Since seeing their release in magazines sometime last year I have been very interested in the dual caliper cable pull design. I rode all last winter on a set of Avid BB7's which are seen as the standard for road disc brakes at this point (though with hydraulic and new cable pull calipers coming out, that may change).
With this in mind, I picked up a set of TRP disc brake calipers and I've have had a chance to put around 400 miles on them and a couple of wet commutes to work.
The brakes themselves:
Overall, they appear to be a quality build. They are solid in design, look good and feel solid overall. The polished aluminum should hold up over time with just some easy cleaning, but I wonder how well the bearings on the pulley will hold up over the winter.
They are smaller and lighter than the BB7's with little to no caliper sticking out past the frame/fork ... with the BB7's there was always at least 1 cm of caliper sticking out from the frame/fork. Basically they are svelt and look good on the bike.
This was both super easy and somewhat hard at the same time. With the Avids, you have the ability to move laterally with the set up to get the pads centered, but also the ability to tilt the caliper a little to make sure it's straight from the beginning.
With the TRP, they have a flat mounting surface that connects directly to the fork or extension on the chain stay. The caliper has plenty of room to move laterally to center the pads, but there is no ability to tilt the caliper. This may cause some problems with set up if your rear end is out of alignment. I had to mess with mine a little and it never set up perfectly to begin with as there was just a little brake rub initially.
With that said, after a ride or two, the pads wore down enough that the rotors are perfectly centered in the caliper and the wheel spins as smoothly as it would with rim brakes and there is no rotor rub even under hard acceleration or out of the saddle climbing.
The first thing I noticed was a much better lever feel. The Avid's were always mushy feeling and under hard braking you could pull the levers (Tiagra 10 speed) all the way back to the bars. With the TRP's they feel like regular road brakes, levers. When set up with zero rotor rub they have minimal brake pull before engagement and at full braking are only about 1/2 - 3/4 of of the way to the bar. This is a huge improvement and that alone makes the change worth if for me.
The brakes work very well in the rain or dry. They have good power that is pretty equivalent to the BB7's in dry weather, however they feel a little weaker in the rain. Modulation is very good and one finger braking is all that's need in dry weather. Due to their slightly weaker performance in the rain, on very steep declines you may need two fingers for hard stopping (10% grades or steeper).
The main concern I have at this time with the brakes is pad wear. I've only had a couple of rain rides, but even with minimal braking needed (other than one long, steep, 1000 foot downhill with several hard stops) I have noticeable pad wear after each ride. Granted, with rim brakes I would have similar wear, but the disc pads are more expensive and look to need replacing after 600-1000 miles in the rain ... or one good, muddy Cyclocross race. I was able to get around 2000 miles on a set of BB7 pads (and still have a little pad left over).
A quality product, the eliminates rotor rub, provides good but not great braking, looks good and is easy to set up.
One primary advantage to the TRP's over the BB7's if you are racing Cyclocross is that you can put a cable adjuster near the bars and adjust the brakes on the fly with even pad wear.
With the Avid brakes, you could put a barrel adjuster near the bars, but since only one pad moves, you have decreased braking as a race goes along because of the increased distance between one pad and the rotor.