Congratulations on your first tri!

I have found that it takes time and lots of riding and perserverence to get speed up consistently on bike. I do duathlons. My coach insists that I stay on the small ring the whole time I ride during a race. One time, I didn't listen to him and paid the price of totally dead legs....my 2nd run was brutal, awful, dismal. My "following directions" skill has improved tremedously.....