Sorry to dig this thread up but... I've had a completely different experience with this setup than pretty much everybody else here. I'm running old XTR V-brakes (they have the 4-bar linkage to keep the pad parallel to the rim) that have 100mm long arms with Ultegra 6700 shifters and it's working brilliantly. One thing worth mentioning though is that you do have to run the pads close to the rim, I'd guess 2-3 mm. However, when I ran SRAM Rival shifters and 80mm mini V brakes before, the pads were just as close. The brake feel is extremely squishy and I can easily bottom the lever, but the brakes have so much power that if I did bottom the lever I'd be thrown off the bike. Pulling the lever a normal amount provides more than enough stopping power even if it feels like the pads haven't hit the rim yet. An unsettling feeling, but easy to get used to. That's helped by the fact that despite the long brake arms, modulation is excellent for some weird reason, even better than the mini V brakes I used. To top it off, because of the longer arms I can release the brake without the aid of an adjustable noodle, unlike mini V brakes.
I'm confused why it hasn't worked for anyone else. The only reason I can think of is that some V-brakes come with arms longer than 100mm and people are using those? Either way, I'm very happy with this setup. I can have it all: huge braking power, excellent modulation, lighter weight than discs, the ability to release the brakes without an adjustable noodle, and a buttload of clearance for both mud in CX races and fenders too!
Last edited by Soundtallica; 10-25-15 at 11:19 PM.