I think by "significant weigh disadvantage" springs was talking about the Flo90/Disc. 2259-1100=1159 gram difference. But even then, using your numbers at bikecalculator.com it is about an added 2 watts to get the 55 second disadvantage down to the 23 seconds they show.

A very basic crit will mean 200+ of these short bursts in just over an hour. That's a few kj of work, non?

Weight matters.

If you get some good wheels like a 404 Firecrest you get the aero and quite light as well so the weight vs aero argument becomes a bit pointless.

You have the added benefit of a lighter wallet too. They appear to be directly focused on triathlons run on relatively flat courses, so obviously the weight is less of an issue. Faired wheels, what an advancement!

They did run with the 90/disc so I'm assuming they are choosing combinations that somebody in the real world might actually use. And it wasn't really a test, it was just a math exercise.

404s aren't light compared to some nonaero or less aero wheels. 202 tubulars are light. 404 firecrest clinchers? Boat anchors in comparison. Of course, you'll be even lighter by about 400g with either after you sell your kidney on the black market to buy them. It is the endless debate that goes on despite the fact that there is data, kind of like the carbon frame vs. X frame debate that rages on forever, usually by old guys set in their ways.

i don't know about a few kJ, but it's probably about 2ish total.

Of course weight matters. That's not the issue. The question is about what is the optimal combo of weight vs aero. IE, what's the tipping point. Here in the states, in a P/1/2 crit, you're definitely going to see more of the better riders on pretty deepish aero tubulars than on box rims. But aero's clearly not the whole story, because you're also not going to see anyone on a disc rear either..

Actually, 9 kJ to be exact. At least per https://www.cyclingpowerlab.com/accel...ndinertia.aspx.

I used a base of an 75kg rider, 7kg bike, 500g front and 700g rear. Then added .5kg to the bike (250g to each wheel). Acceleration was 40-55kph in 5 seconds. Cost difference was 45 Joules per acceleration. 45 x 200 = 9,000 or 9 kJ.

Also equals an additional 8.9 watts during each of those 5 second accelerations (from 909.7 to 918.6) which over the course of a crit would add up to putting out 900+ watts for 16:40 of a 60 minute race. Even if you coasted the rest it would still be over 250 watts average. But this obviously a model, so plug your own numbers in.

I'd like to see your power file showing 9 kJ of work done in a one hour crit, let alone 9 kJ *difference* in work done at the end on a one hour crit after changing to heavier wheels. You realize that 9 kJ of work in 1 hour is almost equal to saying you burned 9000 calories in an hour.

and when I said 2ish total, I meant for the whole race, not the difference between the two wheelsets!

9 kJ is the total difference for the whole race.

And you wanted to see something like this?

Distance: 20.02 mi
Time: 46:56
Avg Speed: 25.6 mph
Elevation Gain: 758 ft
Calories: 680 C
Avg Temperature: 71.2 °F
Details
Timing
Time: 46:56
Moving Time: 46:54
Elapsed Time: 46:56
Avg Speed: 25.6 mph
Avg Moving Speed: 25.6 mph
Max Speed: 34.1 mph
SpeedPace
Elevation
Elevation Gain: 758 ft
Elevation Loss: 712 ft
Min Elevation: 751 ft
Max Elevation: 827 ft
Heart Rate
Avg HR: 176 bpm
Max HR: 182 bpm
Zones% of Maxbpm
Power
Avg Power: 304 W
Max Power: 1,156 W
Max Avg Power (20 min): 322 W
Normalized Power (NP): 329 W
Intensity Factor (IF): 1.053
Training Stress Score (TSS): 85.8
FTP Setting: 312 W
Work: 856 kJ

You do realize a "food calorie" is actually a kcal, right? That is why you can't lose (significant) weight by drinking ice water.

Do realize this is aimed at triathletes, not road racers.

Yeah, I guess I'm the idiot here. I was meaning 9,000 kJ and 2,000 kJ. Insert foot in mouth here. And by that I meant 1 kJ approx equal to 1 kcal burned (or one food calorie). I'm going to just stop posting now.

Ok, one last thing. . . That's a very impressive race, and you need to bump up your FTP

The weight argument is mostly pointless for any UCI race. If you're serious, you can get a bike with virtually any non-disc rim under the weight limit. So the weight penalty is zero.

Rotating mass still matters, but it really depends on the acceleration/deceleration profile of the race. If you're braking into every corner and accelerating out, it'll matter a lot more than a sustained climb.

Thanks, although files can be deceiving.

For the first time ever in a race I missed my clip in at the start. Badly. I panicked and it took several clumsy tries to get in. By the time I got rolling I was off the back in very technical crit with a larger field (100ish). I spent the whole race trying swim up a waterfall, catching the back of the pack only to have a few riders ahead loose touch and having to work to catch on again. I did finish in the pack but near what was now the back, maybe 40th. Nowhere near to being in position to contest the sprint.

But yes, it did make me realize my ftp was set low.

that's nuts for evening mentioning those wheels, heck you could buy easily buy 4 sets of the Flo's for the cost of one of those sets, I don't think the poster would be interested in spending that kind of money. So while the weight vs aero may be a bit pointless with your suggestion it is a bit priceless.

If aero trumps weight to the extent that FLO claims, why don't the pros ride disks and 90mm rims in mountain stages? It's not always windy.

Speculation here, but a couple of things pop into my head.

First, rear wheels do not contribute nearly as much to the aero package as the front. So discs or 90mm are used when the weight won't be noticed at all and there are no other drawbacks and maximum benefit can be gained: flattish time trials. Otherwise their effect is minimal so a lighter, easier handling wheel makes more sense.

For the front, looking at the chart here: https://www.rouesartisanales.com/article-15087917.html, you will see the range of watts absorbed is 17-35. The best tested was the 808, but the 404 is only a couple watts higher. I'm guessing it represents a sweet spot in depth without incurring a weight penalty or significant wind control issues. Even though it isn't always windy, a lot of those guys are really light. And yes, I know that is a test of older wheels, but it shows a nice spread of rim depths and weights.

Interesting question.

In my (non-scientific) opinion, the reason is that they spend 9x.x% of the time riding well below FTP in the peloton. It does not matter if you have disks or box rims if you're going to stay in the same spot most of the time anyway.

The only situations where they get close to their physical limits and where their individual bike characteristics become important are sprints and hill climbs (the peloton often gets spread out on steep grades). In either situation, you need light wheels as much as aerodynamics.

If you look at what they actually ride in mountain stages (e.g. on youtube), you'll see that lots of pros have medium depth, 50-60 mm rims. That's a good balance between weight and aerodynamics: 50 mm rims give you almost as much aero advantage as deep rims (especially below 10 deg. of yaw), and they are light enough that pretty much any wheel with aero spokes and a medium carbon rim is going to be lighter than most alloy wheels. Going from alloy to 50/50 carbon is practically a no-brainer if you can afford it: your wheels get more aero _and_ lighter. Going from 50/50 to 90/90 or 90/disk, you gain a little more aerodynamics and a lot more weight. Very roughly speaking, just going from 50/50 to 90/90 adds 300-400 g, which may be hard to shave off the bike elsewhere.

In time trial stages, even in fairly hilly ones, you're still going to see lots of deep rims and disks.

OK, and, also, disk wheels (and, more generally, all wheels with fewer than 12 spokes, and all kinds of aerodynamic gizmos including fairings and spoke covers) are illegal in mass-start races under UCI rules. (I don't know the history behind this, but, by context of the rule, it sounds as if the regulators are concerned about disks shattering in crashes and creating mess for other riders.)