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Recently I noticed that my bike makes a loud clanking sound when I start pedalling, both from a stand still and after freewheeling. If I remember correctly the problem started after I washed the bike, so my first thought was that some of the degreaser got into some bearings. But given that the LBS has re-greased everything down to the threads of the through axles that option is less likely.

The LBS tried but couldn't detect any play, I have yet to try myself though.

I should also stress that there is just one clank after I start pedalling, which makes me think something is settling in to place, as for what it might be, I have no Idea. It also doesn't mater how much pressure I put on the pedals. I do feel a slight click on the non-drive-side along with the clank, but that could also just be my imagination. I haven't been able to recreate the symptoms when the bike was in the bike stand. The bike is a giant propel 2020 model.

Does anyone have an idea what this might be?

Looking forward to your input

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    One possibility is that it's the freewheel cogs "locking in".
    – Daniel R Hicks
    Commented Nov 29, 2020 at 2:03
  • @DanielRHicks how would I go about determining if this is the case?
    – Job Van den Berghe
    Commented Nov 29, 2020 at 2:28
  • You'll hear the clank from the rear hub when the chain tightens at the start of pedaling. You can reproduce it on a test stand if you hold the rear brakes enough to create some resistance as you start pedaling.
    – Daniel R Hicks
    Commented Nov 29, 2020 at 2:34
  • @DanielRHicks I've noticed that it usually happens after one to three/four full pedal rotations, could it still be what you suggest it to be?
    – Job Van den Berghe
    Commented Nov 30, 2020 at 23:20
  • Could be. If the freewheel/freehub is sticking a bit.
    – Daniel R Hicks
    Commented Nov 30, 2020 at 23:33

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Could it simply just be your freehub? Especially on cheaper hubs, the engagement isn’t very good, so you have a lot of time to build up momentum before the freehub actually engages. This will result in a clunking noise.

Since freehub bodies are decently hard to get to, it’s unlikely that the LBS took it apart and relubricated it. If they did, maybe they used oil instead of the factory grease, which would also result in a sharper engagement noise. Perhaps you got degreaser inside the freehub and broke down/thinned the lubricant?

Check that your cassette is properly tightened. That could be another cause.

Make sure your cranks are securely fastened, and that your pedal bearings are in good shape. I’m not sure what else could cause a clunk on only one side.

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  • could the first thing you suggest be the case after one to three/four full pedalrotations
    – Job Van den Berghe
    Commented Nov 30, 2020 at 23:23

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