Zwift Chat

[CXRAndy]

Actually Paul Enve have some wide rim aero wheels which are designed specifically to 28mm. The profile smooths out the bead joint. This and the fact that running 50-60 psi allows the tyre to roll smoothly over all the crappy surfaces. Once over 28mm the wider tyre frontal area impacts on aero gains

 

[JuhaL]

One of my friend have a Canyon Ultimate CF road bike and now he have a cycle-cross tyre on that bike. Don't remember is it 32mm or wider but very versatile bike for both gravel and road.

 

[Ming the Merciless]

I'm not sure anyone claims wider tyres are more aero do they?

Depends. There’s a guy who has come from F1 and it is not just frontal drag. There is also what is calling the sailing affect which pushes the bike forwards depends on wind angle. So depending on rim / tyre interface it can be more aero depending on the wind yaw.

Of course you can always get a smaller diameter front wheel which will be more aero but less of the sailing effect.

But then bike aero claims have to be put into context as most (other than recumbents) do not put the rider in an optimised aerodynamic position. As this picture below demonstrates if you are focused on the bike tyres first for aero you are looking in the wrong place.

 

[bridgy]

Actually Paul Enve have some wide rim aero wheels which are designed specifically to 28mm. The profile smooths out the bead joint. This and the fact that running 50-60 psi allows the tyre to roll smoothly over all the crappy surfaces. Once over 28mm the wider tyre frontal area impacts on aero gains

So putting aside rolling resistance, are you saying that a 23mm tyre on an aero rim which is also just as optimised to smooth out the bead join would be less aero than a 28mm (or 25mm) tyre/rim combo?

 

[bridgy]

Depends. There’s a guy who has come from F1 and it is not just frontal drag. There is also what is calling the sailing affect which pushes the bike forwards depends on wind angle. So depending on rim / tyre interface it can be more aero depending on the wind yaw.

Of course you can always get a smaller diameter front wheel which will be more aero but less of the sailing effect.

But then bike aero claims have to be put into context as most (other than recumbents) do not put the rider in an optimised aerodynamic position. As this picture below demonstrates if you are focused on the bike tyres first for aero you are looking in the wrong place.

View attachment 502997

Yes good point, and no I'm not focussing first on tyres for aero gains - just querying the claim that wider tyres are more aero (all other things being equal). Worth making the point you did though

 

[Milzy]

Actually Paul Enve have some wide rim aero wheels which are designed specifically to 28mm. The profile smooths out the bead joint. This and the fact that running 50-60 psi allows the tyre to roll smoothly over all the crappy surfaces. Once over 28mm the wider tyre frontal area impacts on aero gains

You beat me to it. Was on GCN show about 2 years ago.

 

[Randyberlin]

Yes good point, and no I'm not focussing first on tyres for aero gains - just querying the claim that wider tyres are more aero (all other things being equal). Worth making the point you did though

When I had a breakdown in Glochester and the British Olympic bronze medal winner Graham Brookhouse was at the bike shop we talked about this. Notice my name dropping there? He saw I was using g gatorsskin 28s and said they were more aero than 23s. He now focuses on iron man tri races and he said even a few watts saved makes a big difference over 112 miles.

 

[bridgy]

Hmmm I'd be interested to read any links you guys have to any articles on this?

I feel we might be confusing faster with more aero. Not necessarily the same thing.

Everything I've read says wider tyres - when optimised for aerodynamics by fitting to a wider rim - can be faster due to the better rolling resistance. But if you had narrower tyres that were also on optimal rims for aerodynamics, they would still be more aero (but not necessarily faster).

I'm no expert at all though and interested to learn more...

 

[CXRAndy]

So putting aside rolling resistance, are you saying that a 23mm tyre on an aero rim which is also just as optimised to smooth out the bead join would be less aero than a 28mm (or 25mm) tyre/rim combo?

In ideal road conditions or laboratory testing, high pressure, narrow tyres are the fastest. In real world, crappy roads wider tyre optimised to the rim are proven to be a little more aero

Also the pneumatic benefits for a more comfy ride, allows rider to sustain higher effort, not worn down with vibration

View: https://youtu.be/yrHxQg1OW0A

 

[JuhaL]

Not an expert either but wheels profile effect also and rolling mass. Light weight is better and faster if we talk about tyres. Narrow tyre could be more aero but something tells me that rolling resistance matters more than tyres aerodynamic qualities.

 

[bridgy]

In ideal road conditions or laboratory testing, high pressure, narrow tyres are the fastest. In real world, crappy roads wider tyre optimised to the rim are proven to be a little more aero

Also the pneumatic benefits for a more comfy ride, allows rider to sustain higher effort, not worn down with vibration

View: https://youtu.be/yrHxQg1OW0A

But Andy that video makes exactly the point I've been making!

Narrower tyres are more aero - he specifically makes that point in the video - even though wider tyres can be faster due to rolling resistance in real world conditions. When people say wide tyres on wide rims are more aero they mean more aero than wide tyres on narrow rims, not more aero than narrow tyres on optimal narrow rims. But even if they are more aero they may not be faster which is what I have been saying

 

[bridgy]

Not an expert either but wheels profile effect also and rolling mass. Light weight is better and faster if we talk about tyres. Narrow tyre could be more aero but something tells me that rolling resistance matters more than tyres aerodynamic qualities.

Yes agreed. All I said was wider aren't more aero than narrow (all things being equal). But despite this, yes they can be faster

 

[bobinski]

Aero? Isn’t the key to optimise yourself first? Get a bike fit, get flexible enough to go lowish, clothing,helmet, perhaps some narrower bars THEN look at wheels, tyres etcIts all cheaper and easier to get big gains before delving into the murky world of manufacturers claims. There was a good gnc vid about this a few years ago. Once you have optimised yourself then you might get another km an hour from decent aero wheel/tyre combo.

 

[<Tommy>]

I think from memory most tests concur 23mm front 25mm rear with matching rim width is the best combo.

 

[CXRAndy]

Rider equates by far the biggest element of drag.