by Gabe Mirkin, M.D.
Cycling is a power sport. The stronger you are, the faster you can go on a bike.
Power = [force that your feet apply to the pedals] x [cadence, or how fast you spin your pedals].
Cadence is the number of pedal revolutions per minute (RPMs). Bicycle computers that show your cadence are available in bike shops and online bicycle catalogs.
Fatigue for a bicycle rider comes primarily from how hard you press on the pedals, not how fast you turn them. If you put too much force on your pedals, you will exhaust yourself early in your ride and may have trouble getting back home. On the other hand, if you spin your pedals faster than is comfortable for you, you will become uncoordinated, waste your energy and end up going slower than you would if you used a lower, more comfortable cadence.
Competitive cyclists pedal at an average cadence of 80 to 105 RPM and they do time trials at 110-120 RPM. If you train to increase your cadence, you will usually improve your cycling efficiency, allowing you to ride longer and faster.
Gears Determine Cadence
Your bicycle has gears so that you can change the force necessary to push on the pedals by using higher or lower gears. You need to reduce the gear ratio to pedal faster, but if you go too low you will spin so fast that you lose coordination and waste energy. If you are grinding and having to put great force on your pedals, your gear ratio is too high and you are just going to exhaust yourself and go slower than you want.
How to Find Your Optimal Cadence
You want to pedal as fast as you can with the greatest force you can maintain on your pedals, but if you spin too fast, your brain cannot coordinate your muscles so you lose efficiency. Try to choose gears that allow you to spin as fast as you can and still feel some pressure on your pedals.
• Spinning the pedals too fast wastes energy and slows you down (Med and Sci in Sprts and Ex, May 2006).
• Pushing on your pedals too hard forces your body to move from side to side and you waste energy and exhaust yourself so that you will finish your ride much more fatigued and ride much slower.
Why A Slower Cadence Tires You Earlier
When you feel tired and your muscles hurt on a long ride, your fatigue is caused by running out of sugar stored in your muscles. In one study, racers spinning at 50 pedal strokes per minute used up far more of their stored muscle sugar (glycogen) than they used up while spinning at 100 revolutions per minute to generate the same amount of power (Eur J Appl Physiol, Aug 2004;92(4-5):443-51) . Their bodies consumed the same amount of oxygen and had the same heart and breathing rates, total rate of power production and blood lactate levels. Interestingly, the extra loss of muscle sugar pedaling at 50 revolutions per minute occurred only in fast-twitch muscle cells that govern strength and speed. Over 30 minutes, the fast-twitch muscle fibers lost 50 percent of their glycogen (sugar) at 50 rpm and only 33 percent at 100 rpm. That means that your muscles weaken far more at 50 RPM than at 100 RPM because you are putting so much pressure on your pedals.
Muscles use primarily fat and sugar as their energy sources during exercise. You have an almost unlimited amount of fat that can last for days, but you have only enough sugar in your muscles and liver to last for about 50 minutes of intense exercise. This explains why athletes in events lasting more than 50 minutes should take a sugar source during competition to do their best.
My Recommendations for Beginners and Recreational Riders
If you are beginner, spend several weeks learning to become comfortable on your bike and ride at any cadence that is comfortable for you. However, as you become more accustomed to your bike and want to learn to ride more efficiently, try to pedal at a faster cadence in which you are still comfortable and feel adequate pressure on your pedals.
Your cadence depends on your leg strength. Beginners may have to start at a cadence lower than 50 if they feel uncomfortable pedaling faster. The key to improving your exercise health benefits is to ride regularly so that you can improve your fitness level and leg strength. Gradually work up to a cadence of 70 or more.
The best way to learn how to ride a bike efficiently is to try to keep your cadence between 80 and 90 pedal strokes per minute. However, you may not be able to do this yet. Most experienced bicycle riders do best when they chose gears low enough to allow them to pedal at this cadence. You will learn to anticipate increased resistance on your pedals. You do not wait for your cadence to speed up or slow down. Eventually when you feel that the pressure on your pedals is going to slow you down to a cadence below 80, you will lower your gears. When you feel that your cadence is going to go faster than 90, you will raise your gear ratio.
As you improve, try to keep your cadence between 80 and 90 for at least some of your ride. If you want to go faster, you may have to lower your gears so that you temporarily increase your cadence above 90, then go to a higher gear and put more pressure on the pedals to keep your cadence above 80. You can use this technique to pick up the pace when you want to catch up with a rider ahead of you.
My Recommendations for Serious Riders and Racers
Serious riders should be able to hold a cadence between 80 and 90 for most of their rides. Since aging reduces power and strength, older bicycle racers are weaker and will use a lower cadence during races than younger riders (Med Sci Sports Exerc, 2010;42(11):p2128-p2133).
If you want to be able to pedal faster and ride faster, you need to strengthen your legs. The fastest bicycle racers exert the greatest downstroke power on their pedals. However, most bicycle racers do not lift weights with their legs because it causes their muscles to feel sore and limits the amount of hard riding that they can do. Instead, you can practice climbing hills as fast as you can. To strengthen muscles, you have to damage them, which you can do by putting enough pressure on the pedals to make your muscles feel a burning sensation while you ride and muscle soreness on the next day. You can do this very effectively by standing up and climbing hills at a fast cadence. Also once or twice a week, ride shorter distances very fast and hard, spinning your pedals more than 90 times a minute.
Gabe Mirkin, M.D., is a sports medicine doctor and fitness guru. A practicing physician for more than 50 years and a radio talk show host for 25 years, Dr. Mirkin has run more than 40 marathons and is now a serious tandem bike rider with his wife, Diana. His website is http://drmirkin.com/. Click to read Gabe's full bio.