Headset stack height - help please

Ok, honesty's the best policy here:

FluffyChicken":o2yk3g8q said:

You have taken the crown race off before measuring ?

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Errrr .... no.

So rather than being inaccurate in my measurements it was rather not knowing exactly where to measure from.

Done now, and accurate to the nearest 0.5mm the steerer is 173mm and the head tube is 140mm.

So I'm looking at 33mm stack height.

Ideally, I would like one of these:
M730 - 32.1mm
M651 - 33.5mm
M736 - 33.5mm

But I'll have to look and see whether I can find one of them in my price range.

Really, since there will be a few modern bits on the bike when I rebuild it I shouldn't mind too much if I found a modern headset that would do the job, but I just haven't seen one yet I liked!

#vintagemtb experts, please step in. I'm pretty sure this is going to work but want to check before I set the cups in the frame and crown race on the fork to test fit. I'm planning to replace this Avenger RX headset with an XT M736. IIRC, both have a stack height of 33.5 but from these photos, the XT unit appears smaller. Pretty sure smaller is OK but larger might be a problem as I'm dealing with a vintage #marzocchi_mtb fork and changing the steerer is not going to be easy or cheap.

Anyway, the steerer is 146mm long (with the race removed) and the head tube is 114mm, so the difference is 32mm. I want the XT headset because of the larger bearings (and to help get the bike closer to a full XT kit, of course).

So, will this work? I'm about to hammer the crown race on and dry-fit everything. The cups will have to come back out as I am having the frame powder-coated.

THANKS!

M736 (1-1/8") = 33.5mm
Headtube = 114mm

Steerer = 146mm

114+33.5 = 147.5mm which is longer than the steerer..
BUT the top nut has enough to cope with that, so you'll just have a 1.5mm gap under the top stem seal.. if everything is perfectly measure and the real world doesn't happen.


the bearings go in the other way around (to your picture), so the flat connector bit is at the top,

Re:

Thanks! I actually went ahead and did a dry test fit - it's perfect, I did notice the gap you mention but I bet it will be smaller once it's torqued down. I'm really pleased!

Thumb up! ;-)

kraeMit":3vn5nxht said:

Thumb up! ;-)

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Thanks, yessir, notice your work in that pic? Fork has never felt this good!

Happy me!