In the world of mountain bike brakes, the bigger players like Shimano and SRAM have been pretty quiet for a few years, but on a smaller scale, boutique brands have sprung up. Radic Performance is one of them, developed by Taylor Grey, an engineer from Auckland, New Zealand. His interest in building a more powerful mountain bike brake like the Kaha stems from his experience developing transmissions and dual clutches for supercars.
The Kaha uses a fully machined four-piston caliper and a 7075-T6 aluminum master cylinder optimized using finite element analysis (FEA). This resulted in a system that is said to be light and stiff enough for the rigors of downhill, enduro and e-bike riding.
Starting at the lever, which pivots on stainless steel cartridge bearings, a 9mm master cylinder piston produces smooth actuation through an easy-to-pull mechanical gear ratio over the course of a short dead stroke (the distance that moves the lever to engage the brake pads) . . Titanium hardware secures the brake set to the bike and Goodridge steel-braided lines are in demand for their durability.
In the caliper are two sets of 16 and 17mm stainless steel pistons that slide through dynamic PTFE seals. Taylor chose stainless steel as the piston material due to its low thermal conductivity, which keeps the heat generated in the pads away from the caliper fluid. Even the oil flow through the caliper has been designed to go through all the chambers in sequence, eliminating pockets where air can get trapped. This also allows the system to be fully flushed when purging. To achieve the best possible bleeding, it is recommended to leave the pads in the caliper to achieve this short dead hit.
One of the coolest things about the Kaha brake is that it can be set to use either DOT 5.1 fluid or mineral oil, and the calipers use the commonly found Hope V4 pads.
Overall the system weighs 320g per side including 80cm braided line and pads. Each set of Radic Kaha brakes is machined and hand tuned in New Zealand for NZ$1,200. Australia orders will first be taken via the Radic Performance website from November 9 at 18:00 NZDT, with delivery expected in late 2022, followed by international deliveries in 2023.