Wheel designs. What exactly goes into a proper wheel design and should I be concerned about this when considering new or custom built wheels? If you are planning on buying new wheels or getting them custom built you should at very least be curious to know what goes into a properly designed set of wheels.
There are numerous approaches to the design of a bicycle wheel and they vary wildly. They are not all equal and some are down right terrible. In the last few decades we have seen efforts to depart from tried and true wheel designs with the desire to create something new. It could be for a perceived aerodynamic gain or for weight reduction or other performance gains. Sadly not all are actual improvements. Some boil down to a different look and could be accurately criticised as pure fashion and nothing more. On occasion there are real world benefits with measurable improvements. Those are rare. Most unfortunately are nothing more than different with no measurable gains.
So what should you be looking for? First off you need to ask yourself how you plan to use your new wheels. Are they for racing, for training or are they for a specialised discipline like time trialing or for a triathlon. Are they for MTB or gravel riding? These are the questions you should start with.
Whatever their eventual purpose you’ll want them to be robust enough to easily survive their daily use. You should consider your body weight with the the actual weight of your wheels. Its foolish to think that a pair of wheels built for a 135 pound racer will be suitable for your 185 pound body. The guy who weighs 135 pounds will be perfectly at home on those 24 spoke wheels while the guy who is 185 should be considering at least a set of 28 hole wheels or he is potentially inviting trouble down the road.
To understand the fine details of wheel design you’ll have to start investigating the individual components that make up a wheel. The individual weights of each component matter when determing whether or not those components will be suitable for you personally. Don’t worry about what someone else is riding. Concentrate on yourself and your specific needs. This is were a custom wheel set begins, taking into consideration what you actually need and giving no thought to the other guy in your cycling club or your favourite pro rider.
Lets begin with spoke count. The trend has been for lower spoke counts which is an effort to mimic what the pros are riding. Remember, they get their wheels for free and they probably own a dozen pairs that are meticulously looked after by pro bike mechanics daily. That’s not going to be your scenario so don’t try to emulate their choices. A few extra spokes in a wheel is going to add the tiniest amount of weight and in many cases will actually improve your ride by adding more stiffness and strength that you’ll actually notice when sprinting and climbing hills. That pair of 28 spoke wheels might feel a lot better than that set of 24 spoke wheels. If you’re a heavier rider you’re going to need more spokes and there’s no getting around that. So don’t give it a second thought.
Next lets consider rim depth. The wonderful thing about carbon rims is the freedom rim designers have with the shape of the rim. This has lead to a myriad of designs and most of them have specific design objectives in view like aerodynamics and weight reduction and lateral stiffness. Many carbon rim designers have introduced at least a few models that are quite deep. Is deeper better? It depends on several things. Like most things there are pros and cons to deeper carbon rims. Their can be aero gains, yet those deeper rims use more material and therefore are heavier. Strong cross winds can make deep carbon rims unmanageable for a novice bike rider. Personally I have found there is a sweet spot for carbon rim depth. I would say you have the best of all worlds if you stay between 32 and about 45 millimetres. That still builds up a nice stiff wheel but doesn’t threaten to give you problems on a windy day. Also you can still get a decent light weight rim at those depths.
Hubs. This could be a very lengthy discussion so I’ll try to keep it succinct. There are many different hub designs. Some utilise common J bend spokes and others use straight pull spokes. Some have large flanges and others small flanges. Some have flanges of different sizes while other have flanges that are identical in size. This can be quite confusing when you start to look closely at the hub designers intentions. Some hub designers pay close attention to the bearing spacing while others are more concerned with the bracing angle of the non drive spokes in hopes of equalising spoke tension of both rear wheels and front disc wheels. There is some complicated math going on here if you go deep enough down the rabbit hole but that won’t be considered in this short overview of hub design. Lets start with flange size. Its been known for quite some time that a larger flange aids in adding more stiffness to a wheel by shortening the spoke length and altering the height at which crossed spokes intersect. This may be a very desirable thing if stiffness is desired. On the other hand a smaller flange will add a degree of compliance to a wheel that may be preferred for cyclocross or gravel riding. If you opted for deep carbon rims you may purposely want a lower flange hub to build in that extra degree of comfort. Its a matter of finding a perfect balance in the wheel so that it ticks all the performance boxes but doesn’t ride like a brick! So you can start to see that there are recipes for spoke counts coupled with rim depth and flange size. Of course there are a myriad of possible combinations and this is where the experience of the wheel builder begins to become very important if you want a wheel that makes sense for your own cycling needs. It can quickly become complicated and requires someone who knows how each choice effects another choice.
And I should really stress that these choices need to make sense mechanically and not merely be aesthetic ones. Too often people will make choices based largely on aesthetics first while barely paying any attention to functionality.
Again the extensive experience of a pro wheel builder will aid you in making decisions that you won’t later regret. This is one of the main reasons for seeking out the help of someone who knows these things intimately. There’s a lot going on in any set of wheels that need to be evaluated for your needs only. I’d be happy to help you navigate that successfully!