spacers on carbon steerer

[huttster]

Hi guys,i am in the process of finding out about lowering the position of my bars on carbon forks,is it ok to move the spacers from below the stem and replace them above until i find a height that is comfortable?I have tried it with one spacer,removed cap and used some washers to tension and then tightened the two bolts on the stem and replaced cap,is this ok to do until i find the height i want and where do you cut it when height found,cheers,

 

[Paul_Smith SRCC]

Yes that’s fine, don’t be quick to cut the steerer down to the new lower height though just incase you then wish to raise it again slightly; as the saying goes “measure twice, cut once”.

Paul Smith

Touring Tips

 

[huttster]

Thanks paul and paul,glad that's ok as i want to ride the bike for a while to be absolutely certain before i go cutting,found advice elsewhere about where and how to cut

 

[snailracer]

Is your steerer tube carbon? If it is, it is prudent to keep one washer under the stem.

 

[huttster]

Is your steerer tube carbon? If it is, it is prudent to keep one washer under the stem.

Yup,is a carbon steerer and at moment there are four spacers under stem and one above so should be enough to play with,thanks for advice.

 

[bad boy]

I am in the process of doing the same thing and have read some really differing opinions on the subject.

If you look at the spez website for instance it actually invalidates the warranty to put any spacers above the stem for that matter I saw a post which included the technical doc from spez to indicate this for bikes that come with a full carbon steerer.

Im certainly no expert, all im saying is when I researched it I found a few things that seemed contradictory to what I had been told.

 

[huttster]

I know what you mean bad boy,i have also read no more than 40mm of spacers under the stem and always keep a spacer above and below but my bike came with none above and 5x10mm below!I have looked at the spez website and i think it means you can have spacers above whilst you get your desired height but there is a warning about doing this permanently as you would be clamping below the supporting expander tube that is inside the steerer,i would post a link but am more shat than hot on the p.c ,before i actually cut the steerer and replace the expander plug i am just gonna take it easy

 

[huttster]

I have just had a closer look at the expander plug inside the steerer and when you do the plug up it indeed expands (suprise,suprise) onto the inside of the steerer,the plug also has a threaded hole in that the top cap bolts into for tensioning,now i have lowered the bars i have also lowered the expander plug so it's under the stem when tightened,just need a longer screw through the cap to reach the plug for now until cutting time

 

[youngoldbloke]

I have just had a closer look at the expander plug inside the steerer and when you do the plug up it indeed expands (suprise,suprise) onto the inside of the steerer,the plug also has a threaded hole in that the top cap bolts into for tensioning,now i have lowered the bars i have also lowered the expander plug so it's under the stem when tightened,just need a longer screw through the cap to reach the plug for now until cutting time

That sounds sensible. Worth noting that some plugs (Deda?) have a lip that prevents you lowering them, so too many spacers above the stem could pose a problem, as thje plug could be expanding against an unsupported area of steerer. Other plugs are much longer and give support over a greater length of steerer, so that it isn't such an issue.

 

[Zoiders]

Listen to Paul.

The clever guy up thread who actualy knows what he is taking about, of course you can move the spacers around, carbon steerer or not, if the idea of carbon on carbon being the only thing keeping the plug form breaking the tube bothers you then put some ally spacers on - not that you actualy need to.

I dunno...bleeding internet rumor mills.

 

[youngoldbloke]

re. "bleeding internet rumor mills"

PDFs from Specialized:
Carbon Steerer 1 Carbon Steerer 2

 

[huttster]

re. "bleeding internet rumor mills"

PDFs from Specialized:
Carbon Steerer 1 Carbon Steerer 2

Yup,that is what i was reading,the expander plug is to be directly under the stem for support before clamping,have done that and replaced the cap bolt with a longer one for tensioning,looking daft with a little chimney above stem for now but not cutting off before totally sure

 

[youngoldbloke]

Here is a helpful little video from Hope re. installation (important to expand the plug in the steerer before tightening the top cap bolt).
Hope

 

[raindog]

Interesting thread. If I've understood correctly, carbon steerers are so delicate the expander plug needs to be directly under the stem clamp to avoid distortion or breakage? I'm just glad all my carbon forks have aly steerer tubes.

 

[snailracer]

re. "bleeding internet rumor mills"

PDFs from Specialized:
Carbon Steerer 1 Carbon Steerer 2

In response to reported breakages, a recent Trek service bulletin recommends spacers above AND below the stem. I think the spacer between stem and headset prevents local distortion of the steerer (due to the stem clamp being not perfectly round, or overtightened) in the region of the headset top bearing, which otherwise results in point overloading of the steerer.

Only somewhat related to the insertion of the bung, and another different failure mode.

Stem and carbon fork manufacturers clearly haven't got their act together, yet - their parts are not cross compatible and they are pointing fingers at each other as well as blaming "user error" .

http://velonews.comp...bulletin_121428