|6 Speed Upgrade Options?||Tarzan|
Sep 14, 2001 9:33 PM
|What are my options for upgrading a 6 speed on a nice Cannondale touring frame with perfect geometry for me? I understand that aluminum cannot be cold-set to go to an 8 or 9, but would it be possible to go to a 7 and take advantage of any existing 7 speed STI/ergo shifters? Obviously, I would also need a new cassette and rear derailleur. Any chance I could use RSX 8 speed parts from another bike??
Or, am I limited to only going from downtube shifters to bar ends for the 6 speed?
Alternatively, do you know of any leads for solid, small touring frames or bikes with a standover height less than 29"? Any leads are gratefully appreciated!
|re: 6 Speed Upgrade Options?||Rusty Coggs|
Sep 15, 2001 5:54 AM
|Check or have the rear dropout spacing checked. Touring bikes were often built with mtb hubs that had wider spacing.If its only 126mm,you can go to 7 speed.|
|re: 6 Speed Upgrade Options?||Dave Hickey|
Sep 15, 2001 2:23 PM
|On my rain bike, I'm using 8 speed RSX shifters(STI) with 7 speed 105 rear derailleur and cassette. It shifts without any problems. You can use 7 speed with 126mm spacing. Actually, you can use an entire RSX 8 speed group. You just need to use a 7 speed cassette and rear hub.|
|re: 6 Speed Upgrade Options?||Tarzan|
Sep 15, 2001 3:49 PM
|Thanks for the quick reply. Do you mean I can use my 8 speed rear derailleur and a 7 speed cassette? What alterations do I need to make to "fool" the shifters and derailleur into working only 7 speeds? Are there any other changes to make? What about chain length? What about front derailleur? Thanks again.|
|re: 6 Speed Upgrade Options?||battaglin bob|
Sep 15, 2001 4:12 PM
|derailleurs are easy to "fool". With any indexed shifting the derailleur is controlled by the index positions. assuming that you are using a freehub you may need a small spacer that will mount next to the cassette to take up the space of the eight cog. your lbs can help you with this. set the deraileur limit screw to stop at the smallest cog. this will prevent the chain from derailing. with this set-up you will have an "extra" click that won't produce a shift. chain length is determined by the gear ratio of the cassette that you are running. check the archieves for info on chain lenght. your exsisting front derailleur will work with careful adjustment. i hope this isn't to technical. if you can pull this off you will gain a complete understanding of how shifting systems work.|
|re: 6 Speed Upgrade Options?||Tarzan|
Sep 15, 2001 6:01 PM
|Well, I am interested in moving up on the learning curve but want to do it with the fewest costly mistakes. HAH!
What you say about "fooling" the derailleur makes sense. And thanks for the info on chain length. Sounds easy enough.
I am confused, however, because it sounds like you think I'm going from an 8 cassette to a 7 since you suggest I might need a spacer. This is wrong. What I want to try to do is go from a 6 speed cassete to a 7 and then use an 8 speed rear derailleur and STI shifters to work the 7 speed cassette. Actually, I'm kinda worried about not having enough space for the 7 speed cassette. Does this change your recommendations?
By the way, what's the difference between a freehub and a cassette and how does this impact this project? Additionally, are the widths of various 7 speed cassettes different? Do I have to get a cassette that will be compatible with the STI shifters?
|re: 6 Speed Upgrade Options?||batty bob|
Sep 15, 2001 7:43 PM
|o.k. here's what's involved. to put a 7 on a 6 you would need to re-dish (center) the wheel to have enough space. the upshoot of this is that the wheel will be weaker overall because of the tension differental between the two sides. i'm guessing since this is a six speed that these wheels are at least 10 yrs. old. re-dishing would result in spoke failure and you would need a new wheel. which leads me to the quick and easy solution. get a new wheel from a good lbs with a free-hub. the difference between a freehub and a freewheel is that a freehub uses a splined mounting system and a freewheel is threaded on. freehubs are the way to go since freewheels are becoming extinct. nashbar has them if you insist on a freewheel, but you get a much better selection with cassettes. as far as compatability issues go shimano and sachs are compatable. campy is a whole different ballgame. bottom line to make this work get a new wheel with a 7sp freehub and all your other stuff should work fine.|
|re: 6 Speed Upgrade Options?||Tarzan|
Sep 16, 2001 1:31 AM
|Thanks! I was wondering about that. I can sleep now! HAH!|
|Actually...||nee Spoke Wrench|
Sep 16, 2001 5:32 PM
|Having done a few conversions of this type over the years, I'm going to go on record as saying it's possible, but you are going to encounter a number of compatability problems along the way. Here's a few I have run into in the past.
1. The rear dropout spacing has already been discussed. When you try to fit a rear hub that is designed for wider spacing you can sometimes make it work by removing a spacer from one side of the hub. before you put it all back together, take a look at the axle length vs. dropout spacing and thickness. You may have to substitute a shorter axle.
2. If you try to put a 7-speed freewheel onto a hub that previously used a 6-speed, you may have to move a spacer from the left side to the right and re-dish the wheel. If you don't, the chain may rub the right chainstay whenever you are in the smallest cog.
3. I've never tried to force-feed a 7-speed cassette onto a 6-speed Cannondale frame, but I would expect some problems. A 7-speed cassette is going to be 130mm spacing. You could probably take 4mm of spacer out of the left side of the hub and re-dish the wheel as long as the axle isn't too long. After you re-dish the wheel, make sure you have enough tension on your non-drive side spokes. Otherwise you are going to have spoke breakage problems.
This won't work with any hub that has an 8-speed freehub body because you won't be able to dish the wheel over far enough to allow for the wider freehub body. 8-speed freehubs can barely be dished adequately to work with 130mm spacing.
4. 8-speed index shifters only kind-of work on a 7-speed cassette. There's more to it than just blocking off one of the clicks. What you will wind up with is a shifter that uses all 8 clicks to shift over 7 cogs. It works well enough to ride the bike, but it shifts funny.
I say go for it. You are going to learn a lot about bicycle mechanics and bicycle component compatability along the way. Just don't expect the finished product to shift as well as a new bicycle with all brand new matching parts.
Sep 17, 2001 4:40 AM
|Thank you for your thoughtful and comprehensive reply and your words of encouragement. I have printed it out for future reference. What kind of stinks is that the price of the frame I'm interested in upgrading has gone to $200 on Ebay so I'm beginning to think it's too much. If you've got a chance, would you check it out? It's listed as a Cannondale Touring Bike Shimano 600.
I'm having a very hard time finding a frame with the right loaded touring geometry since I'm 5'3" and need a standover height of less than 30". The Ebay bike geometry seems perfect except for the narrow rear dropout spacing. I also have a 24 speed Cannondale racing bike with RSX components that I would like to upgrade. So I was hoping to use the RSX to upgrade the Ebay touring bike. Can you suggest other options? Could you do it sort of quickly since the Ebay bidding ends 9/18.
|Here's what I would do:||nee Spoke Wrench|
Sep 17, 2001 6:40 AM
|If, and only if you are sure about the Cannondale size and frame geometry, buy the bike. Opportunities to buy that size frame can't be too plentiful.
If your RSX group is a 7-speed, try to convert the rear wheel to 126mm as I indicated in my last post. If that doesn't work, you can use a 6 or 7 speed freewheel hub as your fallback.
Find a 7-speed set of bar end shifters. For a touring bike, bar ends are far and away my first choice. You don't want to find yourself on Friday night in Elmira, Kansas with a non-functioning STI lever. Bar ends also have a friction mode so you don't have to be so picky about rear cog spacing.
Good luck. Let us know how it turns out.
|Here's what I would do:||Tarzan|
Sep 17, 2001 3:33 PM
|Thanks again and the idea of barcons had crossed my mind. I guess I've given up on trying to upgrade this old frame especially since aluminum, I guess, has a shorter "shelf life". I'm now focusing on the new bikes that are out there. Would you look at my two new discussion items entitled " Cantilever brakes and Shifter Options for Loaded Touring" and "Gearing Modifications for Loaded Touring" that I posted today? Thanks :-)|| |