V - bricks always hurt. Especially when you're first starting out. The key is getting good at making your legs do that running thing when they still want to do that cycling thing. That means practice. You don't have to do long bricks to get this. In fact short reps work really well. I will sometimes do a workout where I ride 5 miles, transition and run 1 mile and repeat that 3 or 4 times through. The other thing I do in a race is tell myself that the first 4 km of the run are going to hurt, no matter what and I can't use how I feel as a guide to how I'm doing. After 4 km, if it still sucks... well then it's time to start thinking about what needs to change, but until then you really have no guage.