I'm trying to replace the crappy Shimano Revoshift (3x7 speed) shifters on my brother's bike with Shimano Alivio 7 speed shifters. The rear shifts like a charm, but I can't get the front to work. The chain is on the small ring and the shifter is in "1". Now, when I try to shift it to "2", the derailleur goes to the largest chainring, skipping the middle one. Obviously, shifting to "3" doesn't work.
I assumed that it would work since this is all 3x7 speed Shimano gear. Could it be that the Alivio shifter isn't compatible with the front derailleur (which I think is one of the cheapest Shimano MTB derailleurs, it only says "SIS")? Or can I somehow adjust the shifter/derailleur to shift properly?