As someone who actually likes building and riding my own wheels, it has been sad to see much of the industry abandon standalone tubeless-ready rims in favor of higher-margin prebuilt wheels. As good as many of those wheels are, there is something special about building wheels (or having wheels built) to your own requirements and preferences. WTB have heard wheelbuilders’ cries and come to market with two models of Frequency TCS (Tubeless Compatible System) rims each in 26in and 29er sizes. For the past several months, I’ve been rolling on the sub-400g Frequency i19 Team TCS rims. Do they rock? Hit the jump to find out!
At a claimed 385g (our samples came built up at a sensible 1,625g using WTB’s now-defunct hubs and mid-weight double-butted spokes), the i19s have the potential to be built into a seriously light wheelset. 
The UST-compliant rim uses standard tape to hold air and is drilled using WTB’s “4D” drilling process to ensure that nipples are well supported and aligned with their spokes. An internal “I-Beam” rib keeps the rims vertically stiff and allows higher spoke tensions than many lightweight rims will tolerate. The 19mm inside width is a bit on the narrow side for 2.2in or fatter tires- but keeps weight down for their intended XC/Trail use.
On the trail, there’s nothing to suggest that the Frequency i19s are some of the lighter 26in rims available. Granted, they don’t have a lot of competition, but it’s probably safe to call the WTBs the stiffest sub-400g tubeless-ready rims on the market. Ours have been subjected to all sorts of loose, rocky terrain and, with narrow-ish 2.4in tires mounted, managed several days in Sedona without a creak or wobble. 
WTB’s “On-Ramp” bead locking profile even kept those 2.4s in place at 17psi- without burping or dribbling.
At $75, the Frequency i19 Teams don’t just feel sturdier than their competition- they’re cheaper too. For anyone looking for a lightweight, trail-friendly rim for a custom wheel build, the WTBs would be my first suggestion. If my early experiences are any indication, all-mountain riders will be well served by the 475g/23mm i23s. At 435g, the 29er i19 is also more than competitive. After nearly everyone else has left it behind, it’s great to see WTB bringing a bit of competition to the tubeless rim market.
marc
