hokiefyd 

There is a good number of those out on the eBays. Searches of "sugino crankset triple" and "shimano stx crank" result in some interesting hits.

One potential issue with the Shimano stuff is the crank arm is drilled for 94mm bolt circle only. The middle ring (32t usually) had inner tangs for the inner ring (22t usually) to bolt to. And, although the inner ring uses a 58mm bolt circle, you can't use just any ring: because the mounting tangs are basically flat against the middle ring, the inner ring uses an offset design which spaces it correctly. In other words, you have to use Shimano inner and middle rings with this type of crank (any 94mm ring will work for the outer ring).

I'm not aware of Sugino (or others) do anything like that, at least with '90s mountain triples. The one Sugino Impel crank I have (a 58/94mm crank arm) has both bolt circles present and drilled, so you can swap any ring with the correct bolt circle.

Most of the search results are 22/32/42 triples on 58/94mm cranks. But there are a few 74/110mm cranks that pop up in the results. More targeted searching for those would probably give better results. You could make a 28/38/48 or 30/40/50 or anything you desired with that bolt circle sizing. You could go as small as a 24t on the 74mm circle and 34t on the 110mm circle (33t is the smallest that will fit in theory, though few of these rings actually exist in practice).

The Golden Boy 

I can take better pix if you like but here's the cranks-

IMO- the nicest triple crank ever- the Sugino AT. Cold forged, and note the aero profiling on both the crank arms and the spider arms.


IMG_1728 by Dave The Golden Boy, on Flickr



The N600- remember this is a cold forged, 600 level crank set. Note the "aero" profiling on the arms-


1985 Trek 620 by Dave The Golden Boy, on Flickr


The M730 XT crank- This was the XT crank from 86 to about 93; again- a cold forged, top of the line crank. But note the lack of aero profiling on both the crank arms and the spider arms.


M1000LT Drivetrain by Dave The Golden Boy, on Flickr

jlaw

Thank you for the primer on crank sets. I can take them apart and put them back together, but my knowledge of design, compatibility, etc. is a work in progress.

I took the DS crank off today and removed the rings. @ The Golden Boy is right in saying they are well made - and the set I have is in good condition. So I am going to keep the cranks and the little ring - replace the middle and large with 36/46 or something close. I read the Peter White site and he says that T.A. rings (Zephyr?) should work with this crank, but they are pricey. He also says that trying to put Sugino rings on a Shimano crank may not work.

I'm thinking of doing as you suggest by finding an ebay Shimano 110/74 bcd crank and re-purposing the rings from it - or maybe I can find some vintage Shimano rings.

...to be continued

hokiefyd 

Yeah, compared with the prices of new individual chainrings, it's sometimes worth it to buy a complete crankset just to get two or three rings you want!

UKFan4Sure

I've got to find me a nice vintage Trek. Back when they were made in Wiscaaansin.

arimajol

I have the exact same bike and replaced the middle chainring. I used this sugino: https://www.treefortbikes.com/Sugino...BoCTjUQAvD_BwE

Fit well and works great. Maybe you can find the biggest chainring size you want from them too. This was a few years ago and I don't recall what the options were.

jlaw

Thanks for the first-hand information. I checked the Tree Fort site and may give the 36T Sugino middle ring a try. I could re-purpose a 47T outer ring I have on another crank to give me a 47/36/28.