banjo_mole 

Does anyone know which size the Shimano 600 "Tri-color" headset was?

1" Threaded, yes, but is it the JIS size races or the European standard size?

If someone knows offhand, or has one they could measure for me, that'd be wonderful.

Thanks for the help,

-Banjo

j. hughes

^I'm pretty sure it's ISO but I'll check later if nobody else chimes in with a definitive answer.

Road Fan

If you have the headset removed, post all the markings that are on it, especially the engraved ones. Something there should allow the standards to be known. Shimano's been pretty good about that kind of marking. Chances are Shimano offerred this headset (600EX, right?) in both the ISO and JIS standards, in order to be sell to any bike company who wanted 600.

wrk101

You can buy a cheap ($2 or less) plastic caliper at Harbor Freight, or a digital for $10 or less. Highly recommended if you are going to do much bike maintenance. It will pay for itself.

+1 I bet Shimano made both sizes.

Fibber

+1 I have several cheap plastic ones that were a give-away at a trade show that are more than accurate enough for most bike issues. Backup is a Mitutoyo dial set for the precision stuff.

I did a quick check and was amazed that digital readout units were so cheap. $12 at Amazon for a stainless steel set.

2fast4u

Shimano made both. Remove the crown race from the fork and the dimension, 26.4 or 27.0, will be stamped on the bottom.

banjo_mole 

AAAGH!

I work by a bike shop. (Unfortunately, not inside it.)
I went there to have the fork crown race removed, and... Well, I lost it at work.
I have the other parts, I'll take a look at those, but, well, crap.

I'll go look at those parts.
And you said harbor freight has non-digital calipers that'll work for like $2?
That would work nicely, although I thought the size difference between the two sizes was tenths of millimeters, although maybe I'm mistaken and it's one-and-one-tenths of a difference. I"ll go dig for that dumb (cracked) headset right now. Be back soon...

banjo_mole 

Ok. So.

No races. The fork race and the one from the top of the head tube are gone.

Bottom fixed cup, unmarked.
Top adjustable cup, has the goofy fake shimano "sealed bearings" and ANOTHER crack I didn't see! Crummy headset...

The top nut is marked, however:

The bottom side is marked:

"NB"

The top, "shimano, japan, via"

... No numerals.

Ex Pres 

Why didn't you have the bike shop measure the crown when they removed the race?

And you may be able to tell from the head tube, too. 30.2mm v 30.0mm

Charles Wahl

I don't have much experience with this, but I've trusted Sheldon Brown, and he said (his headset crib sheet page) that JIS headsets were only used on "Older or lower-quality bicycles from Asia." Does anybody know different? I suppose what he meant by "older" is a question.

Road Fan

And, by the way, I think the difference between 26.4 and 27.0 mm is too small to be reliably read by $2.00 plastic calipers. I think you need a guage taht can measure to 0.1 mm at least or 0.001 inches. Interference fits that work need to be characterized in the thousandths of an inch. The crown race to fork is such a fit.

There are a lot of real good non-digital calipers, but I don't know if they are as cheap as $2.00. All the plastic ones I've seen are very crude and I wouldn't trust them for tenths of millimeters. Look for stainless steel, and either a vernier scale or a dial reading. You'll need to learn a bit to use a vernier. It's not hard, you just have to learn the trick.

cyclotoine

On the over 100 forks I have taken out of vintage bikes, never have I seen one stamped with the dimension.

Nick, It's almost certainly 26.4mm.

banjo_mole 

Well, that just about settles it.

I gather from the statements below my own that JIS headsets aren't as common as I'd thought...

So I must now dig for an ISO that suits my needs, I liked one JIS I saw but it won't work, then.

miamijim

What kind of frame are we talking about?

Ignore Sheldons comments on the topic.

banjo_mole 

Hey Miamijim, we're talking about a Trek Tri-Sport 500, 1986. I found the lower cup (that sits on the bottom of the head tube) and it's outer diameter is 30.22mm. JIS?

PS, it's good to hear from you again pal.

-Nick

bigbossman 

IMO they are as common as dirt. When I built my Palo Alto, I needed an ISO headset. I pawed though the dozen or so "take-offs" in my bin, and all were JIS.

Ex Pres 

30.2mm = ISO, so a 26.4 crown race

WNG

FYI, My 1989 Specialized Sirrus road bike came with a JIS Tange headset. Since it's not exactly a low-end model, these must have been common at least til the early 90s.