Headset fork seat conundrum.

[peetee]

I have an 80's Carlton which requires a 1" threaded headset with a fork seat approx 27.0mm.
All the headsets I have are 26.4 seat and the info provided online rarely offers this measurement in the details.
Can anyone recommend a headset that I can purchase? If it is chrome, Campag record look, all the better.
Cheers.

[Brucey]

1" headsets come in JIS or ISO, and the biggest difference between them is the crown race diameter.

Do be sure that the steerer isn't 26tpi though; if so only a Raleigh headset will fit.

cheers

[Gattonero]

I have an 80's Carlton which requires a 1" threaded headset with a fork seat approx 27.0mm.
All the headsets I have are 26.4 seat and the info provided online rarely offers this measurement in the details.
Can anyone recommend a headset that I can purchase? If it is chrome, Campag record look, all the better.
Cheers.

Get the forks reamed to 26.4 then, since you already have some headsets of that size on hand...

[peetee]

Well, that's an option but a bit of a faff and if there are period style headsets out there that would allow me to keep it original, all the better.

[Brucey]

Like I said before, check carefully that the steerer isn't threaded 26tpi; a lot of carltons were made this way, and IIRC the 26tpi Raleigh headset uses a crown race fitting that is close to 27.0mm. In addition there can be small differences in the head tube ID that can cause issues too. In the worst case if you just machine the crown race to 26.4mm willy nilly then you can end up with the frame that no headset will fit.

If it is a later/better carlton (e.g. from the lightweight unit) then it may be 24tpi but these frames didn't generally have 27.0 crown race seatings. What they did have (often) is a tiny stack height, made for a now-extinct format of shimano headset. This can cause issues too.

So measure up carefully, get all your ducks in a row first and act accordingly.

Headset standards here

http://www.sheldonbrown.com/cribsheet-headsets.html

Note that the JIS standard is basically a knock-off of an English headset fitment, commonly used in the 1950s and 1960s. Headsets such as those made by TDC (as fitted to innumerable CBs, Holdsworths, etc) were made to a similar standard to this. Strictly speaking the 27,0mm crown seating in this and the Raleigh standard is probably 1-1/16" and is 0.0125mm smaller than 27.0mm.

cheers

[peetee]

Its a 1980 Carlton Super Course 531.

[Brucey]

Its a 1980 Carlton Super Course 531.

The #1 thing to find out;

Is the steerer 26tpi?

The #2 thing is

what is the stack height?

cheers

[rjb]

An easy way to check if it's 24tpi is to offer up a 24tpi hacksaw blade and see if the teeth line up Hacksaw blades are usually marked with the tpi but the I'd can become worn if well used.

[Brucey]

in a similar vein, a standard BB cup is 24tpi and a 3/8" axle is usually 26tpi. Either can be used as a thread pitch gauge.

cheers

[Csarvelos]

Hi just wanted to say that yellowjersey.org in the States stock 26tpi 1" headsets
A man called Andrew has been really helpful to me and I have pasted a bit his email below with links That I think you all might like
pic of headset:

http://www.yellowjersey.org/wwhs2.jpg
We've been Raleigh dealers forever, finally went out and had these made for us.

contact order etc:
http://www.yellowjersey.org/ordinfo.html
Thank you

p.s. more Roadster & other Raleigh bits:
http://www.yellowjersey.org/eastbits.html

Hope this helps all us Raleigh nuts

Csarvelos happy to have a headset in the post finally!! They post worldwide

[Gattonero]

Well, that's an option but a bit of a faff and if there are period style headsets out there that would allow me to keep it original, all the better.

To me would be more simple to use what I got on hand, to ream a fork crown to 26.4 is hardly anything to make the frame "not period-correct", if this makes you able to fit a headset you already have to match the frame, instead of buying another!

[peetee]

On the other hand the originality options seem quite appealing if you don't have the tools to do it yourself or don't know of a local, reliable engineering firm. I tried the company up the road about ten years ago and they wrecked a rare BMC cylinder head with a simple skim job.