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by Matt Wikstrom
May 4, 2016
Photography by Matt Wikstrom
TECH NEWS BROUGHT TO YOU BY BIKEEXCHANGE
Custom wheelbuilders have a great range of high-end hubs at their disposal, but when weight is an important priority, the field narrows considerably. Extralite’s CyberFront and CyberRear hubs stand out as some of the lightest on the market. In this review, Australian tech editor Matt Wikstrom takes a closer look at these hubs.
Extralite is an Italian company that was born in 1995. Starting with just a small selection of alloy parts, the company has grown along with its catalogue. There are now parts for road and off-road use, ranging from skewers, hubs and entire wheelsets to cockpit and drivetrain components.
Every part is made in Italy with an emphasis on weight minimisation without sacrificing safety and reliability. CNC-machining is used extensively to create Extralite’s alloy parts, paring away at non-critical mass to yield the minimum structure that is able to contend with the loads placed upon it.
Extralite created its first road hubs more than 10 years ago, the so-called UltraFront and UltraRear hubs. Weighing a combined 221g (front, 62g; rear, 159g), the hubs quickly caught the attention of weight-weenies around the world (for reference, Dura Ace 9000 front and rear hubs weigh 121g and 248g, respectively).
2014 saw the introduction of the CyberFront (49g) and CyberRear (134g) SL hubs that were built to suit standard j-bend spokes, followed more recently by a version (CyberFront SP and CyberRear SP) for straight-pull spokes (front, 49g; rear, 129g). Both versions are now some of the lightest on the market, competing for the attention of weight-weenies against brands like Tune and Dash.
I was recently given the opportunity to not only ride Extralite’s CyberFront and CyberRear SP hubs, but to also build a set of wheels with them, thanks to one of the company’s Australian retailers, Skunkworks Bikes.
CyberFront and CyberRear SP hubs are CNC-machined from what Extralite refers to as “special 7075TX” aluminium alloy. 7075 is a common choice for hubs, and while it is a strong and hard alloy, Extralite goes to the trouble of heat-treating the flanges for extra strength.
The front hub makes use of a 14mm alloy axle while the rear hub uses a 17mm alloy axle. A simple locknut threads onto each axle so that any play between the bearings and the axle can be removed, however there is no locking mechanism to stop it from unwinding.
The axle must be removed from the front hub in order to install the spokes.
A simple locknut allows any play between the axle and bearings to be adjusted.
The rear axle must also be removed before straight-pull spokes can be installed in the non-drive-side flange.
Installation of the drive-side spokes is much simpler.
An o-ring keeps the pawls in place and provides the spring for the freehub.
The freehub design saves weight and is relatively simple to service.
Enduro supplies its Grade 5 cartridge bearings with steel ball bearings for each hub. There are two bearings in the front hub and four in the rear. Extralite adds hard-anodised end-caps to the axles to make them more resistant to clamping forces.
The alloy freehub body is also hard-anodised, and is available to suit Shimano/SRAM or Campagnolo cassettes. The SRAM/Shimano version uses the standard spline pattern while the Campagnolo version has been pared back to four ridges. The absence of splines mean that the cogs can be installed out of sync, so extra care is required to keep the shifting ramps properly aligned.
The freehub pawls and drive ring are made from titanium, but interestingly, Extralite opt for a simple o-ring to retain the pawls and serve as a spring. Compared to other designs, Extralite’s design appears crude, perhaps even primitive, but it serves to keep the weight of the rear hub very low. At the same time, the mechanism is very quick and easy to service.
The CyberFront SP hub is available in four drillings (16/18/20/24 holes) while the CyberRear SP hub is offered in three (20/24/28 holes). There are two colours on offer, black or silver, though the latter is only offered in pre-configured hub sets (front/rear 16/20, 20/24, or 24/28 holes).
Curve’s 38mm carbon clincher rims were laced to the hubs with Sapim CX-Ray spokes.
For this review, a 20-hole CyberFront and 24-hole CyberRear SP hub were mated with Curve 38mm carbon clincher rims with Sapim CX-Ray spokes and DT Swiss hex-head alloy nipples.
Building up wheels with radial spokes is normally quick and easy, but in this instance, the hub axle must be removed in order to install the spokes. This was necessary for both hubs since the non-drive-side side of the rear hub also uses radial spokes. That the left flange of the front hub is also removable complicates the build a little more.
Extralite provides a chart to help with selecting spoke length for each hub, but according to Zak Smiley at Skunkworks Bikes, it takes some practice to use it properly. I don’t expect many home mechanics to tackle a wheel build like this, but for those that are considering the challenge, it’s best to get some guidance on spoke length from somebody that’s worked with the hubs before.
Tightening alloy nipples with a conventional spoke key inevitably results in tool marks, which is why hex-head nipples are a better choice. DT’s hex-head alloy nipples can be tensioned from within the rim with a 5.5mm hexagonal driver to leave the external portion completely unmarked.
DT Swiss hex-head alloy nipples.
Experienced wheelbuilders may have noticed that the flange diameter on the left side of the rear hub is very small, which means longer spokes and therefore less spoke tension. I found that the final tension was less than 40% of the right-side spokes when most other hub designs allow for a ~50% differential.
Less spoke tension on the non-drive-side spokes increases the risk of the nipples unwinding as the wheel is put to use. It also produces extra stress on the spokes as they are loaded and unloaded with every turn of the wheel. While the former can essentially be eliminated through the use of a locking compound on the spokes and/or in the nipples, the latter limits how much load the wheel can withstand.
At the very least then, the CyberRear SP hub demands a high quality spoke, and in this instance, the straight-pull Sapim CX-Ray spokes supplied for the build represent some of the strongest on the market. Nevertheless, the CyberRear hub is best suited to small riders and light loads (even though Extralite does not impose a weight limit on the riders that can use their hubs.)
Once built, the Extralite wheelset weighed 1,294g (front, 601g; rear, 693g) with rim tape sans skewers, an impressive achievement considering the relatively heavy 38mm carbon clincher rims. By contrast, AX Lightness has managed to create a 790g wheelset by pairing the hubs with their low-profile carbon tubular rims.
Buyers can expect to pay AU$900/US$599/€578 for a set of CyberFront and CyberRear SP hubs. The hubs are supplied with a two-year warranty and a choice of a Shimano/SRAM or Campagnolo freehub body.
It’s important to note that skewers aren’t included in the price of these hubs. This is typical for high-end hubs, acknowledging that skewer choice is perhaps as personal as the choice of pedals for a new bike. For those buyers keen to save more weight, Extralite’s Streeters skewers weigh just 30g for the pair and cost AU$190/US$135/€119.
Extralite hubs are stocked by a variety of retailers around the world or shoppers can buy direct using Extralite’s webshop. For more information, visit Extralite or get in touch with Skunkworks Bikes.
From the outset, I should acknowledge that there’s not much that can be determined about the performance of a hub once it is laced to a rim and fitted to a bike. At the very least, the rim and tyres largely dictate the performance of the wheel, so the hub generally won’t have any influence on the feel of the wheels (though I’ve reported on one very remarkable exception).
Having reviewed Curve’s 38mm carbon clinchers on a previous occasion, and spent more time on another set while reviewing a pair of Ritte bikes, I was able to largely anticipate the performance of these wheels.
In short, they were smooth, stiff and light. The mid-profile rims were as versatile and efficient as I’ve noted previously, and provided a race-oriented edge to the performance of the bike.
I didn’t notice any flex in the rear wheel despite the low spoke tension on the non-drive side. At 75kg with a modest power output and a preference for solo rides, I didn’t expect to challenge the rigidity of the wheels, however I did tackle a variety of paved roads as well as unpaved tracks, and the wheel remained sturdy and true.
Perhaps the most pressing question is whether the weight that the hubs save has any effect on the performance of the wheels. I didn’t have another set of Curve 38s on hand with heavier hubs for a direct comparison, but I was able to compare the Extralite build with a set of 38mm carbon clinchers made by Irwin that weighed an extra ~300g (1,588g with tape, sans skewers).
Back-to-back, there wasn’t a lot to notice. I found the Extralite wheelset was marginally easier to accelerate on any incline; otherwise, the wheels were very evenly matched. Indeed, I suspect I would have had a lot of trouble picking one from the other in a blinded test.
The results of this comparison aren’t especially surprising because the weight savings offered by Extralite hubs are at the centre of the wheels. Conventional wisdom holds that rotating mass is far more significant, and my impressions are entirely consistent with this notion. Weight-weenies will always argue that any weight saving is worth something to the performance of the bike, but given a choice, I’d rather spend extra money on lighter rims than lighter hubs.
I didn’t spend enough time on the Extralite hubs to get a feel for their service interval, but Zak at Skunkworks Bikes stresses that the hubs should be serviced once every three months. The freehub runs on a light grease (Extralite’s own formulation called Alugrease Super1) that needs to be replenished, but given the simplicity of the hub design, it’s a 10-minute job that shouldn’t be much of a challenge for an experienced home mechanic.
One final note: the front hub flanges have very wide spacing, perhaps the widest of any road hub. As a result, the design leaves very little room between the spokes and the fork legs. Zak has encountered one instance where the fork legs were too wide near the dropouts to accommodate the wheel, an unfortunate mismatch that was discovered after it was too late.
Anybody that gets a chance to handle Extralite’s CyberFront and CyberRear SP hubs will likely be impressed by the low weight, smooth bearing action and high quality feel. And according to Extralite’s testing, the hubs are robust enough for daily use by most riders, so the only apparent obstacle to their general appeal is the asking price.
A hubset like this really demands lightweight rims and spokes to do it justice, and while it will bring a weight saving of ~200g to any build, the expense associated with the hubs won’t translate into something the owner will feel out on the road. Far better to capitalise on the weight that will be saved by choosing the kind of rims, spokes, and even nipples, to create a truly lightweight wheelset.
It is in that context that Extralite’s Cyberhubs will truly shine.