Different course, same gears
Several studies (like this one and this one) have shown that riding with an abnormally slow cadence impairs running out of T2. If you’re doing a hilly late-season race such as Ironman Wisconsin or Ironman 70.3 Austin, make sure your bike has an easy climbing gear that will allow you to spin your preferred cadence up steep climbs instead of forcing you to grind against a gear that is too big.
Count the number of teeth on the largest gear in your cassette. If it is 25 or fewer, consider swapping your cassette for a version with 27 or 28 teeth. For about $100, you’ll buy yourself a more comfortable bike ride. Using a cassette with an easy climbing gear is especially important if you ride a standard crank (it will say “53” somewhere on the big ring) instead of a compact (which will say “50”).