Rule No. 5: Keep the speedwork up on your run while you focus on the bike.
Spending more time on the bike inevitably means you’ll have to back off on your run, which can ultimately hurt your run split. Petersen says that focusing your limited running time on speedwork will help you keep your running legs underneath you while you work to improve your cycling. “Speedwork would help, because you’re getting so much endurance from the bike,” Petersen said.