I am relatively new to disc brakes on mountain bikes, having only started using them about two years ago. Unlike rim brakes, where it is easy to see the pads and tell how much life they have left in them, disc brake pads are hidden within the caliper. I'm running Magura Marta disc brakes on one of my bikes. These brakes came with what Magura calls a "transport device." Poor choice of a name, in my opinion. For not only is this little yellow piece of plastic used to insert between the pads when the front wheel is removed from the fork for transport, it has other uses as well. Unless you're a true bike geek or a mechanic, you're not likely to read the owner's manual front to back and pick up on the additional functions of the transport device. (Sounds like something from Star Trek, doesn't it?)
There is a half-round channel integrated into the device for holding hydraulic hose to aid in cutting and insertion of the barbed brass insert. This only comes into play if you need to shorten the hose or replace it. Much more likely to be used is the finger of plastic that projects out of the tail end of the device. It is used to check for pad wear. You insert the finger between the "ears" of the pads and squeeze the brake lever. If the finger does not fit between the ears (I'm not making this up!), your pads need replacing. I'd consider this the quick check for pad life. If the pads don't pass the finger/ear test, I would remove the pads and measure them with calipers. Magura states a minimum acceptable pad thickness of 2.5 mm. Make sure the measure at the thinnest point in the pad/backing plate. A pad is only as good as its thinnest point. When I measure my rear pads, they were 2.1 mm and 2.3 mm - both well below the 2.5 minimum. In fact, the pad that measured 2.1 mm was very close to wearing completely through the pad material. If that had happened, I would probably be looking at replacing the rotor as well as the pad, not to mention the possibility of a crash that could cause additional damage to bike and body.
Long story short: I replaced the worn pads immediately. Also of note: When I checked mine, the pad wear was uneven, indicating that the caliper was not in perfect alignment to the rotor. When I replaced the pads, I realigned the caliper as well. It will be interesting to see what the pad wear pattern looks like after I put some miles on them. Of course, this precautionary tale only applies to Magura Marta (and possibly other Magura model) brakes. Mine happen to be the 2009 model year. Always follow the brake manufacturer's recommendations for proper maintenance. This will vary from brand to brand.
No comments:
Post a Comment