how to know when to replace mtb disc brake pads?

avalanche

apart from the obvious when the stop working..., bike shop were adjusting something the other day and replaced the rear pads and said i would need to replace the front ones soon, is there an obvious way of telling when you should replace them. they seem to work fine although the new ones do work much better with a nice electicy buzz sound when braking.

Wez

I normally notice when they start to feel a little rough, then there's the shuddering feeling. Although this is when your pads are absolutely gonzo.

Squeeking should be a sign they're on the way out. That's how I've been doing mine and seems to be just in time when I do. Although this is after sqeeking a while, and isn't an exact science, but thought I'd give an oppinion.

Morgan

Deciding whether or not to replace the pads is simple. Some manufacturers use a gauge of sorts, such as the little bump found on Magura pads (shown on right in picture below). However, most pads should be replaced just before the compound reaches the thickness of the return spring (shown on +left below). Inspect the pads’ contact surfaces. Partially worn pads can sometimes be improved with cleaning. Glazed pads have a shiny hard surface with curved wear ridges in the shape of the rotor. Revitalise them by roughing up the surface with coarse sandpaper or a file.

http://www.bikeradar.com/gear/article/workshop-how-to-remove-and-replace-disc-brake-pads-25208

SerialComplaint

Wez wrote: »

Squeeking should be a sign they're on the way out. That's how I've been doing mine and seems to be just in time when I do. Although this is after sqeeking a while, and isn't an exact science, but thought I'd give an oppinion.

My pads squeal fairly loudly on my brand new Specialised Rock Hopper - loud enough to scare a few peds. Is this level of squealing unusual?

gman2k

Not unusual, but not exactly right either.
New disc brakes need up to 50 hard stops to bed in, and put a wear surface on the rotor.
If the squealing is still happening after a few weeks, mention it to the shop you bought it in on it's first service (usually one month after buying - should be a free service)

SerialComplaint

gman2k wrote: »

Not unusual, but not exactly right either.
New disc brakes need up to 50 hard stops to bed in, and put a wear surface on the rotor.
If the squealing is still happening after a few weeks, mention it to the shop you bought it in on it's first service (usually one month after buying - should be a free service)

Thanks - hoping to arrange the first service for next week.