Climbers, lighter riders and Road Tubeless aficionados will find a lot to like in Stan's NoTubes' latest ZTR Alpha 340 Pro road clincher wheels. At just 1,216g for the pair (530g front, 686g rear, plus 98g for the included skewers) they're on par weight-wise with many carbon tubulars and at US$1,100 they're a relative steal.
The low mass is noticeable when accelerating from a standstill or attacking a steep pitch of road but like all low-inertia wheels, the ZTR Alpha 340 Pros also lend a nimble feel to the front end as they're less determined to stay in one plane – especially at higher speeds.
DT Aerolite spokes and a mild V-shaped rim profile suggest decent aerodynamics, too, though any advantage was hard to discern on the road. The ZTR Alpha 340 Pros are refreshingly easy to handle in strong crosswinds and offer up an excellent ride quality on rough roads.
As we've come to expect from NoTubes, build quality has been outstanding, with both wheels arriving straight, true and with even spoke tension, and staying that way over three months of testing.
The feathery 340g (claimed) rim's proven internal shape and airtight tape setup makes for the easiest tubeless road tyre installation and inflation we've experienced to date. Not only did we have no problems installing a set of Specialized Turbo TLs by hand but they also inflated instantly with a standard floor pump (without the aid of soapy water or other standard tubeless tricks).
Stan's NoTubes' distinctive rim bed profile yields remarkably easy tubeless tyre installation and inflation
They held air long-term almost as well as a standard butyl tube. Only when we picked up a small glass shard did we eventually inject some Stan's NoTubes latex sealant to plug the leak and we haven't looked back since.
The sole letdown is stiffness – as in, there isn't very much of it. In an effort to shave grams, Stan's build their top-end road wheels with just 18 radial spokes up front and 24 in the rear (two-cross/radial with 2:1 drilling), all laced to an American Classic Road 205 rear hub and Micro 58 front one – and NoTubes rims have never exactly been renowned for their earth-shattering rigidity.
It all produces an enviable figure on the scale and admittedly works okay overall but there's definitely some lateral flex in hard corners that makes for a less-than-precise feel compared to stiffer sets we've used, and the effects will only be more obvious with increasing rider weight.
Hub-wise, multiple revisions seem to have finally quelled the demons in American Classic's unique six-pawl driver mechanism and the adjustable-bearing rear hub runs smoothly and quietly. American Classic have recently added three steel inserts to the alloy freehub body, too, which provide a slick solution to cassettes that might otherwise dig into the soft surface. The front hub has been a major disappointment, however.
The American Classic Micro 58 may be light but the bearings aren't terribly smooth and our sample developed play on the first ride
Not only do the bearings runs relatively rough but our hub also developed play after a single ride. Bearing preload isn't adjustable so it's not an easy fix, either, and if you regularly head out in nasty weather you should note that the front hub bearings have no supplemental seals aside from the ones built into the cartridge, which are fully exposed – and visible! – from the outside.
Featherweight riders aren't likely to have much of an issue with the wheel flex but others might instead want to consider one of NoTubes' other ZTR Alpha builds, both of which use a higher spoke count for a little extra beef.
Our recommendation would be to skip the Micro 58 front hub entirely (also used on the Team-level wheels) and go with the value-packed Comp set, which is heavier at 1,430g but just $615 for the pair and built around NoTubes' less maintenance-intensive house-brand hubs. Or, simply pick up a set of rims (available in 28h and 32h) and build them up with the hubs and spokes of your choosing.
One last thing: as with all tubeless-compatible rims (either road or mountain), the ZTR Alpha 340 rims can be used with standard tube-type tyres, and inner tubes can be added in the event of a puncture that won't seal on its own. Unlike NoTubes' off-road variants, though, it's critical that only certified Road Tubeless road tyres be used when running tube-free lest you run the risk of blowing the tyres off the rim and smearing yourself across the road.