TRP Hywire road disc brake system — First look

Taiwanese manufacturer launch plug-and-play Di2 system

TRP have forged a path for disc brake development for both road and cyclo-cross. For 2013, the Taiwanese company are building upon their initial ‘cross offering, Parabox, with a plug-and-play hydraulic road disc system meant to integrate with Shimano’s Di2 drivetrain.


The Hywire system costs US$599 and will be available at retail this fall, post Eurobike and Interbike. However, TRP say it’ll be available on complete bikes as early as this summer. “It’s been in development for a year,” Lance Larrabee, TRP’s marketing director, told BikeRadar. “We saw an opportunity to make a Di2 adaptable system. We’ve been working on button position, and testing with a couple of different iterations.”

The new system will work with Shimano’s two Di2 groups: original Dura-Ace and the new Ultegra version. “The whole thing is designed with an eye toward both road and ’cross,” said Larrabee. “We wanted it to be sturdy enough for long descents, and any other kind of use that it may get.”

The Hywire system is fully hydraulic, unlike the hybrid Parabox, and uses a larger piston and new brake pad compound to better suit the longer bouts of braking and higher temperatures achieved when road riding. “It’s [the piston] a little bit bigger than the rear caliper [of the Parabox] and has the same sized pistons as the front caliper,” said Larrabee. “But it has more pad contact with the same sized piston.”

The hywire/parabox calipers also have new pads that offer more contact area: the hywire/parabox calipers also have new pads that offer more contact area

The Hywire’s calipers are all-new and used front and rear, as opposed to the front and rear specific calipers of the original Parabox system

The new, larger, pistons will also be employed on the 2012 version of Parabox, but even still, TRP recommend road riders use 160mm rotors for best performance. Brake lines maintain a 5.5mm OD and run under tape, terminating at an alloy master cylinder housed inside the injection molded resin brake lever body. 

The brake levers are fixed, and molded from carbon fiber. The shift button lever is also fixed and sports two vertically oriented buttons. The top one is responsible for downshifting to a lower gear, while the lower button drops the chain into a higher gear.

Hywire’s shift-buttons are fixed in position: hywire’s shift-buttons are fixed in position

The hook of the lever seems to put the shift buttons within easy reach