Wheel Thoughts, Evaluations.

We spend a lot of time at the shop discussing wheel choices, and trying to find the best combinations of a rim, spokes, and hubs for riders other than ourselves as well. 

Wheels are often much more than the sum of their parts. Knowing how a particular hub builds to a rim model, how equal the tension ends up being on both sides of the wheel, as well as how stiff the wheel feels are important factors. The other factors (still important) being dent resistance, hub engagement, hub service life, weight, spoke strength (both in building and abrasion resistance when contacting nature directly) parts availability, and the ability to adapt to newer standards all come into play. 

At the shop, we usually talk with a customer for some time to figure out what they want and need out of their wheels, and build from there. I have a strong preference towards DT Swiss, as their parts just work, and speaking with them in Colorado is always an enlightening and fun time. 

Luckily for us, Specialized builds many of their wheels around DT Swiss hubs, or DT hub internals. My favorite type of pre-built wheelset is one that uses hub drillings that aren't impossible to find, regular spokes, (straight pull or j-bend) steel, with a 1.8 or 2.0 threaded end), and a 2:1 lacing ratio or some other way of keeping the drive and non-drive tensions equal or close to it.

The 2:1 style of lacing is very effective because most wheels today have what is called dish. Dish is another way of describing the hub offset compared to the rim. This is because of disc brakes and the freehub body. To create a dishless wheel our hubs would have to be considerably wider than would make sense with modern bike geometries. What a 2:1 pattern does is put 2 spokes on the driveside to 1 on the non-driveside. Because the driveside spokes are shorter, they often hold much more of the load than the non-drive. What we then end up with is a 32 spoke wheel in which the 16 driveside spokes are supporting much more than the 16 non-drive spokes. One way to get around this is to shorten the non-drive spokes and use fewer of them, thus creating a wheel with 24 or 28 spokes that has a much more evenly distributed load.

Another helpful way to do this is to use a hub with offset flanges, or asymmetrical flanges, and a rim with asymmetrical drilling. These are all ways to use fewer spokes, or get more strength out of the build. Some hubs are notoriously uneven tension builds (older Powertap and current Shimano road hubs come to mind).

Wheels get most of their strength from the rim itself, with the spokes playing a supporting role. If one builds a wheel with a flimsy rim and heavy, strong spokes it will hold up for a time, but the spokes will fail more quickly, and the rim will dent and bend more easily than a comparably weighted wheelset with lighter spokes and a heavier rim. This is due to the Fatigue Limit of the components. Steel (and titanium) spokes for example, can withstand a theoretically infinite number of cycles if the cycle is kept under a certain deflection or amplitude. Every wheel flexes as it rolls with a rider, and is subject to additional forces when the rider pedals or turns the bicycle. If the wheel is under-built for the application, the spokes will be subject to far more deflection and will result in breaking of the spokes; often many break within a few hundred miles of each other because they have all reached their fatigue limit at relatively the same time.

We see similar failures with aluminum spokes, but often much sooner as aluminum spokes lack the elasticity and fatigue life of steel and titanium spokes. The aluminum alloys used in spokes will fail eventually no matter how little deflection they come under, and the lifespan shortens as the deflection becomes greater, as seen with a detensioned wheel or a wheel that is under-built for the use. Aluminum has benefits as well, though, and forged aluminum spokes can also help with reliability, helping to create a stiff, strong spoke. Both aluminum and titanium, great materials for so many applications on the bike and beyond, are less than ideal for spokes because of the nature of wheels. Steel and carbon make great spoke materials with the latter not being used much due to cost and complexity. Titanium alloys generally have a lower stiffness and the fatigue limitation of aluminum alloys create issues as well.

There is a lot more that I won't go into here about how heat treating, forging, and shaping processes greatly affect how these materials are used to achieve very specific component specific goals, but that would be a huge article in itself.

It's interesting to see how different riders test the limits of their wheels too. Some people manage to hit spokes a lot, resulting in failure due to abrasion from rocks and such. Some dent the rims from running low pressure, others ride through (all the mud water?) a lot of water and mud with the result of hub bearings needing frequent attention.

So along with my preferences:

DT 350 hubs- These things use the Star Ratchet design, have the best sealing of any hub I've ever used (same for any other DT) standard beaings, build well tensioned wheels, are available in like 100 different types, and they are light too! The one drawback is that DT is still putting Star Ratchet in them with 20 degree engagement, which isn't what most riders want nowadays. The good news is 10 degree and 6.7 degree upgrade kits are available for $100

DT Rims- Good tubeless bead, asymmetrical offerings, welded offerings (stronger than other methods of construction) and many different widths. Quality control has always been good.

WTB Rims- Good tubeless bead, asymmetrical offerings, great choices for Harrisonburg riding and great pricing. Quality Control has always been good.

Stan's No Tubes Rims- Lacking in Quality Control in years past, the new, welded rims seem to have bumped up Stan's game big time. Prices are close to the DT options so difficult decision with the Stan's.

Spokes and nipples: This is pretty open as DT, Sapim, and Wheelsmith make some great stuff. Options include sweet anodized nipples and ones that make it easier to true the wheel.

The 2 wheelsets we've been really liking lately are the Roval Traverse, which come stock on many of our bikes and are a $600 set. They use a less expensive DT hub internal with 15 degree engagement, and easily convertible parts. 30mm internal rim width, and DT revolution straight pull spokes built with a 2:1 front and equal tension rear design. It's a light trail wheelset that we've had a lot of success with. Some folks have broken spokes from abrasion but that's to be expected and will happen with most spokes if they encounter those types of impact.

The other is our demo wheelsets (we have them in boost and non-boost). The boost set is currently on our Stumpjumper FSR demo bike. These have DT 350 74 point (6.7 degree engagement) and carbon 30mm internal rims. They are really stiff, and really light at 1,550g. 

Compared to the Control SL wheels on my Epic the Traverse SL are 7mm wider and noticeably stiffer. It is difficult to discern whether stiffness comes from the rim being wider and better supporting the tire, or just a beefier build; but they feel great. The resins used in the Traverse and Control carbon wheels are also more impact resistant over the Control SL rim. Not that I've had any issues with some hard hits on the Control SL, but it gives an extra piece of mind for folks.

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