How to Convert Your Road Bike for a Triathlon

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A more aerodynamic bike can cut seconds and even minutes off a triathlon time, but you don't need to buy a time trial bike to reap that advantage. Your current road bike, which is more comfortable and easier to pilot, can be modified to give you the same aero position as an expensive triathlon bike, says Dave Harris, owner of Mercury Bicycle Fit in Key West, Florida.

Yes, dedicated tri bikes have impressive looking tubes to better cut through the wind, but 80 percent of a rider's drag comes from his body, says Harris. To really cheat the wind you'll need to make a few minor adjustments and additions to make yourself more aerodynamic. Here's how to do it:

Lower Your Bars
Look at the top Ironman athletes on their bikes, and you'll see that their backs are practically flat as they hunch low over their handlebars. Lower is more aero, but there's a limit. "If you're not able to hold it for 100 percent of your race, you're basically putting your air anchor out," says Harris, who often sees racers on ill-fitting bikes riding with their hands, not elbows, on the aerobar pads.

To figure out your handlebar height, Harris says to start with 4cm of drop from saddle to top of the aerobar pads, and work down from there. If you have tight hamstrings or a hip injury, you'll be limited in how low you can comfortably ride.

Also make sure you aren't positioned too tightly to eat and drink while biking, says Mike Giraud, an aerodynamicist and technical director at Cyclologic Science Solutions in Scottsdale, Arizona. "You need to be able to fuel and digest properly because most of your nutrition is done on the bike." Otherwise you're likely to bonk during the run.  

Add Aerobars
With your handlebars lowered, set up your aerobars so your forearms rest naturally in the pads, says Harris. The pads should be comfortably close your elbows, and your elbows are at a 100º angle. "You want the body resting on your skeletal structure; using your muscle groups less to support yourself," says Harris. If you're too stretched out, install a shorter stem. 

From pad to tip, the bars should be anywhere from level to 10º of rise. See what feels comfortable. The same is true for how wide to space the bars. It shouldn't feel like a chore to be tucked into the aero position. 

Move Your Saddle Forward
A typical road bike has a seat tube angle between 72º and 73º. A triathlon bike, meanwhile, has a more vertical seat tube angle around 79º. That's because you need to shift your cycling position forward in order to move from having your hands on the bars to having your forearms there in an aero tuck. 

You can slide your saddle forward to mimic a greater seat tube angle, but a better option is to go for a zero-offset or forward-facing seat post. A zero-offset post rises straight up from your seat tube, while a regular road seatpost has a 20 or 30mm setback. A forward facing seat post (the more dramatic option) pushes your seat farther forward for a closer fit to a tri bike. Another option is the Redshift Dual-Position Seatpost. This post uses a spring link to push your saddle 50mm forward and back to ride a road, or TT, position.

Raise Your Saddle Height
"The more you slide your saddle forward, the more you're lowering your virtual seat height," says Harris. You'll need to raise your saddle to compensate for the shift and maintain the angle of your knee when your foot is in its most extended position. There should be a slight bend in your knee at the farthest point of your pedal stroke. If your hips are rocking while you spin, you've raised your saddle too far.

Swap Your Saddle If Necessary
Getting into a lower aero position rotates your pelvis forward in the saddle and your trusted road saddle may suddenly cause numbness and pain. If that's the case, ask your local shop to test ride a triathlon saddle. They're designed for a more forward position and prevent soft tissue and nerves from being compressed (the cause of your pain and numbness). 

Fine-tune With Miles
Training rides in the aero position will give you a chance to dial in your new fit, raising or lowering your bars and fine-tuning the saddle position. More importantly, shifting your weight forward will change your bike's handling, and not for the better. "It's a compromise, and you need to get used to it," says Giraud. Start by taking turns slower than usual and braking earlier — having your weight forward means it's easier to throw yourself off the bike with a sudden stop.