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by Matt Wikstrom
September 6, 2016
Photography by Matt Wikstrom
TECH NEWS BROUGHT TO YOU BY BIKEEXCHANGE
Born out of the enthusiasm of two professional racers and mechanical engineers, Alto Cycling has designed its own wheel system to make a grab for a piece of the ultra-competitive wheel market. In this review, Australian tech editor Matt Wikstrom takes a close look at the company’s CC40 carbon clincher wheelset.
Bobby Sweeting and Shawn Gravois founded Alto Cycling in 2014 on the strength of a hub design that the two envisaged while studying mechanical engineering at the University of Florida. Shawn had just completed a Masters degree and Bobby had been working in the industry for two years, so they knew enough to tackle the project without knowing too much to put them off.
For Shawn and Bobby, the wheel was an obvious product to tackle because it holds the greatest potential for improving the performance of the rider. And as devout racers, they also had a wealth of personal experience to draw upon.
Their confidence was fuelled by enthusiasm for their R-Symmetric hub design. If nothing else, they felt certain that a fresh patent application and long hours of modelling the relationship between hub geometry and lateral wheel flex could be parlayed into a catchy headline regarding efforts to reinvent the wheel.
A huge right flange diameter and radial drive-side spokes define Alto’s R-Symmetric hub design.
In the end, Bobby was able to find investors for Alto Cycling and the company was able to get off the ground. I’m sure there were numerous challenges along the way as Bobby and Shawn sought to find a U.S. manufacturer for their hubs and a Taiwanese partner for building rims according to their specifications.
Nevertheless, Alto Cycling started selling wheels under the name Alto Velo in 2015 and was title sponsor for a domestic racing team when a lawsuit was brought against the two by a Californian cycling club. Sweeting had overlooked the importance of the club’s rights to the name “Alto Velo” when deciding on a name for the company. The complaint was eventually settled however the racing team had to be scrapped at short notice.
For 2016, the company is trading as Alto Cycling (using Alto as its brand name) and concentrating on increasing brand awareness along with gaining a foothold in the international market. The company’s website continues to serve as its primary retail portal, however dealers have been appointed in the U.K., Europe, South America and throughout the U.S.A.
All of the wheels in Alto’s current catalogue use the company’s R-Symmetric hub design that is characterised by an oversized drive side flange with radial spokes. Buyers have a choice of one low-profile alloy wheelset, three carbon clinchers (40, 56, and 86mm rim profiles), and three carbon tubulars (also 40, 56, and 86mm rim profiles).
For this review, Alto Cycling supplied a set of its CC40 (40mm) carbon clinchers that has a recommended retail of US$1,900 (~AUD$2,500).
Each of Alto’s wheels is designed and built as a system, much like the bigger factory brands like Mavic, Shimano, and Campagnolo/Fulcrum. The company’s R-Symmetric hub sits at the core of the design, dictating the spoke lacing pattern and the angle of the nipple holes in the rim.
Bobby Sweeting goes into detail about the important elements of R-Symmetry on Alto’s website, but any appreciation of it really demands a good understanding of the importance of hub geometry to spoke tension in the rear wheel.
I’ve touched on some of these elements previously, where the ideal wheel is both round and laterally true with even spoke tension on both sides of the wheel. The rear cogs introduce asymmetry to the rear wheel though, and as a result spoke tension on the drive-side of wheel is always greater than the non-drive-side.
This imbalance reduces the long-term durability of the rear wheel because it produces an excess of stress on the non-drive side spokes. Over the years, wheelbuilders and manufacturers have explored a variety of strategies for alleviating some of this imbalance.
Among the various strategies are differential lacing patterns, asymmetrical rim designs, and differential flange diameters. All aim to reduce drive-side spoke tension and/or increase non-drive-side tension. However any design must take heed of other considerations such as the bracing angle for each spoke, which plays an important part in determining the lateral stiffness of the wheel.
Alto’s R-Symmetry starts with differential flange diameters for the rear hub. At almost 110mm (109.7mm), the diameter of Alto’s drive-side flange is more than twice that for the non-drive-side (48.5mm). A differential lacing pattern is used to build the wheel, with radial spokes on the drive-side and two-cross for the non-drive-side. And in order to maximise the bracing angle for the drive-side spokes, the heads of the j-bend spokes are oriented inwards.
Alto is not the first company to use radial drive-side spokes. In the past, Mavic, Zipp and Shimano have all made use of the same strategy in concert with crossed-spokes on the non-drive-side, just as Alto does. In this instance, Alto finds the R-Symmetric hub alleviates the difference in spoke tension for the drive- and non-drive-side of the rear wheel, claiming a drop of just 35% (i.e. the tension of the non-drive-side spokes is 65% of the tension for the drive-side spokes) compared to 50% for conventional hubs.
Alto is also proud of the extra spoke bracing that R-Symmetry provides, which is at least 0.5° greater than other brands. When combined with a better balance of drive- and non-drive-side spoke tension, there is the promise of a stiffer wheel, and Alto’s testing appears to confirm this.
As mentioned above, Alto’s carbon rims are made in Taiwan according to their specifications. The company pays particular attention to the angle of the nipple holes, ensuring that they are drilled to suit the R-Symmetric hub design. Expanded polystyrene mandrels are used rather than bladders for moulding the rims to reduce the risk of defects and voids in the layup, and according to Alto, lab testing (e.g. impact resistance and brake track heating) is performed over the equivalent of 40,000 miles (64,000km).
Such testing has demonstrated that the R-symmetry design achieves a significant reduction in spoke fatigue as well as any kind of fatigue in the hub. However, all of the experienced wheelbuilders I spoke to still worry about the wisdom of using radial spokes for the drive-side of the rear wheel. In this regard, it’s worth noting that Mavic, Zipp and Shimano have all abandoned this strategy.
There is an expectation from consumers that mid- and high-profile carbon rims provide some kind of aerodynamic advantage. The team at Alto was more concerned about structural integrity, lateral stiffness, and ride quality, though CFD (computational fluid dynamics) was used to analyse the final profile. According to Bobby Sweeting, subsequent wind tunnel testing confirmed that their wheels are competitive but he is reluctant to make any claims because aerodynamic drag is subject to far too many variables (e.g. different frame designs influence the outcome).
Going through the specifics, the CC40 rim is 40mm tall and measures 26mm at the brake track. The semi-toroidal profile has a maximum width of 27.5mm while the rim bead measures ~19mm (17mm between the hooks). The front wheel has 20 spokes (laced radially) and the rear has 24 spokes (laced radially for the drive-side and two-cross for the non-drive-side). Alto uses j-bend Sapim CX-Ray spokes to build all of its wheels.
Alto’s hub shells are made from 6061-T6 aluminium alloy, while 7075-T6 is used for the oversized alloy axles and caps. One end of each axle is threaded so that the preload on the angular-contact cartridge bearings can be adjusted. The freehub comprises four leaf-spring pawls and a ratchet ring with 48 teeth.
Radial lacing is used for the front hub with the spoke heads facing outwards.
One end of each axle is threaded for adjustment.
The radial lacing pattern used for the drive-side -f the rear wheel orients the spoke heads inwards.
The freehub mechanism has four pawls, and each pawl has three engagement points.
The CC40 wheelset provided for this review weighed 1,589g (front, 692g; rear, 897g) without rim tape or skewers. It’s worth noting that there is no weight limit for the CC40s or any other of Alto’s carbon wheelsets, and Alto insists that Swissstop Black Prince brake pads must be used at all times.
The CC40 wheelset sells for US$1,900 (AUD$2,500). Buyers have a choice of eight colours (green, grey, red, blue, orange, yellow, pink, white) for the wheel decals. All of Alto’s wheels are handbuilt in Sarasota, Florida and are supplied with a choice of 11-speed Shimano/SRAM- or Campagnolo-compatible freehub, nylon rim tape, a pair of skewers, two pairs of Swissstop Black Prince brake pads, and a two-year warranty. For more information, visit Alto Cycling.
The CC40 wheelset supplied for this review was fitted with 25mm Continental GP4000 S II tyres. At 70psi, the tyres measured 27mm wide thanks to the relatively wide rim profile.
Before I started riding the wheels, I was interested to compare the average spoke tension for the non-drive- and drive-sides of the rear wheel, and found that it was 60kgf and 120kgf, respectively. According to Alto, there should have been a much smaller differential in tension for the non-drive-side spokes (~35%), but this wheel only achieved 50%.
For comparison, I measured the spoke tension for a Shimano RS21 rear wheel, which has an asymmetrical rim for alleviating the tension differential, and a Campagnolo Bora Ultra 35mm rear wheel, which employs a triplet-lacing pattern for the same reason. The Shimano wheel exhibited a differential of 41% (65kgf versus 110kgf) between each side of the wheel while the difference for the Bora 35mm wheel was 36% (70kgf versus 110kgf).
When I mentioned the results to Bobby Sweeting, he was surprised that the non-drive-side spoke tension was so low, but couldn’t explain why that would be. There was no problem with the dish of the wheel, and while the spoke tension was a little uneven, the CC40 was round and laterally true.
Out on the road, the CC40s performed exactly as I expected for a 40mm carbon clincher. A sub-1,600g wheelset is light enough for me to tackle any terrain, but not so light as to make me think my climbing ability has improved. At the same time, the rims manage to duck all but the strongest crosswinds, so they are well suited to everyday use.
Alto targeted ride quality as one important parameter for their carbon rims; another was lateral stiffness. Regarding the first goal, the CC40 managed to hit the sweet spot for my weight (~75kg), such that the wheels felt firm and robust without ever being harsh. As for the second goal, I never noticed any brake rub, and when fitted to a bike with barely enough clearance at the chainstays for the 27mm wide tyres, the paintwork remained scuff-free.
The CC40s rolled quite nicely at high speeds but I never had a great sense that the wheels were providing me with free speed. I’ve compared different rim depths in the past, with the result that a taller rim profile is always faster (provided that I’m motivated to ride at high speeds). Nevertheless, the CC40s look the part with a rim profile that is tall enough to look fast without ever being impractical.
I’m a fan of wide rims so I enjoyed riding the CC40s. The extra width at the rim bed makes for a wider tyre (Continental’s 25mm GP4000 S II measured 27mm on these wheels), which translates into extra grip and comfort provided the user lowers inflation pressures. Even larger, heavier riders will be able use lower tyre pressures with rims as wide as the CC40 without a noticeable reduction in rolling resistance.
The quality of braking offered by the CC40s was very good. I’ve used Swissstop’s Black Prince pads on a few other carbon wheels, and they have always been a sure performer. For those riders coming from alloy rims, there will be a noticeable difference for any carbon rim, however braking more aggressively is normally enough to make up for the shortfall.
At the end of the review period, the CC40s were still round and true, though a few weeks of riding can hardly be counted as a long-term test. I didn’t have any issues with the hubs either, and overall, these wheels can be counted as a sturdy, versatile offering.
Overall, Alto Cycling’s CC40 wheelset resembles a lot of other carbon clinchers on the market, both in terms of pricing and performance. Alto has attempted to distinguish its wheels with distinctive hub geometry, but based on spoke tension measurements reported above, the R-Symmetry design fails to deliver on its promises.
That’s not to say that there are any defects in the design of the hub per se. The difference in spoke tension measured for the CC40 rear wheel is no worse than the industry norm, so I don’t expect buyers are going to suffer an increased risk of broken spokes. That Alto makes use of Sapim’s CX-Rays, a spoke with enormous tensile strength, promises that the CC40 will be a robust and durable wheelset.
Of course, there may be more to the CC40 than what can be measured with a spoke tension meter and a few weeks of riding. I’ve not seen the results from any of Alto’s lab testing, and I’m not privy to feedback from any of the company’s customers, so I’m reluctant to judge the CC40 harshly. Indeed, the CC40 may be no better or worse than many of its competitors, but as a new company in a very competitive market, the risks seem a little higher than most.