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Handle bar keeps dropping down…(10 posts)

Handle bar keeps dropping down…LinuxDude
Aug 29, 2003 6:43 AM
No matter how much torque I apply at the stem bolt it is not enough. When I go riding even for a short bit the handlebar drops dramatically when I go over rough terrain when I have my hands on the hoods of the STI shifters.

I tried some common remedies like using shimmies made from a soda can to no avail.
Btw, this is a threaded old school stem and the handlebar are both original (both Bianchi). So, I don't see any compatibility issues there.

I think I need to use a shimmy with really rough surfaces. I was thinking of using may be a fine grained double-sided (if there is such a thing) sand paper. What do you rbr masters think? Do you guys have a more delicate yet inexpensive solution?

Need more information...TFerguson
Aug 29, 2003 9:57 AM
A properly torqued, correctly sized stem and bar will not rotate. Something is wrong and I can't tell what from the above information.

Assumptions: You have an old Bianchi road bike with a 1" quill type stem and standard drop bars. Both came on the bike and were fine, but now the bar has started rotating in the stem. The stem has a single bolt to hold the bar. You can tighten this bolt until it won't turn anymore. Nothing else has changed. Any wrong assumptions? Anything I might be missing?

re:Need more information...LinuxDude
Aug 29, 2003 11:00 AM
Yeah, your assumption is right. Except that when I installed modern components on this bike I also played around the orientation of the drop bar. I think I may not have applied enough torque that first time and thus damaged the threads (or roughness) of both the handlebar and the stem. Now, everything I do (as mentioned earlier) doesn't seem to work. This is indeed a weird problem. Any ideas?

Just check a couple of take-off bars and stems....TFerguson
Aug 29, 2003 12:13 PM
All are smooth, no rough surfaces. The bolt torque should be somewhere around 10-12 ft-lbs. Think you are getting that much? It hasn't gotten oil or grease in there for some reason? Is there any reason for the bolt to bottom out or run out of threads before it actually gets tight? New bolt? Maybe try a washer. Sorry, running out of ideas. Maybe others can think of something.
Post if you find the solution. Too often we never learn what fix actually works.

I was having the same sort of trouble until I realized that thebill
Aug 29, 2003 12:24 PM
grease I had applied to the bolts had squished out and got on the bars. I use a bit less grease now, and I haven't had any more problems.
Some manu's recommend roughing up the interior surface of the stem with sandpaper to get better grip on the bars (not sure what a shim would add to this equation). I wouldn't use too fine a grade sandpaper; it would defeat the purpose. I also wouldn't stick sandpaper in there -- maybe it would work, but it adds bulk, and, well, who knows.
threads greased?surly357
Aug 29, 2003 1:17 PM
is the clamp bolt greased? If not the bolt may be binding before it gets a chance to fully tighten. Torque will mean nothing on dry threads or if the bolt head is binding on the countersunk hole....
Has the stem clamp stretched or deformedStraightblock
Aug 29, 2003 2:49 PM
so the two sides of the clamp close against each other before it tightens around the bar? Look under the pinch bolt. There should be a visible gap between the two sides of the clamp. If the two sides are in contact, you won't be able to tighten it enough to hold the bar.

I had a similar problem with a MTB seatpost. After several seat changes and adjustments, the one-bolt clamp had deformed to where it would bottom out on itself, and could not be tightened enough to keep the saddle from sliding backward.
re: Handle bar keeps dropping down…LinuxDude
Aug 29, 2003 8:10 PM
I forgot to mention before, but I had also applied some lube between the stem clamp and the handlebar. Aren't you supposed to put some lube in there?
But anyways, since I have been having problems with the handlebar I tried to dry up the lube by using some alcohol and that did not help.

Straightblock, it seems that I may have a deformed clamp. B/c when I apply the maximum torque I can manage the stem clamp seem like it could not go further.

Thank you all for good responses. I'll try a few more things and if it doesn't work then I may have to replace some parts.
re: Handle bar keeps dropping down…eyetalian
Aug 30, 2003 9:43 PM
service handlebardropper stop
re: Handle bar keeps dropping down…mapei boy
Sep 4, 2003 3:47 PM
After riding my Cinelli bars and stem for about twenty years, it started happening to me, too. It drove me crazy. I bought a new stem (a cool-looking least as pretty as my old Cinelli). It stopped.