The headset on a custom US bike went south. It's a one inch headset with a 26.4 crown race. The pressed races measure out to be 30 mm. I pulled out my trusty Sutherland's and I'm a bit confused. Isn't a 26.4 crown race most commonly found with a 30.2 mm pressed head tube race? I thought JIS was 30 mm head tube race and 27 mm crown race?

Edit: VO's website states that ISO has a pressed race of 30.2 and a crown of 26.4; JIS uses a pressed race of 30.0 and a crown of 27: https://support.velo-orange.com/#headsetarticle.html So I guess I have a weird headtube dimensions and need to mill it to 30.2 or that my I'm doing a spectacularly poor job of measuring the tange levin headset I pulled off my bike.

In replacing a headset what are the key dimensions? I've always thought that the important dimensions are the crown race, the pressed race dimension, threading, and stack height. Is there something I'm missing here?

There are a number of "mixed dimension" headsets available for those who have JIS frames but purchase an ISO fork or have a JIS fork milled to an ISO crown race seat diameter. My '85 Bridgestone 400 required on of those when the fork was modified.

Do you know where you can buy a mixed dimension headset? I went to two bike shops in town. Neither one had the tools or the expertise to mill the headtube to 30.2. I think that this would be the best long-term solution as then the bike would have the ISO standard.

The other possibility is to simply buy two identical velo-orange headsets, one JIS, the other ISO, and use the 26.4 crown race from the ISO headset and the 30.0 cups from the JIS. That is a bit pricey but it will work.

It is an old school custom build US bike and I want to get it working again:

I have a handful of Sun Tour Spb Pro and Sprint JIS headsets headsets. I also have spare crown races so can subsittute a 26.4 if you wish. PM me or email me through the Chain-L site if interested.

The other alternative for you if this is a nice bike you plan to keep for many years is to have the frame reamed to 30.2mm so you have your pick of headsets in the future. Any decent mechanic in a shop that sells road bikes should be able to do this at a reasonable price.

I think the best option is to ream out the headtube to 30.2 so it does fit an ISO standard headset. I spoke to two bike shops in town; the mechanics had no idea what I was talking about and don't, in any case, own the proper tools. I just looked on Park's website, the tools are there but I'm sure as heck not buying cutting tools for a one time job. I think the knowledge to do this kind of work is just sort of disappearing.

I think it's a really nice bike as it is a custom very old school vintage touring bike with pretty lug work, investment BB and fork crown, campy drop outs, etc., so it is worth my time to do this right.

If you let us know where middle earth is, I or someone could probably refer youto someone skilled and equipped to do the job.

BTW0 if it's a steel TiG welded frame, with no reinforcing band at the ends of the head tube, odds are that there's enough giver in the tube to accept a 30.2 without reaming. In fact I avoid reaming these to full size because the tube is thinner than what the spec was designed around, and when reamed to 30.2, or 31.75 headsets tend to get loose over time especially at the lower end. If it does have a band, there's still enough give (usually) to press in a headset, but more force is involved.

Do you happen to have replacement bearings for the shimano 1" cartridge headsets. They don't last forever, but do go a long time.

Sorry, no. In y years as a bike parts supplier, I worked with Campy, SunTour, Mavic, and others, but never with Shimano.

I'd keep trying bike shops until I found a competent one to ream your frame. Otherwise, contact Velo Orange and see if they will "mix" a headset for you or just sell the ISO crown race as a separate item along with the JIs headset

I guess middle earth has now moved to New Zealand but I still live in the original middle earth, Des Moines IA. There must be frame builders in Minneapolis St. Paul who could ream out my headset; there is at least one frame builder in IA I need to contact and see if he would do it. I think my bike should be fine; it is an old school lugged custom built frame set. Reaming the bike to ISO is a long-term solution to the problem but I don't go through headsets very quickly so I'm leaning towards finding the right "mixed" headset. Sourcing a mixed headset (26.4 race with JIS cups) should be possible but a lot of the vendors (and bike shops) have no idea what standards are for one inch threaded headsets. The bike was built by Mike Melton. Here is a pic of the headtube:

VO does sell just crown races by themselves; https://store.velo-orange.com/index.p...set-parts.html

Thanks guy; this is great. This is also weird because I called VO and spoke with someone there who was very knowledgeable about headsets and he suggested that I simply buy 2 headsets, one JIS and the other ISO.

Btw, I can't tell you how many weird replies I've gotten in reaching out to online vendors; the tech support people have no idea about the specs on 1 inch threaded headsets. I guess that's not surprising because it is an out-of-date standard.

De nada.

I will say the spares they sell are intended for their headsets, so they may not work with headsets from another source. At least I think that may be why their rep suggested purchasing two headsets from them. But it is cheap enough to try it and find out. Best of luck!

While the 1" threaded standards may be deprecated in new production, there are still millions of bikes on the road using them, so I'm surprised that there are any shops that are unfamiliar with the standards.

I'm also surprised that you cant find a shop capable of milling the frame and fork to ISO standards, which would eliminate your problems finding a headset now and in the future.