Thanks for the advice Wahine - (and sorry it took so long to write back). It certainly makes sense, and I went to the LBS today and talked to a couple of the racers there and got very similar advice. They also recommended the gel every 45min (recommended Hammergel - the ones that go in the flask for up to 5, I think), then powerbar endurance energy drink. I'm trying this this weekend for a long workout and will see how it goes.

The LT of 181 was tested on a run, but at a time trial I did that lasted 35min I took the average HR for that and it was 180. So maybe 180 is more of my LT on the bike - in either case, it's in the 180 area. And yeah, I wasn't planning on being zone 3 that day - it was supossed to be zone 2, but I was off a rest week, the weather was perfect, and it just felt good. Up until the past month almost all of my training has been zone 1, 2 so my base miles are fine. Thanks for the advice, though, sometimes hearing it from somebody else will help keep myself from giving into temptation .