Just a quick question regarding the bikes I’m seeing in the Tour: from what I’ve picked up, there is an aerodynamic effect by building a bike with a rear wheel cutout - most of the TT bikes have them.
Just curious as to why the aero-tubed road bikes don’t have the same feature. Is it a rule violation?
I’d imagine it would add weight and wreak havoc with the stiffness of the tubes (on a road bike most tubes are as thin as possible.)
Though I have to wonder, what bikes are you talking about?
Gerard explained one time that it’s more difficult to make a legit aero cut out on a 73 degree seat tube than a 78 degree one. That’s why the Soloist doesn’t have one.
Bunch of them have them. Litespeed Ultimate does. Madone has that “fairing” that resembles a cut-out.
I imagine the aero savings would be so miniscule with a rider in a upright position, that it just isn’t worth it. Why shave 0.0000001 grams of drag off when the rider is in a totally un-aero position.
One thing the cutout might do, though, and this is why the Ultimate has it – shorten the wheelbase to make a more nimble (and twitchy) bike. I would guess if you do see it, it is probably more for that than for any sort of aerodynamics.
My aluminium Giant TCR had a bit of a dimple on the seat tube that allowed the rear wheel to get very close. It was a big round seat tube so don’t know how aero this really was.
I was refering to which bikes he was talking about that had aero tubing, but no wheel cut-out. Ohter than the soloist, none come to immediate mind.
Giant and Look also have cut-outs.
Interesting. I suppose that it would be due to the wheelbase?
Gerard explained one time that it’s more difficult to make a legit aero cut out on a 73 degree seat tube than a 78 degree one. That’s why the Soloist doesn’t have one.