I was having a debate with one of my riding buddies the other day and I thought it would be an interesting topic for this forum.
I’ve been doing TR for almost a year, and my FTP is right around 300 watts at ~83kg (185lb). Much of my training focus has been on building raw power, while mostly disregarding body weight. On the flip-side, my friend is focused on improving watts/kg, primarily in the form of body composition and weight loss. He is around 72kg with an FTP or 270.
We live in the midwest, with very few sustained climbs. An analysis of my rides from the last year show that my biggest “climb” was around 2 miles with an average gradient of 3.2. Most rides have a total elevation of 1500 (300m) feet or less.
Given this information, my argument is that in almost all cases, a higher FTP with higher corresponding body weight (within reason) is going to beat a superior watt/kg with lower overall FTP.
At least, it makes sense in my mind. Especially when we’re talking about a ~10% difference. No doubt there are differences in frontal area, flexibility, and rolling resistance that a slightly larger rider will be impacted by.
I’m interested in what people think of this topic. At what point is the crossover of raw wattage to watt/kg benefits?
My view generally lines up with yours. However smaller riders tend to have a better CdA. So in the mountains W/kg is pretty important, on the flats its more driven by W/CdA, flat gravel tends to lean towards pure watts since the speeds are lower (depending on the gravel) and rolling resistance is a bigger factor.
As a smaller rider who was racing cat 1 for a few years in a rolling terrain area, I can tell you w/kg still matters a lot. If the w/kg are close between riders, then the guy with the big watts will likely be favored - assuming the delta is significant enough.
One thing I got very good at being smaller was being in the draft. The big watt boys would really need to drill it and have cross winds to put me trouble. Once the hills came, then the tables turned.
Here’s another one that most people don’t think of. Compare two guys each with 4w/Kg. One at 135#, one at 185#.
When you add in the bike, the kit, the shoes, the water, fuel, spares and re-do the math, the heavier guy will have the higher w/Kg. If you’re dealing with altitude and have to reduce your FTP, it happens again - the heavier guy loses less.
W/kg can be misleading that way in that nobody is comparing your total system weight, which is what really matters.
But there are times where I think the little guy has an advantage. Really steep climbs, and when it’s really hot. Little guys can deal with heat better because of a better surface area to mass ratio. (Look up Bergmann’s rule for this in play in the animal kingdom…) Add to that the increased KJ and fueling requirements of the bigger guy.
Yeah, it’s mostly about watts vs. Cda on the flats, but it depends on the type of racing/riding. If you can’t drop a smaller rider on the flats, he’s resting in your draft. When you get to the climbs, there is nowhere for the bigger rider to hide.
I’m not huge guy, but around 77Kg right now and I struggle when the road goes up. And I don’t have a lot of punch to get up the steep/short stuff. I did a long gravel race last weekend that basically turned into a solo TT and the only place I was losing positions were the segments with steep climbing. The rest of it I was motoring solo and blowing through the same groups that were passing me on the climbs. Whenever I came up on these groups on the flats, I just made it a point to lift the pace enough to discourage them from jumping on. It’s all watts/CdA until the road points up.
Don’t even need a climb - I’ve successfully demonstrated that my ability to tuck in behind a bigger guy’s draft combined with getting extra-aero and producing a much smaller draft, resulted in the bigger ride unable to get a sufficient rest in my draft, and implode sooner.
On the other hand, as a smaller rider with a lower FTP, I suffer significantly more on gravel or other rougher terrain. There’s a static rolling resistance cost, significantly high on rougher terrain, which is much easier to overcome by someone with a 350W FTP vs. someone with 280W FTP.