Choosing the right derailleur

[aryehlaz]

My bike is '97 i believe, and it's got a shimano altus rear derailleur. It needs to be replaced. I was wondering if there are other models I can buy, or only specifically that one. Can anyone help. thank you.

[DaveM]

You should be able to use almost any Shimano derailleur. I think the Altus is a mtn bike derail. Do you have three chainrings in front? If so, you need to stick to mtn derails.
I think Alivio is the current equivalent to Altus. I'd recommend going up a notch or two for better performance. But don't waste your money buying a real high end part. It won't work that much better unless you upgrade your whole drivetrain.
Shimano has a "low normal" and "top normal" option on a lot fo their derails now. Top normal is "standard" and probably what you have. It means that if you released the cable, the derail would spring out to the small (top) gear. Make sure you get the right kind.