Ask the Experts: John Cobb - Part II

John Cobb, bike fit and aerodynamics expert, recently took the time to answer Endurance Corner team member questions. We're sharing his responses as part of a series throughout the summer. In this second part, John provides answers to questions about hilly courses.

EC: How important are aerodynamics on a hilly bike course? Do you make more gains with efficiency in a road bike style position (for climbing) or is it better to be more aero (on TT bike) for 180 km?
John Cobb: I believe you're better off using a tri bike for hilly courses, even St. George. If you use the aerobars correctly and use them for leverage, you can generate more power for climbing. You also get to come down those hills pretty fast. Using the bars for leverage is usually worth 20–30 watts -- that’s a big deal.

EC: My tri bike is currently set up for "flat" riding. If I use it for a hilly course do I need to have anything adjusted to accommodate for more climbing?
John Cobb: You should consider making a couple changes for a hillier course. I suggest lowering the bar setup a couple of centimeters. That's to help build power and to help the handling on the fast descents. You should also recheck your saddle height and run on the low side, this will help relieve hamstring and Achilles problems from hard climbing. 

EC: Will the benefit of a deeper rear rim wheel (60mm) outweigh lighter wheels on a hilly bike course? 
John Cobb: I recommend always trying to run the deepest rear wheel possible. The deep rims are stiffer and the weight difference is usually just a hundred grams or so. The aero benefit will more than offset the weight. Remember that with wheels it’s not just outside aero drag, it’s a great way to save watts so you have more left for the run. A standard 30mm rear wheel takes about 25 watts to spin at 18mph, a 50-60mm rear takes 15–18 watts and a 1080 or H3 takes 10-12 watts. This can easily be a 10% savings of your total power.

In case you missed it:
Part I - Bike Fit