Stucky

Yes- but my point is that the performance difference would be minimal. While, in that scenario, the bikes would be responsible for any and all performance difference, what I was saying is that the fitness of the rider is more important than any tiny gains one might get from a high-tech aero bike. If you normally average 20MPH on rides- going to the extreme ends of quality and technology in the road bike spectrum might mean a 19.89MPH average at the low-end, and a 20.16 average at the high-end [I just pulled those numbers out of my ass, as an example of the miniscule differences we're talking about].

carpediemracing 

I respect the background and the numbers. I probably fall under the "overestimate the speed of wind".

I think earlier this year that I raced in 30 mph gusts, steady was much lower. Lost a tent that was poorly anchored, and a folding table blew over (as well as a bunch of other stuff). Rocked the 3000+ lbs (empty) trailer. The very beginning of this clip (my clip) shows, to me anyway, some hard wind, maybe a 30 mph gust? Same location, 5 years prior, similar kind of gust as the tent-losing gust. I'm curious what you would guess it to be (I can only guess).

Partially because I was sick, partially because of the forecast 50 mph gusts, I skipped a race over Easter weekend this year. I wasn't there so I can't vouch for the actual wind strength but a porta potty got blown over, which has never happened at a race of mine. Lots of wind-related crashes.

asgelle

Instead of pulling numbers out your ass, why not read the literature? As I said before, after training for a few years, there's more to be gained by improving equipment than by training. Of course, those numbers are grounded in testing not pulled out of the air.

Then, I don't buy your characterization of a 0.27 mph difference in speed as minuscule. That might be your perspective, but for others it might be huge. Also, the difference in speed around 20 mph from bad to good equipment is more like 0.75 mph (by test). Based on analyticcycling and using the defaults that means an increase in power from 131W to 140W. You might ask someone who's trained with power what's involved in increasing power by 10W from a well trained state.

therhodeo

It does get that windy here and in KS where I'm from. Its either stupidly hot, stupidly cold, or normally on nice days stupidly windy. I've ridden plenty on days with wind warnings. No aero wheel on front, stay in the drops, stay alert.

wphamilton

I think that your'e probably right about that, although my BSO would be considerably faster since I've made the entire bike aerodynamic with a cowling. So my two cents.

The real problem with hard side-winds is with steering inputs on the front wheel. I think that everyone has been pretty accurate about that. And physical movement of the wheel, if it is lightly loaded.

The other issue is that for the aero shapes on bicycles at a certain yaw angle they're no longer "aero", but instead just a larger area in the wind. So that does limit the utility with respect to conditions. That critical angle varies with the shape and depth of the wheel, and the frame independently, and the tube junctions on the frame.

The analogies with carrying a plywood sheet are off-base in my opinion. True to the extent that force due to the transverse wind is proportional to the area, but just about everything else does not really apply. That effect of the larger surface area, other than the steering on the front wheel, is easily compensated for, for any reasonable design of an aero frame, and to a lesser extent the more aero rear wheel.

Hypno Toad

I feel your pain! Earlier this month I got caught with those wind speed (30 to 50 MPH gusts), I was enjoy a tailwind and not really thinking ahead about my route. Then I took a right turn and that wind turned into a cross wind... and to add to the situation, the wind is coming off a big lake (Lake Minnetonka). I ended up re-routing because it was too hard to keep the bike between the traffic and the lake.

During that ride, my mind was rattling around the options in wheels, aero versus box. I was happy to be on low profile wheels. I've wanted to go aero for the looks, but that ride drove it home, not a great option for riding in all conditions.

Stucky

Tell you what: You read the research and let me know how much my random numbers are off. I'll bet if anything, i was being very optimistic. Do any stufies even exist in which they've compared various bikes of differing quality or aero vs. non-aero in real-world conditions?

Stucky

Exactly. That's always been my contention too. You get a slight gain maybe riding into a head wind; but you lose any benefit from that gain in a cross wind; just as you can climb a little faster on a lighter bike...but you'll also descend slower. I think this is why we virtually never see tests done under real-world conditions- 'cause the slight advantages they laud from wind tunnels and such, would be negated by real world varying conditions. They only amount to a benefit under very specific conditions.

therhodeo

Ridiculous comparison given the amount of time spent climbing a certain distance compared to the time descending the same.

Stucky

Well, if you climb at 5 MPH and descend at 35MPH....sure you're going to spend more time climbing.....

therhodeo

If you climb at 15 and descend at 25 then its still true. Using exaggerated numbers doesn't make the point invalid. Do you know anyone who climbs as fast as they descend?

Stucky

In my case, that is a real-world example- there are plenty of hills around here which I climb at 5MPH and descend at 35MPH- but the speed or the time isn't even relevant; the thing is: Any gains made by a light bike in climbing, would be negated by a slower descent. It doesn't matter if it's 5 vs. 35MPH or 15 vs. 25MPH- what remains the same, is if you have a bike that gives you a 2% advantage over another bike in climbing, you also lose 2% on the descent. That you spend more time climbing is irrelevant; you spend moire time because you are going much slower.....

Jiggle

I can't make a good estimate based on that vid, sorry. Exciting race, though.

carpediemracing 

Thanks for responding and thanks on the comment.

therhodeo

Damning commentary on the state of education in America.

asgelle

I think I just did.
No you underestimated the effect by more than 200%
Many.

asgelle

Again, just not true. TOUR QTR 4-2011

wphamilton

The article shows some net gain by Bernoulli effect for a limited range of yaw angles, for some of the aero wheels.

The reason it's noteworthy is that one or two spoked wheels demonstrated this phenomenon, up to around 22 degrees. Most of the aero wheels are effective for lower angles.

The wind tunnel data seems credible to me. The assertion that professional time trialists never see a yaw angle greater than 15° ("don't matter" as they put it) does not seem that reasonable to me. The related assertion that slow riders (up to 19mph) mainly see wind angles of only up to 17.5 degrees (so anything else is not important) is also not very reasonable. 10 MPH side wind riding at 20 mph is what, 26°? That seldom or never happens with slow riders?

Also, just to note here, he was talking about the aero frames as well as wheels. I believe that frames have a more limited range of yaw angles where they are effective in reducing drag.

justinzane

If you can dig up links to any of those tests, by independent reviewers, teams or OEMs, I'd love to see them. My math and physics skills have faded since college -- and I never took any fluid dynamics in the first place -- so I'm working by trying to apply common sense to a complex physical problem, a sure recipe for failure. Seeing some test data, even if overly optimistic, would help clarify.

justinzane

One thing to add to that is the leverage of the rider's arms. When I'm in the drops, the forward vector component of my arms supporting my torso seems to act as a stability factor. If wind or some other force pushes the front of the front wheel to the side, the forward force of my arms seems to automatically, without conscious change in muscular effort, restore the wheel to straight.

When I'm on the aerobars, though, the far narrower position feels like my upper body does not really contribute to bike stability at all. If the front wheel gets tweaked out of line by a rock, gust or other lateral force, I feel like I have to use my whole body to actively lean against the involuntary turn. I do not know if this is all in my head or a real difference, but at least at my current level of strength and skill, it makes riding in gusts impossible on the aero bars.

I'm betting that if you put my rear axle in a trainer, you could wiggle my front wheel aroung much more easily if I or anyone else were riding in TT bars rather than normal road drops or hoods. Anyone with a force guage is welcome to drop by for an impromptu science session.

shoota 

Sometimes the wind is just too much:

https://www.youtube.com/watch?v=-nQM_38OOVo

asgelle

I don't think we're interpreting the data the same way. As I see it the plot shows that for every wheel at every non-zero yaw angle, drag is lower than was seen at 0 yaw. That is, wheels perform better in a cross wind than they do head on. The exception is the two disk wheels at very high yaw. The fact that some wheels can create a positive force isn't the point for this discussion.

Hypno Toad

- Calm to Nice Breeze: 0 to 10 mph
- Breezy to Serious Wind: 15 to 30 mph
- Stay Home Winds: tornadoes

I've been out in 30 mph winds with gusts near 50 mph at least twice in the last year. Riding in these conditions get me to ride slower, and consider my route to avoid busy roads. But never kept me home. This spring, I had 30 to 45 mph crosswinds, I was crawling with one foot clipped out for quick balance in the gusts - this allowed me to get to a more protected route.

Last June I was on a gravel century (Westside Dirty Benjamin) with winds clocked up to 50 mph. I recall looking up the line of riders in front of me, they all looked like they were leaning into a high speed turn, but were all going in a straight line (well, kinda straight as we'd get pushed side-to-side).

justinzane

Quite right there, though even with something like tightrope walking, or gymnastic skills like the balance beam, pommel horse or what not; almost everyone without training will surrender to gravity quickly. On the other hand, I'm willing to bet that anyone who takes a beginner course at the UK National Circus School [https://www.nationalcircus.org.uk/] will be able to walk ropes, railroad tracks, etc. with far more success than most everyone else even though their genetic basis for dexterity has not changed.

Being, relative to professionals, a thorough and total novice on a bike, I struggle to grab my water bottle and drink while maintaining a good steady line. I'm sure that with more than 11 months in the saddle and with many hours on the rollers that I want, I will greatly improve my balance. Even so, watching the recent Paris-Roubaix, I saw one solo crash where it looked like the sudden change in crosswind protection from a ridge beside the road to an open side caused the rider to lose his line in the gutter by the side of the cobbles and crash. Now in this case, even a couple of millimeters to one side or the other can mean disaster with the holes, broken setts, tractor gouges and whatnot.

Inevitable skill, strength, reaction times and similar factors will mean that a top level cyclist will handle with ease those crosswinds that cause me to call the sag wagon. But, that also does not change the physical forces involved. That which sends me home might cost a Hoonen 50-100W here and there. Or 10-20W or 1-2W...

For a tortise-like weakling similar to me, even 20W extra is a brutal cost. For a serios sprinter or climber, barely noticeable. However, if one set of equipment is the difference between me riding the bike or the couch; the same is probably the difference between one podium spot and the next. Relative skill will change the amount of effect a given crosswind and bike combo has; but the bike and crosswind will still experience similar forces no matter whether it is a turtle like me or rabbit like Wiggins on top.

A pro might feel that gambling on consistent aero gains vs semi-random crosswind changes is a decent bet. For me, I might decide that thin round steel that I can ride almost anytime is a better use of my cash than aerofoil carbon that I lack the strength to handle 20% of the time. Or it might be enough to get me to spend many hours on rollers so that I can handle the Cervelo/Felt/QR/... no matter what.

Knowing the facts helps everyone balance their own skill and circumstance when making equipment choices. Even when those choices can be radically different with the same facts, since the humans are also radically different.
You will never get folks to agree on the effect of wind on any kind of bike. I can't easily stay upright if the wind is greater than about 15 mph. OTOH this spring there have been tons of posts about riding in >30 mph gusts. Go figure. I never could get used to the wind effect on 50 mm deep rims while others don't even notice it. But it is telling that no one rides full front aero discs anymore. In short figure out what you are comfy with and do it.[/QUOTE]

FLvector

Too much wind and 50+mm wheels I like the head shake from the rider in red.

Notice in this windy ride no one has deep wheels and they manage fine. I like their rotating echelon at the end. Nicely done.