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I have a Jamis Dakar Mountain Sport full suspension with Tektro Ariga Comp disc brakes. My problem stems, I think from a misaligned or slightly bent swing arm. When I ride there is a very pronounced rubbing coming from my rear disc, it sounds sort of like a sword being unsheathed. I have disassembled the brake and had the pads cleaned, to no avail, so that’s what has me thinking it is the swing arm. I also have great problems in keeping my rear derailleur aligned and have recently started thinking that it too is related to the mystery rubbing noise. I should mention that this noise is limited to when I am on it and riding.
Has anyone ever had a problem like this? If so, how did you rectify it? I live in Cambodia, so the knowledge of the bike mechs at the lbs is limited mainly to assemblage, routine maintenance and minor repair work.
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Hi there sugimon and welcome to the site!
Although I wouldn’t say it’s impossible , it’s highly doubtful that a bent swingarm is causing your issue. The wheel and calliper are attached to it securely, so anywhere the swingarm goes, the wheel and calliper stay in the same position, in relation to the swingarm.
If the sound is constant (it makes a swishhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh noise):
Two possibilities that pop into my mind are a misaligned calliper or a calliper that isn’ opening enough to allow the rotor to spin freely.
To adjust the calliper, you would loosen the bolts holding the calliper to the bike and then hold the brake lever tight and retighten the bolts without letting go of the brake lever.
If the calliper isn’t opening enough, you can remove the brake pads and use some rubbing alcohol on a q-tip to clean the edges of the pistons below where the brake pads sit to get off all the crud that builds up on their sides. Once you’ve done that, you can push the pistons back into the calliper, replace the brake pads and follow the adjustment procedure I mentioned above for reinstall.
If the sound is cyclic (it makes a swish swish swish swish swish swish swish swish swish swish swish noise)
If your sound is repetative, I would guess that your rotor is bent.take the rotor off and spin the wheel while standing behind the bike and watch the rotor. If the rotor moves or wiggles, then it’s bent and either needs to be straightented or replaced. To straighten, you can use an adjustable wrench and tighten it down until it just fits over the rotor. Spin the wheel slowly to find where the rotor is out of place, place the wrench on the rotor in that spot and gently bend the rotor in the direction it needs to go. I can’t stress gently enough 😀 If you bend too much, you’ll just be chasing the bend back and forth. So just spin, bend slightly, spin, bend slightly, spin, bend slightly, spin, you’re done 😀
Hope this gets you up and running!
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Hmm interesting that you say it doesn’t do it when you’re not on the bike. That makes me think there is something up with the swing arm.
Have you checked to see if the rear triangle is cracked or broken anywhere?
I actually had a somewhat similar issue where my rear tire was rubbing horribly in the drop outs when I was on the bike. Took it into the shop and they checked it over, and they spotted the obvious frame break that was causing my rear triangle to bend under weight.
Not sure if this is the same thing that’s happening on your bike, but it might be a good idea to inspect it closely.
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I had a similar issue with my Rocky Mountain Element, which has a suspension setup almost identical to yours. One of the swing arm bolts was backing out, and would cause a similar issue. The bolt for me was the bottom bolt right behind the crankset. Might want to check the tightness on the all the different bolts for the swing arm.
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