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Discussion Starter · #1 ·
Hi everyone.
After a fairly tiring week of dealing with a crappy bike shop that damaged my bike after I took it there for a chainring/chain/cassette swap, went for a ride with a horrendous creak, came home and the bolt was almost falling off. Making no progress in getting a refund, so I'm back here to once again try to fix something before buying a whole new unit.

Crank is a FC-M7000-11-1.Bolt is stock and not damaged, the thread on the crank arm is. The crank is alloy as far as I know, and I think the bolts that came stock are steel, so no surprises there I guess. I can't tighten it at all.
What are my alternatives? I'm in college so money comes short and didn't plan on replacing the crankset so I'll like to stretch it to mid October if possible, though I'm probably gonna stick to the trainer unless I really want to ride some trails.

Heatlhy thread, stripped thread and bolt:

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pop the threaded part back in, smack it a few times to pop out the inserted part. The arms on the crank are not threaded.

replace with one of these....just couple of bucks to fix.

Also, clean your bike before you work on it. :)

 

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Is this what you have?

My bad if so, assumed it was standard 104 bcd chainring bolt.

You could try some jbweld or similair for aluminum after getting super clean.

As a last effort, If it doesnt hold depending on your comfort level, i would check clearance on backside. Drill the hole straight thru after finding a longer chainring bolt/insert.

File the outer arm flush as possible.

Re-assemble be super careful on the torque of other swiss cheese arms.

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I think cleaning those threads will be useless and probably better going jbweld route but maybe worth trying in combination.

If you do actually buy the tap, consider drilling straight through and tap the entire hole. Then get a longer chainring bolt like this....personally rather see something on the other end but with more threads it should take more torque.

16mm chainring bolt...JensonUSA or check your local shop they probably have some old ones in an extra parts bin.

 

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Discussion Starter · #12 ·
Didn't even know those tap things existed (english isn't my first language), but I think I know what it means.
Gonna do some more research first and try to find a longer bolt to use with shims in the meantime, I cleaned the area today and it sure looks like there's some threads left, so perhaps a longer bolt with blue loctite will be enough. We'll see.

At least now I know it's worth trying. Thanks everyone!
 

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Just as a sidenote. You are having this problem because you use too short chainring bolts. Only three threads engage on the one you have shown. I reckon ( it's been a while ) that shimano ships these cranks with extra long ( like 10 or so of thread ) bolts for the chainring.
 

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Discussion Starter · #14 ·
Just as a sidenote. You are having this problem because you use too short chainring bolts. Only three threads engage on the one you have shown. I reckon ( it's been a while ) that shimano ships these cranks with extra long ( like 10 or so of thread ) bolts for the chainring.
Yeah, I just realized that I'm using a thicker chainring than what it came with. Bolts are 8.5mm and the chainring is 4mm, so that's pretty much half of the threads gone. Not ideal I guess. I'm definitely going with longer bolts for the other holes either way.
 

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Discussion Starter · #15 ·
Just as a sidenote. You are having this problem because you use too short chainring bolts. Only three threads engage on the one you have shown. I reckon ( it's been a while ) that shimano ships these cranks with extra long ( like 10 or so of thread ) bolts for the chainring.
And about the longer shimanos, do you refer to these ones?

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Yeah, mine are definitely shorter. Perhaps part of being SLX means less thread to save costs? Who knows.

Those look good though? M8000 is the bigger brother of that generation of drivetrains, and I'm used to ordering on amazon so that seems like the best option so far. I also found some Wolftooth ones but those are 10mm, so I'd like that extra 1.4mm from the Shimanos.
Can't find any 12mm ones yet.
 
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