Welcome to our Ask a Mechanic column where our expert mechanic Daniel Slusser answers your bike maintenance questions. If you have a question for Daniel, please post it on our Facebook Wall or e-mail Daniel directly at firstname.lastname@example.org. Today’s column offers some tips on diagnosing the cause of skipping chains on a road drivetrain and silencing noisy internal cable runs.
Question: I saw your video online and I have a chain problem perhaps you can help me with. I’ve been riding and changing chains for nearly 40 years but I am stumped with this problem.
I’m riding Ultegra and two months ago I bought a new Ultegra 10-speed chain as my old one was worn. But ever since I put it on I have the problem of when I put a lot of pressure on the chain, such as standing in a big gear, the chain snaps down to the smaller cog. When this first happened, I was riding a 12-28 cassette but after moving to flat land I put a new cassette on, a 11-23. Same problem. I changed the cable and made all kinds of adjustments with no change. I then discovered I had the chain on backwards, but reinstalling it correctly did not help the problem. Any suggestions would be welcome. Full disclosure: I’ve ridden Ultegra for 25 years and have never used the special pin and have never had a problem. I didn’t use the special pin this time either. From: Bob
Answer: My first inclination is that you have a worn cassette, but the chance that both of the cassettes are equally worn is unlikely. The next thing I would check is your hub. Make sure that the cassette body is stable on the axle and is unable to move laterally or wobble radially.
You have probably already checked these last things, but I will go ahead and list them anyway. Make sure that you don’t have any damaged chain links that are either stiff or bent that could be causing the problem. Adjust the b-tension screw on the rear derailleur so that you get a little more chain wrap around the gears (I.e. Adjust the derailleur so that the upper pulley is very close to the cogs without causing any grinding issues). Then I would make sure that the derailleur hanger is tight and properly aligned.
I’m curious if you are using a master link of some kind or reusing a stock pin and pressing it back into the chain? If you are using a master link, that could be your problem. To be honest I don’t have any experience using master links on Shimano chains because I feel it is best not to take any chances with improper chain installation. If you are using a SRAM master link, keep in mind that they are directional and if installed incorrectly they can cause minor shifting issues (and that’s when they are installed on the correct chain).
Question: I bought a Specialized Secteur Elite five weeks ago and the internal cabling for the rear brake makes a rubbing noise when braking, any ideas as to why and how to fix it? From: YouTube
Answer: I have two suggestions: where the cable goes into and out of the frame make sure that the cable isn’t dragging on anything, and that the cable housing ferrules are properly seated in the frame. If the housing is too long it can cause the ferrules to sit cockeyed in the frame. Sometimes greasing them can help. If that doesn’t work, the noise is likely coming from the cable rubbing on the inside of the frame. Plastic tubing for shielding exposed cables is available at most bike shops that can be used to cover that section of cable and prevent any potential rubbing. If the tubing isn’t readily available, it can be stripped from the inside of a section of derailleur cable housing by peeling the outer portion of the housing off like a banana. This may not completely silence the cable noise but it will cut down on the noise a bit.
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. When he is not riding, wrenching, or writing he enjoys spending time with his wife and two children.