Help: Loose Headset with Thomson Stem

[C.H. Luu]

Hi Guys:

I'm having difficulty keeping my headset in the adjustment I had set
it. I adjusted the headset where there is no banging within the head
tube. Aftera short ride, the headset becomes loose and there is play
between the fork steerer tube and the headset. Everytime I tap the
brakes, there's the usual small clunk from the play.

Currently have a Cane Creek C-2 headset with a Thomson Elite Stem.
There are four spacers, two large width and two medium width (I forget
the actual height).

Any ideas or things I need to verify to ensure the adjustment is locked
in by the stem? I do use a torque wrench to tighten the stem as
recommended by Thomson.

Many thanks,
Claude

 

[Lou D'Amelio]

Two possibilities here:

1) Headset adjustment too loose. Although torque wrenches have their
place, threadless stem caps is not one of them. Although a stated value
(usually 20N-m) is given, this is one area where you should tighten to
intended purpose. Tighten till youdon't have any binding but don't feel
any fore - aft movement when you rock the bike on the ground with front
wheel applied.

2) Your star-fangled nut (or steerer plug if you have a carbon steerer)
is too low. It may be barely engaged with the bolt and come loose
after riding. Of course, in this case, it must be raised.

In making your adjustments, be awaree that the Thomson stem (at least
the Elite which I am familiar with and use) has a 1-2 mm space at the
top above the horizontal line of the clamp. This works to distribute
the clamping forces around the steerer tube much like adding a small
spacer above a typical stem. Make sure that the stem is seated on the
steerer tube and the star nut or plug is placed accordingly.

Good luck...........Lou D'Amelio

 

[Alex Rodriguez]

In article <[email protected]>,
[email protected] says...

>
>2) Your star-fangled nut (or steerer plug if you have a carbon steerer)
> is too low. It may be barely engaged with the bolt and come loose
>after riding. Of course, in this case, it must be raised.

The starfangled nut is only needed to make the intial pre-load adjustment.
It is not meant to hold the adjustment. The stem being tightend down onto
the steerer is what holds everything together and adjusted.
--------------
Alex

 

[Llatikcuf]

I have only had this happen once. Headtube faces were not parallel, had
the headtube faced and the problem went away. Might give it a try if
you have not already, keep us posted.

-n