Derailers and chains
 

I have an old bike with Shimano's Biopace setup and I'm looking to replace both of my derailers with newer ones. This uses a narrow SG type chain. I'd like to know what newer product lines would be compatable with this chain and gear type? Will any narrow chain Shimano components work?

Thanks

Quen

http://www.sheldonbrown.com/biopace.html You might find something by emailing this site. They do appear to know about this setup. Normally deraillerus do not break. I mean you take an old bike out of a skip and normally the derailleur still works. Maybe replace the jockey wheels, new cable but normally they are ok.

For front derailer, you have to get something compatible with your crank configuration - road double, road triple, or MTB triple. It also needs to be compatible with the mount type - 28.6mm clamp, 31.8mm clamp, 34.9mm clamp, or bracket mount (aka "braze-on"). Finally, it needs to be the correct pull type - top pull or bottom pull - based on where the cable is coming from. All front derailers for round rings work with the Biopace.

For the rear, it's a bit more simple. If you have a triple up front, you need a long cage, if not you can use a short cage (athough a long cage will work, too).

Thanks for that info. I agree about the derailers normally not breaking, and technically mine isn't broke, but it met the wrong side of a stump and I can't get it strait enough to work 100%. So I figured I would just replace it. I've gotten a good long life out of this bike thus far and I'm hoping to have it around for a while longer.

Just last month I put a Shimano 105 clamp-on triple front derailleur (they come for both double and triple) on a biopace 28-38-48 with friction shifting -- worked fine. I don't think derailleurs care very much about chain width, fwiw.

That's good to know. I got the impression from some of the article I had read that some derailers were made for the different chain widths. But that might only apply to the bikes with nine and ten gears on the rear cluster. Just trying to get all of my facts straight before I buy parts I can't use.

Any 8 speed chain will work with 5, 6 and 7 speed setups. I prefer SRAM chains over Shimano in these applications. Removable link for maintenance and no need for special pins. NOS 8 speed derailleurs are easily obtainable and will work with your existing shifters, as long as you pay attention to the original configuration (clamp diameter, pull direction, cage length) that you are using.