PeteHski

Aero gains (relative to the associated increase in wheel weight) start much lower than 20 mph. Probably more like half that speed, which is why aero wheels are still faster on even fairly significant climbs.

Jrasero

You are correct you can "start" to see aero benefits as low as 15mph but these differences get exaggerated at higher speeds. Take the example of a Soloist vs a S5:

the Soloist has about 190g more drag than the current S5, which is one of the most aerodynamically efficient designs currently. That 190g aero penalty at the 30mph (48km/h) Cervelo tested the Soloist at, translates to a difference of roughly 22 watts, pretty substantial. At the more realistic speed of low to mid 30km/h that most of us average, that gap would narrow to somewhere between 10 – 15w. Compared to the R5 though, the Soloist is another 126g of drag faster, or about 14 watts less at 48km/h.

At 19mph-20mph you start to see moderate aero benefits but it's really until you get to 29mph-30mph+ do you start to see max aero benefits. Most riders on here don't ride at 29mph+ let alone 19mph+ average speed, so yeah while these numbers and marketing are technically true they are really are reserved for people putting down serious power. That doesn't mean us non pros and enthusiasts can't benefit, but this massive "aero is everything" movement IMO is vastly overrated and that's why we are also seeing the move back to all around or light weight aero bikes

PeteHski

It’s not that aero is “everything”, it is simply that aero features (like deeper section wheels) almost always provide a net benefit when taking account of their small weight penalty - even at very low speed. It is parameters like weight and especially wheel rotational inertia that are often vastly over-rated.

Non-aero superlight bikes like the Aethos are a novelty exercise in exploring how light you can make a modern bike if you completely ignore the aero. They appeal to the most dedicated steep hill climbers (with no minimum weight regulation) and those who simply prefer a more traditional aesthetic. But they are objectively slower than their more aero-focused bikes in most real-world scenarios.

Also in terms of absolute time saved over a course, I believe it is actually lower power riders who save the most time. Simply because they are out on the course for significantly longer and the fact that speed increases are proportional to the cube of power. I think RChung has mentioned this before, but I could be mistaken. I know he measures this kind of effect.

Jrasero

Yeah not saying wheels aren't worth the upgrade just that this obsession with aero and watts saved is only optimally seen at higher speeds or in ideal conditions. There are countless comparisons with lightweight vs aero wheels and frankly the difference is minimal and to your point only get widened when you are out on the bike for a very long time but at that point is speed really the objective on a century?

As an Aethos owner yeah it never will be as aero as a Tarmac SL7 but I can tell you from experience putting on some aero bars and even some moderate 50mm depth aero wheels really transform that bike into to something that yeah still couldn't beat a Cervelo S5 but still is faster than a R5. In the end I am big proponent of "feel", just like how wider tires don't necessarily make you faster but rather that they absorb more of the road so you have more confidence to blow through whatever. Even if you have a 65mm deep wheel that technically is faster, if you are being blown around you never will feel as confident as if you were on a 35mm, that's why I know some riders who put out serious watts who still prefer 35mm-38mm wheels

PeteHski

I don’t actually disagree with any of the above. It’s just that in an earlier post you were implying that wheel weight and rotational inertia are somehow more important because of your relatively low power. The fact is that weight on that scale is even more marginal than the marginal aero gains, even at relatively low climbing speeds or hard accelerations. If there is any obsession on this forum it is about weight and rotational inertia.

Obviously there are legit reasons why 65+ mm aero wheels are not always the best choice, but weight is the least important factor.

My own bike is not exactly ultra-aero. It has relatively wide 35 mm deep aero wheels, semi-aero bars and only a token nod to aero frame. It’s also not ultra-light at around 7.7 kg. But it is very comfortable and reasonably fast on long, hard rides. If I wanted to go a bit faster I know that potential aero gains would make the biggest difference overall. But as you say It’s all marginal enough that I don’t really care.

Mtracer

This has probably already been mentioned, but deep section rims act a bit like airplane wings and have stall characteristics. So as air speeds and angle change the forces on the wheels can change very suddenly. And of course, plain old wind gusts. But as other have said, the shape of the rim plays a large role in how well the wheels handle this.

Also, if you're new to this, you will get better and more comfortable. But there are limits. A few months back I had a ~10 mile mountain descent on some 45 mm deep rims. If there had been no wind, I could have gone terminal velocity the whole way on the wide smooth turns. As it was there was quite a breeze and some gusts. While I don't think I was ever on the edge of losing it. I was certainly puckered up a bit until I reached the bottom. Used my brakes a bit here and there too.

Jrasero

Again I think there is what the data tells us in that weight or even rotational weight doesn't matter and then the less scientific reason of "feel". Deeper heavier wheels is fine on time trials or in a race where you are constantly pedaling but on an average ride especially going through town or a major city where there is a lot of stop and go and mounting and dismounting that pain of getting spun up with a heavier wheelset is kind of a drag, so again it really depends where and how you are cycling and this is again where I allude to ideal conditions. It's like the idea of a sports car being faster on an open track but severely limited if you were driving it in a downtown city with lights everywhere.

PeteHski

The only pain in spinning up a few hundred grams of extra wheel weight is in your mind. Once you realise how few extra Watts are required to accelerate slightly heavier wheels then you don't notice. Crosswind sensitivity is real enough though and that's really what limits how deep you might want to go.

Jrasero

The mind is a powerful tool. Maybe I am old school but even though I train with power meters I don't even have to look down on my computer to tell you how my ride went because of feel. I personally feel the difference between 200g+ maybe because I am a smaller rider and no 200g less will not make you faster, but there are very few race bikes where I feel like the bike is too heavy rather weight to me is like black vs white, in that black is only the absence of white. Also the lack of weight again has an underlying effect on the whole bike, since a lighter wheelset should be made of lighter but laterally stiffer carbon, thus I feel more of the road thus at times feel more connected while a heavier wheelset can simply feel muted and disconnected. Again another car reference, but Mazdas were never the fastest cars but they always had the best feel and connection to the road. There are plenty of drivers that would argue they take feel and engagement over a car that's faster in a straight line 0-60 and to me that's the difference at times between aero everything vs lightweight

Chandne

There is some truth to this for sure, especially on climbing or lots of rollers, and I mean a couple of miles of decent-size rollers. This is MTB but I used to lead a group ride every week- same guys. One week I popped in two tubes (I was on converted ghetto tubeless tires) into the Maxxis tires. The tires weighed around 800 grams or so. The tubes were around 200 each. After the first climb, I was noticing I needed more strength to lead the pace and my HR was higher the whole way. Eventually, I had to drop down to midpack. My legs were feeling it for sure. Same thing on the next group ride but I actually fell back near the end and it was more effort. So when my sealant came in, I took out the tubes and guess what- that normal feeling came back and I was back to leading the ride again, without struggling. So 200 grams of weight in each rim or wheel circumference can be felt if you are not easily producing 200-250 watts on average. I can't tell about aero-vs-weight as easily but weight can definitely be felt if it exceeds 100-150 grams if you are climbing. That's why climbing wheel are always quite light around here anyway.

PeteHski

If only we could calculate the effect of 100 g in time lost on a climb for a given power output.

Chandne

Well, in my case, it was more and I was certainly slower (and pissed). It would be interested to do this test with and without tubes again and watch the HR and power output on two separate well-rested days.

PeteHski

The effect of the weight increase is very easy to calculate very accurately. The effect those tubes had on your rolling resistance is more difficult to gauge, but if you really were significantly slower then rolling resistance is going to be the significant factor here.

Let's take your 400g increase and look at how that affects power on a 8% slope. It is literally 1W difference over 200W for an average sized rider. Or just under 2 seconds loss per km at 200W. Those are not the sort of differences you can notice.

Chandne

It's that weight calculation just bike weight, body weight, or has it been associated with sprung vs. unsprung weight. There is a big difference in what type of weight we are talking about. 400 grams of unsprung weight will have a far greater impact than 400 grams of sprung weight. So PSI- with tubeless at that time and 2.2 or 2.3 tires I was running around 28 PSI. When I put tubes in, I ran around 34 PSI. Would the resistance increase that much? It is possible, I suppose.

PeteHski

It doesn’t matter where the weight is when calculating steady climbing speed/power on a slope. There is no difference in this case. The power requirement is the same regardless of body weight or bike weight, rotating or not.

If you were significantly slower with the tubes, that’s down to a significant increase in rolling resistance plus the 1W calculated above for the extra 400g. There is no other explanation, unless you just had an off day by coincidence.

msu2001la

Escape Collective has an article on the absence of super deep wheels in the pro peloton that I found interesting and relevant to the discussion here:
https://escapecollective.com/where-h...p-wheels-gone/

They accurately note that most pro peloton riders are using 60mm as their max aero wheel now - even on flatter stages. Just a few years ago, 80mm was common for "sprint stages" but now wheels of that depth (or deeper) are rare and often only used for TT's.

The gist of the article is that most of these super deep wheels are designed around narrower 25mm tires and not 28mm. Manufacturers haven't really developed super deep 80-100mm wheels that are aero optimized around 28mm tires, and pro teams seem to prioritize that tire size over the added aero benefits of going from 60mm to 80mm. They also note that wider rims that are also super deep would be very heavy.

This bums me out because I think super deep wheels look awesome. I've never owned anything deeper than 45mm but have been tempted to buy something super deep just for the bling factor.

Broctoon

I don't ride with or even encounter--except very occasionally--anyone on wheels deeper than ~60mm. There's one exception. A lady in our weekly group rides is on an Orbea with Superteam rims, I'd guess 60-ish front and about 80 rear. She is compact and muscular, and on her little frame, about 50 cm size, she can get really low. She is fast. Not a crazy fast sprinter, but on the flats she can motor along at a speed that's, well, higher than I'm capable of. And she doesn't spin a high cadence. She's a masher. This to me says aero rules over weight (at least anecdotally). Those Superteams can't be light, and the rider isn't either, for her height. But the whole formula of weight, power, and drag coefficient is obviously working well here.