i used to replace v pads every 2/3 months at ?£10 a pop! now gone over to minis havent had to replace pads yet, but i have found that i can revive my disc pads in ways that i couldnt with vs! i would think (noy doing any calculations) that cost would probably come out at nearly the same!
It probably depends a lot on the conditions you ride in. Mud can eat V pads in a single ride but you get sintered disc pads and they will last much longer in crappy conditions. Disc pads will set you back about £13-15 a set and V's from as little as £3 for a basic set up to £10-12 for a cartidge set.
I would have thought Discs would work out cheaper for pads if you ride all year round and you don't eat your rims either.
There have been instances of disc pads being worn out in a single run. It isn't rumour and I've ridden with someone to whom it happened. Also disc pads are more susceptible to contamination, so if you get them oily then it's finis, whereas V pads can just be wiped clean. I've also had sets of V pads and disc pads last an entire years riding (including muddy rides).
Overall the pad cost is probably similar, although as was mentioned, discs don't wear out rims in normal use.
If youre asking this question in a kind of "disc vs v's" way, then don't even bother.
Pad life is the smallest of reasons to use disc brakes... Power & control being the biggest reason, in all conditions (granted, well set up V's on a ceramic rim will be just as good in the dry), plus the benefit of not wearing out rims, & being able to run rims out of true without any rubbing.
incedently my experiences are much the same as James - get through V pads every couple of months in winter, then about 6 months use through the summer. Mini (aztec) pads, once a year at the maximum (& that includes everything from scottish winters to morzine summers). I;ve found I spend less on disk pads than I used to on V pads.
