TT Bike vs. Road Bike vs. Road Bike with Aero Bars
Updated: Aug 4, 2022
Recently listened to the excellent podcast from Michael Liberzon on scientifictriathlon.com which addressed many common questions I get from athletes on bike selection. Here are some takeaways:
Almost everyone will be more aerodynamic than on a road bike on a TT (or triathlon) bike.
It is not the bike itself that is more "aero". It's the riders position on the bike that makes a TT bike more aerodynamic.
Using an athlete who rides 200 W in an Ironman, the time savings from upgrading to a triathlon bike will be around 17 minutes. In a half-Ironman, you will save around 8:30-9 minutes, 4-5 minutes in an Olympic distance triathlon and 2-2:30 for a sprint race.
The aerodynamic savings will be less for slower athletes (because they are moving slower through the air) but they are on the course for longer so still results in significant time savings.
Triathlon bikes are comfortable while adopting a more aerodynamic position, and road bikes are comfortable in a normal upright position. Aero bars on a road bike can put you in a more aerodynamic position but it may not be as comfortable as a triathlon bike geometry.
When buying a new TT bike, make sure the bike you are buying is adjustable. The cockpit should be easy to adjust and have a broad range.
Only on very hilly course will a road bike be an advantage. Most times the weight advantage (road bikes tend to be lighter) will be overcome by the speed of a TT bike on the downhill and flat sections of the course.
On a very technical course you might consider a road bike with aero extensions.
When should you get out of the aero position when climbing hills? Liberzon suggests consider sitting up around 17-18 km/h. Any lower and the additional power you can produce sitting up outweigh the aerodynamic loss of an upright position.
Practice training grabbing bottles, your race setup and holding that position (no point getting a bike for an aerodynamic position and never be in that position).