justinzane

The other day I was out riding when a wicked front came through and the pleasant ~5mph winds turned into 30mph with gusts over 50. It got so bad that I had to call for rescue because I got so much crap blown around my shades and into my eyes that I was riding blind. Before that, though I struggled on for 10 or so miles wrestling the bike the whole way to stay between the traffic and the ditch.

That experience made me wonder about the positive or negative value of many of the "wind-tunnel-tested" extremely aero bikes and accessories. While it is inevitable that shrinking the left-right dimension of bottles, tubes, etc. helps reduce drag; my concern is the great expansion of tubes, rims, etc. in the front-back/up-down dimensions. Again, it seems reasonable and seems to be born out by experience and testing that this is a great advantage when riding straight into the surrounding air mass.

What I wonder about is how much this exacerbates side forces and what effect that has on energy expenditure and on safety. Since I'm almost always a solo rider, the technique of hiding to the side of the peleton ain't relevant. What is is the amount of energy spent wrestling the bars dealing with gusts and the increased risk of a crash because of the lowered stability.

Just as an illustration, compare the surface area facing a 90 degree wind between these two bikes:



and



Note that I just picked two reasonably expensive, but not truly crazy bike from major vendors. I'm not trying to favor one or the other or even imply that they are for the same purpose or rider. For the sake of this discussion, imagine the traditional steel frame and the carbon ultra-aero frame being built with the same general geometry, same grouppos, etc. What I want to know is for those who ride in strong and unpredictable winds, what ends up being the sweet spot in the range between classic steel racer and the NASA-approved but UCI-illegal aero demon?

gsa103

One thing to consider, especially for wheels, is that many of the aero designs actually do best in modest crosswinds. The simplest way to think about it is like this. Straight on, all bikes have very similar cross-sections. At a slight angle, the giant tubes start to look like vertical wings.

When the bike is actually moving especially at cruising speed (20+ mph), the appearant wind speed is head on or nearly head on. The stability and control issues are only really noticeable in extreme winds (races likely cancelled), or when moving at <15mph, for example when climbing. Professional riders basically only ride these bikes with the idea that they're going fast enough that the wind doesn't really matter. And when it does, they all wind in a ditch.

The best compromise for stability is probably something like the Madone Kammtail profiles. Aero shaping but without so much cross-section that winds while moving at low speeds become an issue.

Stucky

I think it's the aero wheels that catch the crosswinds- even at a 45* angle. The frame? Meh...I don't worry too much about it, as our bodies are more of a sail- and when there's a crosswind, it doesn't matter what position where in. All this wind tunnel stuff is mostly marketing BS- unless you're a pro olr near-pro racer. I like my aero bike for it's looks...but I'd be embarrassed if anyone were to think that I bought it for "the aero benefits".

They can market all this high-tech BS....but they'll never convince me that no matter how much it costs; or no matter what features it has....that it's anything but a bicycle- and what the RIDER puts into it is 99% of the equation.

StanSeven

It's just not safe to be on the roads with 30 mph winds gusting to 50. Compared to a rider profile, the added area of wider frame tubes and wheels are small.

hueyhoolihan

to demonstrate the effects of side winds. carry ten or twenty 4x8 sheets of plywood 100 yds, or so, in the wind. change the angle of the plywood WRT the wind every once in a while. you'll get a clear idea of what's what soon enough.

or better yet... get yourself, alone, in a canoe, out in the middle of big lake sometime in a 20MPH wind. head out in one direction, then return. depending on the wind direction you may never get to your destination, or you may never get back.

Dunbar

50mph gusts are going to be sketch on any bike. I was out today on my Cervelo S2 with Zipp 404's (+ me @ 145-150lbs.) in a wind advisory (30-35mph gusts.) It was a little sketchy in a few spots but really more annoying than anything else (i.e., I couldn't take a hand off the bars to take a drink of water.) Still, I was out there for 3 hours and managed to survive. Normally I'd take my backup bike with shallow wheels but didn't realize it was so windy until I was about to head out and was too lazy to swap my Garmin + lighting over. I don't know how a TT/Tri bike would compare to an aero road bike in these conditions.

redfooj

What I've seen in recent testing is that it is performed at various angles - not just longitudinally. So theoretically you should be able to make a reasonably informed decision or pick out bikes that are optimal in "many" situations.

On a qualitative side note, I've ran my 50cm sections in some reasonable cross winds and didnt feel it was any more detrimental to keeping a steady line than the standard box sections....

Sy Reene

I read comments along these lines somewhat often. Am I imagining things.. when riding thru heavy crosswinds, I could swear I feel the bike and front wheel itself getting blown; it just doesn't feel like the effect of hitting my body?

Maybe imagine a rider sitting still in the bike. Even though you can say that there's roughly eg. 80 lbs. sitting on the front wheel, you don't have to kick that front wheel very hard to make it turn (no need to push the heavy body sitting on the bike).. not nearly as hard if you were kicking an 80lb lead weight sitting on the ground.

redfooj

maybe you have a lot of inertia so your center mass doesnt move much but the subtle movements of your arm is what destabilizes the bicycle?

rpenmanparker 

Be honest with yourselves. Some folks can walk a tightrope across the Grand Canyon. Other folks can't walk a 2x4 across a room. 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.

carpediemracing 

Front wheel will feel the worst in gusty cross winds. This is partially because it's mounted on a swivel (aka the fork) and you not only have to deal with the wind blowing it from the side, you have to deal with keeping it lined up. It feels worse if you're holding the hoods or the tops because you have less grip or less leverage respectively.

Rear wheel won't feel as affected since it doesn't swivel on the bike. You'll feel the wind but it won't be as bad as a front.

Bike as a whole is lighter and not connected to a rider's point of reference (the rider's body) and bike tilts relative to the ground so if the bike gets moved then it feels worse than if the rider itself is blown sideways.

Direct crosswinds are very unusual, at least for me. It's almost always a cross-tail or cross-head.

When I combined a trip + race, I traveled with just one set of wheels (Specialized TriSpoke, aka HED3 after HED bought the rights) to the Miami FL area. THe race was cancelled due to Hurricane George blowing through at a sustained 50 mph, gusts of 80 mph (I think peak wind speeds were measured a bit later at about 100 mph). Because I was young and carefree we went out for a ride, hoping for a big tailwind bit of ride. Although I wouldn't recommend riding in similar conditions the three of us made it about 15 miles out, turned around, and came back. We were leaning pretty hard at times. I weighed about 145-150 lbs but never felt like I was going to blow away.

StanSeven

Three excellent posts by Dunbar, Robert and carpediem. Each has a different but correct perspective for the individual.

justinzane

Quote:

Originally Posted by Stucky

They can market all this high-tech BS....but they'll never convince me that no matter how much it costs; or no matter what features it has....that it's anything but a bicycle- and what the RIDER puts into it is 99% of the equation.

A truer statement's never been made!

asgelle

Actually it's more like 50%. The speed of a rider is the point at which the force provided by the rider (50%) equals the forces resisting motion (the other 50%). To go faster, she can either increase the power generated to propel the bike forward or reduce the resistance opposing that motion. In fact, it's been shown for a well trained, experienced cyclist, there is usually more to be gained by changes in equipment than to modifications to training. Of course if someone isn't interested in going faster, this doesn't really matter.

justinzane

I've got no basis at all to judge, being an almost total noob; but I am curious as to what good, if not competitive, roadies think is in the following categories:
- Calm to Nice Breeze: 0 to ?? mph
- Breezy to Serious Wind: ?? to ?? mph
- Stay Home Winds: ??+ mph

justinzane

True, but if you look at that Cervelo or something like Specialized's Shiv TT bike, add in deep section wheels, the surface area of the bike that does catch the wind ends up acting as a lever below the bike + rider center of gravity which I'm guessing is pretty close to the elbow pads vertically. It "feels" somewhat like the bike is always trying to "escape" instead of being a neutral platform connecting one to the road. If I'm not mistaken, the crosswind thing is why full disc carbon wheels are more prevalent on velodromes than open roads.

And I certainly agree about the not safe bit! I'm noone's idea of a serious racer; but all the same, it irks me to have to call for the sag wagon when I'm on a ride. I probably should have bailed on that particular day 30 minutes earlier, but I really did not expect the winds to get anywhere near as strong as they did. And neither did InAccuweather.

justinzane

That's kinda my point. It's a hell of a lot easier to carry an extension ladder in a crosswind than it is to carry a sheet of plywood. So, what is the balance between riding the ladder or the plywood? Assuming that you do not have a team or the cash to keep a garage full of excellent bikes.

justinzane

Not on topic, but this is kinda what made me think hard about this. I find that I am vastly more comfortable, have maybe 30% better endurance and am a happier riding down on aero bars than I am riding drops or hoods. Since 99% of my riding is about me enjoying tooling around; it occurred to me that it might be good to get a frame with TT/Tri geometry. But, I am not a TT rider just a pokey old guy who is most comfortable "forward recumbent". I'd hate to end up with a bike that was "nice days only".

StanSeven

This is where experience with wind comes into play. People not familar with strong winds feel the gusts on the front wheel and the efforts as a swivel. The instinctive thing to do is tense up arms and hands and grip the bar tightly. Then the gust feels even stronger like it wants to push the bike over and makes for more panic.

FLvector

As CDR noted above, the front wheel is the biggest concern with gusty crosswinds. I skimmed the posts and didn't see it, but another thing to consider is the rider's weight which also plays a roll in how much you might get pushed around by the wind. A very light rider on 50+mm wheels will likely have a much harder time than someone much heavier on a gusty day.

carpediemracing 

What I do is have a couple front wheels. For training (and racing I suppose) I think a tall rear wheel is almost always usable. My standard go-to racing rear wheel is a 90mm tall wheel, and I have a matching 90mm wheel for training.

My go to front wheel for racing is a 75mm tall wheel. I also have a 60mm but it's so similar I basically use only the 75mm, even in gusts up to 35 mph or so (strongest gusts I've raced in). I don't do road races so I don't go too much over 40 mph. At 45-50 mph I know a 60mm front wheel gets pretty sketchy.

For training I have 60mm and 24mm? tall front wheels. The short wheel is a standard Ardennes rim wheel. It's very comforting in high winds so I tend to use it if I remember it. The 60 is what sits on the bike since I rarely break 45 mph on the wheels in training.

Ultimately I bought a 40mm tall front racing wheel for super gusty conditions. Used it once, happened to flat the tire, haven't used it again (no need yet). I'll replace the tire and it'll be a standard wheel for the races.

What I ultimately want to bring to races will be:
40, 75, and one other front wheel, maybe another 75. 75 primary, 75 spare, 40 for wind.
90, 60 rear wheel I already have, if I had a third hub I'd get another 90. 90 primary, 60 spare, another 90 for a true spare that I'd actually use interchangeably with the primary 90.

For training for slower (under 45-50 mph descent/top-speeds) 60 front, 90 rear (current). For anything with descents the 24mm tall front wheel.

Stucky

I don't believe that. I propose that you test your hypothesis: Get a cheap BSO, and do several rides over the same course on it; and several with the best bike you have, and compare the difference in time. Sure, the good bike'll be a lot more fun to ride; may even feel a lot faster- but I'd wager that the actual performance difference won't amount to a hill of beans. [Make sure gearing is the same on both bikes]

Jiggle

Competition long range shooting, I learned from an early age to estimate the wind. In my observation, most people will overestimate the speed of the wind. A 5mph wind will usually be called a 10mph wind. A 10mph steady wind is a serious wind. A 20mph steady wind will be highly unpleasant for any rider.

- Calm to Nice Breeze: 0 to 5 mph
- Breezy to Serious Wind: 5 to 15 mph
- Stay Home Winds: 15+ mph

woodcraft

Unfamiliar concept. Maybe it doesn't get that windy here.

asgelle

You realize that in your example, the bicycle is responsible for 100% of the performance difference? I don't think that was the point you were trying to make.