Originally Posted by
BlazingPedals
I guess you could say that BB7 are 'dual adjustable' in that the inner pad can be adjusted; but the inner pad does not move during braking. The 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.
I would never choose to run BB7s, for exactly the reasons described above. On the one bike that I've had them 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. Spyres, on the other hand, avoid these drawbacks by working like a hydraulic brake, with dual pad actuation. That's not to say that the lever feel and modulation are as good as good hydros, but I'd take Spyres over cheap hydros, and over any other cable disc brake. Bonus: they're stupid simple to set up.