need help on spacing please. old to new.
 

howdy!

thanks for dropping in to look. i've got a 1993 Bob Jackson with shimano 600 parts on it and suntour bar end controls. i was thinking of switching out the bar cons for STI style shifters so my girlfriend will use it as a commuter. the rear cogs are less of a casette and more of a bunch of, well, cogs. it's a 6 speed up the back now, how many more can i squish in there if i change them out? the hubs are campy. will a newer casette work? will i need a new mech? just a new rear one or front and rear both? it uses friction shifting now. is this going to be a hassle to swap out for the change?

thanks for your help!

cheers!

If it's a 6 speed freewheel,you can get a 7 speed shimano index freewheel.Use sora 7 speed sti shifters to shift it and likely a shimano sis front and rear derailers, altho, the rear if new enough 600 may be sis. sydney thinks gf need to learn to use a stick shift or find a lower maintenance one.