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.

his 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.

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.

Pro cyclists don't have to run off the bike - triathletes do.

i wish i could find the thread. i think the idea was that the lateral force increased the rolling resistance somehow, but i don't remember the details. i think someone from ERO chimed in on the thread.

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.

Why do you think that he is very knowledgeable?