Chainring woes

Check the bolt length to make sure the bolts are the same size or at least protrude to the same degree that old bolts and with the old chainring did. It's possible that the new chainring is slightly thinner then the old one and the new bolts just are too long, thus you need shorter nuts because the nuts cannot be longer than the depth of the spider + spacer(s) (if any are being used) + ring(s).

Make sure their tightened properly, but I can't see a mechanic with his skills screwing up there.

Since you did crash the bike is it possible that the cranks received to much stress in the crash and damaged the hole that fits over the BB spindle which would cause the cranks to loosen due to play in the interface??

Other then that the LBS may have to resort to Loctite.

ShimanoX789 said:

Hello,

I ride a Raleigh Road Bike - in April, 2010 I was knocked over by a car and sustained minimal damage to my road bike. I took the bike to my mechanic "who fixed things up." He noted that the chainring was bent and wasn't straightening out to the point of his likening. So, he changed the chain ring and then all the problems started 200-300 miles later.

This Shimano chainring's bolts loosen quickly. When I say quickly, they are loosening within 3 miles of riding to the point where two or three of them have loosened by 3 revolutions.

The bolts have been replaced several times including changing brands and alloys - with no changes in result.

The frame (aluminum) shows no signs of cracking and the new chainring appears to be in perfect condition. All of the basic tried and true methods of repair including the grease etc have done nothing.

My mechanic has served as team mechanics in Corestate and Wachovia Races in Philadelphia for a number of teams.

He has worked on the bike many times in recent days and is completely 100% baffled as to why they will not stay tight.

I am open to any ideas!

Much thanx!

Same model chainring? If not, the CR 'nuts' may be too long, if the CR is thinner. Grease onto the bolt threads, using a nut holder to make them tight.

Thank your for your suggestions. After I posted my question, my friend opted to remove the right crank assembly and replace it with a new shimano assembly.

If you can possibly believe it, after two to three miles of riding, the chainring bolts on the new shimano crank arm loosened.

Tomorrow (Tues, 29th), the a rep from Raleigh was scheduled to stop by his store prior to this. One question may be is whether or not the frame is cracked (Aluminum) - although my friend insists that even if the frame had a crack, it wouldn't loosen up the chainring bolts as it has. So far no crack has been found but when you ride the bike you do hear a "creaking" sound. Its possible that the fork's post is broken but it still doesn't explain the chainring issues.

ShimanoX789 said:

If you can possibly believe it, after two to three miles of riding, the chainring bolts on the new shimano crank arm loosened.

Tomorrow (Tues, 29th), the a rep from Raleigh was scheduled to stop by his store prior to this. One question may be is whether or not the frame is cracked (Aluminum) - although my friend insists that even if the frame had a crack, it wouldn't loosen up the chainring bolts as it has. So far no crack has been found but when you ride the bike you do hear a "creaking" sound. Its possible that the fork's post is broken but it still doesn't explain the chainring issues.

Your friend is right -- a cracked frame should not affect the chainring bolts ...

So, you actually need to confront the possibility that your friend, regardless of his background as a team mechanic, may not be as competent as he should be ...

And, you should probably consider buying a set of Allen Wrenches, etc., and doing your own wrenching.

ShimanoX789 said:

Thank your for your suggestions. After I posted my question, my friend opted to remove the right crank assembly and replace it with a new shimano assembly.

If you can possibly believe it, after two to three miles of riding, the chainring bolts on the new shimano crank arm loosened.

Tomorrow (Tues, 29th), the a rep from Raleigh was scheduled to stop by his store prior to this. One question may be is whether or not the frame is cracked (Aluminum) - although my friend insists that even if the frame had a crack, it wouldn't loosen up the chainring bolts as it has. So far no crack has been found but when you ride the bike you do hear a "creaking" sound. Its possible that the fork's post is broken but it still doesn't explain the chainring issues.

You need to you have your nuts looked at...err I mean look at the chain ring bolts for correct length. Don't forget what I said earlier: nuts cannot be longer than the depth of the spider + spacer(s) (if any are being used) + ring(s).

completely different crankset? or only crank arms? if you are using the same chainrings and bolts to hold them on then that is where the problem is...

i have never had chainring bolts loose on their own in 30 years of riding...

nowadays I often find loctite (thread lock) on chainring bolts coming from the factory, also is there any chance that these chainring bolts are a mixed set? nut one brand and bolt another?

good luck