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Wheel weight vs. aerodynamics

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Wheel weight vs. aerodynamics

Postby Fourthbook » Mon Sep 12, 2011 1:36 pm

Does anyone know or have advice on the speed/efficiency trade-off between wheel/rim weight and aerodynamics for general riding (not racing, TTs or wind tunnel results; rather, club-like rides of several hours in varied conditions and terrains)? I've studied the wind tunnel data at Enve and other makers but have a difficult time applying those 'controlled' results my real world use. For example: a pair of Reynolds Thirty-Two rims weigh about 520 grams while the new Enve Smart 3.4 pair weighs 720 grams and a pair of Enve 1.45 mm weighs 590 grams. My question is: for general use, which rim/wheelset would be most efficient/fast, the lighter but shallower/less aerodynamic Thirty-Twos, or the deeper/more aerodynamic but heavier 1.45s, or the mixed depth/more aerodynamic but nearly a half pound heavier of dynamic weight on the Smart 3.4s?

Is there any data that charts the trade-off between rim weight and aerodynamic benefit of profile depth/shape in real world varied conditions?
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Re: Wheel weight vs. aerodynamics

Postby Gumgardner » Mon Sep 12, 2011 1:58 pm

Good question. You may not get much feedback over here. I'd try posting this on http://www.weightweenies.starbike.com as well
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Re: Wheel weight vs. aerodynamics

Postby pritchet74 » Mon Sep 12, 2011 4:08 pm

If you want absolute fastest, then you want Hed, Zipp, or Enve-Smart. Weight doesn't matter unless you are going up a steep hill, BUT a light wheel certainly feels better when accelerating and is therefore much more fun to ride. And that fun factor is certainly something to keep in mind. I have owned a LOT of wheels. My favorites to ride were Reynolds Cirro and my Edge 1.45. For what it sounds like your priorities are, I would stick with those lighter mentioned options.

I stick with the TT wheels on my road bike, but I am just funny that way.
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Re: Wheel weight vs. aerodynamics

Postby Gumgardner » Mon Sep 12, 2011 4:13 pm

But how does a wheel like madfiber play into it given the depth and the low weight? Would this be a perfect option for him or is it too deep for everyday riding or doesn't it matter since it's 1085g?
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Re: Wheel weight vs. aerodynamics

Postby Ypsylon » Mon Sep 12, 2011 6:35 pm

Gumgardner wrote:Good question. You may not get much feedback over here.


Because he asked a general question in the review section. :teacher: :wink:

I'll move it to the road section and explain my opinion on the topic when I can. Until then, Pritch has a really good point in that the fastest wheels aren't always the most fun wheels, so that's something to ponder about.
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Re: Wheel weight vs. aerodynamics

Postby Gumgardner » Mon Sep 12, 2011 7:24 pm

I just check the 'new posts' section, so it doesn't make a difference to me where it's posted :)
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Re: Wheel weight vs. aerodynamics

Postby Ypsylon » Mon Sep 12, 2011 9:59 pm

Fourthbook wrote: I've studied the wind tunnel data at Enve and other makers but have a difficult time applying those 'controlled' results my real world use.


This is hardly a surprise because it's extremely difficult. The large teams do this before important time trials and calculate an avg yaw knowing wind speeds at different locations and having a very good idea of how fast their riders will go.

Fourthbook wrote:My question is: for general use, which rim/wheelset would be most efficient/fast, the lighter but shallower/less aerodynamic Thirty-Twos, or the deeper/more aerodynamic but heavier 1.45s, or the mixed depth/more aerodynamic but nearly a half pound heavier of dynamic weight on the Smart 3.4s?


To cut a long story short, the Smart 3.4s are the fastest on your list, and the 6.7s are faster still on any "normal" course.

You can play around on http://www.analyticcycling.com/ to get a feeling for different weights and aero drag.

At the end of the day, with wheels that are more aero you will spend less energy to go the same speed or go faster with the same amount of energy, if you are not racing up Mt. Lemmon it will most likely not matter how heavy your wheels are, within reason.

There are reasons not to use "fastest" wheels on a certain course, though. If you are the protected rider in a grand tour and you will be shielded all the way to the final climb and your job is to cover attacks on a 10% incline you indeed want light wheels. But if you don't ride in a huge peloton, this most likely won't apply to you.

If you spend 6 hours riding around on wheels that are so deep that with the conditions on that day are a challenge to handle it will wear you out even if you have to pedal a little less. Mind you, this doesn't come down to purely rim depth, though. My HED Stinger 6 wheels were a little easier to handle than my EDGE 1.38s in cross winds. I guess it comes down to a "better" rim shape of the head when looking at side forces and the heavier rim that was more stable. Both the Smart/ENVE 3.4s and 6.7s should be easier to handle in gusty side winds than the Stinger6s still, so I wouldn't be too concerned about that looking at the wheels on you list.

Lighter wheels might accelerate faster, but remember that you have wind resistance while accelerating as well. So while a system with lighter wheels might accelerate faster from 10 to 20 km/h, it might be the other way around if you want to accelerate from 40 to 50, in a sprint, for example.

Aero trumps weight.

That should answer your question on which wheel is likely faster, if the faster wheel is the best for you is another story. There are other factors to consider like convenience or maintainance, but if you are looking at carbon tubulars and fast, the 3.4s are the fastest on your list, almost every day.
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Re: Wheel weight vs. aerodynamics

Postby pritchet74 » Tue Sep 13, 2011 12:17 am

I would guess that the Madfiber wheels would be absolutely horrible aerodynamically due to their sharp V profile. This is why Lightweight wheels are not good aero wheels. And the problem I had with the LW wheels is that they were really effected by cross winds. I lusted for those wheels for a long time and after one ride I sold them. Huge disappointment. So, light weight doesn't mean a wheel will be a fun wheel to ride.
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Re: Wheel weight vs. aerodynamics

Postby mdeth1313 » Tue Sep 13, 2011 10:40 am

pritchet74 wrote:I would guess that the Madfiber wheels would be absolutely horrible aerodynamically due to their sharp V profile. This is why Lightweight wheels are not good aero wheels. And the problem I had with the LW wheels is that they were really effected by cross winds. I lusted for those wheels for a long time and after one ride I sold them. Huge disappointment. So, light weight doesn't mean a wheel will be a fun wheel to ride.


Yeah- I currently use 3 wheelsets w/ my bike- edge 1.45's with extralite hubs (990g), c-4 2.7 usl clinchers (around 1400g) and hed h3c (somewhere north of 1500g). Favorites- hed h3c. They're just so much fun to ride - even though they're more than a pound heavier than the edge wheels, they feel so damn fast and it certainly feels as if they hold speed better than the other two. A bit of a pain w/ crosswinds, but if you can handle a bike it's not so bad. I've been using them as my everyday wheel. The woosh whoosh sound is also a bonus- helps me keep a nice rhythm. :xBanana5:
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Re: Wheel weight vs. aerodynamics

Postby Gumgardner » Tue Sep 13, 2011 2:28 pm

:xDisco:
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Re: Wheel weight vs. aerodynamics

Postby Fourthbook » Tue Sep 13, 2011 5:57 pm

Thanks all for the insights. Keep'em coming...

As a 155-lbs. rider, I get blown around on the rural Ohio farmland roads during the spring when the wind is often 15 mph w/25 mph gusts on my Reynolds MV32UL tubulars, so cross-wind stability is as much a concern as weight and general aerodynamic drag. I also ride in the Hocking Hills: only 1 - 2 km long climbs but very steep w/tight, twisting descents, and have taken the bike to the Rockies and Sierra to ride in the mountains on vacation. Thus weight is also a major concern. However, comfort is not really a variable as I'll be using carbon tubular rims with the same hubs, and similar spokes and lacing for the wheels regardless of the specific rim choice. Hence, it sounds like a light-weight mid-profile rim (i.e. one in the mid-40s mm) such as the Enve 1.45, Zipp 285v4, Reynolds 46 or the Enve 3.4, would be the best overall, all-around choice. The weight range has the 1.45s as the lightest (590 grams) for the pair, with the Reynolds and Zipp about the same (668 and 688 grams, respectively), to the heaviest Enve 3.4 at 720 grams. From the thread of comments so far, the Enve 1.45s or 3.4s appear to best balance my needs. Do you think the aerodynamic difference/benefit of the 3.4s versus the deeper profile of the 1.45s off-sets the pretty substantial weight difference? I've asked Enve directly but have yet to get their response. I'll post when the reply...
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Re: Wheel weight vs. aerodynamics

Postby pritchet74 » Tue Sep 13, 2011 7:59 pm

Cross wind stability is one of those things that can be improved with riding experience. I am currently riding 2011 Hed Jet 9's as my daily wheels. Back in 2008 I used Jet 9's as my daily wheels as well. 2009 was Jet 6's, and 2010 was H3's. I am a Hed whore that way. Anyways, the Jet 9's are DEEP and you obviously feel the wind with them, but if you ride them every day you just get used to how they feel and you learn how to ride them. I use them in any wind conditions - sometimes in 25 mph+ winds they can be a bit of a handful, but it's rideable. Also, the Jet 9's are easier to ride in the wind than Lightweights.

Rim shapes that have a curved shape are (in general) easier to ride in the wind. Enve 1.45's are more curved than Reynolds Stratus (46) and are better than the Reynolds in the wind.

Concerning the 1.45's versus the 3.4's - if you are concerned about absolute speed then go with the 3.4's. They are absolutely faster, however I would bet that it would be more fun to ride the 1.45's and unless you are in a TT, you will never really notice the difference in aerodynamics. The cost between the 2 wheelsets isn't insignificant either. Finally, with the 3.4's you will have to have brakes that can accomodate the really wide rims. A couple years ago I was really excited to ride Hed Stinger 6's - I bought them new from Hed and when I put them on my bike I realized that it was impossible to use them with my Hooker brakes. They just wouldn't fit. Then I had to sell them to Ypsylon..... my loss was his gain. :wink:

Go with the 1.45's. You won't be disappointed.
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Re: Wheel weight vs. aerodynamics

Postby mdeth1313 » Tue Sep 13, 2011 8:53 pm

pritchet74 wrote: I am a Hed whore that way.


Oh no you didn't! :devillol:
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Re: Wheel weight vs. aerodynamics

Postby Adrien » Wed Sep 14, 2011 9:13 am

Ypsylon wrote:Lighter wheels might accelerate faster, but remember that you have wind resistance while accelerating as well. So while a system with lighter wheels might accelerate faster from 10 to 20 km/h, it might be the other way around if you want to accelerate from 40 to 50, in a sprint, for example.

Aero trumps weight.


Hey guys!

That is a pretty true sentence. However do not forget that accelerating from 40 to 50km/h will require 3 times more energy than from 10 to 20.
So definitely the aero matters for pace riding. As soon as there is an acceleration, whatever the speeds, lightness/rotationnal inertia certainly matters as much as aero.

Cheers.
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Re: Wheel weight vs. aerodynamics

Postby pritchet74 » Wed Sep 14, 2011 11:15 pm

Adrien makes an appearance! :xBanana7
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