Archive for July, 2008

Wheels Wheels Wheels

Saturday, July 26th, 2008

Wheels, wheels, wheels. It is probably one of the most often asked questions I get, what wheels should I use in my upcoming race? Which are fastest? Lightest? Should I use the disc or the deep rim or should I whip out the Hed 3’s? I can’t believe I am even considering writing this article because I know just how involved and technical it could become if I tried to go over every possible scenario and type of course and the ins and outs of aerodynamic drag and how it all relates to the gazillion wheel offerings out there. As always, I will try my best to keep it simple and hopefully, if you are in the market for some cool new wheels, will help you make the right decision.

First of all, remember, aero race wheels fall under the category of FREE SPEED (although it’s not really free – some wheel sets might set you back as much as $1500-$2000!!!). Also, realize that even in a best case scenario, the very most aero wheel set might drop 3-4 minutes from your current 40k time trial personal best (but probably more like 1-2 minutes) if you are now using a basic set of box rims with 32-36 spokes. Extrapolate that over the distance of an Ironman bike course and the numbers start to sound very impressive and very much worth every penny invested if you are on the bubble for one of those Kona slots. The faster you already are – the more aero wheels are going to help you – if you currently ride at speeds less than about 17 mph, aero wheels are not going to help as much as if you currently ride 28+ mph.

Without any constraints on budget, you could have a “quiver” of wheels from which to choose for any course or condition you might encounter. With lots of constraints on budget, however, you might be considering a single wheel, or at most, an “all purpose” pair that is sturdy, reliable and can be used on any course in any conditions and possibly even for training as well as racing. One thing to remember is that the front wheel is the most important wheel as far as aerodynamics goes but it is also the most affected by crosswinds.

There are many factors that affect the price you will pay for a specific wheel and there is some basic truth to the saying – you get what you pay for…. It seems to me that weight is probably the single most considered factor when an athlete is purchasing anything bike related and that includes wheels, for sure. But don’t look at weight (or aerodynamics) alone – look at hub design, braking surfaces and structural integrity. Some wheels are virtually bomb proof AND very fast (but not necessarily the lightest) while others are, well, let’s just say not very fast if you have to pull out of the race or stop and wait for a wheel change from neutral support.

How the heck can you possibly decide? You might be thinking, well, why don’t I just look at the wind tunnel test data that many wheel manufacturers provide and see which wheel set, within my budget, is the fastest? Or maybe I should look at what the fastest riders out there are riding. Or maybe I should just pick the ones that match my bike or jersey colors best? Wind tunnel tests are valuable, but there is just so much more to “how fast is this wheel?” than looking at the drag numbers of that wheel spinning all by it’s lonesome, at one speed, without a rider and a bike being part of the equation. The thing is, if you tested every wheel with different bike frames, different riders, different tire sizes and shapes under different wind conditions and at different speeds and you will get A LOT of varying drag numbers that show both good and bad numbers and your decision would become even more incredible.

So, what do we want? A wheel that is light and aero and sturdy and affordable. Simple. What exactly constitutes a wheel being “aero”? The single most effective way to make a wheel aero is to increase the depth of the rim. Generally speaking, the deeper the rim, the more aerodynamic and the faster the wheel – the fastest being the deepest rim of all – a disc wheel. However, the shape of the rim is a critical component. Ideally, this shape of the rim should be oval or elliptical. Note that the only deep section wheels that legally can have that most aero shape are those made by Hed and Zipp since they both hold the patent which was originally Hed’s. In some cases, it may be a marginal difference but technically speaking, the wheels from these two manufacturers should always be faster than a similarly designed wheel (i.e, same rim depth, same number of spokes, etc) made by someone else. That’s not to say that other wheels aren’t fast. There is much debate whether one wheel is faster than another – the Hed 3 wheel and the Nimble crosswind would be one instance. My best guess is that each wheel may be faster than the other in different conditions but the differences are probably not worth obsessing about for very long. Either would be a good choice if that is the type of wheel you are considering. The next way to make a wheel more aero is to reduce the number of spokes. Fewer spokes mean faster and lighter wheels but not without some compromise when it comes to the strength and lateral stiffness of the wheel. To be really fast, rim depth should be between 50-60 mm and spoke count should be between 16 and 24 spokes (or as low as 3 spokes in the case of composite spoke wheels). Hed makes even deeper sectioned rims that are 90 mm and are among the most aerodynamic wheels made – only a disc is faster – but with more rim depth and aerodynamics comes more susceptibility to crosswinds and handling issues, particularly for lighter riders.

Here are the basic categories or types of wheels (with a few examples of each) you should be considering when in the market (these are just examples and tend to be the wheels that I, personally, would consider using but in not is meant to be an exhaustive list or suggest one wheel is “better” than another (awe, who am I kidding? I think Hed wheels are the best and anyone who I’ve ever coached knows it ;-) ):

Semi Deep: 38-44 mm (Hed Jet 40, Zipp 303, Bontrager Race X Lite Carbon, Corima Roues Medium)

Deep: 50-60 mm (Hed Alps, Hed Jet 60, Zipp 404, Corima Roues Aero, Mavic Cosmic Carbone)

Super Deep: 90 mm (Hed Deep)

Composite Spokes: (Hed 3, Nimble Crosswind, Corima Roues 4 Batons, Mavic IO)

Disc Wheels: (Hed, Zipp 909, Bontrager, Mavic Comete)

All right already, what wheels should I get!!!!

If you want to go as absolutely, no doubt about it, fast as you possibly can, get a disc wheel and super deep or composite spoke front wheel. I mean really, what does Lance ride in the tour TT’s? I can tell you, he is not going to ride it unless it’s the fastest option going for the given course or conditions.

If you can only get one set of wheels and you plan to be going to the show in October consider a super deep or composite spoke for the rear and a composite spoke or deep wheel for the front. A pair of Hed 3’s is a super fast and all around do anything set up – or you could keep it simple and go with a pair of 404’s or Alps – you might give up a little in aerodynamics but gain a lot in peace of mind when the winds really begin to howl (my fastest rides in Kona were on twin Hed Cx wheels which were the same type of wheel as these). So basically, a pair of composite spoke wheels or a pair of deep rim wheels or a combination of the two, will provide you with a very fast, very versatile wheel set.

If you are a very light rider (under 120 lbs) and already feel like you get blown around on your regular wheels you should probably avoid a disc, super deep or composite spoke wheel and consider only the deep and/or semi deep rimmed wheels.

Now for a few other little items….should you get tubulars or clinchers?

If the wheels are to be truly “race only” wheels – get tubulars. The wheels are lighter, the tires quicker to change and you won’t be as tempted to train a lot on them because you won’t want to risk flatting that $90 race tire you’ve got on each wheel!

If you really don’t want to deal with gluing tires, however, and you feel you might be training some on your wheels get clinchers.

What size wheels are best?

The size that fits your bike! No, seriously, in almost every case I would lean toward 700c wheels. Only when a rider’s size warrants a smaller wheel sized frame should 650c wheels be considered. I’m not even going to go into the many reasons why someone would or wouldn’t want to disagree with that. Don’t ride a circus bike!!

Whatever wheel you decide to go with – remember, you will always get more speed from training smart and working on your engine but believe me, I know as well as anyone that part of the fun of cycling is all the cool gear and gadgets we have to choose from.

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