At this year's Sea Otter Classic, BikeRadar had an exclusive opportunity to test ride the new Colnago C59 Disc – one of the first of a new breed of road bikes equipped with hydraulic disc brakes. We borrowed the personal bike of Formula engineer Giancarlo Vezzoli, creator of the bike's brake levers.
The C59 Disc looks clean, with hydraulic cylinders tucked seamlessly into the hoods and internal routing for both the Shimano Dura-Ace Di2 wiring and the rear brake hose. The absence of brake calipers at the fork crown and seatstay bridge is striking. On the road, the system worked okay, but there are still some glitches that will likely be worked out by the time production rolls around in late summer.
As billed: strong braking
As any mountain biker who's made the switch from rim brakes to disc brakes knows, discs work better. Surprise, surprise. Vezzoli lent us his bike with a sheepish apology about the rear brake not being properly adjusted. The first hard pull on the rear lever went all the way to the handlebar, then subsequent pumps required less pull. After a few minutes without braking, the situation would repeat. The front brake, however, perhaps because of better bleeding, worked much better, with less throw required to activate full hydraulic pressure.
Lack of proper adjustment aside, the brakes lived up to the promise of hydraulic discs – hard, fast stopping from high speeds was safe and easy. We took the bike up and down the steep hills surrounding the Laguna Seca Recreation Area where Sea Otter is held, and repeatedly stopped as quickly as possible. Modulation was good enough to rapidly slow down at the bottom of hills without locking up the wheels, although the power was certainly strong enough to lock the rear if desired (we didn’t have the will to try locking up the front).
Colnago's C59 Disc uses a Shimano Dura-Ace Di2 electronic drivetrain paired with new Formula levers and C59-branded Formula calipers
Colnago are specifying their Artemis wheels with carbon fiber rims on the C59. Our test ride took place on a sunny day, but braking in wet conditions should be markedly better than on a bike with full-carbon wheels and standard rim brakes.
However, while slapping disc brakes on a carbon-rimmed wheel might immediately improve some things, it also introduces new dynamics to frame and fork construction. The braking forces generated by a disc brake at the bottom of the fork leg require a fundamentally different fork design than that required by a rim brake at the crown. Vezzoli found that out the hard way when forks on early samples of the C59 quickly broke under the braking load of the 140mm discs.
Colnago addressed the situation by heavily reinforcing the fork legs and also the rear triangle of the frame. In addition, the dropouts on the fork face slightly forward, to counteract the torsional forces from the hub under braking load.
Needs work: the shifting levers
Formula’s levers are so new they don't yet have a name. The working title is RR1. As with the name, the functionality of the levers is a work in progress. Ergonomically, the hoods and levers on the whole are good. The absence of mechanical innards frees up the design considerably. The hoods are slightly thinner – and on the underside, longer – than SRAM or Shimano mechanical systems. We were able to wrap four fingers around the hood between the lever and the bar.
The shifting, however, doesn't work well. The two parallel and slightly overlapping shift levers are far too thin, which resulted in misshift after misshift. A wider surface area for each, or a redesign with paddles, would help greatly. When riding on rough chip-seal roads, the levers also vibrated noisily when our hands weren't wrapped around them. Their pronounced curve back towards the handlebar made for good braking ergonomics while in the drops, but the upper protrusion away from the hoods limited leverage when riding on the hoods.
We borrowed the personal bike of Formula engineer Giancarlo Vezzoli, who created the C59's brake levers
The first, but not the last
Colnago may have been the first major manufacturer out of the gate with hydraulic disc brakes on a road bike, but they certainly won't be the last. With SRAM’s hydraulic system just around the corner, Colnago expect to see multiple competitors with such bikes by the time the Eurobike trade show opens in the fall. By then, the Italians expect to have final versions of their C59 Disc out on the road under customers. They haven't yet set pricing.