I managed to get my hands on some pre-production CX8.4, the newest cyclocross brake from TRP first displayed during this year’s Sea Otter Classic.
Arguably tires are the single most distinguishing aspect of cyclocross bikes as they provide traction, suspension, and flotation over various non-paved surfaces impassable to road bikes. However, the brakes on cyclocross bikes have obsessed me for ages. I’ve never been totally happy with any solution so far. I bet hydraulics will be dope in a few years after technology for a shift/brake lever for discs has matured, but in the short run I’m only interested in rim brakes. Several of us at Bike Hugger tried the TRP CX9 mini linear-pull brake, but I for one didn’t like how it meshed with my preferred SRAM levers. The CX9 seems suited to a lever that pulls more cable than a traditional drop bar lever like the SRAM Double-Tap integrated levers, though the newer Shimano 7900 and 6700 levers fare a bit better because of their longer cable pull. When the lever pulls too little cable for the available lever travel, the system will have too much mechanical advantage at the pad/rim interface. The result is that the brakes have a squishy on/off feel lacking modulation and perhaps the pads sit too close to the rim.
This balance between lever pull and brake arm length is relevant to all linear pull brakes. In the 1990s the success of Shimano’s “V-brakes” caused an industry wide change to long-pull levers for mtb, but the road bike standards for drop bar levers remained unchanged. A drop bar lever paired to an XTR V-brake with 110mm long arms is unusable. QBP’s Problem Solvers brand developed the “Travel Agent” cable-pull adapter to solve this, but the device involving a pulley with 2 different radii is bulky and adds weight and friction to the brake system. Yet it does sufficiently reduce the lever’s mechanical advantage to work with a standard linear pull brake, though the mechanical leverage is still a bit high. Meanwhile, component manufacturers such as Tektro and even Campagnolo had introduced a number of “mini-V brakes” with arms less than 100mm to better match dropbar and older flatbar levers (though not necessarily for cyclocross). Often these products were OEM targeted at entry level city bikes, so the price was attractive but the quality somewhat lacking. Then cyclocross reached critical mass about 5-6 years ago, and the aftermarket for exotic CX brakes went red hot. TRP, Tektro’s premium division, trotted out the CX9 mini linear pull brake last year for riders looking for simplicity and power. Though the brakes immediately won a lot of fans among pro and recreational riders, there were still people holding back gushing praise, reasoning that the CX9 didn’t go quite far enough to solve the leverage problems for dropbar levers.