Tough first, light second.
As riders demand 29ers for all-mountain and aggressive trail use, suspension travel for 29er frames and forks has increased incrementally. Stan's NoTubes is following suit with its ZTR Arch EX 29in Rim -- an updated version of the original Arch.
It's intended for aggressive riding and heavier riders, where the Crest and Flow are intended for XC and gravity respectively. The Arch EX drops 50g from the Arch, and does so with added width and strength. The EX does, however, retain Bead Socket Technology.
Stan's NoTubes has been at the forefront of the tubeless movement, and aside from its award winning sealant, what has put the little company from NY on the map is it's Bead Socket Technology. In a nut shell, BST rims have a larger inner diameter to seal against tire bead. This provides simpler tubeless inflation and a lower rim sidewall that reduces stored energy, which allows lower tire pressures for a more natural and rounder shape with increased volume.
In fact, Stan's BST rims allow riders to run approximately 30% less pressure than conventional rims. This directly translates into enhanced traction when climbing, descending, and turning -- along with a more supple ride and lower rolling resistance. With these virtues, it's clear to see why Stan's rims are almost omnipresent on race courses and trail heads alike.
The Stan's NoTubes ZTR Arch EX 29in Rim is only available in 32 hole configuration, and is Presta valve compatible. The rim does not ship with tape or valve stems -- they'll need to be purchased separately.