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Will a large spacer stack (35mm) cause a headset to loosen?(9 posts)

Will a large spacer stack (35mm) cause a headset to loosen?FTMD
Oct 9, 2003 10:59 AM
I've been having trouble w/a mtb I built recently. I've got 35 mm of spacers under the stem. The headset is coming out of adjustment on every ride so far. I installed the hs myself and believe that it's in the frame correctly. I'm tightening the top cap first, stem bolts second. I can't see any other issue I might have other than a high spacer stack. Any suggestions? Thanks.
re: Will a large spacer stack (35mm) cause a headset to loosen?Mike Prince
Oct 9, 2003 11:16 AM
What I would look for before I said it was the spacers:

- is the star nut/expansion plug pulling up or is it loose
- is the crown race not down all the way and being worked sown the steerer more with every ride
- the bearings and seals could be settling in each ride
- check the steerer to make sure the top of the stem is 3 mm above the top of the steerer - otherwise the top cap bottoms out against the steerer.

A few more q's:

- what kind of headset?
- is it one spacer or multiple? What material?
re: Will a large spacer stack (35mm) cause a headset to loosen?FTMD
Oct 9, 2003 11:47 AM
I installed the crown race with a race setter and to my eye is all the way down. No gaps are showing at least. The steer tube is flush with the top of the stem so I've been using one 5mm alu spacer above the stem to secure that. The star nut was installed with a setter, and it's not loose. The headset is a Cane Creek C2 that had about 200 miles on it. Spacers are all alu.

Q: I hacksawed the steerer tube using the cutting guide I got from park, but the cut is not perfectly level. The saw cut at a slight angle. At this point I'm wondering if this is the culprit.

Very frustrating b/c it was cinch up tight at home and be loose 2-3 miles into the ride.

Thanks for your thoughts.
spacer stack could loosen...C-40
Oct 9, 2003 12:37 PM
Spacers are never perfectly uniform in thickness. If you're using several spacers, they could be rotating and causing the stack to loosen. You would need a micrometer to check for uniform thickenss.

More likely it is the crown race or lower head tube race settling.

The crooked cut on the steerer won't hurt anything as long as there is a gap between the longest area and the top cap.

The stem clamp is what keeps the headset from loosening. Is the stem staying tight on the steerer?
Once you clamp down on the stem boltsMR_GRUMPY
Oct 9, 2003 11:28 AM
The headset shouldn't loosen unless the stem is slipping.
Agree. Tighten stem bolts real good. nmSpunout
Oct 10, 2003 4:49 AM
Tighten the stem bolts real EVENLY.Spoke Wrench
Oct 11, 2003 4:27 AM
If one stem bolt is significantly tighter than the other, you may have only an edge bearing on the steerer tube insted of the whole face of the stem. The best technique is to sequentially walk down the stem bolts a bit at a time. If you use a torque wrench when you do this, you'll find that after tightning one bolt, the torque on the other is a little less than it was before.
It's worth checking...satanas
Oct 10, 2003 12:45 AM
...that a bearing race isn't in upside down. I know this is unlikely, but a mechanic friend did this once, and the symptoms were as described.
re: Will a large spacer stack (35mm) cause a headset to loosen?JimP
Oct 10, 2003 8:40 AM
The instructions that came with my ITM stem said to lightly sand, clean, and thoroughly degrease the inside of the stem and the outside of the steerer to prevent slipping. This can be more problematic with carbon steerers.