Handle bars keep slipping?

i have that problem in the past i tried putting a washer on the bolts to see if it bottoming out , it worked sort of ok but when ever i went over a pot hole etc the bars dropped .
my solution was to change my stem to a four bolt clamp ,which was more secure and has not move since .

Buddy2004 said:

Anyone have any ideas?

what type of stem is it?

Short of replacing the stem, I would try the same fix for a slipping seatpost:

Cut off a piece from an aluminum can and wrap it around the handlebar to create a larger diameter.

A little bit of toothpaste. It has worked great for me on saddle rails and seatposts that were slipping.

But it sounds like the bars may be on the verge of failure, assuming they were the right size to start with.

Buddy2004 said:

Hi,

I have a ~1992 Specialized Epic road bike (bought used) and am having a problem with the handlebars. Over the course of a 60 mile ride, the brakehoods are very gradually moving further away from me, as the bars rotate!

I have tightened the hell out of the allen bolt (single bolt) on the stem clamp and also cleaned the bar in the clamp area with degreaser - still I can't stop it from moving? The stem clamp isn't fully closed when tightened, so it appears to be the right size for the handlebar diameter. I tried placing a strip of electricians tape around the bar where its clamped - just made it worse.

Anyone have any ideas?

With a bike that old and that used, I'd just replace the stem and bars. No telling how many times the clamp bolt has been tightened, or over-tightened. Stresses accumulate in bolts, stem clamps, and handlebars, and can lead to a sudden fatigue failures. Last thing you need is to have the bolt, stem or bars break while riding.

I'm a big cheapskate in general, but draw the line at risking my safety on worn-out front end parts. Not saying it will happen tomorrow, but why fiddle and worry?

It's weird, because when fully tightened on the bars the clamp isn't fully closed - so a strip of tin can probably won't make any difference. The toothpaste solution I will try - spearmint or whitening?(!)

Can bars fail in this manner??? It's a pain to take everything off to investigate, as I would have to undo all the handlebar tape etc. It's difficult to see, but the only thing that would make sense is if the bars are in fact being crushed by the clamp, hence it not tightening effectively?

I will probably take the bars off to have a better look at it and then try the toothpaste, or consider new bars and / or stem.

Thanks guys

531Aussie said:

what type of stem is it?

the stem is fsa 140 with carbon front clamp ,the stem that kept on slipping was itm millelium 2 bolt.

Replace the bar and stem from a 1992 bike. Bars should be replaced every so often any ways as a safety precaution. Yes i have seen bars fail.

Quoted post said:

the stem is fsa 140 with carbon front clamp ,the stem that kept on slipping was itm millelium 2 bolt

.

As for slipping in a 2 bolt stem. There are several clamp diameters. 25.7mm, 25.8mm, 25.9mm, 26.0mm, and the same variations for the OS sets. I am betting you have a non-compatible setup. For example. Take a ITM 25.7mm bar and stick it in a 26.0mm syntace stem, throw in a little manufactuers +/- tolorance and you have a chance of the combo slipping. I try to match the sets when i pick them out. I am currently running the Ritchey WCS OS bar and stem and never had a slipping problem. I did in the past have the problem with a Cinnelli bar in a Profile stem. It would never stay put. They just weren't sized for each other.

Buddy2004 said:

It's weird, because when fully tightened on the bars the clamp isn't fully closed - so a strip of tin can probably won't make any difference. The toothpaste solution I will try - spearmint or whitening?(!)

Can bars fail in this manner??? It's a pain to take everything off to investigate, as I would have to undo all the handlebar tape etc. It's difficult to see, but the only thing that would make sense is if the bars are in fact being crushed by the clamp, hence it not tightening effectively?

I will probably take the bars off to have a better look at it and then try the toothpaste, or consider new bars and / or stem.

Thanks guys

Rideastrong covered the mis-match possibilities very well. If your stem clamp is too small for your bars, you won't get proper clamp-up torque. It may look OK to the eye, but in reality the gap is too big because the clamp isn't sitting down onto the bars.

You could mess around with an inside micrometer, or maybe even use plasti-gage strips to check for gaps if you really wanted to investigate; I'd just replace.

Concerning failure possibility, yes. If the clamp is too small, it will be pinching the bar on the sides, which could create stresses which initiate a crack right where you can't see it. If you've "tightened the hell" out of the clamp bolts even one time, you could have a bolt fail on you, or the threads in the alloy stem let go. I'd spend some bucks and get rid of this problem now.