The 45mm Velocity Dually rim is beautifully crafted in the USA, bringing a strong doublewall rim design to fat and mid-fat tires. The 45mm width is well matched to tires ranging from 2.4-3.8″, and is especially well suited to the 3.0″ Surly Knard. Building a wheel with the Dually was a pleasant experience, resulting in a wheel that is strong and true. However, the Dually is not a tubeless-ready rim, no matter the claim made by the company.
The quality of the rim is very high. Upon receipt, there were many signs of manufacture, including small shavings of metal and a coating of polishing compound, which left metallic grey dust on my hands. Aside, these are all signs of a real Made in the USA product. Upon lacing and tensioning the wheel, I discover that the Dually is a very strong rim, structurally. The spoke holes are nicely beveled to mate with the brass DT swiss nipples used in the build. With a little grease at the spoke hole, the nipples turn freely even at high tension. In total, the wheel built up with minimal fuss. The rim was straight through the entire process. Although it can be manipulated with spoke tension, the rim also asserts its structural strength when tensioning. Unlike a Surly Rabbit Hole rim, there is no twisting at full tension (when laced to in an alternating pattern to each side of the rim). The Surly rim utilizes two rows of 32 offset spoke holes, drilled 7mm from center. The Dually has 32 alternating spoke holes about 2mm from center. These rims feature a high-polish finish.
Tubeless rims, in general
There are several features which enable a good tubeless rim. First, there must be a horizontal bead shelf with an exact diametric dimension matching the tire (622/584/559mm). In combination with a tubeless ready tire of the same dimension (or slightly less), produced to high tolerances, the system will join tightly, seal easily, and resist a broken seal (burping).
Another feature found on some tubeless rims is a bead lock, a term that is used in several ways. What I am referring to as a bead lock is the ridge between the lower center channel and the bead shelf. This feature resists the tire from coming off the bead shelf under extreme side loads or low pressures, as in the event of a deflated tire while riding.
Burping is especially possible in a low pressure system such as on a 45mm rim used with 29+ tires, or on wider rims and tires common on fatbikes. The result of burping may a small nuisance, as a blast of air quickly escapes from the tire and the bead reseats itself, resulting in an audible sound and minimal air loss. The result of complete air loss may be catastrophic to the tire, rim, and rider, especially if the tire is rapidly unseated, especially while descending, cornering, and braking. Also, some tubeless specific rims (those marked UST, for instance) are completely sealed without the need for tape for rim tape. This is a great feature to the end user, but not to the wheelbuilder. All of the rims I have used require tape of some sort to seal the spoke holes on the inside of the rim.
Finally, some newer rims have forgone the hooked rim wall that has been essential to clincher tire systems for so long. If the bead shelf secures the tire tightly to the rim, the rim wall now acts as a limit to prevent the tire from sliding off the rim. Beware, however, that most all tires have the ability to stretch to some degree, and may blow off a rim. This is especially a concern when using non-tubeless folding tires. Best to stick to TR (tubeless ready) tires if you can, but of course you want to mount some Surly Knard 3.0″ tires to your Dually and you are tempted to use the lightweight tire. Your choices include the ultralight 120tpi folding tire and the heavier 27tpi wire bead model. In fact, I’ve found that wire bead tires can serve as a cheap and reliable substitute for proper TR tires.
When using tubeless tires and rims it is prudent to limit maximum tire pressures, especially as the hooked rim wall is minimized or nonexistent is many designs. For instance, Stan’s recommends a max 40psi on most of their rims for this reason, especially as they endorse the use of almost any tire type on their rims, including non-tubeless tires. Their rims have very short sidewalls which maximize effective tire volume. Other companies produce entirely hookless rim sidewalls, including most carbon mountain bike rims available today. Hooked rims are not essential to tubeless or conventional tubed tires systems when rim and tire tolerances are all in line.
Velocity Dually tubeless claims and pains
Velocity recommended to me that the Dually rims would be ready to use tubeless with a layer of high-pressure tubeless tape such as Stan’s yellow tape, or Velocity Velotape. In my first experiments all the tires mounted fit loosely, were difficult or impossible to air up, and leaked too much air at the bead to reach max pressure. They lost all of their air in seconds, indicating an inconsistency between the outside diameter of the bead shelf and the inside diameter of the tire. I initially tested with 120tpi Surly Knard 29×3.0, Specialized Purgatory 29×2.3 2Bliss folding tire, Specialized Ground Control 2.1 2Bliss folding, On-One Chunky Monkey 2.4 folding, On-One Smorgasbord 2.25 folding, and two cheap wire bead tires, a WTB Prowler and Geax Saguaro. None captured air easily and none sealed.
Next I added a layer of Gorilla tape from edge. Several tires held air better than before, but most would not take 20+ psi, and any tire than seated was easily un-seated without effort– the bead on each tire was still easy to break, would not seal, and would be unsafe to ride. I then installed a second layer of Gorilla Tape from edge to edge. Now, I could mount most all tires to pressure, some sealed for seconds while other held air a little longer. I make a habit of testing tires without sealant to avoid messes and to allow for some reconfiguration before the system is finalized. If a tire holds air without sealant, it will likely be reliable in use with sealant.
For a lightweight non-TR tire with an elastic folding bead like the Surly Knard, a third layer of tape is recommended. With a good quality TR tire or even the wire bead Knard, fewer layers of tape may be required. Tires that qualify for UST rating may require only a layer of Stan’s tape, although I didn’t try any UST tires on the Dually. UST tires are unusually thick, heavy, and stiff best applied to extreme riding conditions such as remote rocky rides and/or DH riding. In contrast, non-tubeless tires often work without issue on UST rims as they do on the rims of other manufacturers.
Regarding the tubeless ready claims of the Velocity Dually, I think the rim is under-engineered and undersized. I finally mounted Maxxis Minion 29×2.5 tires before selling the wheelset to a friend, and those tires fit tightly to the rim (with two layers of tape already installed, not sure how they would fit with only Stan’s tape in the center). This was certainly the tightest fitting tire of all with the most significant casing and bead design, but the tire is designed for DH use and weighs well over 1000g. The tire held air without sealant. I loaded the tires with Stan’s and passed them along to Nate. He’s the kind of guy that appreciates gross durability above all else, and is pleased with the wheels on his pink Fatback
Other wide rims and tires
In my quest for wider TR rims, I’ve recently build 35mm wide carbon rims, selecting ultralight models from Light Bicycle which sell direct from China, and the heavy duty Derby which comes through a small firm in California. Both rims are genuine TR designs, which result in a reassuring ‘pop’ when airing the tires to pressure. Two other companies are manufacturing 35mm wide TR carbon rims: Nextie rims are competitively priced direct from China, while the Nox Composites rims come through Tennessee and are especially packed with features including an offset spoke bed for improved spoke tension and strength. The 50mm Surly Rabbit Hole rim can be modified and massaged to accept a tire tubeless. Ibis is selling a wheelset with 41mm wide carbon rims, TR of course. Finally, Stan’s has just released the 52mm Hugo rim, perfectly mated to tire between three to four inches. I’m thinking the Stan’s Hugo may put the Dually and the Rabbit Hole out of business.
The Velocity Dually is certainly an improvement over older designs. This welded dual-width rim is likely the namesake of the 45mm Dually, which is about twice as wide as two XC rims.
The width of the Dually is the perfect host for a 3.0″ Knard.
Wider is better. A Knard tire on a 29.1mm Stan’s Flow EX (left) and a 50mm Surly Rabbit Hole rim (right).
The Surly Knard 3.0″ tire on a Stan’s Flow EX. This particular tire is well worn.
On a Surly Rabbit Hole rim. Additionally, the contact path changes with wider rims, as does the behavior of the tire due to improved sidewall support.
Tubeless is better. Even a chunky tire like this On-One Smorgasbord can get a pinch flat or puncture, but Stan’s sealant can fix it. This was the result of a particulalry hard rock strike on the AZT, descending into Flagstaff. Lael likes to descend fast.
Surly Knard 3.0″ tires are tons of fun, but they aren’t tubeless ready, and they aren’t especially tough. The 120tpi folding version is light and fine, while the 27tpi wire bead tire is reasonably tough, but not especially tender. Hey Surly, how about a 60tpi tubeless ready line of tires?
For a rim and tire like this, the split-tube tubeless method works best.
Otherwise, there is a risk of making a mess on your way to discovering how much Gorilla Tape is required to achieve a proper tubeless seal. The split-tube method relieves the pressure, and makes a tight seal.
Tubeless systems on fat tires can be complicated, at least until dedicated TR rims and tires are available. Taping a Rolling Darryl to mount a wire bead Nate.
I spent time riding the Duallys on the Salsa Mukluk, set-up as a big boned 29er with 3.0″ Knards, or 2.25″ and 2.4″ knobbies.
29+ vs 29. Those are 2.3″ Specialized Purgatory tires on Stan’s 29.1mm Flow EX rims.
Clearance in a Fox Talas is tight. A bike with 3.0″ tires and a 120mm fork is incredibly fun and capable. Check out this custom creation from Meriwether Cycles.
Riding narrower 2.1″ and 2.2″ tires on the Dually, briefly. Also pictured are a Surly ECR and Surly Krampus.
Now, Nate is in charge of the Dually wheelset. With a pair of 29×2.5″ Maxxis Minion DHF tires, they’re ready for a full summer of riding in AK.
For now, I’ve migrated to 35mm rims, optimized for the 2.35″ to 2.4″ tire I expect to use over the next year. Anyone make a genuine tubeless rim in this width? Yes, but only in carbon. Stan, how about a 35mm rim?