I have a chance to buy an older Trek 520. After checking the serial # and the vintage Trek site it appears to be a 94 model. It also has other small numbers on the bottom bracket...then larger #'s that say 520 21. The bike component group is Shimano LX. It has a 7 speed LX free hub wheel, and 135mm dropouts on the frame. I like it that it has Deore LX trekking chainrings with 175mm crank arms.
Is it fair to assume this is a 21 inch model?
Would this 7 speed freehub accept 8 speed or 9 speed cogs, assuming I change the shifters? Or is this one of those older 7 speed Shimano freehubs that only accept 7 speed?
Is there a way to tell more about the freehub other than just trying an 8 speed cassette?