Magura RT 8TT: A Quantum Leap In Tri Braking Performance

Cervélo teamed up with Magura to create a hydraulic rim brake specifically for the P5, and the brakes are also compatible with any tri bike.

Scroll through the photos at the top left of the page for more on the Magura RT 8TT.

The hydraulic stopping system designed by Magura, a premier MTB brake manufacturer, is compatible with all road wheels. The lever mounts to any standard triathlon basebar and the caliper can be installed on any standard fork or frame brake mount.

Although standard brake cables and housing both feel solid in-hand, the pressure applied through the cable and housing stretches the brake cable and compresses the housing, resulting in a mushy feeling and greater lever travel under hard braking. As the cable slides within the housing it creates friction that further hampers brake performance, a problem that has become more common thanks to the proliferation of hidden and integrated brakes. Anyone who has ridden a triathlon bike with extremely tight or circuitous brake cable routing is all too aware that a brake with twisted housing lacks stopping power and lags before reopening after braking. Once a few drops of sports drink leak into the housing, braking performance become even worse. Hydraulic brakes solve all of those problems. Although bikes with straight and simplistic brake routing certainly reduce the problems with cable-actuated brakes, a single ride aboard a mountain bike with hydraulic disc brakes makes the potential of hydraulic brakes immediately obvious, even though these are rim brakes, not disc.

The Cervélo P4’s rear brake, one of the first truly integrated calipers, suffers from those issues and the Canadian company wanted a better solution for the P5. Rather than starting from scratch to design a hydraulic brake themselves, they approached Magura and suggested the two companies work together to create a hydraulic brake for the P5. Magura handled the hydraulic mechanism and Cervélo integrated the brake into the bike.

PHOTOS: Cervélo P5

Cable braking systems use pulling force to squeeze the rim but hydraulic systems only push, they can’t pull. Hydraulic systems functions like this: A plunger is pushed into the hydraulic line running through the basebar when the rider squeezes the brake lever and forces fluid (the RT 8TT uses mineral oil) through the line. This fluid doesn’t compress and a twisted line doesn’t impair its movement, so the hydraulic line transmits all the pressure to the far end of the system, which actuates the brake. This fundamental change from pulling to pushing forced Magura to design a unique road caliper that functions with a hydraulic system. The Magura RT 8TT brake caliper has a piston that sits beneath two brake arms that actuate about pivot points above the piston. The piston drives upward and forces the upper segment of the arms outward to the sides, which rotates the brake arms and forces the lower portion to squeeze inward toward the rim.

Magura claims the RT 8TT can create 44% more force than the nearest competitor listed in their presentation. On the road, it feels substantially more powerful and responsive than a cable-actuated brake. Perhaps the biggest difference in braking feel is the way stopping power ramps up with only a small increase in the pressure on the lever. Instead of putting a death grip on the brake lever to max out the brake caliper’s stopping force, the RT 8TT requires only a subtly tighter squeeze on the lever. Although it would certainly be easier to flip ass-over-teakettle with these brakes than with cable brakes, stopping power isn’t excessive or jerky. With just a little experience, we were able to quickly adjust our internal gauge for the pressure needed to slow the bike. These brakes are not, however, as powerful as hydraulic disc brakes on mountain bikes and they have a little more give when squeezing the rim as well. Although they don’t offer the same stopping performance of a hydraulic disc brake, they are strong and offer a supremely consistent, reliable connection with the brake caliper. They are a fantastic improvement over any other hidden or integrated brake. Don’t be surprised if every high-end triathlon bike comes with hydraulic calipers within a few years.