Originally Posted by
JJam2112
Has anyone put on bigger wheels and upgrade the cassette? Do you have to widen the rear? If so how did that go?
I assume you mean bigger tires -- there really aren't bigger wheels than 700c/29-er. (Well there are some 36" wheels out there but those are extremely niche.)
If you have an old hybrid like a 90s-era Trek Multitrack the rear spacing is 130mm. That's pretty much the standard road bike hub width (although that might be changing with discs but that's not really relevant here.) Pretty easy to find hubs in that width, no real good reason to widen the rear.
If you're working with a 80s-early 90s rigid steel MTB the rear spacing is probably 135mm. Even with the 26" wheels that they all had. Again, that's a common standard. Even if you swap in some 650b or 700c wheels in there (a common modification but the details and specifics are covered elsewhere) you won't have to worry about the width of the rear dropouts.
However, if you do have to mess with the rear spacing for some reason--like you're trying to stuff a 135mm hub into 130mm-spaced rear, and it's a steel bike,
sometimes* you can get away with just squeezing it in there by hand. Steel is flexible.
*not always though, but it's worth trying first before you go to the effort of cold-setting.