I have a 1987 Trek 560. I have a (partial) Dura-Ace 7410 headset (missing fork crown race). Is it possible to install this headset on this frame? If so, please do inform a headset noob.

Your 1987 trek 560 will undoubtedly have a 1" steerer on the fork and the head tube will be speced to accept a 1" headset such as the Dura-Ace 7410. So yes your frame/fork and this headset are compatible

The only question is weather you have enough steerer for the stack height of the dura-ace headset (37.6mm) This is the minimum lenth of fork steerer that is needed to properly install and adjust this headset. A longer steerer tube can be cut down or spacers added below the locknut to take up excess space (within reason) but if you do not have at least 37.6mm from the fork crown bearing seat to the top of the fork steerer then you are SOL.

You will still need the proper fork crown race...either one specifically for this headset model or one compatible unless the one currently on your fork is compatible.

-j

I was just reading about stack height. I found my currently installed headset on ebay and it has some info that may be useful: https://www.ebay.com/itm/New-Old-Stoc...-/390647760690

So with that info can you determine any more diagnosis? Thanks!

I know that some of the treks from the era your is from came with Campagnolo components which use ISO dimensions...this marries up with your current headset being ISO speced.

The ISO spec as it relates to a headset is the fork crown race seat dimension which is 26.4mm. Shimano speced this headset in both ISO and JIS (27mm). There are sources online for Shimano crown races in both JIS and ISO specs...the only two issues I am unsure of are:
1. Is your 7410 headset JIS or ISO spec...and does that matter other than the fit of the crown race on the steerer?
2. Whether the angular area that contacts the bearing balls on an obtainable replacement shimano crown race is correct for your 7410 headset.

-j

I just checked Sheldon Brown's website and from what I understand the crown race must match the rest of the headset (or at least the bottom cup of the headset) so the question is to you...do you have a JIS or ISO 7410 headset?

The ISO/JIS spec not only relates to the fork crown race seat dimension but also the size of the bearing cups.

-j

OK...JIS primarily refers to the head tube cup size. 30.0 is JIS while 30.2 is ISO, 27.0 fork races aren't exclusive to JIS headsets, they're also found with ISO headsets.

The question here is what size fork race do late 80's Treks take. 27.0 or 26.4?

If this is the original fork, it should have left the factory trimmed for 42mm stack and the crown race seat milled to ISO 26.4mm diameter, and the head tube should also be ISO 30.2mm. A couple spacers should be all that is needed to make it work, assuming you can source the proper crown race.

The Trek authority has spoken!!!!

Thanks John.

Here's the official Shimano doc. Mine says BC1 on it.

https://www.google.com/url?sa=t&rct=...53760139,d.eWU

So is this what I need?
https://www.ebay.com/itm/SHIMANO-vint...item3cd6653c58

No. The Shimano document you linked to is for a cartridge bearing headset, but the crown race you linked to is for a cup-and-cone type headset.

Oh ok. So there is probably no chance the current headset that is installed has the correct fork crown race correct?
Can you find the correct one online or tell me what to search for? Thanks!

Is this the correct one?

https://www.ebay.com/itm/Shimano-26-4...item20d521de44

What headset is currently installed on the bike? Why does it need replacement?

My bad I thought I had said what the current one installed was. It's a Halla Vesta Sealed (https://www.ebay.com/itm/Hatta-Vesta-...item485ad66196)

I want to replace it for two reasons. One, it's pitted and two, I have a full DA group I'd like to put on this bike.

Yeas, but I think there're cheaper ones on eBay...and no gaurantees its compatible with DA.

This one is cheaper but I think it's the same as the one I linked already.

Instead of trying to salvage that 7400 series loose ball headset, why not try to find a 7500 or 6500 series cartridge bearing headset? they are more durable and easier to adjust.

I was under the impression the 7410 was a cartridge bearing headset..

Digital vernier calipers are so handy.

you can measure the frame ID and the headset race insert OD and read the numbers .. and compare..

I just re-read that doc and Shimano is using the terminology Cup and Cone but you said cartridge. I'm a little confused now..

A Google check shows you are right. The HP-7400 was loose bearing but the HP-7410 was a cartridge bearing headset. I know the HP-6400 was loose bearing and HP-6500 is a cartridge bearing so I assumed the Dura Ace versions followed the same convention.

Anyway, I know that the HP-5500 (105) and 6500 (Ultegra) used the same "crown race" and think it's likely the 7410 used the same one. The instruction sheet that came with the 6500 also covers the 7410 so it seems likely they share a lot of parts.

That's a good point.