Why I’m a Weight Weenie

Okay, I’ll admit it… I’m a weight weenie, and I’m proud of it. The reason is really pretty simple: I race mountain bikes and I like to win. I don’t like losing. And winning a bicycle race depends on having the best combination of technical skills, effective power, and luck on any given day.

Here is the problem. Luck is largely uncontrollable, although it is amazing how much luckier those who are best prepared tend to be. Technical skills are acquired very slowly and over years of riding and consistent practice.

That leaves only one element that can be readily manipulated: effective power. All power is not equal. Think about it. A semi truck engine might produce 700 horsepower and a new sports car might produce 350 horsepower. Which one is faster? The sports car, in virtually every category, from acceleration to climbing to top speed. Why?

The sports car has a much higher “effective power”. Effective power can be measured in terms of power-to-weight. Let me explain what I mean. That semi truck and trailer might weigh as much as 95,000 pounds, while the sports car will likely tip the scales at under 4,000 pounds, and that’s why the sports car is faster.

Power-to-Weight Ratio. The best way to describe effective power is in terms of a ratio of power-to-weight (“PW”). Let’s take the illustration above and put it in cycling terms. First, one horsepower is equal to 745.7 watts. One pound is equal to .45 kilograms. Let’s convert:

Semi Truck and Trailer

Power (watts)

700 x 745.7 = 521,990

Weight (kg)

95,000 x .45 = 42,750

Power-to-Weight

12.21


Sports Car

Power (watts)

350 x 745.7 = 260,995

Weight (kg)

4,000 x .45 = 1,800

Power-to-Weight

145.00

As you can see, the sports car has nearly 12 times the power-to-weight ratio of the semi and that explains why it beats the truck so handily. Even though the truck produces twice the power as the sports car, the effective power of the sports car is twelve times as great. And in racing, what really matters is your effective power.

Now let’s take that a step further and apply it to bicycle racing. On any given day, any rider will have a specific amount of power. Sure, over time that can be increased by consistent training, but on race day, it is what it is. That means that after committing to an ongoing program of both strength and skill training, there remains only one variable which can be manipulated so as to gain an advantage in racing, and that variable is weight.

Rider Weight. When discussing the topic of weight, the first and most important thing to consider is the weight of the rider. It never ceases to amaze me how someone will spend a thousand dollars to save a pound of weight and yet he is carrying an extra 10-20 pounds around his waist. Body weight is the easiest and least expensive weight lose. Think of it as free speed.

But how much weight should you lose? I’ve seen many height to weight formulas over the years but the best formula I’ve seen was derived from a sample of professional cyclists. Start with a base of 100 pounds and then add 6 pounds for every inch over five foot (or 60 inches) you are. In other words, a rider who is 5’2” should weigh 112 pounds (62 – 60 = 2; 2 x 6 = 12; 100 + 12 = 112).

I am 5’7” tall so my ideal weight is 142. My weight varies from day to day, but I keep it between 140 and 145 at all times. If you are 6’ tall, your ideal race weight would be 172 pounds. For females a good rule of thumb is to calculate the men’s number and then multiply it by 90%.

Height (inches)

Men’s Ideal Weight (lbs)

Women’s Ideal Weight (lbs)

60

100

90

61

106

95

62

112

101

63

118

106

64

124

112

65

130

117

66

136

122

67

142

128

68

148

133

69

154

139

70

160

144

71

166

149

72

172

155

73

178

160

74

184

166

If you are not at your ideal race weight, the first place to start changing your power-to-weight ratio is by dropping body weight. Not only is it free, but it will make you feel better. Here is a little known secret: If you were once significantly overweight, and you drop down to your ideal weight, the physical advantage is huge. Your musculature and joints are accustomed to carrying all that extra weight and so they are stronger than someone who has never been heavy.

A friend and professional mountain bike racer, Robert Marion, played offensive tackle at a collegiate level and weighed 265 pounds and yet was only 5’9” tall. After losing weight down to 146 pounds, he has significantly more power than riders who had never been heavy. Of course he also trains hard every day.

But Robert was winning races almost from the beginning because his body had been accustomed to creating lots of power, based on his then much bigger physique. Today he has a maximum 20-minute average power of 387 watts, and an impressive power-to-weight ratio of 5.9 putting him among the top riders in the world. Last week he told me that he wants to drop another five pounds. Why? Free speed.

My own personal maximum 20-minute power is 254 watts and at my weight of 64.4 kilograms, my power-to-weight ratio is 3.9. If I dropped 5 pounds without losing strength, my PW would be 4.1 or in other words, a 5% increase in my power-to-weight ratio. Free speed.

Bike Weight. Let’s assume you have lost all the body weight necessary to get you to your ideal race weight. If you continue to lose weight, you will likely be losing muscle mass and not body fat, resulting in a decrease in total wattage output. At that point, the remaining weight advantage must come from your bike and equipment or you will be going backwards.

weight weenie

When it comes to losing bike weight, it has been said, “Light, strong, cheap. Choose two.” As a rule of thumb, from a mid-level bike it costs a lot of money to start making it lighter, and it gets more expensive with every pound you lose. That’s why a top-level bike might cost $10,000 as opposed to $3,000 for it’s mid-level counterpart, and yet the weight difference might only be 2-3 pounds. A good rule of thumb is the first pound costs $1,000, the second $2,000 and the third pound costs $3,000.

To make things even more confusing, all weight is not equal. There are basically two types of weight: static weight and rotating weight. Static weight is dead weight and it is what it is. Examples of static weight are handlebars, stem, seatpost, frame, and fork. Take a pound of weight off the static weight and it is a pound.

Rotating weight is quite different. A pound of rotating weight is effectively much greater, depending on where that weight is located. The further out in the radius from the rotating center, the greater the multiplier effect. At the hub, the multiple may be only 2:1 while at the tire, the multiplier could be as much as 5:1.

Another way of saying it is that losing one pound of tire weight is equivalent to losing five pounds of static weight. Spoke weight might be only three times as much as static weight. Pedals being light are more important than hubs, and so on, all because of that multiplier effect.

It would follow, then, that the more weight you can lose, and the further from the rotating center you can lose it, the more desirable in terms of power-to-weight ratio. Picture a 29er mountain bike wheel. The outside diameter, depending on the tire you choose is nearly 30” or the radius is 15” from center to outside edge.

If the rotating center is a factor of 2 and the outside edge is 5, you can estimate roughly what the multiplier effect would be by how far out it is. Start with a factor of 2 and for every inch from the center, add .33. So a pedal that is 7 inches from the center of the crank, has a multiplier effect of roughly 4.3:1 or in other words, saving only half a pound in pedal weight is equivalent to saving 2 pounds 2 ounces on the frame and fork.

Effective Power-to Weight. Now let’s put it all together, and you’ll understand why I am a weight weenie. By effective power-to-weight (“EPW”) I am referring to my maximum 20-minute power divided by my total weight: rider, gear, and bike. This is entirely different from simple PW that measures only the rider, or motor, so to speak. EPW takes into account the entire package — you, your bike and your gear.

Years ago, I weighed in at a hefty 235 pounds, quite fat for my 5’7” height. Now, 93 pounds later, I am at my ideal race weight. If I lose weight from my body, I will likely lose muscle mass and decrease power output, so I must turn to my bike for weight savings. Now let’s look at the bike.

My first mountain bike, a Redline Monocog, weighed in at over 29 pounds, was made of steel, and with no suspension rode like a tank. Great bike, but not a great race bike. I’ll show you why. Add 29 pounds of bike, 5 pounds of clothing, helmet, shoes and gear, and you have 34. Add that to my body weight of 142 and you have 176 total weight.

But all that weight is not equal. So if you re-calculate it using the multiplier for rotating weight, the tires, wheels, pedals, cranks, and chain all effectively weigh much more. Using the multiplier, the bike effectively weighed 63 pounds. Add my body weight and 5 pounds of clothing, helmet, shoes and gear, and now you have 68 pounds or with me, 210 pounds or 95 kilograms.

My effective power-to-weight ratio was 2.67 or 254 watts divided by 80 kilograms. Now let’s look at my current race bike, my Raleigh Talus Carbon Pro that weighs in at 20 pounds. But again, because of the multiplier effect, the bike effectively weighs 36 pounds. Now, with the extra 5 pounds of gear and my body weight, the combined effective total weight is 178 pounds.

Without losing a pound of body weight, but by losing weight on my race bike down to 20 pounds, my effective power-to-weight ratio has increased to 3.14 for an 18% increase in effective power, while adding suspension and handling to my bike. That’s why I’m a weight weenie. Yes, I train hard. And I work on my skills. But I also count my grams — how many and where they are located.

The bottom line is that losing weight is all about gaining speed. Sure, some weight saving produces more speed than others. Sure, the first place you should start is your own body. But when you’ve lost all the bodyweight you can afford to lose, and you are training as hard as you have time to train, you might want to consider becoming a weight weenie like me. Less weight equals more speed and when you want to win races, more speed is good.