[duke walker]

i have an older xt wheel/hub 7 speed 13-26. id like to go 11-34. there is a 7 speed 11-34 at harris, but it sure looks like a big step from the #6 to#7 cog. how well does that work?
or, how about an 8 speed 11-34. . would i need a different hub, and therefore a new wheel? (i know i will need a new chain, maybe a longer cage derailler,, and maybe a new shifter)

 

[comptiger5000]

You would definitely need a new shifter, and you may need a new hub, or at least a new freehub body. At that point, you may as well go 9 speed, as 8 and 9 are the same width cassette, but 7 is narrower.