DropDeadFred

At what point do you consider a deep wheel to have an aero advantage or affect?

Is the 303 an aero wheel or more of a stiff deep section wheel?

If it weren't, why would zipp employ the firecrest design to the 303 if there were no aero benefit and taking a weight penalty?

I understand the difference in the firecrest or wide rim design over the traditional design, I'm just trying to understand where the aero over weight advantage takes place.

shoot!

asgelle

https://www.analyticcycling.com/ForcesSpeed_Page.html

DropDeadFred

do you have a paint it by numbers version?

Seattle Forrest

A 303 is more aerodynamic than a 202 or a 101.

jmX

Ok, if you want a weight vs aero breakdown for climbing a somewhat respected "expert" named Hunter Allen (yes, you've probably heard of him before) pushed out a new book very recently. You could also probably generate the same table using the link posted by somebody a few posts above this one.

On page 3 there's a table showing weight vs aero up a 20km hill climb. (WARNING: The results are posted as TIME, so BDop, don't even worry about looking at it. Instead you should simply formulate your clever reply and post it without considering it as useful data. Cheers.)

If you wanna be sneaky and don't want to buy the book, simply go to amazon.com and "look inside this book". Page 3. https://www.amazon.com/Cutting-Edge-C...4953492&sr=8-1

fa63

Read this: https://www.rouesartisanales.com/article-15505311.html

It is advertised as being a little bit of both.

It makes for a stronger wheel and better tire profile (better ride and handling, in theory). 303 is Zipp's recommended wheel for rough roads / CX.

Aero trumps weight; unless you are climbing 10% grades all day.

carpediemracing 

The analytic cycling site may have a flaw in calculating moment of inertia (I think that's what it's called). It swings a wheel, hung by the hub, from side to side. This measures the overall weight of the wheel (right?), not the rim vs hub. For example, if I have two wheels, but one has a light hub and one has a heavy hub, but their overall weight is the same, if I use the swing method of measuring inertia, the wheels should act similarly/identically.

However, it would be very different accelerating a 2 lbs rim with a 1 ounce hub versus a 2 lbs hub with a 1 ounce rim.

I may be wrong and if I am then someone will correct me I'm sure.

I contacted the site a few months ago but was politely brushed off.

It seems that a better way of measuring moment of inertia (but that would take into account bearing friction, so not sure how to figure that in, maybe lock the hub into a standard "hub holder" bearing set) would be to measure how long it takes to spin up the wheel with a given weight. I know one tester (not sure who, I think it was Bicycling or Velonews) put a string around the rim, a weight on the end, and measured how long it took for the weight to fall a given distance.

asgelle

Analytic cycling does not calculate moment of inertia. It takes it as an input. https://www.analyticcycling.com/ForcesSource_Page.html

Not that it matters for road riding. Acceleration effects are so small that unless someone is taking extreme measures to determine the input parameters, errors from parameter estimation will greatly exceed any acceleration effects (not to mention errors in acceleration terms).

Also, you can't fold bearing drag into moment of inertia as the ******ing force derived from each depends on different aspects of motion. Bearing drag force is a function of speed while forces from moment of inertia depend on acceleration. The two are independent.

Bob Dopolina 

There is a lot of data/hype out there that several brands use to show why their wheels are either the fastest on the planet or, at the very least, actually ADD speed under certain conditions (there are moon phases and such involved but they swear it's true).

Distill all that down and I'd say that anything above 30mm deep will show an aero effect under enough conditions to be considered aero but it's not just height; Shape is also a factor - and a pretty significant one under certain conditions.

Aero.

They wouldn't.

As already posted (and linked to) aero trumps weight until you start climbing in significant amounts. Then you need to factor in things like time spent climbing, at what grades, on what surfaces, under what conditions vs the tims spend desending, at what grades, on what surfaces, under what conditions and then consider the weight of the bike/rider, the fitness of the rider, the colour of the bike and how many cameras are present.

Only then can you make a ballpark guestimate that may or may not fall within the margin of error for most of the tests used to sell said aero wheels.

Or, 42.

Bang!