Cycling performance is ultimately about going faster on the bike. Sheer power - the ability to apply force to the pedals - is certainly important, but so too is body weight. In fact, when experienced cyclists compare themselves to one another, they often refer to the power-to-weight ratio.
The power-to-weight ratio is most commonly expressed as sustainable average power measured in watts over a particular duration divided by the body weight of the cyclist expressed in kilograms.
Power to weight = average watts over time (duration) / kilogram in body weight.
For an aspiring masters cyclist who wishes to be competitive in masters-level road races, a sustainable power-to-weight ratio above 5.0 watts per kilogram for 5-6 minute VO2 max efforts is desirable. For a time trialist competing in 30-60 minute time trials, a power to weight ratio above 4.5 watts per kilogram is necessary to be competitive.
So, let's take the example of a cyclist who weighs in at 154lbs or 70 kilograms. If that cyclist wants to be competitive in a masters level road race or time trial, then he will need to be able to sustain 350 watts for 5-6 minutes (5.0 watts per kilogram) and/or push 315 watts for 30-60 minutes (4.5 watts per kilogram) during a time trial competition. The effect of the power-to-weight ratio is demonstrably true on uphill courses as well as on even modestly rolling courses. The rider with the best power-to-weight ratio and who practices the principles of cycling economy is often on the podium when the race is over.
Our aspiring cyclist can and should work on both sides of the equation - improving aerobic capacity and lowering body weight. But while aerobic capacity (5-6 minute maximal efforts) and its close cousin, lactate threshold, are limited by genetic parameters, body weight can be managed, controlled and reduced.
What if our cyclist committed to losing 5kg of body weight by the start of the race season? At 65kgs lean, he would only have to push 325 watts for 5-6 minutes or drive 292 watts for 30-60 minutes to be competitive in the same races. Stated another way, his power-to-weight ratio increases to 5.4 watts per kilogram at 350 watts or 4.84 watts per kilogram at 315 watts. Losing five kilograms of body weight results in a remarkable 7.7-8% increase in cycling performance. That means that each kilogram of body weight is worth 4.5-5 watts of power. That's huge, especially if you're a masters level cyclist and your best VO2 max days are behind you.
So, as you begin your training year, full of goals and aspiration, consider a lactate threshold test to measure your sustainable 30-60 minute power and focus on lowering your body weight by eating nutrient rich foods and restricting your calories by a mere 250 calories per day. Over 3-4 months, you will improve your cycling performance and go faster on the bike.