Bicycle Mechanics - Disk brake pads - when to change

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Juha
08-26-11, 01:27 AM
I'm a complete n00b when it comes to this new-fangled concoction called disk brakes. My most recent bike (a CX bike) has them. How do I check the pads for wear, how do I know when to change them? I mean before I slam into a brick wall due to failing brakes...

--J

dabac
08-26-11, 01:54 AM
Treat them pretty much as people treat their car pads.
The casual approach: look at the remaining thickness and make a judgement call. Less than 1/3 left, replace. Helps if you have a replacement pad available to see what you started out with.

The careful approach: pull pads out for close inspection, check for uneven wear and remaining material. Reinsert or replace as seem fit.

The happy-go-lucky-approach: Ride bike until obvious change occur, squealing, scouring of rotors, brakes losing power. Then change.
jimc101
08-26-11, 02:02 AM
As dabac, but also, if you are getting uneven wear, would investigate why, and fix this.

There is no real need to change disc pads before the get down to just before the metal of the pad shoe, however, depending of how well your brake compensates / adjusts for wear, you may want to change with less wear if you start to need to use too much lever when braking.

Contamination is another reason to replace, and also the rotor will need a good clean with IPA / disc cleaner if this happens

MichaelW
08-26-11, 03:04 AM
Bikeradar (http://www.bikeradar.com/gear/article/workshop-how-to-remove-and-replace-disc-brake-pads-25208/) have a good guide with wear guidelines.
digger
08-26-11, 06:35 AM
For the pads I use on my Avid BB7s, they state that the pad has to be replaced when the total thickness of the pad material plus steel backing reaches a thickness 3mm.

Problem is...it still looks like a new pad!
AEO
08-26-11, 06:42 AM
For the pads I use on my Avid BB7s, they state that the pad has to be replaced when the total thickness of the pad material plus steel backing reaches a thickness 3mm.

Problem is...it still looks like a new pad!

new pads+backing are about 6mm thick and you should clearly be able to see the lips of the steel backing are not the same as the pads.
http://www.wheelbase.co.uk/shop/images/products/645.jpg