Headset woes

[eck]

I was about to replace the 1" threaded headset on my winter bike. I'd had a Stronglight something (the one with the needle bearings) on for a few years. I'd just bought a cheapo replacement from the lbs. But having removed the old one, I've just found that the crown race (? the ring that fits over the fork crown) is a very loose fit.   It just dropped staight on, and there is a lot of slack. 

I'd have thought that they would all be the same size but obviously not. Do these crown races come in different sizes?
I guess I'd be safer replacing like with like rather than just hope that a different replacement might fit. 

Any advice gratefully received. Thanks

[LittleWheelsandBig]

You have probably replaced an ISO headset (26.4 crown race, 30.2 cups) with a JIS headset (27.0 and 30.0).  There are plenty of other sizes too but very unlikely.

[eck]

Bu jove, I think you're right. I'd no idea that there were different sizes of crown race, but having measured the old and new ones, they are definitely different. Thanks for that.
Now, to find one that fits! 

[salar55]

Better get yourself down to Big Al,s for another stronglight headset or the bearings and races.

[eck]

Better get yourself down to Big Al,s for another stronglight headset or the bearings and races.

Aye, if only I had a whole day to spare!
Just ordered one from the nice man at Spa Cycles though.
Cheers 

[Steve Kish]

I've seen this mismatching fixed by tapping a centre-punch around the contact point on the fork crown, thus raising it by a few thou.

[Arellcat]

Thought I would dig up this thread, for I too have some impending headset woes.  I have a 1991 Specialized Stumpjumper Comp, with Tange Prestige tubes, one-inch headset, and so on.  Originally it would've had a Specialized headset (probably Tange-built) that was replaced at some stage with a Shimano Ultegra unit with cartridge bearings.

I want to replace the headset because the stack height on the Ultegra is too tall.  Since there aren't enough threads on the steerer to include the tabbed washer, the locknut has to bear directly on the top cup, and it's difficult to get the headset correctly adjusted and difficult to keep it adjusted.  I put up with it for a long time but not any longer.

I thought bikes from that era, Spesh included, used JIS headsets, and I was about to buy a good old Tange Levin CDS from Spa Cycles, but I decided to remove the Ultegra headset to doublecheck things.  Here's where it gets strange.

Both cups on the Ultegra measure 30.0mm OD, and the headtube ID is 29.76mm on the top and 29.80 on the bottom.  Those sound like normal JIS measurements to me.  But the fork crown seat OD is not 27.1mm, not 27.2mm, it's not 27-point-anything.  It's somewhere between 26.3mm and 26.48mm, and that says ISO to me.  The crown race itself is a bit corroded in places, and has an ID of 26.0mm in some places and 26.2mm elsewhere.  Perhaps it's a rusty 26.4mm.

It's almost as though the headset shipped with a mismatched crown race and whoever installed it just hammered it on good and proper.  Would it actually manage to carve away a third of a millimeter of steel in the process?  It wasn't desperately difficult to remove, however, with my toolmaker's clamp and a rubber mallet.  A JIS crown race would rattle around something terrible with the fork the way it is currently.

Thoughts?  And potential solutions anyone?

[LittleWheelsandBig]

Fit an ISO headset. I would get the headtube machined to ISO standard first but some folk wouldn't (and just bodge it in).

[Brucey]

I agree an ISO is the way to go.  The headtube may or may not accept the ISO cups easily, depending on how accurate your measurements are.

cheers

[rogerzilla]

The crown race SHOULD be about 0.2mm smaller than 26.4.  It's an interference fit and stretches as it's banged into place.

Incidentally, Raleigh headsets from t'olden days (up to the mid-80s, dependent on model) are JIS sized but with that irritating 26tpi* fork steerer.  Never get a Raleigh head tube faced if the facing tool will also ream it to ISO, as most do.  You will have to shim the top cup, as you are tied to Raleigh for at least the top end of the headset.  DAHIKT.

*all 1 1/8 threaded steerers are 26tpi - 1" ISO and JIS threaded steerers are 24tpi, though.

[Brucey]

The crown race SHOULD be about 0.2mm smaller than 26.4.  It's an interference fit and stretches as it's banged into place.

that degree of interference is too much between a crown race and a crown, both of which are pretty rigid. Might be OK on with stretchier bits though.

cheers

[Arellcat]

I think I will try to find a bike workshop locally that can ream the 0.2mm for an ISO unit, which is really the sensible—and probably only—option.

I don't imagine there is enough steerer to use the lower half of the Ultegra and the top half of $threaded_headset.  I'm aiming for a stack height of no more than 35mm, and ideally 33mm or less.  The Ultegra is 40mm.  I would like to keep the headtube at its current length, rather than having said workshop carve a load of metal off the top and bottom.

[Brucey]

There is a budget Tange headset with a ~33mm stack and a Levin will be about the same if you omit the tab washer; but then you will be back to the same predicament as you have at present I suppose.

With a simple headset it is best if you replace the clipped balls with loose balls from the start.

Simple headsets are much the best IME because there are fewer places to wear and rattle.  I wouldn't worry about a lack of tab washer with such a headset because you should only have to adjust it about once every five years anyway.

cheers