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I have a friend who shopped for Aero wheels recently and I heard a lot of talk about how this wheel was more rigid than that wheel and so on.

While I understand that a more rigid wheel should have less loss of energy, can it really be felt? I have entry level wheels and I don't feel any "softness". Is the rigidity of a wheel something that makes a difference only when you're a racer and want to shave off a few tenths of seconds?

(I guess it can be something important for heavily loaded touring bikes, but I'm more interested in "racing" road bikes.)

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Besides efficiency, for sure a more rigid wheel can stand more abuse (be it intended or not) from potholes and other obstacles. So, Aero rims tend to keep true with harsh use more than "extra-super-thinnest" rims. –  heltonbiker Sep 23 '11 at 19:05
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4 Answers 4

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For the average rider the answer to 'should I care?' is probably not. If you are racing a lot of time trials then it's possible that it will make a difference.

Some of the primary benefits of a spoked-pneumatic wheel are traction and shock absorption. There is a trade off between increased rigidity (as well as higher air pressure) and both of those benefits.

So, a high rigidity wheel may increase energy transfer, and decrease rolling resistance. At the same time the harsher ride is going to increase fatigue, and the added vibration over anything but the smoothest surfaces will result in a decrease in traction. Overall for the typical rider it's probably a wash.

It's largely the same story for the Aero benefits as well. Unless you are primarily concerned about going fast in solo efforts the benefit would be minimal.

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If you are a 'large' person you may notice significant differences between wheels. My weight has been all over the place, but at my current 190 pounds (and especially at over 200 pounds) I notice significant flex in "standard" light-weight road wheels. The flex is especially apparent in the front wheel when cornering downhill at speed.

When I bought my first road bike I was at 210 pounds and when test-riding it on steep curves I could feel (and see) the bottom of the Velomax Aero wheel flex to the inside of the turn by an inch or more. After swapping for a similar Velomax wheel with a few more spokes I didn't have any noticeable flex when cornering.

Similarly, when climbing out of the saddle on less-stiff wheels I will often hear a 'pinging' noise that I think comes from the spokes re-seating themselves as the wheel flexes.

When testing wheel sets, just make sure that you take some hard corners and steep climbs. If you don't find the amount of flex to be a problem for you and your weight then they are likely stiff enough. If they feel like wet noodles under you or 'ping' when climbing, try something stiffer.

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I run around 230 and I've never noticed front wheel flex. (Of course, I've always ridden touring bikes with 36-40 spoke wide-rim wheels. ;) ) However, I have noticed "pinging" as spokes seat themselves. This isn't uncommon in a new wheel of any weight, and doesn't, by itself, indicate a problem. –  Daniel R Hicks Sep 27 '11 at 23:10
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This question is akin to, "I have a Chevy and a buddy of mine went into a BMW dealership..."

If you are happy in the Chevy, do not test drive the BMW! Once you do, you will likely notice all sorts of inefficiencies that you did not previously :-(

As Jahaziel and Gary.Ray point out aerodynamics, bike handling and overall comfort are all factors and ultimately personal choice. Mix into the equation average miles per ride, type of terrain, road surface, rider weight, typical wind and climate conditions and the variables are unfortunately endless...this is both the beauty and the curse of finding the perfect set up!

Based on the fact that you mentioned racing, I encourage you to hit the BMW dealership or in this case the LBS! Most shops have test wheels...so give a few a whirl and make your own experienced/educated decision. A good set of wheels is the single most significant upgrade to any steed!

I have ridden all types and many brands...so do not hesitate to ask more specific questions about manufacturers or models!

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I know the question is about road bikes, but I submit some of my experience as MTB rider hoping to trow a little light on the subject.

As a mountain biker who has used a variety of components ranging from lower end cheap products to middle range stuff, I have noticed some differences in wheels, but especially in technical trails, rock gardens and the like.

In the case of mountain biking, wheel rigidity helps maneuverability, and the rider gets a more precise feeling and at least, the sensation of a faster bike reaction to rider's input. A more rigid wheel assembly also gives the rider a lot better feedback about the bike's interaction with the terrain.

In mountain biking, wheel flex has the effect of fading the smallest vibrations produced in the tire-ground interface. This effect is further amplified trough suspension components, so it gets more difficult to "feel" when a tire is about to skid or to determine if you can get faster over the current ground type. Such kind of assembly can also introduce estrange vibrations thus causing incorrect feedback. (I used a wheelset that constantly gave me the false sensation of rolling on a flat tire, even if the tire was properly or overinflated)

As for pedaling, I noticed a little side to side flex when climbing the steepest sections.

Another aspect of it, is that a flexing wheel, specially a cheap one, is more prone to material fatigue and failure. Wheel flex is a result of the quality in the materials used and the labor qualifications while assembling, so even high end materials can be turned into a under performing wheel by inexpert or lousy labor.

A properly assembled wheel will perform correctly and also will need to be trued less often. (For example, a guy once assembled a XC wheel set for me, using aluminum rims and 36 common steel spokes, which I abused with downhill use, including 3+ feet drops and very long loose rock sections, and they only had needed to be trued once after 3 years of use, and I really could tell whether they needed it because the bike uses V-brakes!)

As for road bikes, I have little experience, but I guess most of this still applies.

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It should be noted that there's a significant difference between rigidity against radial loads and rigidity against oblique loads. There's likely fairly little correlation between the two. I'd guess that some disk wheels have fairly low rigidity against oblique loads even though they are quite stiff radially. –  Daniel R Hicks Sep 22 '11 at 22:27
    
@DHR +1 Although, the difference between the two types narrows in MTB wheels due to the significantly wider gap between the hub flanges. –  cmannett85 Sep 23 '11 at 6:35
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