At last year’s Interbike, Guitar Ted and I were talking to Bill Shook of American Classic about their new AC 101 rim for 29er riders who want to DIY their own wheel build. This was a first for the AC folks as they had been pre-built wheels only up till then. To talk a bit more about the new rims, I asked Bill some questions that centered around the 101 rims and I have those Q&As below, but first some words from the AC website:
“Many of our customers asked us for rims because to them, there is something personal in crafting their own wheels. Bill Shook responded to this call with the new high end AC rim line. Our initial focus is on performance tubeless mtb rims because of the demand for high quality, wide, lightweight tubeless rims for competition and training. With use of engineering, Bill created a 25mm wide rim profile in a high strength aluminum alloy that blends lightness with robustness. The rims use our proven bead barb technology to hook on the tire bead to help keep the tire in place without burping. Rims are hand joined and sleeved at our AC facility to assure roundness and uniform strength. After finishing, our AC rims are inspected by real people who carefully gauge and examine them to match our quality spec. The result is the highest quality rims that build up well, hold speed and handle decisively on the trails. 101′s are better than any other rim out there.”
Q&A With Bill Shook:
Answers from Bill Shook, Company President and Engineer, American Classic 4-5-13
TNI: This is quite new for you folks at AC (American Classic)…offering a rim only. Why did you do this and is this just the beginning of more stand-alone rims to come?
AC: Customers asked us for rims. There is growing trend that people like to build their own wheels, a craft movement. Disc 101 is the first model. It is made at our AC facility. We will have more rims for mtb and also for road for season 2014. They will be introduced at the Eurobike Show 2013.
TNI: AC is a believer in wide and light as far as rim design, or so I take it from your approach to things. Why is wider better?
AC: There are many reasons why wide is better. Wide rims mean riding lighter, smaller performance tires with cushiony, high air volume and firm surface grip. Larger width tires offer more air volume but they are heavy with a sluggish ride quality. The desired combined wheel and tire qualities are achieved by stretching out the smaller tire casing on a wide rim and effectively making the tire bigger. Also, smaller tires on wide rims reduce tire roll on the rims. With a narrow rim and a wide tire, the rim floats from side to side on the tire. Using a wider rim with a smaller tire minimizes float for improved handling, confidence and control. The rim is lower weight at the extreme outer edge of the wheel decreasing rolling resistance and boosting speed. Our wider, lighter rims translate into crisp accelerations, firm ground control, faster rolling on the flats and decisive handling for the extra edge needed by competitive athletes.
TNI: How do you balance out keeping weight down when you add cross section width to a rim?
AC: It is done mathematically. I set engineering goals of being light, stiff, strong, aerodynamic and wide. It is now a reality in our Disc 101 rims.
TNI: I see that 32 spokes is a pretty constant spec in your pre-built wheels and this is true with the 101s as well. Yet many wheels on the market run 28 or even 24 spokes. Why is this not true for AC MTB wheel products?
AC: 32 spokes builds a stiff, strong, durable wheel a perfect combination with our light rims including Disc 101 rims. Many companies go to lower spoke counts as a way to lighten the wheel and this design choice compromises the overall stiffness and durability. We don’t have to make that compromise and offer the best.
TNI: The 101s are pretty light…381g ea in a 29er rim…and that is, to make an obvious comparison, right in there with a Stan’s Crest rim. The dimensions are similar but the 101 is a taller profile at 18mm. I have ridden Crest’s before and I found them to be marginal, stiffness wise, at my weight of 190lbs. Who is this 101 rim for…type of rider, conditions, etc?
AC: The Disc 101 rim is an excellent all around cross country tubeless rim for racing and training. I designed it with performance and durability in mind while still keeping it light. It is a top choice for larger athletes without compromising performance. It is very stiff due to the geometry of the rim profile. For the rider on a budget, the Disc 101 rims let you ride my great AC technology at a reasonable price. One ride and you will see.
TNI: This build that TNI has done, the 101s as an SS wheel set, was something we talked about in person before we went forward with the build. We talked about my weight, intended use, hubs (non-dished SS rear hub), etc, and decided it was a reasonable build. How does a potential buyer of the 101 rim come to that same place? How do they know what is right for them?
AC: That’s an interesting question. We can only discuss the rim as it stands for this Q & A. The rider/wheelbuilder chooses the hubs, spokes, nipples and type of build (3 cross etc). That is the crafting element of wheelbuilding that people enjoy. If the rider/wheelbuilder contacts us to discuss their personal options in relation to our Disc 101 rim, we are available to assist in the decision making process as we did with you when you spec’d this build. We are happy to offer our technical expertise in wheelbuilding to our customers.
TNI: Let’s talk tubeless. What do you do to make your rims a solid set-up for tubeless use? In general, I think that the state of multiple ‘standards’ in the bicycle industry as it relates to tubeless set-ups is a mess for the consumer. Some tires do not fit some rims well, UST vs. others, etc.
AC: I designed all our AC tubeless rim with a bead barb running along the edge of the bead shelf. When installed, the tire firmly pops into position over the bead barb. The tire bead centers and tightly grips the circumference of the rim creating a sealed environment to hold the liquid sealant without burping.
Quality control on soft goods like tires can be challenging. Hard items like rims can be accurately measured with a QC protocol, they either to spec or not. Tires are stretchy and difficult to measure consistently in a QC protocol, hence there are tires that do not fit. Sometimes carbon beads are damaged if they get bent and broken in packaging or installation. This problem will cause the tire to come off.
Tubeless ready tires usually work best. I don’t care for UST tires because they are heavy, inflexible (poor ride quality) and hard to install.
We have excellent tubeless installation directions on amclassic.com If the rider follows the directions, they can easily accomplish tubeless set up for our wheels.
TNI: Any thoughts on the future of MTB wheels? Are we past due for a new standard that finally gives us a proper wide front hub to get a stiffer wheel? Will carbon come in and be the new high end choice as costs come down (IF they do come down)? 5 years from now, what might our typical MTB wheel look like?
AC: The idea of a wider front hub giving a stiffer wheel is not a good idea and will decrease performance. As the flange spacing becomes wider, there is more side to side force from each spoke and less radial. The fastest wheels are the lightest rims and tires balanced by performance and durability. Meaning a wheel can be very light but if it does not perform or falls apart, it is no good. If the rim must resist more side loads and the peak loading is increasing because of the radial loads being carried at a less advantages vector angle, then the rim must become heavier to survive. This is not a performance increase.
Carbon is not the best choice for impact loading. Carbon should not be built too close to the limit because the failure mode is catastrophic. If it breaks, it will fail utterly and collapse. If it is overbuilt to avoid such a failure, then it does not have a competitive advantage over aluminum. Aluminum can be built much closer to the edge because the failure mode is bending not breaking. It does not make sense to pay a large amount of money for a rim that is not better than an aluminum rim, and in fact may be not as good. There may be a design using carbon or another mix of materials in the future to solve these inherent problems. Also the price of carbon is not going to come down drastically.
In 5 years from now, we may see much wider rims but with smaller tires to get the same air volume with much less weight. It may be reasonable to ride 1.65 to 1.75 tires on 32mm rims or more. This will reduce the rolling weight but keep the air volume and that makes higher performance. We may also see new materials to allow lighter rims.
I weighed the 101 rims at 380g/383g, well within spec. They have a fairly deep center channel in the rim compared to the typical AC rim. I also set them up with the tape and swanky alu tubeless valve stems from AC. The valve stems I like, but I have mixed feelings with the golden tape. It is fragile and you need to be careful NOT to pre-stretch it when applying which, if you have installed a Stan’s tape before, is not what you would expect to do. It is finicky to lay down smoothly and the first wrap failed on me by splitting at the valve stem hole (which I melted in). However, I had installed the tape the first time with tension (stretch) and that was my error…think about an inflated ballon and a sharp pin…so the second time I applied it with hardly any tension. Still finicky, but better. You will need that second o-ring on the valve stems to seat well on the new rim shape. The look of the rims is subdued for sure, in fact, I would not mind a bit more pizazz graphics wise, but better to show restraint than have a rolling billboard. The suggested retail of the 101 rim is $99.00 each.
For the hubs, I chose a set of Sun Ringle Dirty Flea (yep, odd name) SS hubs.
Bike Type: XC, Trail, All Mountain, Dirt Jump
Rear Hub Specs:
- 6061 T6 Alloy Body
- 7075 T6 Alloy Axle
- Four sealed cartridge Bearings
- Bolt On – 10mm
- Lock Ring Included
- QR End Caps Available Separately
- 28,32 Hole Count
- 335g – Without Bolts
- 395g – With 10mm Bolts
I weighed them at 172g (15QR) for the front hub and 398g for the rear including the axle bolts. The serious looking bolts are an option and weigh 29g per set (bolt/cap). As a pair, they weigh about what a typical 5mm QR assembly would be and these two 3/8″ bolts will hold the world in place if need be. I spoke to Scott Boyd of Sun Ringle about the revised hubset and this is what he had to say.
The Dirty Flea Single Speed is all new. We knew that single speed riders put more torque into the hubs, and FH bodies and axle durability were the issues we heard about our competitors hubs. Here are some things we did for ours:
- Qty 4 6902 Bearings – qty 2 in the hub shell and qty 2 in the FH body.
- 15mm Diameter Axle (OD) – larger diameter for strength
- 3/8” Bolts to fasten to frame. The bolts act as the dropout and fastener. Strong and burly, but comparable weight to a skewer.
- Aluminum FH body for light weight
- Length of the FH body was designed to fit with belt drive system…or plenty of room for chain line adjustment.
- Wider hub flange for even spoke tension
- 142×12 Compatible – Axle and end cap change
- Included with lock-ring (you know the one thing you always forget to order) [A nice, red, alu lock-ring, I might add. Editor]
The hubs are not the lightest, but the cost is reasonable for the grams you get. The front hub in 15QR guise (convertible down to 9mm) is $110 suggested retail and the rear hub that is convertible to 142×12 (extra cost for conversion kit or order it that way from the beginning) is MSPR $215.00. That is a rare bird right now…an SS freehub-type rear hub that goes 142×12. They feel like they have very little drag in the hub, both in the free hub pawls and the bearings. Supposedly these tested out as some of the fastest rolling hubs Sun Ringle has, so that bodes well for SS use where momentum is a precious commodity. The engagement is OK at 15 degrees and I am told that there is a pretty easy upgrade path if you need a faster take-up. They are decently quiet as well, if that is important to you.
We used DT Swiss Comp spokes and alloy nipples to complete the build. JeffJ did the build and he was pleased with the way the 101s tensioned. The final numbers were as follows: The 15QR front wheel with no valve stem or tape was 767g and the rear wheel with bolts/caps and no stem or tape was 997g. Total that and you get 1764g. Not flyweight taken as a whole, but that is a light rim so if it runs well down the trail, that should be a good feeling wheelset being that the extra weight is in the hub-set, if any.
So what to run them on? Well that is coming right up as we do a refresh on a nice steel SS frame, discuss the component choices and set-up and then go riding.
Note: Sun Ringle’ and American Classic sent over their products at no charge to Twenty Nine Inches for test and review. We are not being paid, nor bribed for these reviews and we will strive to give our honest thoughts and opinions throughout.