Okay, I'm totally green when it comes to triathlons and I want to do my first sprint in the spring. That means I'm already behind in training. I'm curious about which crank I should use on my bike. I recently replaced my Ultegra 53/39 with an FSA 50/34 (but I've held on to the Ultegra). The compact is great for the hills I typically ride in this area, but would the 53/39 be better suited for the 20-something mile long rides you usually see in sprints?