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awitt
01-18-2019, 05:14 PM
19023
This bump appeared on the rim of my front wheel today. I started to hear a scraping noise from one part of the rim. It sounded like a rock in the brake pad but it wasnít constant so that couldnít be it. When i got home and wiped off the rims I found the bump shown in the photo. Itís not a scratch or divot, it looks like the end od a tiny rod sticking out of the rim. I tried some fine grain metal sandpaper but it made no difference with light pressure and I donít want to use more force. I know I probably need a new wheel, these are the cheap ones that came on the bike. Iím just wondering what it is. The rims are Mavic Aksium on Mavic hubs. The bike is a cannondale synapses carbon di2 with 105 brakes.

awitt
01-19-2019, 01:47 PM
Itís a piece of debris that was ground into the rim and covered with aluminum residue from normal braking action. I have to buff it flat and make sure the brake pads are clean.

Harry Meatmotor
02-19-2019, 11:07 AM
19023
This bump appeared on the rim of my front wheel today. I started to hear a scraping noise from one part of the rim. It sounded like a rock in the brake pad but it wasn’t constant so that couldn’t be it. When i got home and wiped off the rims I found the bump shown in the photo. It’s not a scratch or divot, it looks like the end od a tiny rod sticking out of the rim. I tried some fine grain metal sandpaper but it made no difference with light pressure and I don’t want to use more force. I know I probably need a new wheel, these are the cheap ones that came on the bike. I’m just wondering what it is. The rims are Mavic Aksium on Mavic hubs. The bike is a cannondale synapses carbon di2 with 105 brakes.

A single-sided straight razor blade works really well to slice these little barnacles off of the brake track. Just be careful since you're working so close to the tire sidewall.

awitt
02-19-2019, 11:58 AM
Thanks harry meatmotor!