Bicycle Mechanics - Chainring bolts keep loosening

I recently replaced a chainring on my bike, and now I can't keep the chainring bolts tight!

I tighten them up as best I can, and everything is fine for a few minutes. After that, the clicking starts, several clicks per pedal revolution, very regular. When I check the bolts, they have loosened very slightly and are no longer as tight as I made them. If I tighten them again, they're quiet for a few more minutes, and then they start clicking again.

I don't have the tool to hold the back of the chainring bolt, so it turns a little, but it quickly seems to tighten up. Is this my problem?

Should I try some Loc-Tite? What strength?

The crank is a Shimano 105. The big and small chainrings are 105, and the middle one is Ultegra (the only replacement the LBS had). The bolts that are coming loose are the ones on the outside (big ring).

Suggestions?

Tim

It sounds as though you are riding mainly in the middle ring, and that it in turn has enough radial slop to induce epicyclic rotation of the chainring nuts. I have never encountered this problem, even with 130mm chainrings milled to fit my 128mm Nervar Star spider, but I think LocTite may be a reasonable solution (so to speak).

You need the little tool that backs chain ring bolt, a dime or penney will work. This is the only way to get the bolt tight enough. If you use loctite, you are really going to need the tool if you ever want to take the rings off.

You can use teflon tape instead of loctite to keep these bolts from loosening, and it will be a little easier to disassemble later on...

RevChuck is right.

In addition, make sure your new chainring is not slightly thinner than the old one (like going from a 8 to 9 speed thickness). If it is, your old stack bolts could be bottoming out before you can get adequate preload on them.

hayneda
who reminds you that stack bolts on a fixer or singlespeed need to be even tighter

Chainring bolt tool (http://www.performancebike.com/shop/Profile.cfm?SKU=4794)

Do yourself a favor and get one. I used to screw around with dimes, pennys and screwdrivers. This is such a great cheap tool that there really is no replacement for.

Stops alot of squeeky drive train problems.

Thanks everyone for your help! I'll pick up one of those tools and see if I can get the bolts tight enough.

Tim

Chainring bolt tool (http://www.performancebike.com/shop/Profile.cfm?SKU=4794)

Do yourself a favor and get one. I used to screw around with dimes, pennys and screwdrivers. This is such a great cheap tool that there really is no replacement for.

Stops alot of squeeky drive train problems.
Ohhhhhhhh... so THAT's what that tool is for. I've owned one for a while and not known what the heck I could use it for. Sweet :) This is gonna be way easier than the penny trick now.

Ha, I asked about a 38T ring and asked to buy a bolt tool, the mech (different lbs) said he had only one, for the shop.
Next day when I purchased the ring, I asked the owner for the chainbolt tool (I was just going to swap the ring out there) he thought I meant buy...I kept my mouth shut, and he sold it to me.

Somebody was out a tool, I check my bolts often. :D

Nail polish works pretty well in this application. I have this problem on SS bikes where I am only using one ring. Loc Tite is good, but makes removal of the bolts more difficult as someone pointed out. I like candyapple red myself, but you might try pink, or even black if you are feeling naughty.