Well, I decided to do my LT test using the running method this year. Last sunday I did a 4.3 mile, 30 minute run and revealed-at least to me-pretty impressive numbers. For the entire run, I averaged 173bpm. When doing a "self" test, you take the last 20 minutes of the run, ride, swim, etc. and that gives you a good indication of you LTHR. Last year I figured on 176, this early in the year revealed that the average HR over the last 20 minutes was 178. I felt pretty good in that range. I felt as if I could sustain that pace for a bit longer, too.
Running is a good way to get this result, because I think it is easier to get to your max HR and keep it there. On the bike, you always have stop signs, driveways, etc. Even though I hate running, it is a nice break from cycling when the weather is not as nice.