I’ve determined that the poor performance from my rear brake mounted behind the bottom bracket is due to just not enough cable pull from the Vision TT brake levers (they are the mini design from a couple years ago). Even when the TRP brake is adjusted perfectly and nearly rubbing on the rim, there just isn’t very brake actuation (lack of cable being pulled) before the lever bottoms out. Anyone have experience with different levers with noticeably more cable pull?
Had Vision levers, SRAM TT levers and I’m currently on Dura Ace TT Levers (carbon) and they are by far the best ones of the bunch and the SRAM ones the worst. I decided to go with Shimano after reading an extensive review of various levers where they had the best feedback http://university.tri-sports.com/2010/08/11/stop-triathlon-bike-brake-levers/. The only other brand I would have considered would have been Bontrager because of the built-in barrel adjuster which is nice for when you’re switching between training and race wheel especially if you have one of those hidden rear breaks. I have a classic rear caliper and an Omega front which has it’s own adjusting mechanism so it wasn’t worth the extra $ for me.
I can’t speak to the amount of cable pull, per se, but I’ve used a number of aero brake levers on a number of different TT bikes and the best I’ve found, by far, are the Bontrager XXX aero levers. They have built-in cable adjusters that work really well, they’re fairly light and they’re very comfortable in the hands.
the newest sram top model is pretty decent. They also have brake adjustment at the lever. I do agree with the statements above about the bontrager and dura ace levers, i like the feel of those levers the best in terms of a mechanical only lever, they seem stronger and more substantial.
What you’re looking at is leverage ratio. Generally, the longer the brake lever arm, the more cable the lever will pull for a given angular displacement (squeeze) of the lever.
I’d second the mention of the Bontrager XXX.
Thanks for all the feedback so far.