Need help with 6-speed drivetrain
I just picked up a 1986 Cannondale ST800 Touring bike. This bike is a time machine...
I bought the bike because its a 27" touring frame (68.5cm c-c, and 73cm to the top of the seat collar. I've been looking for a larger frame for a long time, and I'm very happy to have finally found one.
It has nearly a complete (and almost NOS) Suntour 6-Speed Accushift drivetrain. 6-speed Accushift barcons, Superbe front derailleur, Superbe Pro rear derailleur, Phil Wood hubs, 6-speed freewheel, etc.
The Suntour stuff just cracked me up. I'm no Luddite by any means, and I'm not out to prove a point by not having Shimano or Campy. In fact I really want a non-traditional group bike, and my heart is set on putting together a Mavic SSC project. The Suntour stuff I'm completely ambivalent about. If it works fine. The funny thing is how much Suntour stuff I actually have (come to think about it). For whatever reason I've picked up (and not on purpose) a lot of Suntour bits over the years. I think other than this nearly complete Suntour Superbe touring bike I've got some GPX hubs, Blaze shifters and derailleurs, an XC Pro front derailleur and crank, and I think one XC Expert thumbie (don't remember which)...
Some of the stuff like the Superbe Pro pedals which look like they are brand new I'm not going to use. I'll probably list those on eBay so someone who is trying to complete a vintage restoration can complete their product. Longterm, I have no plans to keep anything from the Suntour Superbe drivetrain, but I really just want to ride the bike right now.
The problem is that I've removed the Suntour BB and Sugino crank. In its place went in a Phil Wood BB and a set of custom Zinn 205mm cranks. Its a big bike and I've always wanted proportional length crank arms. I have a 980mm cycling inseam. The 205s are actually a bit conservative (using the .210 factor instead of the .216).
Well, now I don't know what chainrings to use on the bike. The Zinn triple crank uses 130/74 BCD five bolt rings.
Aren't chainrings speed specific? Considering everything is 9/10 speed these days where am I going to source high end rings?
I was thinking about using TA rings, as they are available in a wider selection of tooth counts. I'm not sure about the capacity of the Superbe front derailleur. I do have plenty of other derailleurs on hand if I need to swap out the front derailleur. If need be I could use a Suntour XC Pro front that I have or a Shimano XT front derailleur.
I'm not sure what range is allowed by a Superbe front derailleur, between the big/middle/small rings. Does anyone know the tooth difference allowed? Would the XC Pro front derailleur give me a wider range than the Superbe? How 'bout the Shimano XT front? A Mavic 870?
What is a good range of rings for a touring bike? I really want a low climbing bailout gear (I live in Colorado) for the mountains.
Can I use any current TA ring (they are available from Peter White and Harris Cyclery) or are front chain rings speed dependent?
I know 6 speed is outdated, however, the huge size of the bike and the 48 spoke Phil Wood hubs made me pull the trigger. The rear spacing is 126mm and its a freewheel, so I can't upgrade to 8 speed (which I think is the best touring choice).
What rings would work (any? all?), and what tooth counts? I know I want a 38 middle ring since that's the smallest the 130 BCD will handle. Does that dictate what the big and little ring will be due to max tooth difference on the front derailleur?
Last edited by mtnbke; 10-17-09 at 01:29 PM.