... However they tramsmit more of the fine higher frequency road buzz.

Carbon on the other hand are quite stiff against the lower-frequency forces, leaving the role of compliance much more in the tyres. This can feel really sharp and direct, or skittish, depending on your perspective, especially with mid-corner bumps. However the composite layup is better at absorbing the higher-frequency buzz, and takes the shock off bigger bumps; you still feel them, but there's less sting in the hit.
I had a thought, but it got run over as it crossed my mind.

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Re: Wheel Cornering Performance

Postby CKinnard » Thu Jul 19, 2018 10:33 pm

If you want a reliable wheel for sprinting, take a leaf out of Mark Cavendish's book. He's been riding ENVE SES 4.5 for the last 2 years in the GTs, and is fast approaching a new record for stages won.
https://enve.com/products/ses-4-5/

As for what maintains traction better through corners (wheel or frame flex; tire pressure, friction, contact patch and shape, temperature: center of bike and rider mass; trail) you could tie yourself in knots.
I'd be careful concluding that a more flexible wheel maintains better traction through a corner. For that to be true, the flex would have to build smoothly into the corner and be released smoothly coming out. Any deviation from smooth loading of flex energy into the wheel will compromise traction. It is difficult to imagine such an ideal scenario, and any roughness on the road surface is going to make that wheel flex compromise traction.

I'd prefer a stiffer wheel with 25-28mm hot tires at 80-90psi and optimized center of gravity to get me through a corner at higher speed.
Rely on the tires and CoG to optimize traction, not wheel (or frame or fork) flex.

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foo on patrol
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Re: Wheel Cornering Performance

Postby foo on patrol » Fri Jul 20, 2018 12:04 am

I have a set of Craftworx 30mm CF singles and have no problems with them on the Tri course that we do up here. Deeper rims will be stiffer than the ones that I have but in saying that. I also run 88mm CF rims on that course also with no problems and we are for every turning and jumping on the brakes hard for corners and bloody round a-bouts. :wink:

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cerb
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Re: Wheel Cornering Performance

Postby cerb » Sun Jul 22, 2018 8:41 pm

madmacca wrote:One possibility is that the internal rim width is different between the wheels.

This will affect the shape of the contact patch and tire volume, which will affect handling.


I reckon this is the answer to the difference in performance you are feeling.

Matching the tire to the rim size can give you a much smoother tip through the turn. A wide tire on a narrow rim makes a bulbous shape and once you get to a certain angle, it tips in faster. If you are used to this, it can make for a nice nimble feeling.

However, the same tire on a wider rim gives a smoother profile and there is no change in the progression as you lean the bike in. If you aren't used to it, you end up under-steering. But once you are used to it, it is much smoother, more predictable and therefore safer.

I've raced on fulcum racing 5's, custom velocity aerohead rims with 32f/36r, Roval CL45's, Campag Eurus & SwissSide Hadron 60's. My experience only relates to crit racing, but for 90 degree corners above 50kph, they all cornered about the same. The only notable difference in cornering was due to the tire width/rim width combo and the smoothness of the lean-in progression. Their other characteristics were all quite different though.

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Re: Wheel Cornering Performance

Postby ft_critical » Tue Jul 24, 2018 7:58 am

Great responses thanks. I do ageee that there are so many variables it is hard to know. It does seem logical to me that rim profile, spokes and spoke count would impact stiffness and flex under load though. There should I would think be a a difference in cornering performance resulting I would imagine. My wheels seemed all primarily designed for 23mm tyres.

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