I recently bought a bike overseas rather than at LBS (no LBS had the type of bike I wanted). Now the bike makes a strange noise and I can't bring it in for servicing (buy from LBS when you can!). Could anyone give me any pointers to what could be the cause of this?

When the chain is on the largest (size 34) or second largest cog and I am either free wheeling or back pedaling, there is a squeaky sound. When the chain is on any other cog there is no so such sound. Visually, there is no contact of any part where contact should not be.

Below is a link to a video. What could this be?

Thanks, Mark

video recording of the behavior and sound

  • 2
    Why can't you bring it in for servicing to a LBS?
    – Batman
    Jul 22 '17 at 17:40
  • Doesn't look like a bike I would give to people who have never handled a cyclocross bike before. Really strange problem, by the way.
    – ojs
    Jul 22 '17 at 17:45
  • 1
    I don't really have a great idea but a few easy things to try: (1) Have you taken out the wheel, spun it out of the bike and reinstalled it? (2) Is the brake rotor completely clear? (2) Check the lockring on the cassette and the freehub body: take off the cassette, inspect the freehub visually, put on a spoke protector (no reason not to have one of these) and reinstall the cassette. Also, if you have multiple chainrings in the front, does the same behavior occur if you're in either chainring and on the big cog?
    – Batman
    Jul 22 '17 at 17:55
  • 1
    Sounds like your rim is squeaking against the frame or your disk brakes against the rotors.
    – RoboKaren
    Jul 22 '17 at 23:05
  • The brake rotor does clear and does not seem to be the cause, as the back pedaling proves. Thank you for the suggestions Batman; I will follow these and take off the cassette for inspection (probably next weekend) and see if this solves it. I'll try to pick up a spoke protector at the same time.
    – marckr
    Jul 23 '17 at 0:54

It was the freehub; when it is pulled away from the wheel while turning it makes the sound. I guess putting the chain on the largest cog makes it pull the freehub slightly out.

I have not solved it yet: this freehub apparently needs a 11 or 12 mm hex key to be removed rather than 10 mm and 10 mm is the biggest I currently own.

  • Great work - thank you for the closure. And its an excuse to buy or make a new tool! If you can't find a large hex key, consider making one out of reinforcing rod / rebar, using a grinder or a file+patience.
    – Criggie
    Oct 26 '17 at 23:31
  • 1
    Thanks, I ordered a 12mm after estimating the width with a 5mm and 7mm hex key put together in the hub.
    – marckr
    Oct 27 '17 at 12:43

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