Bicycle Tutor

A bike I'm repairing has a Shimano 200gs long-cage rear derailleur running 6 speeds. The rear wheel needs to be replaced and if I choose a cassette it'll be minimum 7 speeds and I might go 8. Can this derailleur support 8 speeds?

All of the scant info I have found on the 200 gs is that it is a 6/7 speed, 32 tooth max freewheel/cassette. It was discontinued in the mid 90s and replaced with the Altus. Maybe someone else has the shimano docs available with more info. Good luck with your repair.

I couldn't find much online either but the guys at my bike shop said 7sp would be tight. Thanks.

I looked at http://www.sheldonbrown.com/cribsheet-spacing.shtml (scroll down for cassette spacing). from 6 to 7 speed is an additional 3mm cassette width, 8spd is another 3mm. So I guess they're probably right...
I would (probably) try the 8 speed and then finally replace the dérailleur with a newer one (mid range Shimano of yesteryear).

Note that a 6 speed rear wheel is narrower than a 7 speed cassette freehub rear wheel. There might be a problem with the frame spacing. If and only if it is a steel frame you might be able to respace it.

The frame spacing is adequate for up to 9 speeds at 135mm. I may just replace the derailleur anyhow because the first 4 or so threads on the barrel adjustment hole are stripped limiting that feature. The entire drivetrain is being replaced so I might as well do it all.

This is my first time shopping for components so I have some questions.

The frame is labeled as a MTB frame though it is more like a road frame, what sort of components should I select? I'm interested in road components such as 2 chainrings and "compact" RD. I'm looking at a 7 or 8sp in the rear and I don't know how brand crossing affects component selection (Sram vs Shimano).