WHEELSET SELECTION CRITERIA
What matters most in choosing between all-around wheelsets? In some ways, this is much like choosing a car. Depending on who you talk to, there are a lot of different factors to consider. Depending on who you are, some of these factors are more important than others.
Let me try to simplify and organize the many selection criteria into four groups: performance, design, quality and cost. In the all-around category, you shouldn’t have to sacrifice on any one of the first three of these. For example, you can find high performing all-arounds that are also made well, go fast on flats, and that also climb very well.
Here are the selection criteria that make up each of the groups mentioned above:
Performance: Versatility, aerodynamics, stiffness, acceleration, comfort, handling and braking are the key measures I’ve used to assess all-around wheelset performance.
The most desirable all-around wheels will provide the versatility to ride all the different types of terrain (hills, flats, false flats, straights, corners, sprints, mountains, fast downhills, windy roads) that you’ll experience and a range of training and many events (club races, centuries, club, charity, group rides) you’ll do, without compromise.
All-around wheels will be aerodynamic enough for you to notice a difference in speed and your ability to hold that speed with much less work when you are well underway on flats and downhills. Many promoting mid-depth and deep section ‘aero’ wheels will correctly tell you that 70-85% of your energy goes into overcoming wind resistance but won’t tell you that aero wheels won’t make you any faster until you get going at speeds of 20mph (or 32kph). If you average 18mph (29kph)+ you probably will be riding at 20mph+ at least 1/3rd of the time (on flats, downhills and perhaps leading a breakaway or sprinting) and will benefit from the improved aerodynamics from all-arounders.
If you aren’t going that fast, you really won’t benefit from buying wheels deeper than 25-35mm. For the purpose of this review, I’ll assume most of you will be going fast enough to get aero benefits.
For those of us measuring our power output, recognize that independent tests (here is one) show you will reduce your drag (and improve your aerodynamics) somewhere between 10-15 watts going from shallow depth aluminum wheels to mid-depth carbon ones at 20mph/30kph and higher speeds. Very roughly and unscientifically speaking, that could yield a 5% to 7.5% wattage improvement for the cycling enthusiast putting out an average of 200 watts during his or her ride. Sounds like the bump you’d get riding every day with ‘good legs’ or ‘good sensations’, non?
Note also that your choice of inner tubes and tires, rolling on tires that are slightly narrower than your rims, and setting your tire inflation pressure right can reduce your rolling resistance to create an additional 5-10 watts of benefit. So, there are lots of ways to improve your aero performance (see here for how to position yourself right and here for other gear that will make you more aerodynamic).
The flip side of going faster with a deeper, more aerodynamic wheel is that taller rims catch more of the crosswinds out on the road and can affect your ability to control your bike. A great deal of the development in recent years has focused on creating rim profiles that deflect crosswinds to maintain your ability to steer the bike when winds come at you from different angles. So handling in crosswinds, in addition to minimizing the drag from the apparent wind you create and the real wind coming at you from closer angles, is an important part of the aerodynamic performance consideration.
Stiffness determines your ability to transfer your power to your wheels without them deflecting laterally or side to side (and therefore wasting energy) under the load applied by your pedaling. A stiff wheel will do a great job of transferring your energy and power when you really step on it to sprint, throw in a dig, close a gap or when you get out of the saddle to charge up a hill. Stiffness comes from the combination of rim, hub, and spokes working together rather than being dependent more so on any one of those three.
How responsive your wheels are when you engage or ‘spin up’ the pedals to go harder or faster demonstrates their acceleration, determined more so by how much the rims rather than the entire wheels, how stiff and aerodynamic they are, and how fast the rear hub engages.
Stiffer wheels also tend to handle better in the turns, going where you want them to go. A wheel that is less stiff will be less able to follow the line you want to take. Of course, your technique has a major effect on how well you handle a turn or in and out of a group of riders.
You will also want enough compliance or vertical deflection in your wheels so they are comfortable on long rides and over uneven road surfaces. Some people believe that stronger, heavier riders need a stiffer, less compliant wheel to support them, and lighter riders need the opposite to accommodate them.
That’s probably true at the extremes (greater than 220 lbs or less than 110) but most riders weigh well between those extremes. If you are in that weight range (and fortunately I am), I’ve learned you can have a sufficiently stiff and compliant wheelset at the same time that also gives you great power transfer and a comfortable, well handling ride.
How hard you are on your pedals can discount the stiffness, and how high you run your tire pressure can negate the compliance designed into even in the best wheels. So don’t mash you pedaling during shifting or over-inflate your tires if you want to get the most out of your wheels.
Braking is a critical performance criterion. hen first introduced, wheels with carbon brake tracks were clearly inferior to aluminum ones, some said say dangerously so. The joke went that brakes would only slow but never stop a carbon wheel, that is until the heat generated from braking either blew out the tube or warped the rim.
Here again, technology and design have advanced considerably, improving carbon wheel braking performance through the use of new resins, weaves, brake track finishes and brake pad compounds.
While most believe that braking on a bike with an all carbon wheelset is still inferior to doing so an aluminum one, the gap has narrowed significantly and the risk of explosive blow-outs has been reduced on current generation wheels to those who use alloy wheel braking techniques.
Riders using carbon wheels have learned they need to use the pads designed and sold for their specific model of carbon wheels, allow more distance to brake when the roads are damp, and not hold on or “drag” the brakes for long periods of time on downhills (instead alternate between front and back wheel brakes). If you want all of the benefits that carbon clinchers bring you over alloy ones, adopting these braking techniques along with using the latest generation wheelsets has made braking performance differences between carbon and alloy track wheels quite small.
Sorry to interrupt you in the middle of a riveting explanation of wheelset selection criteria :), but to come up with reviews that better fit what and where you will be buying gear, would you be good enough to answer the question below?
Design: Design defines how manufacturers want their wheelsets to perform. Sometimes they perform as designed, sometimes not. The key design criteria are wheel weight and material, rim depth, width and profile, hub and spoke selection, and brake track and wheel finish.
The best all-around wheels will be among the lightest, principally to enable quick acceleration each time you shift gears on the flats, increase your cadence or head up a climb. Weight is determined primarily by choosing between carbon or alloy rim material, the hub and number of spokes on each wheel, a tubular or clincher rim design, the lay-up and resin choices, and the rim depth, width and profile (which in turn determine the amount of material used in the wheel).
At the end of the day, rim depth will determine weight differences more than the other factors since most high performing all-around clincher wheels are now carbon, come in the same spoke range (16-20 front and 20-28 rear), and we’re focused on clinchers rather than the admittedly lighter tubular wheelsets. So a wheel with a 40mm rim depth will weigh less than a 50mm wheel, all else being equal, which of course they aren’t from model to model. Some of the deeper wheels in the all-around category weigh as little or less than some of the shallower ones so it’s not a direct relationship between depth and weight.
While I’ve been told that a 100 gram (or 3.5 ounce) weight difference in a wheelset is noticeable, for me and I’ll guess for most of you, it’s hard to feel that weight difference between different wheelsets on a bike. I think it’s more likely that you can really feel something at around 150 to 200 grams of difference, typically the weight premium you pay for the convenience of having a clincher vs. a tubular wheelset of the same model. That said, lighter is always better but below about 100 grams, the difference provides more of a marketing advantage than a real performance one.
Wheelset weight is a surprisingly hard to number to pin down. Why? There’s no standard for what should be weighed and companies measure and market it differently. Some publish the rim weight alone believing that the difference between the rims is the weight that matters most. Many publish the weight with everything except for the quick releases (QRs) or except the QRs and rim tape. And then the wheels can be built up with different hubs and spokes. Some make essentially the same wheel in tubular, clincher and disc brake options but they will only publish the tubular (or lightest) model weight.
Further, the weight published by the wheel manufacturers is almost never the same as the actual wheelset weight. Of those reviewers who measure wheelset weight (rather than just report what the wheel manufacturers have published), the weight differences are often around 50 grams and sometimes considerably more than the “claimed weight,” a term used by many reviewers and retailers to apparently absolve them of responsibility for actually measuring and reporting a weight different from what has been marketed.
I’ve studied the claimed weight and actual weight measured by reviewers for many of these wheelsets and weighed them myself. The bottom line is that most of the carbon all-around wheelsets I’ve evaluated, whether on the basis of claimed or actual weight, are within 100-150g of each other, a difference I think you could certainly brag about but most of us aren’t going to be able to notice on the road.
The rim’s outside width, the width of the rim across the brake track, has increased significantly in recent generations of carbon wheel design. Tests have shown that a wider tire enabled by a wider rim reduces a tire’s rolling resistance and also improves both comfort and handling. A couple of generations ago, most carbon wheel outside rim widths measured across the brake track increased from 19-20mm to 22-23mm. The most advanced current generation of carbon rim wheels have outside widths of 25-27mm. Wheels made for road disc bikes get a couple mm wider.
Rim inside widths, or the width across the bead hooks that grab the tire inside the rim, have increased from 15mm to 17mm to 19mm (rim) and 21mm (disc) over the last few generations.
With rims that are wider on the inside and outside and with wider tires, you can put a greater volume of air into the tires, yet still have them support your same weight at a lower tire pressure. This softens the ride, making it both more comfortable and better handling. Running a lower pressure also puts less stress on the wheel structure and extends its life. Running it at the same pressure lowers your rolling resistance by creating a smaller “contact patch,” essentially putting less of the tire’s length (and more of its width) in contact with the road.
As mentioned earlier, crosswinds can affect your ability to steer a bike with a set of 35mm and deeper rimmed wheels. Using carbon allows wheel designers to shape the profile of rims to offset this effect. Traditionally rims had a ‘V’ profile, with the rim linearly increasing in width out from the narrower inner or leading edge, where the rim meets the wind and spokes, to the outer one, where it meets the tire and the wind exits.
To deflect crosswinds, the newer design wheels have focused on making the leading edge wider and more rounded (somewhat like a ‘U’ ) and in some cases by also curving the rim wall from inner to outer edge like an oval or what designers call a toroid (or ‘0’ shape), instead of it running without any width variation. Some have made other adjustments along the inner edge in an attempt to deflect crosswinds like Reynolds swirl lip generator (SLG) design or Zipp’s sawtooth rim that varies in depth.
Finally, spoke and hub choice and rim finish are clear design choices, though I think they are more about personal preference and performance more than actual performance. Most quality all-around wheels including many of the ones I’ve covered in this review, come with spokes and hubs made from one of the two or three major spoke manufacturers.
The larger, integrated cycling product companies typically make or design and have hubs to put on their wheels. Still others use the same, top-end DT Swiss 240 hub either branded as such or with the wheel maker’s brand on the hub shells and the 240’s mechanical component ‘innards’ underneath the shells.
Spoke number, alignment, and shape (round, elliptical or bladed, butted or not noting thickness changes along the length of the spokes) do vary considerably from wheel to wheel. The number of spokes used and how they are aligned or ‘laced’ is part of the overall design used to create a wheel’s strength and stiffness. They have a minor effect on weight (we’re talking a few grams here and there) and their shape has minimal influence on aerodynamics though some wheel makers market the heck out of their bladed spokes.
While having fewer spokes, having them laced in a unique pattern or having flat ones may set the look of certain wheels apart for the rest of the crowd, focusing on spokes in isolation really doesn’t get you any closer to choosing between one wheelset or another. If you true your own wheels, it may be more important to you whether the spoke nipples are accessed outside or inside the rim, but that may be something to know rather than use to make a choice.
Hubs used on the best wheels are generally very good and, as mentioned above, many come from the leading manufacturer DT Swiss. Most are made of stainless steel and come in a sealed package while others are ceramic and move more freely.
These choices largely affect durability and maintenance, which shouldn’t be issues if you own good wheels. At the extremes, hub choice can affect weight and acceleration but in a minimal and hardly discernible way. Hub flange diameter and placement can also affect wheel stiffness when considered in combination with the rim, spoke and assembly of those components and the hubs.
Hubs use different mechanisms and have ‘pawls’ and slots the pawls engage to get the rear wheel spinning when you begin pedaling. This affects how quickly the wheel engages when you first start rolling or increase your cadence. Much of the differences in the number of pawls or points or degrees of engagement from one good hub to another are hard for cyclists to notice on the road.
More importantly to most of us, some hubs may roll smoother when you are going down the road or freewheel quieter than others when you are coasting, though these are often subjective differences and only affect performance if the rolling isn’t smooth at all or the noise of the freehub annoys you so much that it affects the enjoyment of your ride. There’s actually one manufacturer that makes truly excellent hubs but has distinguished itself by creating an identifiably unique sound coming from its hubs that it also offers in a wide range of colors.
In simple terms, the latest generations of carbon rims from the best wheel makers use resins and manufacturing processes that make carbon clinchers more durable than alloy ones and their rims resistant to overheating. Better brake track finishes and brake pads have greatly reduced and in most cases eliminated brake squealing typical of earlier generation carbon wheels. They also contribute to dissipating heat created at the rims.
New brake track finishes have brought the dry weather braking performance of carbon clinchers nearly on par with alloy wheels and wet weather braking within range. These finishes vary in detail but are typically textured or etched surfaces or have added materials on top of the smooth resin making up the rest of the rim, both creating more friction and wicking more water during dry and wet braking. Other companies still have braking surfaces that are smooth and essentially unchanged from the rest of the rim and perform less well than the newer finishes.
Rim finish – everything from matt to glossy rims with bold white or ‘blacked out’ lettering – is a personal choice. While it has no effect on performance, I understand that looks and brand will matter to some road cycling enthusiasts, especially if it makes you think you are going faster or are more excited about riding your wheels and bike with some of these distinctive design touches.
At the end of the day, evaluating and comparing wheelset performance is very subjective. Wheelset aerodynamic performance, for example, is probably one of the most marketed characteristics and provides an example of why you need to be careful buying into the hype. While aerodynamics is one of the most important and distinguishing criteria for racers in a wheelset’s overall performance, it is also one of the hardest characteristics for the cycling enthusiast to objectively assess and compare and is far less important to your speed than your position on the bike and your fitness.
Here’s why. Most companies have done extensive wind tunnel testing in a controlled environment on their own wheel designs and against competitors’ wheels to help develop the current generation of carbon wheels. Very few publish the results and when they do they are often selective, on incompletely labeled charts and with little detail about their testing protocol.
While most tests look to see how much drag the wheels produce at different angles to the wind (‘yaw’), there is no common approach to testing the wheels, for example, either on and off a bike or on specific brands and types of bikes and tires. Of course, some bikes and tires are themselves more or less aerodynamic.
You are really only getting a true measure of the front wheel’s aerodynamic effect. On the road, the airflow over your rear wheel is disturbed by the ‘wake’ created from the front wheel and the down and seat tubes in front of the rear wheel. You are also creating a good deal of turbulence at the intersection of the rim and spokes as your legs pedal like egg beaters. Go ahead and try to model the aerodynamics of that situation!
With wind tunnel testing in hand, wheel manufacturers market the most flattering parts of this incomplete, non-comparable wind tunnel aero information and often market the qualifications of the engineer who led the aero design and supervised the wind tunnel analysis along with a combination of “unique” technological breakthroughs available only in their wheels.
I understand that companies must have some tools like CFD (computer fluid dynamics) around which to design and that wind tunnels provide necessary baseline measures, (and that all of this makes for good marketing), but how well these tests relate to the real world of on-the-road cycling with varying road, wind, bike and rider conditions seems very hard to correlate.
While most people will say aerodynamics and weight are two of the most important measures of a wheel’s performance, as you can see, neither of them are conclusive based on numbers alone. You really have to take what the wheel manufacturers and their retailers tell you about these performance and design features with a great deal of skepticism.
In place of their claims, which the buyer guides and some bike shop salesmen repeat back with great enthusiasm, I’ve drawn from the experience of independent reviewers and enthusiasts who have ridden many different wheels in different conditions on the road over many miles and that of my own experience with specific wheelsets.
Quality: Durability, warranties and service/support are the selection criteria that define wheelset quality.
Rim, spoke and hub durability all matter though rims and especially carbon rims are usually the weakest link and most expensive to deal with. Most hubs put on all-around wheels sold in the performance all-around category are very durable and easily serviced as part of an annual bike check-up or if there is a problem. Modern-day spokes are strong and relatively easy and inexpensive to replace, something you rarely need to do as a result of normal riding.
Carbon rims are far more durable than they used to be and most are stronger than alloy rims. While I’m not aware of any tests that compare alloy and carbon wheel lifetimes, anecdotally most service shops will tell you that carbon wheels will last longer than alloy wheels under normal conditions. Wheels with fewer spokes will reduce the weight some but increase the stress on a wheel.
At the end of the day, it really comes down to the rim manufacturing quality and how well the company stands behind their product if something goes wrong. Most major manufacturers make very durable wheelsets in this all-around category and offer competitive 2-year warranties that cover materials and workmanship.
Some companies are just more responsive than others to issues that require direct service or support. Online forums are filled with stories about company service, both good and bad, and most companies have established their reputation. Fortunately, most are good.
Most local bike stores and online retailers that are certified dealers or specific wheel brands stand behind the products they sell. It’s pretty easy for them to do so; they send the wheelset back to the manufacturer in most cases.
Ultimately, the manufacturer determines the service response to a damaged wheel – repair time, replacement, cost if any, etc. I’ve tried to sort through both the durability ratings and warranties offered by manufacturers but also listened closely to what shops and other enthusiasts say about the durability and service/support response to different wheelsets.
Current generation carbon wheels don’t have issues on typical flat and hilly terrain. The biggest issue continues to be overheating and deforming all-carbon wheels during extended braking, for example coming down a long mountain pass and dragging the brakes or holding them for long periods of time like you would do with an alloy wheel. Manufacturers do not warrantee damaged carbon wheels caused by overheating, but as mentioned above, the latest generation carbon wheelsets will not get damaged in this way unless you drag the brakes.
I’ve written more about the quality of carbon wheels today and the best technique for braking a carbon rim brake wheel on mountain descents in a post reviewing carbon clinchers designed for mountain climbing and descending here. If you only feel comfortable being able to use the constant braking or dragging technique and want the best braking surface short of going to disc brakes, I recommend you choose a carbon-alloy or pure alloy wheelset.
Cost: While you often get what you pay for, some all-around wheels cost a lot more than others with only a tenuous relationship between cost and performance, design or quality. All-around, non-custom wheelsets north of $2000 appear to be priced based on their brand name, business model, product and market strategy, and product volume more than any other factors.
Some companies spend a lot to advertise and sponsor professional cycling teams to create a distinctive wheel-focused brand appeal and purposely sell low volumes. Others look to be ubiquitous with a broad range of cycling products including wheels and use their large distribution networks to achieve more profit through higher volume sales on lower priced wheels and range of other cycling products. For us, cycling is a sport, a past time, a passion. For them, it’s a business.
Some manufacturers also dictate selling prices to retailers and threaten their distribution agreements if they stray from those prices. In some countries it’s legal, in others it isn’t and the market pricing reflects this.
For example, many online retailers based in the UK often sell high performance, all-around wheels at 20% off the manufacturer’s recommended price and occasionally discount these up to twice that amount. You will seldom see this on a current model year wheelset sold in a US local bike shop or US-based online retailer. Because of what’s known as Minimum Advertised Price or MAP agreement, the retailer has to agree to price it at the MAP if they want to sell the company’s product. And, the courts have ruled that it’s legal.