Ask a Mechanic: Drivetrain Noise and Cable Issues

Our weekly column is back, where our expert mechanic Daniel Slusser answers your bike maintenance questions. If you have a question for Daniel, please post it on our Facebook Wallor e-mail Daniel directly at daniel.slusser@artscyclery.com.

SRAM’s Red Cassette is an exceptional component, but is notoriously loud.

Question: Hello Daniel, I need some advice from you if you don’t mind. I am using a Sram Red groupset and I’m having issues with noise coming from the rear derailleur. When I start riding, its o.k.; no sound whatsoever, but after about 10km the noise starts again and lasts until I reach home. It sounds like bearings without grease. I have dismantled the rear derailleur, checked the pulleys and serviced it, but it is still there. When the noise first started I thought it was coming from the rear wheel so I changed to another wheel and the noise is still there. Do you ever have this problem? Any idea what I should do? Should I replace it, it’s only three months old. I would appreciate any help. From: Ben

Answer: Ben, it sounds like this noise might be from the cassette. Sram Red cassettes are known to be very loud. The powerdome construction tends to amplify drivetrain noise like the horn on a Victrola. You might try using a Sram powerglide or any Shimano cassette.

If this is not the problem, the only other possible causes would likely be a poorly adjusted rear derailleur, bent or loose derailleur hanger, or an inadequately lubed chain. The chain one makes sense given that the problem starts only part way into a ride. Let me know if any of these solutions work for you.

Question: I am having a problem with the rear shifting on my Cervelo S1 with a full Ultegra SL group. I took it to my LBS and the mechanic diagnosed it as cable stretch and readjusted the tension. This seemed to fix the problem for about 1 ride, but after that the shifting went bad again. I checked the cable anchor bolt and it is tight, any idea what is wrong? From: Randy

Answer: Randy, I’m “a-frayed” that your cables need to be replaced (hint: your issue is likely due to worn or frayed cables). If there is a lot of drag at the shifter (resistance to the shifter moving) then the cables are worn and should be replaced. If there is little to no drag at the shifter, your cable could be coming apart inside the shifter. As each strand of wire breaks the cable gets longer and the tension goes down causing unreliable shifting. If this is what is happening, then you need to nip it in the bud before the cable snaps entirely and the frayed head is left jammed inside the shifter rendering it a dead, rigor mortised lump of gears.

Daniel Slusser is a professional bicycle mechanic with over ten years of experience. He holds a bachelor’s degree in business administration from HSU and a master’s degree in history from Cal Poly University. When he is not riding, wrenching, or writing he enjoys spending time with his wife and two children.

2015-03-20T13:06:44-08:00