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Chainring bolts falling out??!!

bompingtonbompington Posts: 7,674
edited April 2019 in Workshop
So I'm here on the west coast on holiday, enjoying my usual 40 mile loop on the single track roads of Argyll.
8am, 2/3 of the way through, sun shining, frost still on grass, feeling like I was going well up the final big climb, when there's a nasty noise.
At first I thought it was another case of seized jockey wheel, then I looked and saw that the chain appeared to be outside the cage of the rear mech. Head scratching until I looked closer and saw that it wasn't, there was just something stuck between the chain and the pulley: pulled it out and more head scratching, until I recognised it as half of a chainring bolt.
Sure enough, one was missing. And two of the remaining four were loose as well.

The question is, why? Is this yet another maintenance thing that I should be doing but has never occurred to me? How safe is it to ride without it?


  • shirley_bassoshirley_basso Posts: 5,654
    I'd get them tightened up.

    Issue is several fall off in the same spot and then the chainring bends and chain falls off.
  • rafletcherrafletcher Posts: 1,235
    I’ve never had that, they mustn’t have been properly tightened.
  • frisbeefrisbee Posts: 691
    I locktite mine. I locktite most fixings just as a matter of routine.
  • cougiecougie Posts: 22,512
    Back in the day I had multiple bolts coming loose. Hasn't happened for a few decades now - not sure what's changed.
  • AlejandrosdogAlejandrosdog Posts: 1,975
    cougie wrote:
    Back in the day I had multiple bolts coming loose. Hasn't happened for a few decades now - not sure what's changed.

    yes it seems much less of an issue these days.

    spot of loctite should keep them in place.
  • bompingtonbompington Posts: 7,674
    :evil: :evil:
    ... and now I discover a bit too late that Chainreaction's next day delivery doesn't apply here in the wilds... and yes, that is hidden somewhere in the small print, but no sign of it when you order, and they're more than happy to let you pay the fee for it.
  • bompingtonbompington Posts: 7,674
    ... but on the plus side, thanks for the advice to tighten the bolts up, now that you mention it I realise it might be a good idea.
  • shirley_bassoshirley_basso Posts: 5,654
  • super_davosuper_davo Posts: 816
    I had the exact same issue on my 105 chainset on my winter bike. Before I went away on a tour of the peaks I changed the 52-36 rings to 50-34 and noticed one of the bolts had fallen off. I hadn't touched the chainset from new a year before. Don't know how long I had been riding like that but could have been a while. The four bolt chainsets are very stiff so seemed solid on three but not sure if it would have been the same on two.
    I was able to borrow a bolt from another bike for the riding, but the replacement wasn't cheap as had to buy a pack of four genuine Shimano bolts.
    So yes, well worth checking periodically and loctiting.
  • keef66keef66 Posts: 13,123
    Hmm. Perhaps I'd better check all mine. I've been in the habit of assembling them using copperslip so I could be sure they wouldn't corrode and seize solid.

    Maybe I'll start using some mild Loctite instead. IIRC most new chainring bolts come with some kind of thread sealant already applied.
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