Scary moment with crankset bolt

I was riding along indoors yesterday on zwift on my orbea gravel bike, and I started hearing a clicking noise, thought it was the chain.

Ignored it for a bit, but suddenly there was a bit crashing sound and the pedals locked up. On further inspection one of my shimano 105 crank set bolts had worked it’s way totally out and wedged between the crank and bb. Fortunately no carbon damage that I can see, but it would potentially have been bad on the road for this to happen.

I checked the rest of the bolts, and two more were quite loose. This bike is about 2 years old at this point, and I have never thought to check the crankset bolts. Is this something I should be doing regularly? Has anyone had this happen to them? I have a torque wrench so I’ll torque them down and check regularly from now on, but it was a weird issue.

Steal some of the Mrs. nail polish for a low grade thread locker compound or Blue loctite if you want more lock.


Nice! Was already going to use some to cover the scratches on the paint so I might just throw some nail polish on the bolts too.

OK resurrecting this thread. When the bolt came out, it apparently took a good chunk of my bottom bracket with it… Only slight exaggeration sadly. I’m not able to take it to the shop for a while, but it looks pretty deep. What say you all, safe to ride like this? Seems like it cleared quite a bit of carbon out :face_with_open_eyes_and_hand_over_mouth:

That exact same thing happened to me. Also Shimano 105.

It’s hard to tell from the pic but I think it damaged a few layers of carbon. I’m not an expert but I wouldn’t ride without consulting with an actual expert.

I honestly don’t what I could’ve done to prevent it. I do regular maintenance and use a torque wrench. I don’t know how it happened but I’m starting to wonder if it’s a 105 thing.

I haven’t seen many other cases but then, I never saw someone having a problem with Ultegra and Dura-ace (for different issues) but the recall happened after hundreds of reported failures, so who knows…

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Yeah, It’s stressful knowing that I might have not done something that then damaged (and I’m afraid possibly ruined) my frame like that… I’m sadly thinking you’re right. Fingers crossed it’s repairable.

It’s very likely repairable. There are great options out there. Ask locally but also check Calfee and Ruckus Components. You can send them pictures for a quote.

I asked the mechanics in a couple of lbs and they told me the only maintenance they do is check the torque. Even when they take the whole bike apart they don’t separate the chainrings.


I’ve had carbon repaired from reputable people and it rides like new. I’d get it repaired and never worry about it again


Riding buddy of mine got a rock wedged between his crank amd the frame and seriously damaged the carbon bb area. I think it was like $300 to get it repaired and painted back to match. Obviously pricing will vary, but if a cross bike with big damage can be fixed and successful raced after, this damage should be pretty fixable.

The bb area is pretty heavily built up already, I bet it would be fine as-is.

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I’ve repaired a few items using glass cloth and epoxy resin. A frame, tub wheel and a crank!
Have lasted for years so far. Ain’t pretty but worked and cost a few pounds.

Photo: fsa crank arm that cracked around the axle. Part of a £1k + power meter so I didn’t want to bin it. Has done about 5000 miles of mixed terrain riding in all weathers since. I didn’t paint it so I could keep an eye on it for delamination, but it’s holding up well.

Super simple: clean and sand the carbon, apply layers of cloth and resin, wrap it in a plastic bag (polythene doesn’t stick to epoxy), bind it up real tight with tape, leave it for 24hrs. Done!


Well I’m certainly not going to try to fix it myself out of my wheelhouse. But well played! And you are all making me feel better about it being a relatively simple repair, so thanks.

It’s just papier mache with carbon cloth and glue. Carbon frames are so simple to work on as they accept adhesives. A professional repairer would tackle this with ease.

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