How many watts of a disadvantage?

Assume two riders of equal stature are riding at 25 mph in identical clothing and gear.

Theoretically speaking (since watt gains don’t stack perfectly), how much faster (in watts) would someone on a top of the line aero bike with deep aero rims and high-end tubeless tires be versus a cheap alloy bike with cheap box rims and cheap training tires with butyl tubes?

Assume the positions are similar.

On another note, what is the biggest power or equipment disparity you can overcome by riding in someone’s draft?

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I don’t know the answer to your question, but thought you might find the following Youtube videos interesting as they are related to part of your question at least; aero vs standard. Obviously this isn’t a scientific test, however I think it’s been shown elsewhere that the biggest and cheapest gains you can make are to your position, i,e getting aero, on the bike and tight fitting clothing.


A range of info to compile:


I’m going to say 50-60 watts - more at a higher speed. The tires alone can be 20-30 watts depending on what truck tires you run on the cheap bike.

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I figured it might be something like this… that’s like a zone and a half…



I thought the whole ‘straight arms’ thing had been shown to be incorrect a few years ago? Can’t find my reference point(s) but, I was sure that a parallel lower arm was proven to be more efficient.

You mean forearms parallel to the ground with bent elbows?

Yes, that’s more efficient.

I think the gains are even higher that way.

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Aside from body position, it seems from this that the best return for investment is a skin suit? That’s a real game changer for not a huge amount of ££ (or $$)

Good info :+1:

I think tires are one of the cheapest upgrades you can make - they are a consumable, so when they wear out, replace them with something better. That way you aren’t having to throw out a perfectly serviceable (if un-aero) piece of kit. I replaced the cheap stock tires on my bike with Conti GP 4000s, and got about 2.5 times the lifespan of the cheap tires, so price per mile is a lot closer than you think.

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The estimate of 50-60W given above seems reasonable, and in line with the Free Speed data if you strip out the body position but add in the rolling resistance from cheap tires.

As to your second question, I’ve seen estimates of up to about 40% reduction in watts for drafting. So assuming the rider at the front is pushing 300W for that 25mph, somebody on the same equipment in the middle of the pack would only need to be pushing 180W. That’s full on peleton though, sitting behind one other rider is a lot less than that, I’d guesstimate maybe a 50W saving at 25mph (hugely variable depending on wind, tarmac, respective body sizes, etc). So similar to the equipment disadvantage. So in theory that equipment disparity could be overcome by sitting in the draft. But highly unlikely you get to sit in a nice steady draft the whole race, or if you do that you’re the only one getting that benefit. Maybe more relevant if you’re got 2 riders training together with a ~50W disparity caused by respective FTP and equipment. In that scenario they could actually ride together and both get a decent workout provided the stronger/better equipped rider was happy sitting on the front the whole time. At least until they hit any hills…

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Here is another good one I forgot to share above.

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You are 100% correct! During the presentation of these two slide the point was made that a more aero body position could be chosen…but the point of the study was to measure and identify savings due to equipment. Assuming a more aero body position would swamp all the other individual equipment changes. It’s good for 25W to 30W (red number Watts;-)

I was looking at the power data of people I was riding with (on NOICE bikes) and the numbers were high but not insurmountable. However, I blew up in just a few minutes of surges to 26-28 mph (staying in the draft), which had me wondering if equipment wasn’t playing a big part.

Of course, I hadn’t trained in over a week, so there’s that…

I had 4000s for a while, but they kept getting sidewall cuts long before the rubber wore out, so I became wary of buying $$$ race tires. Now that I actually race I think I need to get better rubber.

Yes, because the in spite of the significant gains from an fully optimized aero bike, the rider still accounts for about 2/3 of the total drag.

So every little bit of drag on the body is essentially amplified when compared to the rest.

I always race on good tires, but if I’m training on bad roads I either swap out the tires or ride a different bike/wheelset in training. If you’re doing high mileage outdoors the cost of using something like 4000s the whole time can add up quite a bit! Latex tubes are also worth the cost and hassle for racing, but not so much for everyday training.