Originally Posted by
garage sale GT
Either style of hub brake might make the bike pull to the side a bit under severe braking.
That doesn't happen if they are properly set up.
Originally Posted by
Giffen
I don't think this is true in general.
Even if you could modify the rod levers to actuate a drum (which is possible), you would still have to disconnect the rod brakes themselves. You couldn't actuate both brakes off the one lever.
3DGal: Another option would be to make the rim less slick, either machining it or putting something sticky on it so that the pads would grip better. Back before modern brakes, trials and BMX riders would smear tar and other things on their rims so their brakes would work better.