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Trying to replace the headset cups and race faces on a steel frame for 1" fork. Removed the old cups by gently knocking them in a circle with a steel pipe of the correct diameter. However, the new cup are a hair too small - although no wobble, they are freely inserted and removed from the head tube. The slack is much less than a mm.

The LBS said that this is normal, and that they can fix it, by inserting something in between the head tube and cups. So is it normal? The headset is this one and the fork is a cheap Zoom 1 inch threaded fork.

What should be inserted, so that the cups can be correctly installed? (I was planning on using the hummer and piece of wood technique)


I purchased a calliper. 30.0mm cup, 30.2mm frame. Тhe cup is really easy to insert while pinching it with fingers, although it does not wobble.


I purchased 2-component glue and nailed the thing in place.

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Do you have access to calipers to measure the ID of those cups? –  WTHarper Nov 20 '13 at 13:17
This is a great reference: sheldonbrown.com/headsets.html –  WTHarper Nov 20 '13 at 13:19
@WTHarper, I will purchase a precision caliper and measure. In a day or two. That bike has to get to the road (and mountains)! –  Vorac Nov 20 '13 at 14:32

4 Answers 4

up vote 1 down vote accepted

What the LBS may intend to do is add some Loctite or similar chemical retaining compound. The compound is going to glue the cups into the headset. The material will fill in the very small space between the two pieces. The space may be due to machine tolerances with the frame being on the large side of the spec and the headset on the small end of the spec or previous damage to the frame.

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I will probably try this advice, as the gap is too small to put sheet metal in. Today I purchased precision calipers and am going to post precise measurements shortly. –  Vorac Nov 21 '13 at 9:07
I am going to try this approach. I purchased a 2-componnet resin glue. Will report in a couple of weeks if this has worked. –  Vorac Nov 25 '13 at 8:56
I've done it with wobbly fork crown races. It works, but it'll be a lifetime fix. –  WTHarper Nov 25 '13 at 13:12
The advantage of using the correct product ("Loctite Bearing Lock" vs two part epoxy) is that it Loctite will retain the cup and be removable later if needed. –  mikes Nov 25 '13 at 21:23

They are most likely going to try and shim it with a small piece of metal, a bit of old beer tin or similar.

You can buy these off the shelf for mismatched seat tubes/posts but I've never seen a headset specific one.

Once everything is assembled and clamped down it should be as good as new.

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The gap is very tiny. Would kitchen aluminum foil work reliably? –  Vorac Nov 21 '13 at 9:08
There could be a concern with galvanic corrosion with steel cups and an aluminum shim, especially if the frame is steel. –  mikes Nov 21 '13 at 11:34
@mikes, good point. Note also that headset vs. frame materials is addressed in another question, and also it seems alloy headsets are common in online stores. Would there be a difference between using an aluminum shim and an aluminum headset? –  PositiveK Nov 22 '13 at 1:24
A fine layer of anti-seize should be enough to keep things happy and uncorroded. Foil might not be tough enough for a long term fix. If the gap's really that small, a good helping of Loctite might be ok. Wouldn't be my first choice though. –  alex Nov 22 '13 at 4:21
@alex, and what would be your first choice? Btw I updated the question. –  Vorac Nov 22 '13 at 9:29

Sheldon Brown, has a page with headset dimensions. According to him, some Austrian frames have slightly larger headset cup size 30.8 compared to standard one 30.2. So maybe you have old Austrian frame?


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A friend helped me with the measurement and the frame seems to be 30.2mm. But why are the cups smaller - I thought there is only one size :( –  Vorac Nov 25 '13 at 8:56

I've encountered the same issue, and have tried a 'quicksteel' type metal repair putty. I'll se how it goes. If it's no good, I'll buy some feeler gauges and make shims from the thinnest strips.

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