Older fork meets younger headset....is the age gap too much? (Compatibility question)

Hello,

I spent the most part of yesterday evening trying to install a new one inch threaded headset onto a 80's(ish) Bob Jackson frame, to no avail. Two problems...

1. The crown race doesn't seem like it'll fit. I've installed a good few before, I know it involves liberal use of a hammer, but this one wouldn't seem to budge at all.

2. While trying to screw on the adjustable race, I just ended up starting to rethread the fork, it wouldn't go. The threads do seem pretty old and worn anyway. Bear in mind that the headset I removed was one of those old ones that's neither 1" or 1 & 1/8".

So is it possible that the an older fork isn't compatible with a newer headset? Also, could the threads on the fork be worn beyond use/repair? Should I just get a new fork?

Any advice appreciated, cheers!

I had an old fork, the crown race wouldn't fit ( i had to file it) and the threaded bit at the top slipped all the time, it was a french threaded fork i think. they have a different sized tpi. i put a newer fork on and the same headset was ok...could you have a french fork?

Hello,

1. The crown race doesn't seem like it'll fit. I've installed a good few before, I know it involves liberal use of a hammer, but this one wouldn't seem to budge at all.
   
   
   
   
   
   

The crown race seat can vary in size, I think some are 27mm and some are 26.5mm.

I had this problem with a modern fork and a Campag record headset. I took it into a bike shop, and they milled it down free of charge (Cycle Surgery West hampstead)

Not sure about the thread question, but Sheldon has a good bit on fork/headset compatibility.

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

Yup theres different sizes. i had the reverse problem of crown race being too big on forks which required some shimming I made of copper plate.

John Howard Marshall?

Lol'd at the title.. apparently the age gap thing is worked out as follows.

You take your fork age and halve it - then add seven years.. that is the youngest "headset" your "fork" can be compatible with

:)

Cheers all!

n3lson - seeing as it's a Bob Jackson, I'd assumed the fork would be English threaded!

sasmon - guess I could try filing the bottom of the fork down a bit.

Balki - ?

iro_dan - cheers, thought that used to be the case, but in this day and age???

Appreciate the responses y'all...

I think there are just 2 sizes for fork races for 1" forks and head sets:
26.4mm is most common. I think Campagnolo is always 26.4mm.
27.0mm is a bit odd, mainly for cheaper bikes.

I think there are just 2 sizes for fork races for 1" forks and head sets:
26.4mm is most common. I think Campagnolo is always 26.4mm.
27.0mm is a bit odd, mainly for cheaper bikes.

Thanks DC,

It was a cheapish headset so therein may lie the problem. I just assumed all 1" headset would be compatible with the fork. At least I know now, just a shame the bike shop salesperson didn't....