Wheel Aero Drag....Under 20 MPH

[Ralph]

My son wants me to spring for a new set of factory built wheels on a new frame I am building up. Something along the lines of Campagnolo Neutrons.

I had in mind just using my barely used IRD 32 spoke Cadence rims with some new Campy Record hubs. We have a terrific wheel builder in our area who will build the wheels for under $100 labor...and she is available any time for touch up truing, repairing, etc. That would set me back about 1/2 as much as new bought wheels. I don't mind buying new wheels (wife has given me permission LOL), but wonder why do it?

I am aware my body mass, bike position, clothing etc, make up the vast majority of aero drag on a bicycle...some say up to 65%, and is the first area to look for improvement. But I'm an old guy, so doubt if I will be lowering my bars or taping my shoes anytime soon. And I don't ride overly upright anyway. My position is not very bad as is. Though a pure racer would have a flatter back. I don't have much hair, so at least no pony tail flapping around.

Some say bike frame makes up next aero drag area....about 20%, and I'm not much interested in changing my frame and parts to improve that. Some also say friction in bearings and tire rolling make up about 5%, and that aero wheel drag makes up about 10%.

If those numbers are anywhere near accurate for me, my body shape, my position, my bike, the way I ride my bike, etc....what is the point in buying slightly more aero wheels when I do the vast majority of my riding in the 15-20 MPH range. I would only be slightly inproving on a number that is only about 10% of the total drag anyway....if studies I have read are anywhere near accurate. And with more traditionalm wheels, I can get them repaired at about any bike shop, anywhere in country. Although if traveling, I do have other very sturdy wheels, so reliability is not the only question. My main question is would I notice any difference when riding Neutrons over more conventional 32 spoke wheels for the way I ride? I know this subject is beat to death, but when searching thru past discussions, I did not see question posed quite this way. BTW....I ride about 100-125 miles per week, year around. That may not be enough miles to make me a good racer, but at my age (68), I can still do a century if I wish to suffer the next day. LOL And still ride with some younger riders.

[wasfast]

The short answer is very little difference between the 2 wheels in actual speed and at that rate of speed,

I think you made our own conclusion, i.e. that it's not going to be much if any improvement, especially measureable.

For a quick overview of aerodynamic contribution, see this years Velonews Buyers Guide. While targeted at TT racers, the concepts are the same.

Often parts are talked about as "aero" as if there is a binary attribute where "non-aero" suddenly becomes "aero". A 30mm rim has slightly less drag than a box rim but it's not night and day. Likewise as the rims get deeper, the drag is generally reduced. Yaw plays a factor also. Zipp and Hed have charts that show the drag vs yaw to give you some idea.

The faster you are going (like 25+mph) and the deeper the rim (assuming modest yaw numbers) the more the wheels help but the rim and/or speed difference will need to be pronounced from the wheels.speed you currently have.

There are lots of questions similar to this asked on slowtwitch.com about whether getting race wheels/new frame/helmet etc is "worth it" for riders under 20mph. The answer is it can be because while the speed is lower, the overall time spent on the bike for the same event is longer than faster athletes. Quantifying the improvement is where you see that the difference is small and is also cumulative so longer events like a full Ironman bike leg (over 100 miles) let it add up. This amount is several minutes, not an hour for example.

Having some new wheels can be as much mental as actual. If you're excited about new wheels, feel good about riding them, like how they look on the bike etc, that's really going to be the benefit.

[oldpotatoe]

My son wants me to spring for a new set of factory built wheels on a new frame I am building up. Something along the lines of Campagnolo Neutrons.

I had in mind just using my barely used IRD 32 spoke Cadence rims with some new Campy Record hubs. We have a terrific wheel builder in our area who will build the wheels for under $100 labor...and she is available any time for touch up truing, repairing, etc. That would set me back about 1/2 as much as new bought wheels. I don't mind buying new wheels (wife has given me permission LOL), but wonder why do it?

I am aware my body mass, bike position, clothing etc, make up the vast majority of aero drag on a bicycle...some say up to 65%, and is the first area to look for improvement. But I'm an old guy, so doubt if I will be lowering my bars or taping my shoes anytime soon. And I don't ride overly upright anyway. My position is not very bad as is. Though a pure racer would have a flatter back. I don't have much hair, so at least no pony tail flapping around.

Some say bike frame makes up next aero drag area....about 20%, and I'm not much interested in changing my frame and parts to improve that. Some also say friction in bearings and tire rolling make up about 5%, and that aero wheel drag makes up about 10%.

If those numbers are anywhere near accurate for me, my body shape, my position, my bike, the way I ride my bike, etc....what is the point in buying slightly more aero wheels when I do the vast majority of my riding in the 15-20 MPH range. I would only be slightly inproving on a number that is only about 10% of the total drag anyway....if studies I have read are anywhere near accurate. And with more traditionalm wheels, I can get them repaired at about any bike shop, anywhere in country. Although if traveling, I do have other very sturdy wheels, so reliability is not the only question. My main question is would I notice any difference when riding Neutrons over more conventional 32 spoke wheels for the way I ride? I know this subject is beat to death, but when searching thru past discussions, I did not see question posed quite this way. BTW....I ride about 100-125 miles per week, year around. That may not be enough miles to make me a good racer, but at my age (68), I can still do a century if I wish to suffer the next day. LOL And still ride with some younger riders.

Nothing significant but a suggestion, get an aero front wheel for those days you want a wee 'aero' advantage.

[echelon_john]

if i'm riding centuries when i'm 68 i'll spring for a set of Lightweights...cost, fragility, perceived vs. actual benefit be damned!

good on ya, mate!

that said, at the speeds you're talking about there will be very little noticeable difference in aerodynamics, but you may notice the additional stiffness/harshness of deep section wheels. i like your shiny new hub option, built by somebody you know and trust.

good luck,
john

[McQueen]

"My son wants me to spring for a new set of factory built wheels on a new frame I am building up.."

So, your son rides? And does he live, say, within easy driving distance from you to borrow said wheels?

68? Bravo! - I sure hope I'm riding that amount when I'm your age.

[flickwet]

to have a nice set of wheels built by someone you know and can speak with and will be available for service, I'm sure she would be delighted to do the work vs more expensive, machine made, aero wheel with little additional benefit, but huge liability in cross winds, heck the good karma of the handbuilts alone will speed you mightily along

[dogdriver]

I agree with McQueen's assertion that your son is perpetuating an evil agenda for you to finance his race wheels.

Remember that airspeed in the drag equation is a square function-- the main reason that most decent riders can maintain 20mph on a flat course, but hardly anyone can go 26mph. That said, if you dress fast and feel fast, you are fast. Get the wheels...

[Tobias]

We have a terrific wheel builder in our area who will build the wheels for under $100 labor...and she is available any time for touch up truing, repairing, etc.
Is she cute? ;)
Some also say friction in bearings and tire rolling make up about 5%, and that aero wheel drag makes up about 10%.
Ralph, rolling friction is a lot more than that. Probably at least 25 percent of the total at the speeds you are talking about, and maybe as high as 50 percent.

[J.Greene]

If you were my dad I'd tell you for the tenth time that at your speed wheels don't matter. Just ride and enjoy your time outdoors.

[Tobias]

If you were my dad I'd ask you if you wanted to go for a ride with me. ;)

I don't have that option.

[oldguy00]

My son wants me to spring for a new set of factory built wheels on a new frame I am building up. Something along the lines of Campagnolo Neutrons.

....

Shallow dish wheels like Neutrons and Ksyriums are NOT aerodynamic. Especially Ksyriums...
Buy a set of Neutrons if you like the way they look. Same for any other wheelset. You won't see any speed improvement due to aerodynamics until you get to a wheel like a Zipp 404. And even then, depending on the type of riding you do, you probably won't notice that much.
Just buy the wheels that will make you happy with how your bike looks, and make you want to ride it more.

[AndrewS]

The IRD based wheels sound pretty nice to me. Depending on the hub and spoke/nipple choices they could come out pretty darn light.

Have you thought about the aesthetics? The one set of wheels I have with more deep aero rims look weird to my regular aero eyes.

The point being, you want to like your bike: ride, looks, drag, etc.

[thwart]

Man, if I had a good wheel builder easily and cheaply available, and liked the look of standard spoked wheels (as I do :p ), I wouldn't think twice about it. There's something about riding wheels that your hands (or someone you know well) have built that just makes cycling more enjoyable.

That said, Neutrons (or Nucleons) are awesome wheels that you'd never regret buying.

And as others have said, my understanding is that unless you're topping 25 mph on the flats, those fancy aero wheels are pretty much a waste. And they ride more harshly as well.

[Peter P.]

According to a chart and article I have, switching from a "conventional" 32H wheel an aero wheel will save you approximately 100grams of drag.

At 20mph, and using a 40km TT as standards, you can expect to save about 52seconds.

Ask yourself if the cost difference between the standard wheels and the aero wheels you're considering is worth saving that time.

My litmus test always is, "Will it put me on the podium?" I usually wind up going home with my money still in my wallet.

[DfCas]

Aero starts to matter between 12 and 13 mph. I find that deep section low spoke wheels dont feel as nice as basic 32 spoke shallow rims, but they are noticable on downhills.

The rear wheel is in dirty air and matters just as much as the front.

For more info than you want, check out analytical cycling.

http://www.analyticcycling.com/

[oldpotatoe]

Man, if I had a good wheel builder easily and cheaply available, and liked the look of standard spoked wheels (as I do :p ), I wouldn't think twice about it. There's something about riding wheels that your hands (or someone you know well) have built that just makes cycling more enjoyable.

That said, Neutrons (or Nucleons) are awesome wheels that you'd never regret buying.

And as others have said, my understanding is that unless you're topping 25 mph on the flats, those fancy aero wheels are pretty much a waste. And they ride more harshly as well.

'Wisco', as in Wisconsin?
Close to Madison?..go talk to Andy Muzi..great wheelbuilder.