This is just an observation. I entered a KISS race yesterday in the D category (under 2.5w/kg). I went all out and finished with an average of 2.45w/kg, so I assumed I’d be pretty close to the leaders. I averaged 188w with a weight of 73kg. When I reviewed the results, I came 11th. The winner of the race finished just over 2mins ahead of me with an average of 2.48w/kg (over 11 miles). I was surprised that such a small average difference would have yielded such a time gap. When I looked at the leaders weight (100kg), I noticed that he was putting our 266w average over the 11 miles.
Therefore, I can only conclude that being a heavier rider allows a much greater wattage, this in turn allows a faster speed to be achieved. Thus, being heavier (assuming you can put the power out), puts you at a greater advantage in category based racing.
I’d be interested in others views on this.
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Peter, perhaps I misunderstand you here, but couldn’t one just as well conclude that races favor power output as opposed to mass? And, if so, might that not be expected, particularly if the course was at least relatively flat and therefore relatively indifferent to mass? I suppose relatively flat races might indirectly favor the heavy if they are heavy due to muscle mass that gives them power. Let me know if I misunderstand you, however.
Peter, I am not sure this is any different than real life. More watts on the flats makes you faster. Weight doesn’t matter as much on the flats, although larger riders might have higher wind resistance
That London route is pretty much flat except for the one hill, w/kg is only applicable when going up or down. In real life heavier guys does pretty well on the flatter routes that is where we can keep up with the Race snakes and when there is a head wind (hint hint ZWIFT).
The interesting thing I noticed is the Mr. Square Wheels (the winner) took almost a minute out of your time on the hill.
Thanks for you input guys. To be honest it doesn’t bother me, it was more an observation. I guess my point is that I would expect that the speed generated at 2.5w/kg for a 73kg rider should be the same as a 100kg tiger at the same 2.5w/kg. It would appear thats not the case. Though I hadn’t noticed that Gerrie. I was putting out way above the 2.5w/kg up hill, so he must have been really putting in some power.
The relevance of weight (and therefore the relevance of watts/kg) increases with deviation from flat. The flatter the course, the less relevant watts/kg and the more relevant just watts is.
Hi Travis, this is my point. It therefore favours the heavy 
Peter, in favors people that put out more watts. If bigger people put out more watts then that’s because life is unfair
Hi David, if its a game of more watts then the categorisation based on w/kg doesn’t work. I understand what you are saying, but this only makes sense for the A category.
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It depends on the race. If its essentially a flat course then the rider with the higher power output is favored. If its a climb-heavy course, then the rider with similar watts/kg but less mass will be favored, at least in real life. I don’t have the reference off the top of my head, but if you google it, I’m sure you’ll find it. I don’t have enough experience with Zwift to know if there are any nuances with a tight course vs an open course, in real life the braking that occurs going into the corner and the accelerations out of the corner also favor those with more power and bigger anaerobic engines. Use Zwift as a tool, have fun. There are lots of ways to tweak it in your favor and if that doesn’t bother you, then I for one could care less. Just know that it won’t translate on to the road.
P.S. the difference has to do with the overcoming gravity–to ascend you’re fighting the constant acceleration of gravity which is greater the more mass you have. On the flats, what you’re fighting against the most is wind resistance–frontal area.
I think as far as straight wattage , it is much easier for heavy people. I can stand up and use my weight to get high wattage on hills. I weigh in around 105 kg. However, it takes more watts to move up the hill.
The race categories for flat courses do favor the heavier rider as far as stratifying the competition.