INTERBIKE 2009 – American Classic was showing three new wheelsets, including the Magnesium rimmed clinchers above.
Actually, what’s new with these is the white/blue color combo, not necessarily the wheelset itself, but they sure do look sweet.  The rims are sub-300g, making for a complete wheelset at 1275g (540g front / 735g rear).  The rim is treated to prevent the corrosion that magnesium can be susceptible too, and they use a special alloy to further inhibit corrosion.  MSRP is $1,599 and they come with Ti skewers and ceramic bearings for smooth rolling and very low rotational weight.  More pics of these after the break.
Hit ‘more’ to see the new tubeless 26″ and 29″ mountain bike wheels with a proprietary inner rim shape to provide a better tubeless seal and their all-new 420 Aero3 road wheels…
American Classics’ new tubeless mountain bike wheels will be available in either 26″ or 29er versions, but both will use their new inner hub extrusion that creates a ridge to help seat the tire and keep it in place.
The flat section just inside the rim’s wall is where the tubeless tire’s bead sits.  For the uninitiated, a tubeless tire pressed down against the floor of the rim as much as the sidewall, so it needs a builtup surface to seat itself on.  That’s why many conversion kits work by building up the floor of the rim in addition to covering the spoke holes.  With AM’s design, the flat floor is already there, and they added a proprietary ridge on the inner edge of the floor to “pop” the tire into place and keep it there.
Besides going tubeless, the new rims are wider at 26mm (up from 22mm for their other rims).  Despite going wider, the new rims are 10g lighter and they’re stiffer.  They’re available in white or black, and pricing for the 29er wheelset is $820 (white) and $780 (black).  They’re pretty light, too, weighing in at 1600g (748g F / 852g R) for the 29er set and 1486g (691g F / 795g R) for the 26″ wheelset.  They have a 235lb rider weight limit.
A relatively unique feature of American Classic disc mountain bike wheels is their raised rotor bolt bosses.  Founder Bill Shook explained that when the bosses are machined smooth, they can create  a stronger section toward the center of the hub, which can warp the rotor as the outer edges of the boss may weaken and warp inward over time.  The raised bosses keep the pressure equal across the mounting area to reduce or eliminate that source of rotor flex.
The last new set of wheels are the 420 Aero3 road wheels, the latest iteration of American Classics’ do-everything road wheel.  Shook claims they’re good for racing, training, triathlon and cyclocross, with the deeper rim profile aiding navigation in the latter like a rudder in mud.  For 2010, the wheels get a lighter hub and new spoke lacing patterns on the rear.  Rather than a normal 2-cross, the rear gets 8 radial spokes on the non-drive side with a wider flange spacing and 16 three-cross spokes on the drive side.
Rear hub (above) and front (below).
18 radial spokes on the front, bladed all around for aerodynamics.
Tried to capture the bigger dish angle on the non-drive side, but it’s not as evident here as in real life.
There are a few other things Shook walked me through to share how his wheels are different (he’s the lead engineer as well as the founder of the company).  The first is the aluminum nipples.  We all know alloy nipples tend to be weaker than brass, but they’re much lighter.  Shook designed his to have an extra section above the ball that seats into the rim hole.  This allows (A) the spoke to be threaded in deeper (and in fact they spec longer than normal spokes for their wheels), which has the effect of (B) pushing the tension through the ball and across a greater area rather than (C) pulling all of the tension directly through the hole.
Next, all pawls within the hub engage simultaneously.  Some hubs use alternating pawls and more engagement points to reduce the angle of “float” before engagement, but AM ensures that all six pawls engage at the same time for more power.  The spring (you can see the end of it circling the inner bearing) clicks along the teeth as the hub spins while coasting…
…but as soon as you start pedaling, the spring catches the teeth and spins that part clockwise, forcing the pawls to engage.
Lastly, the freehub bodies on Shimano/SRAM compatible models use a hardened steel cassette insert (darker material) in several places around the freehub to prevent your cassette from mashing into the softer aluminum.  If you’ve ever changed a cassette, and we’ll just pretend that you have, you know exactly why this is a great idea.
