V-brakes on classics like those? are you going mad? 
fit some new pads and adjust the straddle cable first (I never had trouble locking/modulating with canti's BITD)
good info on the latter here: http://sheldonbrown.com/cantilever-geometry.html

fit some new pads and adjust the straddle cable first (I never had trouble locking/modulating with canti's BITD)
good info on the latter here: http://sheldonbrown.com/cantilever-geometry.html