I made a couple of incorrect assumptions in yesterday’s blog, and I need to follow up on that with some new information that has come to light.
Yesterday I received my replacement brake pads, and I decided to measure a brand new pad with my digital caliper. As you can see in the photo, the the new pad + pad backing is exactly 4.00 millimeters thick. The backing is 2.20mm thick, and so that means a brand new pad is 1.8mm thick. This puzzled me, because Avid recommends that the pads be replaced when they are worn to 3mm. Clearly the recommendation applies to the entire assembly (pad + backing), and not just the pad. This important distinction was not made clear in the recommendation, and I made an incorrect assumption that Avid was referencing the pad alone.
Obviously this new information alters the theory I put forth in yesterday’s blog. Specifically, it turns out my brake pads were very close to the end of their life, but still within the manufacturer’s specs as a “good” pad.
So why were my brakes screwing up?
Well, this morning I took a look at the used pads once again, measuring each of them. Turns out one side of the pads were worn more than other side (this was true of the front and the rear brakes). I think my brake issue could have been corrected by simply adjusting the calipers so the pads were properly centered over the rotors. Again, while the pads were all near the end of their life, they were still within specs. I no longer believe that pad wear caused the braking loss/increased lever travel I experienced on Tuesday.
I’ve updated yesterday’s blog with the new information about how to properly measure pad wear. The main points of yesterday’s blog still stand: check your brakes for proper operation on a regular basis, and don’t ride on a bike that is not functioning properly!
So with the new pads on the bike, the lever travel is back to where it should be. In the future I’ll be more diligent about maintaining my brakes.
Unfortunately with my injured calf I could not bed in the new brakes. Bedding in a new set of disc brake pads is an excellent HIIT cardio workout! Avid recommends that you bring the bike to about 12-15 miles per hour, then brake firmly until the bike is traveling at about walking speed. Repeat this 20 times. Then you have to accelerate the bike to 15-20 miles per hour, and brake firmly until you are traveling at walking speed. Repeat 10 times. Wait ten minutes, then do the other brake. I’ll have to wait until my calf is feeling better to tackle this.
As for my calf, it’s still hurting, but definitely on the mend. When I first get up in the morning or rise after sitting for a period of time the pain in my calf is pretty bad. Once my calf warms up a bit, however, the pain is not nearly as bad. I expect to be back on the bike by Saturday. 🙂