on 9/20/10 9:45 PM, James Warren at jimcwar...@earthlink.net wrote: > I'm looking for information on Shimano 3-speed internal hubs with the > following idea in mind. In the following pictures: > > http://www.cyclofiend.com/Images/rbw/rr36_pg27.jpg > > the rear derailleur shown is not functioning as a rear derailleur. There is no > cable attached, and the derailleur is only there to take up a lot of slack so > that I can have vastly different chainrings up front shifted with a front > derailleur. Right now, the bike has three rings in front, 24-36-48, so the > bike has three gears total. (In the photo, there are two gears with a > pants-guard. This set-up has worked fine whether as a 1-speed or 2.) > What I would like to do is get a bit of gear-shifting in the back through use > of an internal 3-speed hub. I would like to make the bike an internal shifter > in the rear but still retain its 3-chainring derailleur system in the front, > for a total of 9 gears (3x3). Is there any reason that I couldn't use an > internal 3-speed hub, like Shimano's, but while using this hub, still have it > work with the dummy derailleur mounted as shown in the photos so that it takes > up slack and allows me to still do wide range shifting in front? > > I realize this is a bit complicated (due to rear spacing and lack of > derailleur hanger in rear) and I'm trying to research it myself, but any > pointers would be appreciated if it's not too much trouble.
You've already done most of the heavy lifting on that system. Since you are sticking with a coastable setup, there shouldn't really be that much of an issue. You really just have the same setup, with differing ratios which don't change any chain tension or angle. There is the spacing issue - 120 mm, which may nix the Shimano 3 speed (and I think those were coaster brake models, but I'm not sure). But, S-A stuff can be found that way, to be sure. There's probably no reason you couldn't run a 7 or 8 speed hub, if it was spaced correctly. It would be problematic to run the derailleur with a fixed hub like the S-A S3X. Derailleurs/tensioning devices and fixed setups are generally thought to be Bad Ideas. AASHTA - http://www.sheldonbrown.com/singlespeed.html#tension You're really just using the arm of the rear derailleur for tension. And for the range you are running, I don't think you could drop back to a Paul Melvin. But, if you widen your gearing aft, maybe you could run narrower up front... (For those looking to mount a derailleur on a tab-less fork end, you just need to find one of these - http://tinyurl.com/derhanger ) It seems like you are really most of the way there, right now. - Jim -- Jim Edgar cyclofi...@earthlink.net Cyclofiend Bicycle Photo Galleries - http://www.cyclofiend.com Current Classics - Cross Bikes Singlespeed - Working Bikes Gallery updates now appear here - http://cyclofiend.blogspot.com "Maybe a bike, once discarded, pines away year after year for the first hand that steered it, and as it grows old it dreams, in its bike way, of the young roads." -- Robert McCammon, "Boy's Life" -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To post to this group, send email to rbw-owners-bu...@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en.
