Sea Otter 2011: TRP Parabox cyclo-cross disc brake

TRP offer first discipline specific hydraulic disc

TRP is one of the biggest players when it comes to manufacturing rim brakes for cyclo-cross. The manufacturer currently offers wide and narrow profile cantilever brakes, as well as a linear pull model, but the big news for 2012 is the addition of a ‘cross specific hydraulic disc brake, available this July, called the Parabox.


The new Parabox brake uses a steerer tube mounted, and cable actuated, master cylinder to run a hydraulic caliper system. The system is run via conventional brake levers through short runs of cable that attach to the lever arms on the hydraulic master.

Lance Larrabee, TRP’s marketing director, told BikeRadar that the leverage ratio of the master cylinder arms work best with SRAM’s lever pull, but that engineers are working to accommodate Shimano’s longer cable pull, as well.

The hydraulic master is actuated by standard road brake levers; this also allows use of in-line bar top levers:
Matt Pacocha

The hydraulic master is cable actuated by standard road brake levers; this also allows use of in-line bar top levers

The key component of the system is the single piece master cylinder that is partitioned to offer two separate reservoirs and mounts to the steerer tube. The master adds 20mm of stack height and runs TRP’s smaller ’cross specific calipers.

TRP offer 140mm and 160mm rotors for the system, including the option of a 140mm front rotor. While the Parabox brake is currently in the field for testing, it’s only rated and recommended for on-course cyclo-cross use.

TRP will offer a 140mm front rotor option:
Matt Pacocha

TRP will offer a 140mm front rotor option, however, they showed the 160mm model at Sea Otter

When BikeRadar asked about the system’s heat resistance, Larrabee said that its performance is good for its intended use, but that it hasn’t been extensively tested for road use, and that it ‘needs more testing’ before he could comment on its performance during long road descents.

The brake is due to be offered in July, and he said that road testing will occur before it is sold.

Felt showed a prototype of their new fx frame equipped with the new trp disc:
Matt Pacocha

Felt showed a prototype of their new FX frame equipped with the new TRP Parabox disc brakes

The system — master, two calipers, two rotors and hardware — has a total claimed weight of 450g, which is roughly 250g more than the equivalent rim system, however, it doesn’t take into consideration any weight that is gained in the hubs or lost from the rims. It is undoubtedly possible that wheel manufacturers could optimize a carbon rim for ‘cross without a reinforced brake track.

While pricing for the Parabox is not set, Larrabee estimated the entire system will cost somewhere between US$400 and $500, but wouldn’t include brake levers.

A new linear-pull ’cross model, too

Also new for the 2012 cyclo-cross season is a modified version of the CX9 linear pull ’cross brake, called the CX8.4, and is specifically for those riders who may have complained the CX9 brakes to be too powerful for use with SRAM brake levers.

TRP’s new cx8.4 brake prototype arm (left), compared to the cx9 set:
Matt Pacocha

TRP’s new CX8.4 brake prototype arm (left), compared to the CX9 set

The new brake sports all of the same features of the CX9, but with arms that are 6mm shorter. This mellows out the brakes’ power and should increase both modulation and rim clearance.


The CX9 will remain in the line for those who like lots of power or those using Shimano’s latest STI levers, which offer a longer cable pull than SRAM, thus better complement the TRP’s original version.