Originally Posted by
stratman
Be aware that there is a difference in Shimano STI levers, starting with models introduced after 2008 IIRC. It's SLR vs NSSLR (at least, I think those are the acronyms Shimano use). What basically happened was that the amount of brake cable pull changed to slightly greater, at the STIs, after 2008, but with less mechanical advantage. That's my understanding.
Now my actual experience:
On a new build, in 2018, I installed Avid BB7s with Shimano Sora STIs. The brakes stopped the bike, but I was underwhelmed by the performance. I accept the slightly sub-optimal nature of breaking from the hoods, of course. Nevertheless, they didn't seem that much better than the cantilevers on another bike (with STIs).
So I went backwards in model generations, and installed a pair of Shimano Ultegra nine speed STIs, ST-6510, which are pre 2008. There was a substantial difference. I could now, for instance, lock up the back wheel and induce a skid, even on dry tarmac, braking from the hoods.
BB7s and "old" Shimano STIs are a very good combination, in my experience. I've bought several NOS spare shifters, for the future. BB7s are simple and robust, allegedly a lot more than the TRPs.
I came to this thread to make the same point. I forget when exactly Shimano made the change to 'long pull' for their STI levers (definitely by 5800 but possibly at 5700) but calipers that work well with 5600 won't play as nicely with 5800 and vice versa. The oft-recommended (in this thread) TRP Spyre is one of those calipers. With a short pull lever, you are going to be nearly bottoming out on the handlebars at max braking force (or actually bottoming depending on bar/lever combo and setup). The TRP HY/RD is similarly designed for long pull Shimano road levers).
The BB7 road caliper is designed for short pull levers and I've been using an Ultegra 6500 lever (front only) with one since 2008. My more recent disc brake bike paired short pull Campagnolo road levers with TRP HY/RDs but I had to make custom arms to get that combo to perform well. Campagnolo and SRAM road levers all pull about the same as short pull Shimano road levers for reference.