Noticed that in some of the hillier IMs like France/Whistler/Lanzarote/etc, some Pros are choosing not to ride a disc wheel, and some of those Pros are supposed to be very knowledgeable including ex pro cyclist.
I know that unless it’s a steep uphill only TT, disc wheel should always be faster, but curious on why they are making that decisions to not ride with a disc.
Could it be just the weight difference? Dif seems to be aprox 350gr when comparing to a light 60mm profile rear wheel, so not significant considering the aero benefit of a disc.
Other factors?
wind? for most people it’s the front wheel depth that is important for wind stability, and also from those hillier IMs seems only Lanzarote is the one that have the wind factor.
It would depend on how you had to come down those big climbs. If it were a super twisty mountain road, with bad road surface, I would opt for a non disc wheel. I just remember even on flat courses with tight turns, having that disc slip out when cornering. A few turns is no big deal, but if you had 100’s, then all that braking might add up to negating the advantage. All depends on your skills too…
Have you never ridden a disc before? Just spin one in your hands sometime and then turn it, see how much more it fights you than a regular wheel. Also discs are typically stiffer wheels, so when you get to max lean on a turn, it does not give like a less stiff wheel would, thus breaking loose a tiny bit earlier…
Now I get you’re probably talking about established pros here but I can speak for myself and say that as of now I won’t be running a disc at Eagleman 70.3 which is dead flat and maybe just a little windy. Not because I don’t want to run one but simply because I don’t have/can’t afford one at the moment. I ran an aerojacket on my Chinese 88mm on my previous bike but now that I have disc brakes and no wheel sponsor I’m kind of SOL on the wheel front. I imagine that might be the case for some others as well.
Noticed that in some of the hillier IMs like France/Whistler/Lanzarote/etc, some Pros are choosing not to ride a disc wheel, and some of those Pros are supposed to be very knowledgeable including ex pro cyclist.
I know that unless it’s a steep uphill only TT, disc wheel should always be faster, but curious on why they are making that decisions to not ride with a disc.
Could it be just the weight difference? Dif seems to be aprox 350gr when comparing to a light 60mm profile rear wheel, so not significant considering the aero benefit of a disc.
Other factors?
wind? for most people it’s the front wheel depth that is important for wind stability, and also from those hillier IMs seems only Lanzarote is the one that have the wind factor.
Let’s take one example from those Pros I’m talking about.
C. Wurf in IM France, and if I’m not mistaken also in Cannes triathlon few weeks ago.
He do have a disc and equipment available, as he have used it for other races.
And my understanding is that at least in cycling, he’s very knowledgeable and have done testing with experts and top pro cycling team.
I ride a disc for virtually every race. I ride a HED so it’s stiffness is similar to conventional wheels, but I am not convinced that a tiny difference in rim deflection will cause a noticeable difference in friction during a turn. Force vectors will be substantially the same.
Also for very sharp turns you won’t be going super fast, the difference in gyroscopic effects between wheels should be limited, especially when there’s only about a 15% difference in total weight of the wheel, and much of that extra weight for the disc is centered at a radius signifcantly within the outer radius of the wheel.
This sounds a lot like the cyclist mumbo-jumbo about how they can really feel the difference in the siffness of different top frames when they ride them.
Also for very sharp turns you won’t be going super fast, the difference in gyroscopic effects between wheels should be limited, //
Why do you only talk about a couple turns, maybe in a race. How about the 100 that are long, sweeping, high speed ones, you know the ones that you get coming down a mountain?? You gonna choose a wheel for the 2 turns, or the 100??
And you are right, most people will not turn well enough to test the difference in holding power, but most pros do, so there you have it…
I assumed that as he comes from a pro cycling background and have been involved with Team Sky (now Ineos), which is known to have a lot of attention to details and “marginal gains”. But I have never seen Chris Froome ride a hilly TT without a disc, so that assumption I made could be wrong
Pro cyclists don’t have to run off the bike - triathletes do. Maybe that has something to do with an ex pro cyclists choice? A solid disc can be harsh - a spoke wheel more forgiving for the run?
Also for very sharp turns you won’t be going super fast, the difference in gyroscopic effects between wheels should be limited, //
Why do you only talk about a couple turns, maybe in a race. How about the 100 that are long, sweeping, high speed ones, you know the ones that you get coming down a mountain?? You gonna choose a wheel for the 2 turns, or the 100??
And you are right, most people will not turn well enough to test the difference in holding power, but most pros do, so there you have it…
Still not buying it. So if we go a little deeper into physics, the required coefficient of friction to prevent loss of traction increases as lean angle increases (if you do a little bit of math, it reduces down to tan(lean angle) = coefficient of friction)) A less-stiff wheel will increase the effective lean angle at the interaction point of the tire and the road, requiring more friction between the rubber and the asphalt, meaning that a less stiff wheel is actually MORE likely to slide out in a turn than a stiffer wheel is.
I would love to see a world class criterium race with disc wheels. Maybe do 1/2 and 1/2 and see who actually comes out of the corners better! I know who I’m putting my money on…Good talk, but since I have my own data points on this, like with a lot of aero claims, I will go with what I know to be true, and not what the math says in some incomplete equation…
