1" headset stack height, 30.0mm, 30.2mm and reaming headtube

Hi all,
I'm new to 1" headsets & quill stems etc, so am wanting some advice about stack heights & cup sizes.
I'm removing the paint from a 1984 Dawes Galaxy frame & want to replace the headset while I'm at it, but notice there are various stack heights!
I've attached a photo of the headtube that I'm stripping down & added my own thought on what the stack height might be. I'm thinking you just add all of the exposed parts of the headset (minus the part of the cup that sits in the frame) including locknuts, spacers etc?
So my thinking is that I just add dimension A to dimension B on my photo & I'll have my stack height?
Also, I've read that there are 2 different cup sizes... 30.2mm & 30mm. is there anyway of knowing what the Dawes frame might take before removing the headset.
Any recommendations of a cheapish sealed bearing headset would be most welcome.

Sorry if this has been asked before, but really appreciate any help from you guys

Re: 1" headset stack height

That is pretty much it, or the other way around
measure your headtube
measure your steerer
steerer less headtube gives you the stack height

I would guess the Dawes will be ISO headset with 30.2 cups and 26.4 race.

Take your old race our and measure the internal diameter which will be 26.4 or 27

Re: 1" headset stack height

Harryburgundy":2yhnyml5 said:

That is pretty much it, or the other way around
measure your headtube
measure your steerer
steerer less headtube gives you the stack height

I would guess the Dawes will be ISO headset with 30.2 cups and 26.4 race.

Take your old race our and measure the internal diameter which will be 26.4 or 27

Click to expand...

That's very useful Harry. Huge thanks

Re: 1" headset stack height

After removing the headset cups, they appear to be 30.0mm after measuring them with a caliper.
This as I've found, are a lot less common than 30.2mm.
Would it be OK to turn/file down the bottom race seat to 26.4mm and ream 0.2mm out of the top/bottom sections of the headtube so 30.2mm cups will press in, or maybe ream out a bit less & take a little bit off the headset cups... Or would this not be advisable?
Also, the headset I removed seemed to have the ball races built into the top & bottom cups! As I've not much experience with 1" threaded headsets, I don't know if this is normal or not.
The races each contained 24 ball bearings.
Again, I'd really appreciate some advice on this.

Re: 1" headset stack height, 30.0mm, 30.2mm and reaming head

Did you get the crown-race off the forks? many (not all) have the dimension (26.4) engraved underneath. I wouldn't think a Dawes Galaxy would be JIS, but you never know... anyway, it's easier to be sure of 0.6mm discrepancy (crown-race) than 0.2mm (headtube sleeves). I don't want to second-guess your calipers, but obviously reaming is irreversible, so, you know.. be certain of the measure before commiting yourself to the cut.

Also, the headset I removed seemed to have the ball races built into the top & bottom cups! As I've not much experience with 1" threaded headsets, I don't know if this is normal or not.

Click to expand...

Your headset does sound unusual, I've not had much experience with anything but 1" threaded headsets, but probably a pretty small sample of the range of variations possible- I don't remember ever encountering captive bearings.. but again, you never know..

Re: 1" headset stack height, 30.0mm, 30.2mm and reaming head

torqueless":3sgvncbn said:

Did you get the crown-race off the forks? many (not all) have the dimension (26.4) engraved underneath. I wouldn't think a Dawes Galaxy would be JIS, but you never know... anyway, it's easier to be sure of 0.6mm discrepancy (crown-race) than 0.2mm (headtube sleeves). I don't want to second-guess your calipers, but obviously reaming is irreversible, so, you know.. be certain of the measure before commiting yourself to the cut.

Also, the headset I removed seemed to have the ball races built into the top & bottom cups! As I've not much experience with 1" threaded headsets, I don't know if this is normal or not.

Click to expand...

Your headset does sound unusual, I've not had much experience with anything but 1" threaded headsets, but probably a pretty small sample of the range of variations possible- I don't remember ever encountering captive bearings.. but again, you never know..

Click to expand...

torqueless,
Many thnaks for your reply
It's defiantly a 27mm fork race & I couldn't see any measurement stamped anywhere on the fork! I thought the bearing races most unusual, but have mostly delt with 1 1/8" threadless headsets before (coming from mid to late 90's mountainbikes)
I will try to get a photo of the headset up sometime this week & will carry on with the stripping of the paint.

PS... I've heard vernier calipers called "very near" calipers before, so I understand what you mean.
apparently I've read on the web that some people think it's OK to press a 30.2mm cup into a 30.0mm headtube! :facepalm: The internet seems to have turned people into experts overnight!

MANY thanks for your valuable advice

Re: 1" headset stack height, 30.0mm, 30.2mm and reaming head

if you can't find the correct headset size, then reaming the headtube is a lot less damaging than just forcing on oversized cup in there! As for stack height, try and find a headset with the same or less height than the current one, and add spacers if necessary. It's a lot easier to add spacers than it is to find a low stack height headset if you cut the steerer!

Re: 1" headset stack height, 30.0mm, 30.2mm and reaming head

If it's a 27mm crown race, then you are probably best going with a JIS headset...or you will end up with JIS forks and ISO frame. Are they that hard to come by? It is likely to be a Japanese headset I guess. I bought a Shimano 105? headset once and had to take it back because it was JIS. That one had about the lowest stack i'd ever come across- IIRC not much more than 30mm. There must be Shimano, Suntour, Tange and others around in JIS size.

Re: 1" headset stack height, 30.0mm, 30.2mm and reaming head

Hi all,
Many thanks for your very valued advice

I've found this on on eBay that's JIS & looks OK. I'm not after anything fancy at all.
What do you think to it?

http://www.ebay.co.uk/itm/JIS-1-Threade ... 3f24e4025a

Re: 1" headset stack height, 30.0mm, 30.2mm and reaming head

Unusual for a Dawes frame/ fork to be JIS......

Personally I'd blow another tenner and get something a little more upmarket, that knurled topnut would catch my eye all day long .

http://www.spacycles.co.uk/products.php ... 2b32s115p0

Shaun