mtmann

I know this one comes up periodically, but thought I'd throw a recent observation and a question into the mix. I recently acquired a couple bikes circa 1989/1990 that run 7-speed Suntour X-Press Accushift trigger shifters. One, a 1990 Bianchi Osprey MTB, is all Suntour EXCEPT the rear freehub/cassette, which is 7-speed Shimano Hyperglide. I believe these are stock components - front and rear wheel match and are perod correct - and shifting seems crisp and accurate. The other bike is a 1990 Trek 750 hybrid, also running identical X-Press trigger shifters and a 7-speed freewheel on the rear which I assume is Suntour (haven't pulled it yet to check). Based on these 2 bikes, the 7-speed Suntour X-Press trigger shifters are compatible with 7-speed Shimano cassettes.

My question: If I decided to replace the X-Press trigger shifters with 7-speed Suntour Accushift thumbies, will it still shift a Hyperglide cassette? I can run the experiment myself, but if someone else has experience with this and it didn't work, It would save me the trouble of finding out for myself. Thanks.

Gonzo Bob

I don't have any experience with Accushift MTB but I did have a bike with Accushift road (GPX components). I was able to use a Shimano 7-speed Uniglide freewheel and also a wheel with a 7-speed HyperGlide cassette and indexing worked OK. Suntour and Shimano 7-speed spacing isn't exactly the same but it is close enough that it can work.

dddd

Around 1994 or so, just a year or two before their demise, Suntour changed their 7-speed gruppos to what was called "Plug'N-Play", which began the use of Shimano-compatible freewheels and cassettes.

Prior to that though, Suntour's 7-speed freewheels had a very different spacing, with the biggest 3 sprockets using much narrower spacers than the smaller sprockets.

I'm not sure exactly what you have there, but am wondering how sure you are the model year of that bike and whether the wheelset is original.

I remember re-spacing a Shimano HG cassette to work with 7-sp Accushift Command shifters. I used a digital caliper and sandpaper to make thinner polymer spacers, a lot of work that I wouldn't have done if it wasn't observed to be needed for race-quality shifting on my Epic road bike from the early 1990's. Gad, I still have that bike(!), but now with a 7sp Suntour freewheel.

pcb 

X-Press was a not-very-successful lever that was only available for a season or three, IIRC, '88-'90 or so. It was absolutely not Shimano-compatible in any way whatsoever, at a bike-spec'ing manufacturing level, and I don't remember anybody spec'ing a Shimano freehub with SunTour ders/shifters. OE had trouble getting all-SunTour drivetrains to shift properly, they wouldn't throw Shimano in the mix. Bianchi's Product Manager was Bill Horner, very sharp on component spec, I'd be very surprised if he did that. Show me a catalog with that spec and I'll believe it, but otherwise it's pretty inconceivable the bike left the factory that way.

That your X-Press lever is shifting a Hyperglide cassette well is a gift, you shouldn't assume another SunTour shifter would work as well. They are not supposed to work together, doesn't mean you shouldn't try, it might shift OK, but it shouldn't. I don't want to sound jaded, but most of my professional life from '84-'89 revolved around poorly-performing SunTour drivetrains, so I can't work up any enthusiasm about trying stuff that shouldn't work.

mtmann

Using the vintage Trek site I was able to date FD, RD, and Dia-Compe cranks to late 1989. Front and rear rims are Araya and match, and since the bike is in good shape and paint mostly VG, I assume it wasn't beaten too hard and there was no need to replace the wheels - if they were replaced, they were not upgraded or updated. Rear hub is a Shimano FH-HG20, which has a solid axel and is period correct. Also, rear bearings are pretty rough, so if it was replaced, it wasn't any time recently. I'd love to see a 1990 Bianchi catalog to check specs for sure, but the frame is lugged and made in Japan, so it wouldn't be much later than 1990 - many had already switched to Taiwan TIG frames by that point. I can't say for sure, but all the detective work I've done points to a 1990 bike with stock components. If anyone else has a 1990 Bianchi MTB and could tell me what the drivetrain specs are re: Suntour/Shimano, that might help as well.

dddd

Most of Shimano's freehubs have a 2-letter date code stamped on the flange or on the barrel. The smaller cogs of the cassette also should have been stamped.

The first letter "O" corresponds to Shimano's 1990 production. "N" would be 1999.

That's the only way I could say if the wheels were more or less likely to be original.

There are several possible circumstances of why the wheels might have been changed, perhaps something as trivial as someone switching the wheels for those from an un-used alternate (spouse's?)bike that had a preferred set of tires mounted.