Trek 1100 question
 

I recently got an older Trek 1100 road bike and I'd like to upgrade the rear wheel and cassette. Does anybody have any idea on how big I could go with for the cassette? I also want to upgrade from the currrent/stock derailleurs that are on it. Came with 7 speed SunTour 4050 Edge.
Thanks for any input.

If its rear spacing is 126mm I'd probably just leave it as-is.

If it's 130mm you can go for 11 speeds if you want (is that what you mean by "big"?). The wheel+cassette+chain+shifters will be pretty expensive for that setup. You can possibly save a bit by staying with the downtube shifters and running them in index mode.

If by "big" you mean a big cog, then I'd probably just get a MTB derailer that can handle 32 or 34T cog.

Sorry, I should have been more specific when I said "big". I was referring to how many speeds I could go up to. I had read somewhere that I could only go up to 8 spd. I'll measure the width and see what I've got for space to work with. Thanks LOP

Very likely 126mm spacing = seven speeds max. 8/9/10 all use 130mm spacing. Some people cram wider wheels into aluminum frames, others do not recommend it. I do it with steel frames all of the time, but steel is much more forgiving. Some later aluminum frame bikes were spaced at 128mm, allowing the owner to use either spacing standard, 126 or 130.