I’m building a TT frame and notice on the some pro’s TT rigs their front brake is mounted behind the fork for obvious aero benefits. I have never seen a clear side photo of the mystery units, only a mtb noodle snaking the cable around back of the fork. Are they using an “optimized” longer reach unit like the Tektro 521 or Shimano R600 caliper? Cheetah uses a rear mounted Magura but it is hydraulic and obviously wont work with DA. The folding Bromptons have a funky bottom pull front caliper but it would still hit the frame. Anyone know what brake they use or is it my imagination?
Not sure but I know the current Telekom (Giant TT) frame has this arrangement on the fork. It appears to be a standard brake and caliper.
This sounds like a Bunnyman intervention moment !
I imagine that is has more to do with the fork to prevent it from hitting the frame. I would have to see a pic; do you have a link with a setup like this?
Not sure of the exact type of brake, but if you are building the frame, are you building the fork also? Because many standard off-the-shelf forks, if retrofitted for a rear mounted brake, would indeed require a longer reach brake. However, if you are acutally building a fork yourself, then making the fork blades as short as possible (so the final fork will accept only wheels with racing tires), and/or minimizing the fork rake, and/or drilling the brake centerbolt hole at a nonstandard angle will allow you to use a short reach brake mounted on the back of the fork crown.
But as others have mentioned, in the entire frame/fork design a far more important issue is building a set up where the rear-mounted brake would clear the downtube and still allow you to turn the front wheel fully. Also, you need to find a type of brake that can be fed the actuating cable from the side (vs. from the ‘top’, like a convention dual-pivot shimano brake).
My guess is that all this effort is not worth much aerodynamic advantage. You would probably do equally well with a good TT frame and and an aero brake (like the old Campy ‘delta’ brake) mounted on the front.