Chain ring bolts

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francovendee
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Joined: 5 May 2009, 6:32am

Chain ring bolts

Postby francovendee » 24 Jun 2019, 3:55pm

The inner nut/bolt has two very narrow slots on the outer edge that I'm finding very hard get a screwdriver in. I can't stop the whole thing turning and I don't think it's tight enough. Any suggestions?

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robgul
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Re: Chain ring bolts

Postby robgul » 24 Jun 2019, 4:00pm

There is a special tool for these - but a very wide screwdriver works - see https://www.parktool.com/product/chainr ... ench-cnw-2 for the Park version

Tip: I always put a drop of low-ish tension (blue) Loctite on these bolts when I do them up

Rob

Brucey
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Re: Chain ring bolts

Postby Brucey » 24 Jun 2019, 6:56pm

remove the bolt, clean and grease the threads, and run the two halves of the bolt in and out of one another all the way, making sure that there is absolutely no obstruction to the threads.

Also make sure that the bolt will reduce enough to clamp the chainrings to the spider (if you have just replaced the chainrings and the new ones have deeper counterbores, they may not clamp).

FWIW this is absolutely not one of the places I would ever use threadlock of any kind; if the bolt is slack enough to back out, it has long since not been tight enough to do any good. IME bolts that "come loose" do so initially not by backing out, but by fretting between the chainring and the spider etc removing micro-burrs from new parts. IME chainring bolts that are greased and properly tightened onto parts that have bedded in already never come loose.

Note that if the bolt is checked as above for an unobstructed thread and lubricated on the threads (but not on the outside of the sleeve part) the bolt should both loosen and tighten easily without the use of a tool on the sleeve part.

A big screwdriver won't do with many chainring bolts; the centre part usually protrudes far enough that it will obstruct the blade; if so, a special tool (or a specially ground screwdriver) is required. You can buy tools for this job quite cheaply; they are usually not very good though.

Some folk favour the chainring bolt design that uses two allen keys citing that it is easier to tighten and loosen the bolts. Well it might be, but these bolts are not as strong (fewer threads in engagement) and also present a horrible crevice to the weather, so seize up more easily. Thus IME they can cause just as much trouble, but its just different trouble.

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

francovendee
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Joined: 5 May 2009, 6:32am

Re: Chain ring bolts

Postby francovendee » 25 Jun 2019, 8:12am

I did wonder about grinding out the centre of an old screwdriver but I'll take the bolts apart first and see if I can get them to tighten up after I clean and grease them. Thanks

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Mick F
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Re: Chain ring bolts

Postby Mick F » 25 Jun 2019, 8:20am

Yes, keep the threads clean and greased.
If and when I remove mine, that's the treatment they get. Never needed a screwdriver or any tool ever.
Mick F. Cornwall

skyhawk
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Re: Chain ring bolts

Postby skyhawk » 25 Jun 2019, 6:46pm

Hmmm just done mine, I used a 1p ?
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francovendee
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Re: Chain ring bolts

Postby francovendee » 26 Jun 2019, 8:22am

skyhawk wrote:Hmmm just done mine, I used a 1p ?

Not sure how, as on mine a screwdriver doesn't fit because the centre part is higher than the 2 small slots on the outer edge.