The OLD changed to 135mm in '92 according to the catalog. I'm assuming Deore XT hubs mean 135mm, yes? Same year they switched over to the 7 speed cassettes on the R500 from the 6 speed freewheel. I don't think they ever had a tourer with 130mm. Downloading all the catalogs from the 80s through the 90s is a long process for me. I still haven't figured out when they went from road brakes to cantilever.
I'm inclined to agree, but I just don't know for sure. rccardr has rejuvenated many of these ST frames and may know.
Ah, well there it is then. Does the cantilever have any advantage over the sidepull aside from tire width ability? How wide of a tire can your '89 take?
I think an argument can be made for using dual pivot calipers.
Brad