# Specialized compression caps



## Bikephelps (Jan 23, 2012)

Are there any special requirements for Specialized compression caps? I seem to remember the fork can't extend past the stem.


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## Dunbar (Aug 8, 2010)

Bikephelps said:


> Are there any special requirements for Specialized compression caps? I seem to remember the fork can't extend past the stem.


You mean the steerer tube. Correct, you can run spacers above the stem temporarily while you dial in the fit. But you should cut off the excess steerer tube once you confirm your fit.


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## Bikephelps (Jan 23, 2012)

Dunbar
Thanks, I did mean the steerer tube. Do you know why the steerer tube needs to be trimmed after I dial in fit?


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## Dunbar (Aug 8, 2010)

I believe the compression plug is not designed to have any spacers above it. I don't remember the exact reason but there's a strongly worded warning in the Specialized instructions about it. Other manufacturer's use a different type of expander plug which does not have this restriction.


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## roadworthy (Nov 11, 2011)

The reason is because the greatest stress on a steerer is the interface between the bottom of the stem clamp and the carbon steerer tube. When torqueing on handlebars when sprinting, the bottom edge of the stem clamp creates a stress riser trying to shear the carbon steerer. The expansion plug reinforces this area. Spacing the compression plug upward raises the bottom edge of the plug which removes support of the plug under the highest stressed area.
Hope that helps.
A picture of the plug below:


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## Bikephelps (Jan 23, 2012)

Thanks. Great info, much appreciated.


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