Buyer's Guide to Disc brakes
brake (Seb Rogers)
Hydraulic disc brakes have become must-have stoppers for your bike. Here's our guide to what to look for...
Get the right brake for your riding
Disc brakes are now coming as standard on most bikes over £500, but what should you be looking for when it comes to shopping for your ideal stoppers?
Bleeding hell
Don't fret about bleeding brakes. If you have to trim the hoses to fit them, you might need to re-bleed the brakes, but most shops will fit them for free. Otherwise, they should be fine if you leave them alone - we can't remember the last leaky set we had, and we can count the number of unplugged pipes we've seen after crashes on one hand. Changing pads is the only regular maintenance needed.
We've bled each set here to find out if any were really fiendish, but few require more than an extra pair of hands and some patience.
Power tripping
Power varies with each calliper and its pad surface/leverage, but the biggest difference is in disc (or rotor in the US) size. The bigger the disc, the more leverage your brake has on the wheel and the faster it can stop it. 140mm (5.5in) discs are the smallest and a bare minimum for braking on the back wheel. 160mm (6.3in) discs will slide a rear wheel easily, but only the most powerful brakes will really stand a bike on its nose easily with a 160mm disc up front. That's why many brakes now use a 180mm disc up front. For ultimate downhill stopping power you want 200mm (8in) discs, although some 225mm (9in) discs are available in the aftermarket.
Big discs also heat up less and cool faster than smaller ones, again making them better suited to DH/ heavy duty usage. They do weigh more though, and not all forks and frames are warrantied - or have space - for the largest discs.
Control
The brakes should apply their power smoothly and progressively, or you'll just launch yourself over the bar or slide your tyres rather than making the most of the available traction.
Life
Finally, the brakes need to be easy to live with, easy to set up in the first place and easy to adjust to the feel you want. They also need to be as maintenance-free as possible in the long term, whatever the weather.
Bigger discs mean more stopping power and better heat management, but extra weight. Vented discs cool better, and wavy or toothed ones clear muck faster than round ones. Floating discs resist warping better, save weight and look pimpy.
Calliper
One-piece (monoblock) callipers are generally stiffer and they feel more positive at the lever. Long multi-piston callipers provide a bigger braking area but are harder to align. Most manufacturers are moving to slotted Hayes style post mounts that provide easy set-up.
Hoses
Brake hoses need to resist massive hydraulic pressures without popping, and they need to resist squashing or splitting too. Braided metal hose sheaths look neat, but they're generally available as aftermarket-only options.
Pad (not visible)
Resin pads provide good stopping and produce less heat but don't last long in dirty conditions. Sintered semi-metal pads squeal and heat up more but bite better and last longer when it gets wet.
Lever
The interactive end of the brake. Lever reach adjustment is now joined by adjustable bite point (when the brake starts working) on many sets. Make sure the levers fit your hands and preferred bar positions relative to the shifters though. Carbon levers look pimpy but rarely save much weight over alloy ones.
Jargon buster
- Bedding in - Wearing off surface glaze and contamination on new brakes to get them up to full power.
- Bite point - The point at which the pads make contact with the disc and the brake begins to work.
- Braided hose - Hydraulic line using a woven metal layer for added protection against crushing and bursting. Using this can improve the response of the brake too.
- Center lock - Shimano's spline and lock ring disc fitting method.
- Hayes mount - Increasingly popular brake mount on forks. Uses two threaded posts running parallel to the disc and a slotted calliper for easy adjustment.
- Heat fade - Loss of power when a brake overheats on long descents.
- IS mount - 'International Standard' brake mounting using two drilled tabs parallel to the disc. Light but needs faffing with washers to get a rub-free brake fit.
- Lever reach - The distance between the lever blade and the handlebar.
- Modulation - The subtle control feedback of the brake.
- Monoblock - Calliper forged or milled from a single piece of material, rather than two halves bolted together.
- Post mount - See Hayes mount.
- Pots - The pistons or cylinders of the brake. Single-pot brakes have one piston on one side and one fixed pad; twin pots have a piston on each side; four pots have two pistons on each side; six pots have three...
- Disc or Rotor - The round braking surface of the brake that mounts on to the hub and sits between the brake pads.
- Six bolt - Standard rotor mounting using six bolts threading into the hub.
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