Disc brakes have invaded the road bike market over the past three years. Unlike the high tech mountain bike equivalents, most road bikes are fitted with undersized 140-160 mm rotors and cable operated calipers. Hydraulic systems are now available from both SRAM and Shimano, but they are very expensive and typically fitted on high end models. Moreover, the hydraulic system per se only partially goes to solve the problem of undersized disc rotors and might in fact bring more problems than it solves, when it comes to overheating.
Currently, I run a generic Hayes CX 5 cable operated rear caliper and a semi hydraulic cable operated front (TRP HyRD) which give me the braking force needed to stop a 70 Kg man on a 10 Kg bicycle. In the past, over heating pads and rotors has been an issue when coming down double digit gradients sustained over more than one Km.
I recently fitted a front Shimano 99 Freeza rotor, built with an aluminium core and fins to speed up the cooling. That certainly is a step up in hardware, but ultimately I have learnt that keeping discs cool is not down to hardware, but braking technique.
I had to retrain myself to use the brakes in short, sharp squeezes, alternating periods to rest the pad and allow it to cool. Using this simple technique virtually eliminates the problem of overheating and brake fade. This week, I tested the technique coming down San Giacomo di Andrate in the western Alps, which boasts a 2 Km section at 13% with twists and bends and Santa Maria di Scalaro, which has 22 hairpins over 6 Km at 10% average. The latter descend is so technical that it took over 10 minutes to come down alive and at the bottom my hands felt exhausted, but no brake fade! Here’s a map for the Strava crowd, refer to the second climb/descent.
Here’s three simple rules to avoid A & E when descending a steep road with disc brakes, or in fact any brake.
- Use sharp and short squeezes (1-2 seconds max)
- Don’t allow the speed to build over 50-60 Km/h if the road is steep and twisty or you won’t be able to slow enough before the next bend using short squeezes as above.
- Listen to your pads, they do sound different as they heat up: they might squeal or hiss, it’s a warning sign, it means your squeezes are too long, keep them shorter.