Nuts About Bikes

Get your brakes in gear

You'd be surprised how fast those brake pads wear away ... especially if you do a lot of miles each year. We did a brake check the other day - decided to share a bit of know-how on the site to inspire you to do the same.

In the groove

If your brake pads have safety grooves, it makes the job a lot easier. The groove is designed to wear away and eventually disappear. But if it's gone, so are your brake pads and it's time to for service. Click the pic for an enlargement and you'll see the groove.

padThis pad is about halfway through its lifecycle. Still plenty of groove there. At the bottom of the groove valley is the minimum amount of meat your pad needs to stop your bike safely. So when the groove wears away, you're at the service limit.

Take a floor tour

Depending on your steed, you should be able to check the padsafety groove without disassembling any parts. You may have to get on your back and creep around the garage floor to get a good view, but try looking from the top, first. Use a good light and try to find a spot where the caliper, disk and associated hardware are out of your line of sight. If you can see the groove, you're good to go.

No groove?

If you can't see the groove, that does not necessarily mean you're ready for new brakes. Not all brake pads are grooved ... so if you don't see a groove, try to find a spot where you can clearly see how much brake pad is left on the metal frame. Use a blast of air, brake cleaner or an old paintbrush to clear away brake dust to get a good view. (If you use brake cleaner, be careful of painted surfaces.)

But before you do any cleaning – while you're down there, look for any wet spots that could indicate a fluid leak. That's an emergency and should be taken care of immediately.

Check your owner's manual or service book for your bike's minimum brake pad limit. Each bike is different - but generally if you can see an eighth of an inch or more pad, you're in good shape. Under an eighth of an inch and you'll want to get a pro to take a look.

If the hardware won't let you get a good view, let your mechanic make the call. And never use anything on brake pads other than plain air or brake cleaner. If you grab the wrong spraycan (of, say - WD-40 or similar) you'll contaminate your pads and create a safety hazard.

Give her a drink

As the pads wear, the fluid level in the master cylinder will drop so you may need to top it off. Check the sight glass to ensure the fluid is past the minimum level. If it's not, here's the step-by-step.

  • Get the bike level
  • Protect all painted surfaces, brake fluid will eat through paint
  • Clean the master cylinder cap
  • Note the type of fluid your bike requires: DOT3, DOT4 or DOT5. To avoid trouble, do not mix fluid types
  • Carefully remove the cap and any plastic or rubber bits below
  • Open a fresh bottle of brake fluid and top it to the recommended level
  • Reassemble and clean any drips well before removing paint protection

Remember - barring any leaks, the only way your fluid level can drop is through pad wear. The brake fluid fills the space that used to be occupied by brake pad. So if you've added fluid, chances are your pads have worn a bit. Be sure to do a full pad inspection every time you add brake fluid.

Every other year or so, you should flush out the old brake fluid and put in new. This is usually a two-man procedure, with one pumping the brake lever and one working the relief valve on the caliper. Details are beyond the scope of this article but it's something you should put on your calendar to either learn yourself or ask your wrench to take care of.

Bringing up the rear

If you have aft disk brakes, the process is the same. But if you have an internal drum brake, you'll have to pull the wheel to visually inspect the shoes. Though most bikes have some sort of external indicator of brake wear, you cannot trust it to be 100 percent reliable. Be sure to check the rear brake when changing tires, updating wheel bearings, sprockets or performing any other work that requires pulling the rear wheel.

Safety first.

- Sal, Editor
November 2008