Bicycle Mechanics - Derailleur Question

I have a dinosaur 86 trek 500 series road bike. But it runs good except for the rear derailleur. Now I want to replace this with a semi decent setup. But I am needing some advice. first off its a 5 speed cog(Cassette) I want to know if I buy a 8 speed derailleur can I use a 8 speed cog on the same wheel with the derailleur and a 8 speed chain? Also it has downtube shifters so i would replace them with indexing ones. Does all this sound logical? Or is there a better way to do this (other then complete bike replacement) Also is it possible to use the 8 speed derailleur with the 5 speed cog?

Any input would be beneficial!

Thanks

Hope its not to confusing

Brian

No no no... 5spd is basically 5spd... you're kinda outta luck on thsi one. If you do upgrade, go 9spd since 8spd is basically extinct, otherwise you will be stuck with the same problems in the future.

Ok. Lots of questions, several possibilities.

You know, the derailluer may just need to be properly adjusted.....

First of all, yes, a 9 speed derailluer will work with your 5 speed drivetrain, or an 8 speed, or 7, etc. The only real difference is the width of the teeth on the pulleys. A new chain may be in order, as the 5 speed may be too fat to fit within the derailluer cage.

Your 5 speed wheelset will not be compatible with an 8 or 9 speed cluster. These are cassette style, the 5 speed is a freewheel. The only option in that case would be to get a new wheelset, or rear wheel at least. This will be spaced at 130mm, your frame is 126mm. Some cold-setting may be required, typically you will be able to just stuff it in there.

Indexed shifting will only work for you if have the coordinating shifters and cassette. I.e. 8 spd with 8 spd. If you get newer indexed downtube shifters or barcons, they will have a friction setting so you could use them with the old wheels until you upgrade at a later point.

I have an '87 Trek 400 Elance that I ride everyday, upgraded with a full 8 speed setup using bar-end shifters. Everything works very well, although I leave the shifting in friction almost exclusively.

That Trek isn't a dinosaur, its a classic. I have three and they are wonderful, hold onto it and treat it well. Check out www.vintage-trek.com for more info on your bike.

-Pete

Your 5 speed wheelset will not be compatible with an 8 or 9 speed cluster. These are cassette style, the 5 speed is a freewheel. The only option in that case would be to get a new wheelset, or rear wheel at least. This will be spaced at 130mm, your frame is 126mm. Some cold-setting may be required, typically you will be able to just stuff it in there.

There are 8 speed freewheels,but I wouldn't go there.Seven speed is easier, cheaper and dooable.

Man u are in hard luck...this is what i say u do...GO SINGLE SPEED. its the best thing to do trust me !!! very useful too. So if u mind getting up on ur pedals once in a while...go single speed its the way to go..unless u have a dual-suspension bike.

My rear wheel is fairly new ( like 2 mnths) is there any way to find out what I can throw on there?

B

My rear wheel is fairly new ( like 2 mnths) is there any way to find out what I can throw on there?

BIf it's a freewheel,which might be the assmption with 5 speed,you can replace it with a 7 speed shimano index capable one, get a shimano index capable RD and 7 speed shimano index sifters.