Headset loosens! Must I replace the stem?

John Crankshaw said:

I've just tightened my headset for the umpteenth time since building up my
bike last August. I'm thinking I need to replace the stem. What do you
think?

What I've got: Thomson X2 10 cm. Cannondale Premium Plus carbon fork with
1-1/8" carbon steerer, about 1.25" of spacers below the stem. Easton EC-90
31.8 bar. Cannondale Six13 frame.

When installed the steering tube is 1.8 mm below the top of the stem.

How I installed it the last two times:

1. degreased the steering tube and stem surfaces where they mate (with
alcohol).
2. roughed the surfaces lightly with medium sandpaper.
3. used Tacx carbon assembly compound.
4. torqued the stem bolts to 45 inch-pounds per Thomson spec.

Last time I did this technique, the stem went 2 months before loosening
slightly. Without Tacx, it'd go a few weeks only.

I've never had a stem loosen like this one does.

Anybody have this happen to them?

never had that happen to me like that; but it sounds like the fit
tolerances have gone a bit loose; a new stem might help, all
manufactured parts have size variations, if you can take a precision
caliper with you and buy the stem with the smallest diameter (assuming
of course there is sufficient quantity to sample). I wouldn't rough
the carbon steerer anymore

John Crankshaw said:

I've just tightened my headset for the umpteenth time since building up my
bike last August. I'm thinking I need to replace the stem. What do you
think?

What I've got: Thomson X2 10 cm. Cannondale Premium Plus carbon fork with
1-1/8" carbon steerer, about 1.25" of spacers below the stem. Easton EC-90
31.8 bar. Cannondale Six13 frame.

When installed the steering tube is 1.8 mm below the top of the stem.

How I installed it the last two times:

1. degreased the steering tube and stem surfaces where they mate (with
alcohol).
2. roughed the surfaces lightly with medium sandpaper.
3. used Tacx carbon assembly compound.
4. torqued the stem bolts to 45 inch-pounds per Thomson spec.

Last time I did this technique, the stem went 2 months before loosening
slightly. Without Tacx, it'd go a few weeks only.

I've never had a stem loosen like this one does.

Anybody have this happen to them?

If it's genuinely loosening, have you considered blue (breakable) Loc-
Tite on the clamp bolts?

It's not the bolts that loosen...the stem slides up the fork setting that
tell-tale loose-headset rattle over bumps.

"Hank" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

John Crankshaw said:

I've just tightened my headset for the umpteenth time since building up
my
bike last August. I'm thinking I need to replace the stem. What do you
think?

What I've got: Thomson X2 10 cm. Cannondale Premium Plus carbon fork with
1-1/8" carbon steerer, about 1.25" of spacers below the stem. Easton
EC-90
31.8 bar. Cannondale Six13 frame.

When installed the steering tube is 1.8 mm below the top of the stem.

How I installed it the last two times:

1. degreased the steering tube and stem surfaces where they mate (with
alcohol).
2. roughed the surfaces lightly with medium sandpaper.
3. used Tacx carbon assembly compound.
4. torqued the stem bolts to 45 inch-pounds per Thomson spec.

Last time I did this technique, the stem went 2 months before loosening
slightly. Without Tacx, it'd go a few weeks only.

I've never had a stem loosen like this one does.

Anybody have this happen to them?

If it's genuinely loosening, have you considered blue (breakable) Loc-
Tite on the clamp bolts?

I have some questions:
- what headset are you using? Internal?
- is it properly installed? No rings swapped?
- is 1,8 mm enough? Measure how far the topcap 'enters' the stem.

After setting the proload with the topcap and tighten the stem on the
steerer I torque the top cap further to 4 Nm. It helps, I don't no why.

Lou

"John Crankshaw" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

It's not the bolts that loosen...the stem slides up the fork setting that
tell-tale loose-headset rattle over bumps.

"Hank" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

John Crankshaw said:

I've just tightened my headset for the umpteenth time since building up
my
bike last August. I'm thinking I need to replace the stem. What do you
think?

What I've got: Thomson X2 10 cm. Cannondale Premium Plus carbon fork

with

Quoted message said:

Quoted message said:

Quoted message said:

1-1/8" carbon steerer, about 1.25" of spacers below the stem. Easton
EC-90
31.8 bar. Cannondale Six13 frame.

When installed the steering tube is 1.8 mm below the top of the stem.

How I installed it the last two times:

1. degreased the steering tube and stem surfaces where they mate (with
alcohol).
2. roughed the surfaces lightly with medium sandpaper.
3. used Tacx carbon assembly compound.
4. torqued the stem bolts to 45 inch-pounds per Thomson spec.

Last time I did this technique, the stem went 2 months before loosening
slightly. Without Tacx, it'd go a few weeks only.

I've never had a stem loosen like this one does.

Anybody have this happen to them?

If it's genuinely loosening, have you considered blue (breakable) Loc-
Tite on the clamp bolts?

I'll check the topcap 'into the stem' distance. But as I can tighten the
headset initially, I think that's OK. I didn't think the topcap was supposed
to even help hold the stem in place, but it must help.

The headset seems properly installed, BTW. It is an internal headset.

John

"Lou Holtman" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

I have some questions:
- what headset are you using? Internal?
- is it properly installed? No rings swapped?
- is 1,8 mm enough? Measure how far the topcap 'enters' the stem.

After setting the proload with the topcap and tighten the stem on the
steerer I torque the top cap further to 4 Nm. It helps, I don't no why.

Lou

"John Crankshaw" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

It's not the bolts that loosen...the stem slides up the fork setting that
tell-tale loose-headset rattle over bumps.

"Hank" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

On Mar 17, 2:16 pm, "John Crankshaw" <[email hidden]> wrote:
> I've just tightened my headset for the umpteenth time since building
> up
> my
> bike last August. I'm thinking I need to replace the stem. What do you
> think?
>
> What I've got: Thomson X2 10 cm. Cannondale Premium Plus carbon fork

with

Quoted message said:

Quoted message said:

> 1-1/8" carbon steerer, about 1.25" of spacers below the stem. Easton
> EC-90
> 31.8 bar. Cannondale Six13 frame.
>
> When installed the steering tube is 1.8 mm below the top of the stem.
>
> How I installed it the last two times:
>
> 1. degreased the steering tube and stem surfaces where they mate (with
> alcohol).
> 2. roughed the surfaces lightly with medium sandpaper.
> 3. used Tacx carbon assembly compound.
> 4. torqued the stem bolts to 45 inch-pounds per Thomson spec.
>
> Last time I did this technique, the stem went 2 months before
> loosening
> slightly. Without Tacx, it'd go a few weeks only.
>
> I've never had a stem loosen like this one does.
>
> Anybody have this happen to them?

If it's genuinely loosening, have you considered blue (breakable) Loc-
Tite on the clamp bolts?