twisting handlebar with aero bar

I have clip on aero bars on my handlebar and I can't get the stem clamp
on the handlebar tight enough to maintain the position of the
handlebar. Normally, the handlebar stays in position but when I'm
riding on the aero bars (which is the norm) and I hit a bump, I hear a
little click noise and the handlebar rotates downward which puts my
aero bar out of position (tilted down). I've tried re-positioning the
handlebar and re-tightening as tight as I can but the handlebar
continues to rotate when I hit a bump.

So I'm forced to conclude that there is not enough friction between the
stem clamp and the handlebar. I've considered that maybe I need to
remove the stem clamp (it's threadless and easy to do) and sandpaper
the clamp to roughen it. Or perhaps I could insert double-sided
sandpaper to give some grip.

Anybody else have this problem and any suggested solutions?

Denis

wrote:
I have clip on aero bars on my handlebar and I can't get the stem clamp
on the handlebar tight enough to maintain the position of the
handlebar. Normally, the handlebar stays in position but when I'm
riding on the aero bars (which is the norm) and I hit a bump, I hear a
little click noise and the handlebar rotates downward which puts my
aero bar out of position (tilted down). I've tried re-positioning the
handlebar and re-tightening as tight as I can but the handlebar
continues to rotate when I hit a bump.

So I'm forced to conclude that there is not enough friction between the
stem clamp and the handlebar. I've considered that maybe I need to
remove the stem clamp (it's threadless and easy to do) and sandpaper
the clamp to roughen it. Or perhaps I could insert double-sided
sandpaper to give some grip.

Anybody else have this problem and any suggested solutions?

Denis

I've been able to increase friction between the stem clamp and
handlebar to reduce slipping. I used 80 grit emery cloth to rough up
the mating surfaces on both the stem and bar, sanding longitudinally
(though I don't know if that's important).

Also, cleaning the mating surfaces with alcohol or acetone may help. It
certainly helps carbon seat posts stay put!

Also, greasing the bolt (threads and shoulder) should help. Don't over
tighten.

Good luck!

In message . com,
writes
wrote:
I have clip on aero bars on my handlebar and I can't get the stem clamp
on the handlebar tight enough to maintain the position of the
handlebar. Normally, the handlebar stays in position but when I'm
riding on the aero bars (which is the norm) and I hit a bump, I hear a
little click noise and the handlebar rotates downward which puts my
aero bar out of position (tilted down). I've tried re-positioning the
handlebar and re-tightening as tight as I can but the handlebar
continues to rotate when I hit a bump.

So I'm forced to conclude that there is not enough friction between the
stem clamp and the handlebar. I've considered that maybe I need to
remove the stem clamp (it's threadless and easy to do) and sandpaper
the clamp to roughen it. Or perhaps I could insert double-sided
sandpaper to give some grip.

Anybody else have this problem and any suggested solutions?

Denis

I've been able to increase friction between the stem clamp and
handlebar to reduce slipping. I used 80 grit emery cloth to rough up
the mating surfaces on both the stem and bar, sanding longitudinally
(though I don't know if that's important).

Also, cleaning the mating surfaces with alcohol or acetone may help. It
certainly helps carbon seat posts stay put!

Also, greasing the bolt (threads and shoulder) should help. Don't over
tighten.

Good luck!

The paper shim (even one with grit on either side) is a bad idea as the
paper fibres could fail dramatically. If you must shim, metal would be
better.

Are you sure the stem clamp is intended for the diameter bars you are
using?

Some modern stems and bars have sizes marked on them. Otherwise you can
use callipers (digital or vernier) to measure them.

The following web page has a link that will allow you to download the 3t
manual in pdf form. The manual includes information on installation in
general and recommended torque for the clamp bolts. (Page 43 of the
English version).

http://www.3ttt.com/ing/fr_manuale.htm


--

Martyn Aldis, e-mail
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Are you sure the stem clamp is intended for the diameter bars you are
using?

The stem clamp is the right size. It fits snug and I've been using the
same stem, handlebar, and aero bars for several years. This is the
first year I've had problems with the handlebar rotating on me.

Denis