Question: During a recent tour in the mountains of Virginia, a tire blew out on a long and dangerous downhill. The rim was very hot, so I assume that braking overheated it. Can I get disc brakes for my road bike? Or is this a technique issue? — Charles A.
Coach Fred Matheny Replies: Yes, in the past few years disc brakes have become more and more prevalent on road bikes. And with UCI voting to allow their use in the pro peloton, they’re likely to grow in popularity.
However, they aren’t necessary for safe riding and descending. Rim brakes provide plenty of stopping power for single bikes that aren’t heavily loaded. Tandems may be a different story if ridden in hilly country, but cantilever and V-brakes do a fine job in most cases, perhaps assisted by a drum brake.
I’ve ridden through mountains in Virginia and West Virginia on a transcontinental PAC Tour and know what those long, steep, twisty descents are like. In such conditions, avoid “riding” the brakes all the way down the hill. Keeping the brakes on even lightly causes nonstop friction that heats the rims. Air in the tire expands. When a certain pressure is reached, the tire can blow off.
Instead, let the bike roll free but brake firmly for short periods to keep speed under control when approaching curves or turns. This on/off method gives the rims chances to cool.
It requires good timing and technique.
On a fast descent, shift your weight to the rear of the saddle, sit up to catch more air, squeeze the levers firmly, and use more front brake than rear brake because the front is more effective. Remember, if you jerk the front brake without using the rear at the same time, you might tip forward. Applying both brakes aids balance as well as speed control.
One other thought: Do you run your tires at high pressure? If so, they can’t heat up much before they become overinflated. Try lower pressures, not just when riding in the mountains. Recent research has shown that optimal pressures are in the 80-100 range. You’ll have more margin for error when braking, and you’ll enjoy a smoother ride with better traction in corners.