Dbarkertarmac

It seems as more and more companies are jumping into the "Aero" road bike category, Specialized ( venge ) Scott ( foil ) are a few that have jumped into the Cervelo "S" series "Aero" road bike market

I have always had a love for the look and idea of the cervelo bikes ( perhaps I just love there marketing dept ) and they have certainly had success at the pro level. So I have a few questions regarding the idea.

1. is the idea of a "Aero" bike only practical for the aero sized rider? While in terrible shape at the moment and just getting back into the sport it would be a waste of money for me... but even when I was in good shape I was still a big guy ( around 215, 18-20 mph ave over 40-50 mi rides solo )

2. In all the "tests" Ive seen done by the MFG's and there claims of watt savings there all done in a wind tunnel with a stationary bicycle. I certainly understand the performance gains that can be shown under those conditions, but what about real life? What about the fact the cycling action is a wobble back and forth? what about crosswinds? Do these things that cant be tested in a wind tunnel negate some or all of the aero gains that are shown in a wind tunnel versus a non aero bike?

3. What is the true trade off of an aero bike? i.e. Cervelo S5 vs. R3 or a Specialized Venge vs. Tarmac given like components/wheels and the same rider.

Runner 1

I think aero bikes are awesome. Less effort to go faster? Yes please!

1) Do you like going fast? If so, it's not a waste. In so much as some of the trivial things people pour money into.
2) They design and test airplanes in wind-tunnels. It's too bad those aren't real-world conditions. /s
3) Maybe some slight comfort. To get "more aero" the bike may be set up to put you in a lower and tighter position.

hhnngg1

For looks, aero = win for me. That alone is reason enough for it.

In terms of actual performance, not much at all. Cervelo and others claim all their aero advantages in a carefully controlled wind tunnel, but the effects in real-world are really negligible - we're talking like <10second per hour of racing if you're going at pro speed between an aero frame and a normal tube frame.

Consider that aerobars in a TT position, are by far the greatest structural advantage you can get on a legal bike (mainly due to rider position) and that at best saves 40-60 seconds per hour of racing. And aerobars >>>> aero frame in terms of time saved.

Basically, don't expect to swap bikes and all of a sudden be keeping up with groups you were getting dropped on. I doubt you'll even see a difference in your speedometer or on a fixed time trial course total time.

Dbarkertarmac

I guess I cant just wrap my brain around testing a bike in a wind tunnel in a stationary position..... Its the fact alone that the sways back and forth and the front wheel is working in a countered motion negating a lot of the pretty aero design?

runner 1 Yes, an airplane is tested in a wind tunnel...... But is not solely marketed and sold based upon a few hours in a wind tunnel as the bicycle mfg's do

hhnngg1

They test in a wind tunnel because you cannot measure a the difference for all their fancy schmanzy aeroness in real world conditions. The difference isn't big enough to reliably measure it - you could surely rig some insanely complex setup to try and do it, but your net result would likely be less than seconds, and not significant.

It's all about the marketing, seriously. If they could show real-world benefits without the wind tunnel, they'd be marketing that front-line.

echappist

Depends on the situation. Faster you go, the more of a difference it'll make. In a dash to the line where everyone's going at least 35mph, it'll be quite significant (given placings are separated by 1/4 of a wheel length or less), all other things equal.
Mostly correct. Aerobars (except the cane creeks) aren't mass start legal. And it's not the aerobars that save you watts, it's the position into which you contort yourself that does. The invisible aerobar is equally effective, but it's damned hard to hold it going up a 3% slope whereas doing so on Aerobars is easier.
In a velodrome and with a powermeter, you'll see a difference. 10W is not that much as far as speed increase or time decrease when you are going fast, but 10W is noticeable.

patentcad

The real 41 Bottom Line on this will be: how does this impact average speed?

echappist

Too many variables to account for in the real world, and you can't get any repeatable results. However, testing in a closed velodrome gets you very good data, and people who have access to one can test their CdA using this method

Davinci..

Some perspective.
Here is a chart calculated by aerosportsreseach.com for Velonews. Keep in mind, theses numbers are for a rider moving along at pro TT speeds. 50km/h or 31mph. And I don't think many if any of us get anywhere near those speeds.


And aero frame is the least effective, and most costly way to reduce aero drag. In fact. you could pick up a pair of $30 shoe covers, and it would give you more benefit(drag reduction) then the best aero frames on the market..
Aero frames are more about sex appeal and marketing then function. Now if you are a pro tour racer where every watt and second counts when it comes down to the line. You can bet your ass you're going to want to be on one. And that 17 seconds over an hour, could really mean something.

Dbarkertarmac

I have no doubt that for elite level athletes there IS a real differance..... Im not and never will be. I have trained on a TRI bike setup and could defiantly see the value of aero bars and an aero bike, but that was also on a tri bike course, with no real climbs or gradient to speak of. But aero bars and a tri position are no fun ( for me ) on my more typical 40+ road rides that will contain extended climbs ( as much as central mass and southern NH will alow ) and some steeper gradients.

Dbarkertarmac

Davinci, nice post. thanks for sharing!

looks like ill order some shoe covers lol

patentcad

I can't believe how much they say a skin suit saves. Is that for real?

c_mack9

since i recently switched from an entry level aluminum trek 2.1 to a felt ar5 i feel like i can, for once, offer a little help on this subject. both my bikes were similarly equipped with 105, the ar5 is 4 pounds lighter and has a better wheelset on it. i have a pretty darn flat 25 mile route i have been trying to avg 18 mph on. my fastest avg time was 17.8 mph and i never could break the 18 mph mark. i got the ar5 last week and ono my very first ride i shaved off 3 or 4 mins and avg 18.0 for the first time. felt claims their ar series saves 1 second per mile, which isnt a lot but over a 50 mile ride, thats almost a whole minute without putting forth any more effort from the rider. dont expect anything a lot faster, but im super stoked i got this bike.

echappist

how do you know that your effort was consistent? air pressure and temperature can greatly affect speed.

going from 83 minutes to 80 minutes requires way more drag reduction than what an aero frame can provide. Placebo and new bike effect probably accounted for most of that.

Dbarkertarmac

C_mack

I had a similar experiance when i went from a stock set of wheels on my original bike ( spec Allez elite ) to a pair of mavic Ksyrium ES wheels. In your opinion how much of this was "aero in the bike vs your old bike vs aero in the wheels and weight savings? ( i guess teres something to be said for stiffness in the frames as well )


edit: Im not knocking or taking shots at your claims or bike just honestly curious

patentcad

It's the New Bike Factor. Gives you an extra .5 mph for about a month.

Runner 1

Has anyone ACTUALLY tested the discrepancy between wind-tunnel and "real-world" conditions? Sure, of course there is a difference, but I think the difference is overstated by orders of magnitude. It's the trendy thing to say around here.

Cross-winds? Accounted for. Variability of road surfaces? Accounted for. Turbulence? Yep, they can test that too.

Please, link me to a study if you know of one. I'll change my mind if there is good evidence.

jsutkeepspining

Go over to the tt thread in the 33. shoe covers do not save 30 seconds. drw said that most actually create drag, with only a few making any small difference 30 seconds isn't small difference.

I'm also really doubting the skin suit time saving.


The moral of the thread is aero road bikes are cool, and save you a couple of watts. So, if you're looking to buy a new road bike it wouldn't be a bad idea to test ride an aero road bike.

Dbarkertarmac

Back to my original question then, why do the test a stationary bicycle then? I'm not disputing anyones claims, I'm asking for a explanation of them!

asgelle

Because the time scale of bicycle motion is slow relative to the time scales associated with the airflow, the flow can be considered quasi-steady.

Godsight

Because most shoe covr are the lycra which dosent give a good thight fit. Proper shoe cover for TT or for the the track are latex shoe cover and yes they do help when every second matters. Same thing for skinsuit, some are better than the other as you can sse in the chart, the skinsuit they used to get those number is a special skinsuit nike surely for the olympic and lance for the tdf. A normal skinsuit that everyone can buy will still give better number than bibs and jersey.

If you want to get aero, get aero bar, tt helmet and that should cover you until you start losing TT by a couple second (1-5 sec). Until then , just train more. When you are at that point, get shoe cover and aero wheels. And if you ever get to the point that a state or national title is on the line, the garage wind tunnel solution might be useful which is explained by chris boardman there: aerodynamics made easy

patentcad

Here's another take which says a skin suit saves about 30 secs over 40km @ pro TT speeds. But even if it only shaved 10-15 seconds off my last TT, that can bump you up a couple of places even in a local amateur TT.

rpeterson

I've worn my trisuit to a few local TTs this year instead of the usual bibs and jersey and it saves more watts than I save when I remember to throw the disc cover over my powertap. And that's just with a sleeveless trisuit, I'm sure a full on skinsuit would be way better.

c_mack9

like i said, the aero benefits arent even claimed to add much speed. i dont know if the aero was more beneficial than the wheels, or the stiffness or what.

are yall the same skeptics that want to argue wind tunnel results? they're there so that all of these factors arent in place. if you dont believe wind tunnel results and say "but does that translate to real world performance" why would i expect you to believe real world results. i agree, it probably wasn't the aero benefits of the frame that sped me up but it sure wasn't the conditions. i have ran that route in all kinds of varied conditions and the fastest time i ever had before this bike was extremely hot and muggy so im willing to bet the aero frame helped more than the weather. i never claimed the aero benefits is what knocked off those 3 or 4 mins, but im sure they lended their hand to it. i doubt im fast enough to get ANY aero benefits from the frame but i sure do like riding it

asgelle

Here's an example of how you might want to write up a test to answer the skeptics. https://www.trainingandracingwithapow...r-javelin.html