TallRider

SHORT VERSION: are there any 1" threaded JIS-dimension headsets with sealed cartridge bearings and less than 38mm stack height? Even finding a JIS headset is difficult, let alone with cartridge bearings, let alone under 38mm stack.

LONGER VERSION: I'm rebuilding a 1981 Nishiki. The existing steel headset with loose balls is okay (no "indexed steering" damage to visual inspection of the races or turning of the fork), but the races don't appear to be in great shape. I'd like to eventually replace it with a cartridge bearing headset.
I have 38mm to play with (length of fork steerer tube minus length of head tube), but 2mm is taken up by a cable hanger for centerpull brake.
The current loose-ball steel headset is low stack height, like most classic headsets, and requires 4 or 5mm of spacers (plus the cable hanger) to cover the steerer tube. But my memory is that most cartridge-bearing headsets had at least 38mm stack height, usually a bit more. And finding any of this in JIS dimensions (30.0mm headset cup fit, 27.0mm crown race) seems less likely.

Ghrumpy

Look for a Shimano 105. Has the right stack height, and even though the Ultegra probably came in JIS too, I'd suspect the 105 is easier to find a JIS version of.

ThermionicScott 

Tange-Seiki makes at least one. The Falcon FL250C has a 35mm stack height (38 if you include the spacer, which you wouldn't, since you'd use the CP cable hanger.)

HillRider

The long out of production Shimano HP-6500 was a cartridge bearing 1" threaded headset with a 37.6 mm stack height. It was ISO dimensioned but milling a JIS fork crown race seat to ISO diameter is a relatively routine job by a decently equipped LBS. I had this done on a 1985 Bridgestone 400 many years ago when the OEM headset wore out.

TallRider

Thanks for pointing out the obvious - and real thanks, because I hadn't made the connection that the cable hanger replaces the washer.
I've found two vague online listings for the Tange cartridge headset, and there are some Shimano headsets still floating around eBay. I have no particular rush on this, so I'll set up eBay alerts for the Shimano, and keep an eye out for the Tange.

I actually have a JIS crown race for Shimano cartridge threaded headsets, that looks to have been manufactured that way.
From your knowledge, did Shimano ever make full cartridge headsets in JIS dimensions? (I have Shimano caged-ball 600 and 105 headsets in JIS dimensions on 1980s Centurions, maybe the last widespread production bikes to use JIS dimensions).

cpach

Tange Levin CDS is 33.3mm stack height. Loose ball, but good quality. Also I'd be inclined to mill the crown race to ISO for convenience of replacement parts sake.

3alarmer 

...this is what I would do if I had the ambitions of the OP. It's a pretty simple job with the proper tool, takes maybe ten or 15 minutes at most.
I have a local frame builder here who will do it for 15 bucks. Once you have the crown race seat milled to today's standard, you ought to be able to skootch about any headset you want on there.

Andrew R Stewart 

Agreed with both the suggestion to mill down the crown race to 26.1/26.0 and to consider a Tange headset. Andy

79pmooney

Tange has a very cheap, very low stack OEM headset. Much of the low stack is in the nuts above the races, You can combine this and a better Tange to get the good races and the stack you want; Tange makes HSs to fit all older Japanese bikes. Since the OEM costs roughly $8 and the good ones say $35, you have little to lose. (Except you don't get cartridge bearings. You will have to settle for ball races that will only go 8-10,000 miles. (Probably another 3000 if you are willing to put in larger balls when the indexing starts.)

Those headsets look decent and work so well I have little issue putting them on nice bikes.

Ben

Ghrumpy

Psst. It's 26.4.

And it's not "today's" standard. The Campagnolo/Professional standard is much older than the JIS standard, but the JIS standard was adopted part and parcel from an even older British standard, threading and all.
More to the point, today's standard is anything but 1" threaded.

The problem with milling the crown race to 26.4 is that Professional (NOT ISO*) Standard headsets also use 30.2mm cup skirts, so you really should have the head tube milled for that too, especially if the cups are aluminum. Pressing an aluminum 30.2 headset cup into a 29.9 head tube bore is going to shave a lot of metal from your cup skirt.
Are JIS headsets really that rare a bird that you need to resort to that? Honest question. From the responses, it would not appear so. Any NJS-certified headset will be JIS standard dimensions. Might cost a bit more, and probably won't be sealed, but will almost certainly be very good quality, and will fit.

*ISO headset standard is thread profile and 30.0 cup skirts ONLY. Crown race seat diameter is not part of the ISO spec.

JohnDThompson 

No, they're not rare, but still if your frame/fork are prepped to ISO standards you have an even broader headset selection. Most headsets that are available in JIS dimensions are also available in ISO dimensions, and you can add to that number all the headsets that are only available in ISO dimensions.

TallRider

I suppose if the world no longer has JIS headsets, I could get the frame (well, frames - I have at least 4 frames with JIS standard) milled up to 30.2 and 26.4.
For now I'll probably stick with available JIS headsets and keep an eye for some nicer Shimano cartridge headsets on eBay. ISO threaded isn't going away, and I know I'll have more options there. The fact that Tange JIS headsets will very likely stick around, and my 1984 Centurion Comp TA is still going smooth and strong on original Shimano 600 loose-ball headset (larger balls than typical caged bearing headset, if I remember correctly) means I don't feel much need to get the frame milled to ISO.

Of course, maybe I decide to do this in the future and no shops have the equipment anymore. Most shops don't have equipment to ream out steel seat tubes or spread and align steel dropouts anymore.

TallRider

I looked over Ebay again. This time there are a number of NOS Shimano cartridge JIS headsets, but the going price is around $100.
For now, the original cheap steel headset is smooth enough and not pitted.