Question: I have an old road bike that I want to turn into a time trial machine. When positioning aero bars, what part of my forearms should contact the armrests? How far apart should my elbows be? Should the seat be level or tilted up or down? — Mark C.
Coach Fred Matheny Replies: Your road bike can work well for time trialing. The advantages of a “real” TT bike are aero frame tubes and better handling when you’re on the aero bars with weight forward. As in most matters of performance, it’s the engine that counts.
That said, small position adjustments CAN increase your aero efficiency. Here are my general rules for setting up a road bike for time trialing:
- Move the saddle forward. One centimeter should do it. This helps prevent your thighs from hitting your chest when you’re in a low riding position.
- Tilt the nose of the saddle down. But only slightly — just a degree or two. This will reduce pressure to the soft tissue of your crotch. It will also tend to make you slide forward, but because your arms are supported on the aero bars, it won’t be a factor.
- Align your arms so they’re in front of your legs. Use a mirror to check. This shields your legs and makes you compact so you catch less air. You don’t want your elbows sticking out in the wind.
- Set your arm angle. Viewed from the side, your upper arms should extend forward from your shoulders about 30 degrees when your forearms are on the armrests. Experiment with this. Some riders like their upper arms to be almost perpendicular.
Don’t worry about forearm contact. Once you have your upper-arm angle adjusted, it really doesn’t matter where your forearms make contact with the armrests. That’s determined by stem and top tube length. Usually, the middle of the forearms is comfortable. If you aren’t comfortable, you might have to change your stem length.
When you get your bike set up like this, train on it. Make small adjustments until you feel comfortable, efficient and strong.
Tip! Test the aero efficiency of different positions by riding on a level windless road at a steady set speed. Check your heart rate and power (if you have a power meter). The lower your HR, and higher your power, the better in a given position. This isn’t as effective as a wind tunnel test, but if you pay attention to how you feel and how your body is reacting, you can come pretty close to your ideal position.
Coach Fred Matheny is an RBR co-founder who has four decades of road cycling and coaching experience. He has written 14 eBooks and eArticles on cycling training, available in RBR’s eBookstore at Coach Fred Matheny, including the classic Complete Book of Road Bike Training, which includes 4 eBooks comprising 250 pages of timeless, detailed advice and training plans. The Complete Book is one of the many perks of an RBR Premium Membership. Click to read Fred’s full bio.