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Subject: Stuck Handlebar Stem
From: Jobst Brandt
Date: May 11, 2001

Frozen aluminum stems were a common occurrence because conventional stems were poorly anchored in the fork, having only an expander at the bottom and the top free to pump from side to side with handlebar forces. This was OK in the days of steel stems and steel steer tubes but aluminum accelerated corrosion in this interface, expanding greatly with oxidation, in spite of grease in the interface that only turns to an emulsion in the rain from lateral pumping action.

The expander bolt must be backed off about 1/2 inch to hammer the expander wedge out of engagement with the bottom of the stem. When the expander is free, the bolt should be loose with the expander dangling on its other end down in the steer tube. Now the stem should be rotatable with moderate force. If this is not the case, then it is a corroded frozen stem. Many forks have been damaged by twisting the bars forcefully in an attempt to free the stem. Don't do it. Pouring ammonia onto the gap is ineffective unless the stem is not truly frozen. The thin oxide interface to be dissolved is thousands of times as deep as thick. There being no circulation, this method works only in abstract theory.

A skilled mechanic can saw off and drill the stem out until it is a thin shell, then break through one side of the shell with a grinder to extract the stem. Because aluminum corrosion expands enough to stretch the steel steer tube, it cannot be loosened by force. Riders often are happy when their stem stops creaking only to find later why it got quiet. It was no longer removable. The main advance achieved by threadless head bearings is that the stem is no longer subject to this failure. It is more a stem improvement than a head bearing improvement, although it also makes adjustment simpler and less expensive.

Get it removed by a competent shop. Frame builders do this regularly.

Jobst Brandt

Spoke Divider

See also Sheldon Brown on Stuck Seatposts

Spoke Divider

More Articles by Jobst Brandt
Next: SIS Cable Info
Previous: Aligning a Fork

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