Do early 90s Specialized use JIS headsets

[Titiritero]

Currently overhauling a 1992 Specialized Stumpjumper I recently bought, the basic one with full DX. Among the many surprises, the bearing cages on the headset were slightly bent and the top one is missing one bearing. I've been to every single bike shop in my city and nobody has anything matching or spare bearings. They all recommend not to bother and get a new headset. And that is my doubt.

"The internet" seems to suggest those early 90s Specialized had JIS headsets, but I'd rather be sure. I could measure it, but my calipers are not digital so 1) I don't know if I'll be able to tell the difference between 26.4 and 27mm and 2) that means I would have to remove the headset to check and I'm still not 100% sure that I would just run with the existing one if just one bearing is missing.

Has anyone more reliable info? Thanks

 

[Tootyred]

Im suprised a bike from 92 used 1" headset. Most by then were 11/8"!

If the races are in good condition, just put new loose balls in with new grease....job done for another decade.

 

[Tootyred]

Without measuring you may never know as even if your model did have jis...it might now be now.

When it became clear that manufacturers dalliance with jis was loosing traction, many converted to iso. My team marin from 89 is a classic example. Dead jis xt headset, replacements scarce, so crown cut down in the shop and steel iso cups pushed in to stretch the headtube.....

That was 1991! So you probably need to measure to be sure. The crown is far easier to measure than the headtube as the difference is quite visible.

 

[Titiritero]

Thanks for the responses. Yes, it's a 1", apparently Specialized was one of the latest to move to 1 1/8". Actually, maybe they even went directly to ahead without passing by threaded 1 1/8"...

Trek Multitracks used 1" threaded headsets until they were discontinued in 2000. Why change if the old system works... ?

In the end Google told me of a little bike shop that seems to be run by an amateur guy that has loads of old spares, and he was able to find a bearing cage identical to mine, so bike is nearly finished. I might never have to find out if the headset is JIS or ISO in the end...

 

[montair]

No direct help on the question. ~1991 My road bike (Raleigh Equipe with added105 group set) was nicked and the LBS had a Stump Jumper that had a damaged frame which was being returned. I managed to buy the replacement frame and fork. The frame was the same yellow and purple colour way but the forks where black as i was told at the time all replacement forks where always black. It looked quite cool as 99% of people had colour coded frames and forks. This was nicked within a year !

 

[bikeworkshop]

I'd always rebuild an old headset with loose balls - because you (almost always) get more in there, they are no longer in sync with the dents or brinnelling left by the old ball bearings, so it should function better.

The cages are fitted in the first place to reduce assembly costs.

 

[Attempted Mustache]

I may be wrong but I had thought the only difference between 1 inch ISO and JIS was the crownrace internal diameter? Hence the Madison Elite headsets I’ve been using to replace the original JIS one on my ‘88 Cinder Cone coming with both races;

https://www.sjscycles.co.uk/headsets/mpart-elite-1-inch-threaded-headset-black/

 

[27motorhead]

I'd always rebuild an old headset with loose balls - because you (almost always) get more in there, they are no longer in sync with the dents or brinnelling left by the old ball bearings, so it should function better.

The cages are fitted in the first place to reduce assembly costs.

100% this. Thanks for using the phrase brinnelling too!

Cut & paste from the interweb...

The definition of brinelling is the permanent indentation of a hard surface. Bearing brinelling occurs when the internal raceways of a bearing have been permanently damaged. The indentations can quickly lead to improper operation, like chattering or excess vibration, which in turn can accelerate other forms of wear.

 

[bikeworkshop]

Headsets live almost all their lives in a single position, straight forward, so the races become indented by the balls by ground vibration.


It's a reason why those "heavy duty" headsets with large bearings like the FSA Pig are a bad idea.

Less(bearings) is More(brinnelling)