Gap between crown race and forks

Hello, I'm replacing my old headset and I have been unable to get my crown race flush with the forks. The gap is about two millimetres and even the whole way round. Most of the advice I could find online was for carbon bikes but mine is steel. Does this sound like it would be a problem if I left the gap as it is?

Thanks.

That doesnt sound right. Crud / paint getting in the way. ISO / JIS sizing problem?

Any pics.

Shaun

Should go all the way down. Sounds a bit like you might have a 27mm crown and the race is a 26.4mm

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Hi again, this is the gap I'm talking about



and here is another view of the crown race



It's a shimano 600 headset I believe. The steerer tube is pretty much free of dirt and grit as I gave it a good clean before hand. I've been pressing it on using the pvc pipe, hammer and blood, sweat and tears approach and can assure you it is not going to go down any further than that.

Thanks

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So what I'm trying to find out is what is the worst case scenario if I left it with the gap and if it really must be flush then is there anything I can do other than buying a new headset?

Thanks

Does it stop the stem from fitting into the forks? If not you have 2 possibilities.
1) Leave as is & hope it doesn't shift - not the best option..
2) Remove the race & cut a slit across it to allow it to fit, which may work. I've seen it done with MTB's and some crown races are designed that way.
3) Buy a new slotted crown race - assuming it will be compatible with the 600 headset..

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If I find that the crown race is tight fit I usually seat it with a brass drift. I haven’t heard of the PVC pipe method but I would guess that there would be too much flex in a plastic pipe to seat the race properly if I understand your description correctly. I have never been unable to fit a race because it was too tight… perhaps I have just been lucky but have had loads of problems with them being too loose. If you cannot seat the the race by driving it on I would be inclined to build up the headset and then ride the bike up the road; as long as you are confident that the race is partially seated. You may find that the race will seat as you tighten it all up anyway, but once you get some weight on it it should seat on its own. You will need to adjust the headset as you go…so don’t go too far from your tools. Even when races appear the be fully seated the headset often needs further adjustment after a few miles as everything settles down.

If anyone thinks that’s a really bad idea please say so.

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I use a length of 28mm copper pipe to drift them in - the copper is soft enough not to damage the fork or the crown race .The tube needs to be cut perfectly square so I used a pipe cutter . Gently warm the crown race at low heat in an oven for about 5 minutes , apply a little grease round the fork tube and all taps in nice and easy without too much effort .
The tube is not cheap to buy as most merchants only sell it in 3m lengths but bought mine cheaply as an offcut .

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Never tried this myself but don't see any real problems with it. As a last resort could you fit a very narrow headset spacer over the steerer first then place the crown race on top of that?

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gerryattrick":29n365gj said:

Never tried this myself but don't see any real problems with it. As a last resort could you fit a very narrow headset spacer over the steerer first then place the crown race on top of that?

Click to expand...

Might be a bit unnerving when it slips down as the bike is ridden!
As above I would move on from PVC to metal, I've had to do that with more reluctant crown races. A proper steel setting tool is a revelation.

Mark.