For 2011, American Classic did far more than just update their graphics.
Their carbon rims are entirely new, from the inside out, and they took the super lightweight Micro front hub and made it stronger without adding a single gram. They also added a new 85mm deep carbon tubular rim to the mix, their deepest rim yet, and made an entirely new, stronger carbon disc wheel for time trials and triathlons. Oh, and their new design keeps the nipple on the outside, so you can true the wheel and make repairs without having to unglue your tire!
As always, President and lead Engineer Bill Shook has lots to (enthusiastically) share, so jump on past the break and see what’s new and get the story behind the changes (or check out their 2011 Mountain Bike goodness in this post)…
Starting at the center, the venerable Micro 58 front hub, which weighs in at just 58g, has been improved by moving material around the hubshell. The section between the end cap and flange has been beefed up, and the flange is a little thicker and stronger. Weight stays the same because material was only moved, not added. The new “wave” design enhances the bearing bore strength versus the original straight design.
The new rims, which carry accross the Carbon Tubular 38, 58 and 85 and the Carbon Clincher 58 (all shown below), are made for them in Taiwan entirely to AC’s spec and design. What makes them different is that the carbon layup is specified on the inside of the rim as well as the outside. The outside is your “basic” aero profile and is actually a stock design that you may see on other branded wheels, but it’s what’s inside that counts.
“We used house molds from a Taiwanese manufacturer, so on the outside they’ll look the same as some other wheels, and those designs are pretty well nailed down,” said Shook. “Inside, we created our own molds to control the shape and position of the spoke nipple bed put into a proprietary ring that’s not only our design, but has a specific fiber layup.”
“In the upper part of the rim where the brake track goes, there are pre-molded parts we designed there, too. The critical part was getting the nipple bed shaped just right and the fiber orientation at the transition from the nipple bed ring to the sidewall. The goal was to make the ring strong enough to have proper nipple extension from the outside of the rim for easy truing but strong enough to meet our standards.”
“Their normal rim had a very thick nipple bed, which required internal nipples. I wanted it thinner for two reasons. First, I wanted the rim to be lighter. Second, I wanted the nipple to stick through far enough that we could get a spoke wrench on the nipple. By pre-molding the piece, I can control the thickness and by controlling the fiber orientation, I can control the strength so that the rim doesn’t just split from the pressure of the spokes pulling on the nipple. The result spreads the forces of the nipple away from the spoke hole better.”
“Besides being lighter, the big benefit to the rider is that you can true a tubular deep carbon wheel without having to take the tire off.”
The Carbon 58 tubular (and clincher) is the recommended wheel for cyclocross, although lighter, better riders can use the 38. Weights for the 38 are 594g F / 776g R (1370g pair). Weights for the 58 are 612g F / 844g R (1458g pair). Check their full comments on using these for ‘cross in this post.
The Carbon 85 Tubular is their deepest wheel ever. Weights are 715g F / 901g R (1616g pair).
The Carbon 58 Clincher shies away from the full carbon rim, using an alloy brake track. I asked Bill why they don’t have a full carbon version and here’s his reponse:
“Basically, I haven’t seen one yet that’s right, and I don’t think they’re safe yet, so we don’t feel safe putting our customers on them. I don’t think any (full carbon clinchers) can handle the heat from extended braking well enough to be safe. Some companies are simply beefing up the rim in that section, but it doesn’t solve the problem of heat build up. Some companies include brake pads that have downgraded braking performance, which isn’t acceptable, and you can’t control what pads the customer ends up putting on their bike down the road.”
“The problem is, carbon doesn’t spread heat, so it builds up right at the brake track, which then softens the resin. Combine that with the high pressure from the tire and it’s a recipe for disaster. There’s two ways to address the problem: use a material that will transport the heat better (alloy) or use a resin that can withstand higher temperatures without becoming soft, which we haven’t developed or seen. That’s why we use a metal rim surface for the brake track.”
It’s worth noting that this is only an issue with clinchers because the tire pressure is pushing outward against the sidewall. With a tubular, the forces on the brake track are not directly influenced by the tire pressure. Also, AC’s 2011 carbon tubular rims have a new resin at the brake surface to improve braking.
Weight on the 58 Clincher is 836g F / 1044g R (1880g pair).
After putting in the design work on the internal rim design, American Classic has agreements that protect this intellectual property from being used by others that manufacture at the same facility.
Lastly, there’s the new Carbon TT Disc wheel, made for time trial, triathlon and track use. The newness is an internal flange and honeycomb design so that it won’t rock side-to-side. That means your power goes into forward motion, and it’ll track straight in the corners. Weight is 1325g.
On all of the carbon wheels, they’ve started using a new, higher end carbon material, which further refines the look and feel (smoother) of the finished product.