Replacement shifter to fit brake lever?
I'm looking to replace my gear shifter which is currently mounted on the brake lever. I'm currently using an old Altus A20 system, will I be able to find any shifters that fit my brake lever. The only brake/shifter combo's I can find are for V brakes and I use cantilever. Is there any other compatibility issues with gears shifter for example could I switch to grip shift without changing my dérailleur?