Stan’s NoTubes started shipping revised Alpha 34o tubeless road rims near the end of May. The revised rims get a slightly thicker, stronger spoke bed and are shipping now on both complete wheelsets and as standalone rims.
NoTubes’ Mike Bush says the change was made to allow them to build wheels with a higher spoke tension. With Road Tubeless tires in particular, as they’re installed and inflated, they can cause a significant drop in spoke tension on the wheel. On the drive side rear, the drop could actually put the tension below recommended spec. Previously they had supplied spoke washers, but many builders weren’t familiar with their use. Some folks would over tension the spokes, which could cause the rims to crack or, in rare cases, the spoke would pull through. Bush says they would warranty such cases even though it wasn’t technically an approved issue.
The new rims only add a bit of weight (10-15g with extrusion variances), putting the new rims at about 380-385g, up from 370g.