[tdarko]

Colt,

Actually you are using completely different muscles when cycling and running and the toughest brick is actually the swimming brick and if you notice this is why there is an extra day off that week. The run/bike brick is still effective b/c when you get to your run, though you are working different muscles your are still starting an aerobic exercise in a pre-fatigued state.

I wouldn't go into a triathlon w/o going through the transitions and incorporating both brick workouts in to the plan.