cjenrick

I just read about 1000 posts on this time worn subject, and to my surprise, not one person mentioned anything about aerodynamics.

Everything else is mentioned, "how much do you weigh? how much weight do you carry? are you using aluminum nipples, a wheel is only as good as it's builder, the hub, spokes, rims, and ties comprise the total system, 36 spokes ride smoother, 32 spokes are rigid, 36 spokes are stronger, 32 spokes are lighter, are you using 3 cross or 4 cross? are you using stainless, are you using double butted, are you using DT? how much spoke tension? "

on and on.

what is the real reason for using 32 over 36?
wind!
not one person out of all those posts got this.

turn your bike upside down and put it in the biggest gear.
crank the pedals as fast as you can.
what limits the speed you can achieve?

wind. the wheel turns into a fan at higher speeds.

the less spokes, the less fan effect. this is the reason for disc wheels.

my question is, what are the power savings when using 32 over 36? is there a percentage figure out there?

thanks for any help.

veganbikes

Most of the time when we are talking wheels with those numbers of spokes we are typically talking to someone looking for a heavier duty wheel so strength and such is more important than aerodynamics.

Yes the point you have brought up is not a bad one but honestly most people aren't worried about the "fan" effect on a 36h wheel and if they are they probably aren't riding a 36 or higher spoke count wheel.

I don't know what the power savings would be and I doubt it would be an easy calculation as a heavier wheel could act as a flywheel as you get higher speeds but would be slower at lower speeds (plus a host of other factors)

SurferRosa

Sheldon taught me to use 32 in the front, 36 in the rear.

Cyclist0108

This clearly explains why my ceiling fan has 5 blades instead of 30.

Wildwood

I use the number of spokes the hub dictates.

Standard classic wheel - around riding without worrying about truing = 36 spokes is best for my 190unaerodynamicpounds
Lighter weight classic wheelset = 32
classic tandem wheelset = Phil w/ 40 spokes.to extra sturdy rims


But isn't 32+ spokes kinda mute
I thought everyone was running 20/24/28 spoke wheels in mid&high level road bikes. And the Urban category.

edit: is this the mtb forum?

FTB

I am struggling to understand why anyone riding 36 or 32 spoke wheels for that matter are concerned about aerodynamics at all.
The difference between 2.0/1.5/2.0 spokes and bladed spokes such as aerolites on a 24h shallow alloy (long spokes) wheel is <<<<1w iirc. Like negligible difference. How wide open your mouth is would have a bigger difference.
Point being the difference between a thin db spoke like a rev/laser etc^^ and a slightly (relatively) wider spoke like sg champions etc would be less than the previous delta most likely.
I do not think there will be any tangible difference other than placebo, but the rule of thumb is for every +4 spokes, you double the fatigue life of the wheel (or spokes) which to me is more important especially if you already have 32 spokes nowadays

What rims are you using? Are you racing?
ride yo bike

Germany_chris

I'll second that the folks thinking 32/36 spoke wheels aren't much concerned with aero, in my case I ride 36 because I have bags all over my bike.

Koyote

In my experience, one broken spoke slows me down much more than four extra spokes.

Troul 

the air drag from your legs might be greater than the drag produced by the amount of spokes.


buy 36 holes rims, use 28 spokes. Potential durability of a 36 holed wheel, but with the weight savings using less spokes.

Koyote

I’m not sure that it works like that.

Rides4Beer

24/24 on my road wheels, 24/28 on my gravel wheels. I'm 185lbs and ride hard, no issues.

And yes, more spokes does equal more drag, found a test showing 20 bladed spokes saving about 10w over 32 round spokes.

Darth Lefty 

I thought the reason to choose 32h is that it's getting really hard to find 36h

asgelle

Will no one rid me of this meddlesome false dichotomy? (and this one is especially stupid).

rydabent

First of all I find it VERY hard to believe that 4 more spokes are going to cause that much more drag.

Second, does anyone have the specs that show that with the same style rim and hub what the max load a wheel can carry with both 32 and 36 spokes.

Troul 

These "tests" of drag are done in a stationary state. Put the real world test to spoke count using the same person, same everything else, but swap out the wheels for just a different number of spokes.

asgelle

I don't know to which test you're referring, but virtual elevation tests certainly have the wheels rotating. The better wind tunnels have translating beds so wheels are rotation there too.

Koyote

It's not a "false dichotomy."

If you were a serious racer, you'd have a leg amputated -- the aero benefits are indisputable.

Troul 

not following.

70sSanO

If I decide to use my bike as a fan instead of the A/C this Summer, I’ll let you know how much savings I get off my electric bill. I’ll use a 32 spoke wheel in July and a 36 spoke wheel in August.

John

Troul 

coupled with an electric driven device, it'll have more thrust for aero efficiency.

topflightpro

This. Once you're at 32 spokes, aerodynamics and wind resistance are pretty much irrelevant discussions. If we're talking 20 vs. 32, then yes, it's relevant. But if you're building wheels with 32 spokes or more, strength, stiffness and durability are your main concerns.

(Note: I've got a set of 32-hole hubs on order. Going with 13mm deep and 21mm wide rims - cause aerodynamics don't matter for this wheelset.)

tomato coupe

The best overall wheel performance is obtained when the number of spokes is a prime number. I suggest 31 in the front and 37 in the back.

Iride01

cjenrick maybe you can do a study and enlighten us. I've never cared that much myself. But if it turns out to be a game changer who knows where and what level the bickering might get too.

Wildwood

Not to change the discussion away from 32 or 36 spokes,
BUT
if the subject is aerodynamics -
Shouldn't the feedback move toward rims and their shape, with tire width as a factor ('oh, i ride faster on 38s, cause the front tire wake breaks the air for my knees!' )


edit: maybe that high cadence pedaling is enough to slow you down!




Clear your handlebars, and your aerodynamics and Mind will follow!

msu2001la

Do people buying 32 or 36 spoke wheels really care about the aerodynamic differences?

This feels a bit like debating lap times of various cargo vans.