@M_V, you seen this? http://www.sheldonbrown.com/cribsheet-IG-cable-pull.html
If I've read it right it's 4.7mm per click
I wonder if you could use 8speed Shimano shifter which is 5mm per click, I know later Shimano IGHs are quite sensitive to cable issues but maybe the 4 speed isn't?
@M_V, you seen this?
http://www.sheldonbrown.com/cribsheet-IG-cable-pull.html
If I've read it right it's 4.7mm per click
I wonder if you could use 8speed Shimano shifter which is 5mm per click, I know later Shimano IGHs are quite sensitive to cable issues but maybe the 4 speed isn't?