I've ridden extensively on BB7's, and helped a friend install and test his Spyres. I might choose the Spyres, but my touring bike came OEM with the Avid.
Originally Posted by
BlazingPedals
... So BB7 are slightly easier to set up than BB5, but otherwise work the same.
I would avoid the BB5, of course -- having to recenter the caliper as the inner pad wears is
too fiddly.
Originally Posted by
BlazingPedals
... The [BB7] caliper works by the outer pad bending the rotor until it contacts the inner pad. It's a recipe for warping the rotor out of true, and the more gap between the inner pad and the rotor, the worse the effect.
Originally Posted by
Rolla
... On the one bike that I've had [BB7] on, I was either truing the rotor or re-centering the caliper constantly. The upside was that I learned how to do those things really well, but only because I'd had so much practice. ...
As these two point out, minimizing the gap on the inner pad of the BB7 is crucial to good performance; a big gap will bend the rotor and make braking feel spongey. For BB7s, you will likely need the tool and skills to true your rotors from time to time. However, I don't find this skill exclusive to BB7; I have had to true rotors on my road hydros as well -- rotors can easily go out of true from heat under hard braking or from hard knocks when taking the wheel in and out.
(Admittedly, I went years without truing rotors, dealing with squeaky braking and rotor rub. A rotor truing tool is one that, now that I have it, I find indispensable.)