Deej345 wrote:
Returning back from injury and building up my strength on the bike hoping to race next season. I am 170 lbs with a 254 FTP. My question is around watt/kg I am 170lbs 77 kg (3.2watt/kg) BUT weighing with my bike loaded with race bottles full, changes this number to 200 lbs (yes I have a weighty rig but it rides straight in any winds! and my Island is flat). How do I compensate for the added weight on the open road? or should I do my next FTP test with the bikes weight added to my weight to get a true picture of what race day WATTS should be?
Thanks in advance,
DJ
W/kg is used as a rule of thumb to predict performance because it's very important on hills, has an effect on rolling resistance and also gives some indication of potential air resistance losses. It is not useful as a training target. Where elevation changes or rolling resistance are concerned, it's your total weight that matters. The rider+bike+clothing+water+food+repair kit are all resting on the tyres and must all be lifted up the hill. However mass does not effect air resistance directly. A heavier bike does not create more drag than a lighter one and a full water bottle is not less aerodynamically optimised than an empty one. W/kg is only useful for aerodynamic purposes in so far as it can be used as a very approximate rule of thumb. It ignores position, equipment/clothing choice.... all of the specifics of any given rider.
Train on watts. Your performance will take care of itself and musing over W/kg values will not gain you anything unless you have a specific reason for wanting to optimise it (perhaps competing in hill climb events). This is especially true if you don't really understand exactly what the figure relates to and is useful for.
To answer your original question: when W/kg is discussed it almost always refers to rider weight and should be clear from the context and discussion if this is not the case. This value tells you about the rider's ability to produce power relative to their mass. it tells you nothing about their bike, or position, and cannot accurately predict a race performance without additional data.