A brick workout is doing two parts of the triathlon together, to practice the transition. Today I biked the 11 miles of the triathlon route (except a detour that added a hill) in 50 minutes then ran my usual 1 3/4 miles in 24 minutes. I'm really slow, but I am happy because that is exactly the same time it usually takes me to do the run--I wasn't slowed down at all by having done the bike ride first, even though I pushed myself pretty hard on the bike. I didn't even feel more awkward than usual when I started running.
I don't think there is much I can do about being slow--I ran steadily at 85% of maximum heart rate, which is a pretty good level of effort. I didn't feel worn out; I could have kept going but because my knee still twinges sometimes I'm going to be careful to keep increasing distance very slowly. Maybe this Friday I will go up to two miles.