Bicycle Mechanics - Derailler compatability

I'm looking for a chorus or record rear derailler. I currently have a 7 speed cluster on my rear wheel. Most campy deraillers that I see on ebay are 8-10 speed. Will an 8 speed hub only work with an 8 sproket rear cluster?

The 8sp derailleur should be compatible, provided you pick one that suits your gear cluster's size range. You wouldn't want to use a short-cage road derailleur with a 12-32 cluster, for example. One other possible catch would be if your chain was a rather wide chain and you tried to use it on a 9sp or 10sp derailleur which was made for a narrow chain.

If you have infinitely-adjustable friction shifters, then things are pretty simple: install the derailleur, adjust the limit screws and hook up the cable, for the most part. If you have indexed shifters then please give more info about the parts you've got so far.

Campy 8 speed indexing uses a cog spacing of 5mm. That is the same as Shimano 7speed, so it should all work OK with Campy indexed gear shifters.

KH brown,why don't you do us all a big favor and tell us what cogset you are using and what shifters you are trying to use the derailer with,so we dont' have to GUESS?? Naybe then you can get a good answer.

MichaleW ..What are you talking about.You don't even know what he is working with.

Thanks for your replys. As you can see I'm new to this. I'm in the process of upgrading my old Bianchi Axis. The Bianchi is from the late 1980's. The best I can tell, it has rear sprokets ranging from 13 to 29. The cluster is suntour. The bar end shifters are Suntour Accu Shift. So far, I've picked up Campy Chorus cranks, rings, bottom bracket, and front derailler. Hope this makes things a little clearer. Thanks for your help.

Kinda,but not really.Is it index shifting?You trying to keep it index? What shifters are you planning on using? how many speeds int the rear? Things get really complicated with compatibility issues and index shifting,especially when you start mixing manufacturers, and vintages. Shimano and suntour 7 speed index stuff is generally compatible.Campy shifters/derailers have different cable pull/deralier throw ratios and generally are not compatible with shimano systems,but there are exceptions.Everything works in friction.For minium hassle, with what you have,I would suggest a shimano index capable rear derailer,but not a pre 9 speed Dura Ace.

Yes, I believe that it has indexed shifters. It's one of those old click shifter setups. You pull or push one click and it shifts one cog. I am flexable on the index issue. Would it would be better to change shifters? What about the Campy bar end shifters? Yes, there are 7 cogs on the rear wheel.

Most linear (downtube levers or barcons, in contrast to Rapid-Fire and integrated brake/shift units) indexed shifters can be operated in a friction mode or modified to do so. This is the universal solution and opens wide the possibilities of drivetrain component mix-and-match, while simplifying driveline maintenance and improving reliability. With downtube levers or barcons, indexing provides very little, if any, tangible benefit, anyway.

Well, actually shimano has the patent on dual mode index/friction shifters. His suntours have a ' soft click' which are almost friction and get around the patent. Campy makes index OR friction. If you just have to have a campy derailer, you can use your suntour shifters in the soft click(friction) mode.Otherwise for indexing, get a campy 8 speed downtube shifter or barend if you can find it or a adapter pod from www.rivendellbicycles.com that adapts downtube to barends. and a campy 8 speed rear derailer.Since campy 8 speed spacing is 5.0mm it will then shift the 5mm spaced suntour cogset. A pre 2001 campy 9 speed RD will also work but might need a narrower chain.