15 steps to a faster bike split
By Craig Turner
This report filed September 17, 2001
Ironman events are all tough, but Kona takes it to a whole new level. Maybe it's the heat, the humidity, the wind, the emotion...or just the fact that it is the world championships.
There are dozens of factors that come into play in an Ironman, and success at Kona depends on them all. Whether your definition of success is an age group win, a new PR or simply finishing the punishing course, there is much you can do before the race even starts to help you meet your goal. Having built nearly 1000 bikes for Ironman racing, and dozens of pro bikes for Kona, I have seen the essentials for success come down to (1) Aerodynamics, (2) Energy Conservation and (3) Bicycle Durability. Sounds simple, doesn't it? It is, but there are a lot of things that come into play.
Where does all that energy go on that 112-mile bike split? Why does it seem so exhausting, and what can you do about it?
1. Unbelievably, 64 percent of your energy output goes straight into overcoming the aerodynamic drag of your own body on the bike. That drag is a function of the frontal area of your body and the side shape of your aerodynamic position. For Ironman distances, you need a compromise between aerodynamic efficiency and comfort. Keep your arms in a narrow position as long as the wind does not get too strong, and keep your back flat, parallel with the ground, as long as you don't experience neck pain. So, for Kona in particular, consider a slightly less aggressive position.
2. What's the next biggest energy consumer? You guessed it; it's the drag of the bike. About 31 percent of your energy goes into overcoming bike and wheel drag, with two-thirds of this being bike drag. A clean front end to the bike is key. Use an aerodynamically-shaped fork, select a frame with an aero-shaped down tube, and use an aero-shaped integrated aero bar from Cinelli, VisionTech, Profile or TTT. Watch the position on some of these bars as the time trial bar part can have a large drop and make climbing difficult. Faired-in head tubes also help, as do aero seat posts. Keep the area beneath the saddle clear of your spare tires and tubes, because this is a high-pressure area and air needs to travel cleanly between your legs.
3. As you probably know, aero wheels can also save valuable minutes. It's great to use a composite three-, four- or five-spoke or deep rim wheel on the rear, but do not use them on the front if your race may be windy. For the front in windy conditions, I recommend a carbon rimmed aero wheel with bladed spokes. The front wheel sees clear air so select the best you can afford. All that aero drag adds up to 95 percent, so what makes up the other five percent?
Well, it's called rolling resistance of the tires and mechanical inefficiency. To reduce rolling resistance, use latex tubes and tires with a smooth surface, and tire pressures as high as you feel comfortable with, within the manufacturer's recommendations, of course. Don't forget that unless you are on a cushy beam bike, every bump requires you to react, which in turn takes energy. The more comfortable a frame, the higher the pressures you can use.
Sounds strange, conserving energy in an Ironman race? Yes, that's exactly what you must do on the bike. How many races have you seen pros push super-hard on the bike, only to be overtaken on the run? Fortunately there are many actions you can take to help conserve energy.
1. Keeping your core body temperature as low as possible helps tremendously in maintaining your wattage output. Ensure your clothing has a quick wicking ability. Look at the fabric, test it, and be wary of totally Lycra products. Using a helmet visor can lower your face skin temperature 30 degrees. Look for helmets with maximum venting, and repeatedly dump water through it whenever you get a chance.
2. Do you want to be on an IV after the race? If not, consider this. A 150-pound triathlete's body contains 180 cups of water. The marathon alone can suck out up to 38 cups (21 percent) of your water. You will need to drink at least six to 12 ounces of fluid every 15 to 20 minutes on the bike and run. The heavier you are, the more you need to drink. If you don't think you can drink at that rate without a handlebar-mounted bottle, then use one of those refillable devices. It is better to stay hydrated and be less aero than it is to become dehydrated, confused and disoriented. And remember that water overload can dilute sodium levels in your blood, which can lead to hyponatremia. The New Zealand Ironman reports that 18 percent of finishers (and three times more women than men) had this condition. So be sure to use a sports drink that replaces electrolytes.
3. Carrying calories on the bike is an issue. Many Ironman triathletes need to consume 1000 calories per hour [note: you may burn this many, but trying to replace more than one third of these calories will most likely lead to gastric distress, blockage of stomach emptying, or other problems that can end your race - dgf], and there have been many ingenious ways to carry these calories. One method becoming popular is to carry two large bottles with 1000 calories in each, made up from a powder such as Carbo Pro or Ultra Fuel. Add to this a few gel flasks that you can wash down at aid stations. If you want to carry solid food, I recommend a fanny pack in order to stay aero. If a little bit of extra drag does not bother you, and you want easier access, then look at the handlebar mounted Bento Box from TNI. But, above all, keep pushing those fluids, calories, electrolytes and sodium if you want to perform at your best.
4. Ironman is a race, right? Wrong. It's an exercise in pacing yourself and spending the right number of calories at the right time. Don't worry if you get overtaken, use your heart monitor and run your race according to your plan. It worked for Mark Allen.
5. Pushing the optimum cadence of say 80 to 90 rpm will conserve your energy. Yes, it feels good to push a bigger gear, but resist the temptation. Get a computer with cadence and mount it on your aero bars with a special computer mount, and don't get lazy; use those gears to your advantage, and stay in the cadence zone.
6. To help stay in the cadence zone, ensure your cassette has 14-, 15-, 16- and 17-tooth cogs for close ratio shifting. For higher speed descending, and to avoid spinning out, consider a 53x11 on 700c, and a 56x11 on 650c wheeled bikes.
7. Getting sore distracts you and takes energy. Use a neoprene saddle cover, or one of the new Selle Royal gel saddles for deluxe comfort. Also, use double layers of bar tape to stop your hands getting numb.
Your bicycle must perform flawlessly.
1. Get new cables if any are frayed. To get new cables to "stretch in," for a week, after each day of training, leave the chain on the large cog and large chain ring, and then have your bike shop readjust your derailleur cables. After the cables have been "stretched in", always leave your chain on the smallest cog and smallest chain ring.
2. Use tubular tires to reduce the risk of flats, but use the trick when gluing. Leave a one-inch length of tire and rim unglued on the opposite side of the wheel to the valve stem. When removing the tire, put your plastic tire lever into this area to help remove the tire. For clinchers, I recommend the Crank Brothers super fast tire lever.
3. Check your frame, cranks, fork and aero bars for miniature cracks. Get your bike shop to do this every few months. Replace any items where cracks are starting.
4. Always carry two tubes and a spare tire for clinchers, or two tubular tires (pre-stretched and pre-glued).
5. For tools I recommend two C02 cartridges and an adapter and a mini tool such as the Minoura Handy Pocket 10, which includes Allen wrenches, screwdrivers and sockets. These pro secrets will make your Ironman bike split easier, leaving more energy for the run. Have a great race, relax and enjoy.
Craig Turner is the president of Nytro - the Encinitas, California, triathlon retail store and mail order company. Contact him with questions at firstname.lastname@example.org.