A roller cam brake is essentially a single-pivot brake but with a small cam to increase the leverage to a similar level to that of a dual-pivot brake. That means you get dual-pivot performance with the weight and simplicity of a single-pivot design.
We’ve had a couple of issues in the past with roller cam operated brakes – the tiny grub screws that are used to clamp the inner brake cable, and getting the brake centred properly during installing. Genetic’s Metazoa brakes successfully address both concerns.
The inner brake cable is still clamped by screws through the barrel that sits under the end of the roller cam. But Genetic has used larger screws (3mm Allen key) and added two flat sections to the barrel. This means you can use an 8mm spanner to hold the barrel, and also that the screw clamping the inner cable does so over a larger area of the cable, so there’s less chance of damaging the cable by overtightening the screw. It weighs just 0.2 grams more than the grub screw versions found on other brakes, but is a huge improvement.
The centring problem has also been cured by the simple addition of a screw that moves the spring location pad. No longer do you need to find a slim 13mm spanner to turn the nut holding the spring. You simply tighten the brake with the screw undone, and make sure the pad is against the rim. Then tighten the screw until the pads are balanced the same distance from the rim either side. Quick, painless and simple.
The standard pads are on the soft side, making initial braking a little grabby. But after a while, as the pad and rim bed in, they become smooth and progressive, offering plenty of control and more than enough power. The standard pads aren’t great in the rain but a pad upgrade is quick and easy thanks to the simple and robust pad holders. We tested these with all common brake levers, and on aluminium alloy and carbon rims. In all instances they worked very well and gave controllable braking with plenty of power.