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by Matt Wikstrom
August 23, 2017
Photography by Matt Wikstrom
There has been enormous growth in the high-end carbon wheelset market in recent years, yet only one wheel has been there from the beginning. Introduced at a time when carbon fibre was still a novel and exotic material, Campagnolo’s Bora wheelset has steadfastly served racers for over 20 years.
There are now three Bora models to choose from and in this review, Australian tech editor Matt Wikstrom takes a look at how the Bora Ultra 50 clincher performs.
If there was ever a wheelset that didn’t need an introduction, it is Campagnolo’s Bora. The iconic wheelset, which takes its name from the northerly wind that blows over the Adriatic Sea, has been in the professional peloton for the last two decades yet its opulence and desirability has not faded.
When Campagnolo introduced the Bora wheelset in 1994, the all-carbon 50mm rim was laced to alloy hubs (8-speed) with 16 spokes, front and rear, for a total weight of little more than 1,600g. It was a purebred racing wheelset and remained tubular-specific for 20 years until a clincher version was introduced in 2015.
The Bora range now comprises three rim profiles for tubular tyres (35/50/80mm) and two for clinchers (35/50mm). The options for the 35mm and 50mm rims are further divided into two builds: the Bora Ultra version features a cost-be-damned carbon hubset while Bora One wheels have alloy hubs that lower the asking price by ~30%.
The candidate for this review was the Bora Ultra 50 wheelset with clincher rims, which weighs in at 1,420g (front, 623g; rear, 797g) without skewers, and sells for a recommended retail price of €3,065 (AUD$4,100/US$3,900).
The Bora Ultra 50 wheelset shares almost all of the same features as the Bora Ultra 35 wheelset that I reviewed a few years ago. The hubset, spokes and lacing pattern remain unchanged, however the rim profile was updated with the addition of a clincher rim for 2015.
As a result, the external width of Bora 35 and 50 rims increased from 20mm to 24mm and a 17.2mm bed (measured hook-hook) was provided for clinchers. At the same time, the angles of the traditional V-shape profile were softened to create a slightly rounder version, however the rims remain distinct from the toroidal shapes of other brands.
The major reason for increasing the width of the rims was to preserve the aerodynamics of the wheels when wider tyres (25C) are installed. And by softening the angles of the rim profile, Campagnolo appears to have made some effort to keep pace with new thinking on aerodynamic rim profiles. Nevertheless, the NACA airfoil shape that served as the template for the Bora is decades old.
Now, it is generally accepted that toroidal profiles offer superior aerodynamics for bicycle wheels because air can flow as easily in both directions over the tyre and rim (i.e. the rim is just as good as the head or tail of the foil it forms with the tyre). In contrast, a V-shaped rim functions much better as the tail of a foil than its head, so when it becomes the leading edge of the wheel (i.e. downwind of the front hub), the difference in airflow slows the wheel down and affects its stability.
So what kind of aerodynamic penalty does that mean for the Bora? Unfortunately, data on the relative performance of the Bora 50 versus toroidal wheels is sparse, at least in the public domain. Wind-tunnel testing from 2008 reported that the 2005 Bora G3 wheelset absorbed 16% more power than Zipp’s 404 from the same era while a more recent study carried out in Taiwan indicated that the Bora 50 suffered 12-38% (depending on the yaw angle) more drag than Zipp’s Firecrest 404.
While the exact penalty may be moot, it’s clear that the Bora 50 gives up some ground to toroidal rims, and therefore, is unlikely to woo aero-weenies. Be that as it may, the differences that can be measured within a wind tunnel are far greater than what will ever be experienced in the real world. That’s because the rider accounts for the bulk of aerodynamic drag (~70%) compared to a minor component for the wheels (~10%). For those hunting for marginal gains, such differences might make a difference, but for everybody else, it may not be felt at all.
The rim bed of the Bora rim does not have any holes for the spoke nipples. This makes it easier to glue tubulars and there is no need to install rim tape for clinchers. Importantly, Bora clinchers are not tubeless compatible. And in the event of a broken spoke, extra time may be needed to guide a new nipple through the rim using a magnet.
One other feature of the Bora rim is that extra layers of carbon fibre are used to offset the weight of the valve stem and balance the wheel. These layers are hidden within the rim, directly opposite the valve, so they can’t be adjusted to suit different valve types/lengths. Nevertheless, the wheels sent for review exhibited only a slight imbalance (in favour of the valve stem) once the tyres and tubes were installed and rotated smoothly at high speeds.
Every Bora wheelset is hand-built using proprietary straight-pull stainless spokes and external alloy nipples. The front wheel has 18 spokes laced in a radial pattern while the rear wheel uses 21 spokes and Campagnolo’s G3 Geometry. This lacing pattern is a variation of triplet lacing where every spoke on the non-drive-side is positioned in between a pair of spokes on the drive-side. Thus, there are twice as many spokes on the drive-side of the rear wheel.
This lacing pattern does a lot to equalise the tension of the spokes on each side of the rear wheel. The amount of tension on the non-drive-side spokes is typically half that of the drive-side spokes for a conventional rear wheel. In the case of the Bora 50, it is significantly higher: ~70% of the drive-side tension. By reducing this differential in spoke tension, G3 Geometry creates a more robust wheel that is less prone to spoke fatigue.
The geometry of the rear hub adds to the robustness of the rear wheel. The diameter of the drive-side flange is significantly larger (68mm) than the non-drive-side flange (38mm), which improves the bracing angle of the spokes, and hence, the lateral stiffness of the wheel.
As mentioned above, the Bora Ultra 50 has a carbon hubset, which adds a lot of opulence to the wheelset while reducing the overall weight. Carbon is used for the shells of both hubs as well as all the flanges except the drive-side of the rear hub. By contrast, the Bora One hub shells are all alloy and add a little extra weight to the wheel set (44g).
Campagnolo is just one of two major manufacturers (the other being Shimano) that specifies loose-ball bearings for its high-end wheelsets. It’s a time-honoured design that is highly serviceable and individual components, such as the races, seals and bearings, can all be replaced when worn or damaged.
The Bora Ultra hubset has alloy axles and Campagnolo’s so-called CULT Technology, which comprises ceramic ball bearings and stainless steel races. The parts come together much like a headset with a threaded locknut for adjusting the amount of play in the axle and the tension on the bearings. The same alloy axles and ceramic ball bearings are used for the Bora One alloy hubset, however standard steel races and cones are used instead.
Bora hubs feature oversized alloy axles and loose-ball ceramic bearings.
A threaded locknut holds everything together.
There is a compression ring under the locknut that slides into the cone. The two parts must be separated before the axle can be removed.
A dust seal sits on top of the bearings.
A look at the ceramic bearings in situ.
Each component of the bearing assembly can be separated for cleaning and inspection.
The arrangement of parts is identical for the rear hub.
A couple of 5mm hex keys are needed to remove the end cap…
…then a 2.5mm hex key is needed to release the locknut.
Unwind the threaded locknut to get into the guts of the hub.
Compression ring and cone, in situ.
A small screwdriver can be used to lift out the dust seal.
The ceramic balls are held in place by a plastic retainer.
There are three-pawls in the freehub body held in place by one spring that encircles the body.
A look at the ratchet ring inside the hub. The drive-side bearings sit below the ratchet ring.
No discussion about a carbon wheelset would be complete without a word about the braking surface of the rims. The brake track of Bora rims is treated with 3Diamant, a proprietary process that involves some machining of the surface. It creates an extremely smooth track, yet Campagnolo claims that it also improves braking in both dry and wet conditions.
It is worth noting that 2018 Bora wheelsets will feature a new treatment for the brake track that has been dubbed AC3 (All Conditions Carbon Control). Comprising a change in fibre orientation and an obvious texture for the brake track, Campagnolo claims that AC3 bolsters braking in the wet by over 40% compared to 3Diamant, making for a tantalising upgrade to the wheelset.
The total weight of 1,420g (front, 623g; rear, 797g) of the wheelset is good for a clincher, but at a promised 1,215g, the tubular version is even better. As for the Bora One 50, the clincher version weighs 1,464g (front, 644g; rear, 820g).
Campagnolo’s pricing does a lot to preserve the opulence of its flagship wheelset. At a recommended €3,065 (AUD$4,100/US$3,900), Bora Ultra 50 clinchers are clearly a high-end product. For those considering the tubular version, they will save a little money (€2,830), while Bora One clinchers are much cheaper (€2,120/AUD$2,800/US$2,700).
The presentation of the Bora Ultra 50s suits its high-end pricing. The rims and hubs have a lustrous high-gloss finish that highlights the carbon weave like a set of high-powered showroom lights. The black spokes and nipples reinforce the stealthy intentions of the wheels while buyers have a choice of bright (white and red) or dark labels (grey) to finish off the package.
Every Bora wheelset is supplied with a choice of a Campagnolo or Shimano/SRAM freehub body, bright or dark labels, a pair of skewers, two pairs of Campagnolo’s proprietary brake pads, and a three-year warranty. For more information, visit Campagnolo.
I spent the entirety of the review period riding the Bora Ultra 50s fitted with 25C Continental GP4000S tyres. At 60psi, the tyres measured close to 27mm due to the 17mm rim bed. I found the tyres were a pretty tight fit, so a set of levers might be needed when installing and/or removing the tyres.
Overall, the Bora 50s behaved exactly as expected for a wheelset with 50mm tall rims, adding an aggressive poise to the bike while increasing its susceptibility to crosswinds. And in general terms, I couldn’t separate them from any other 50mm wheelset that I’ve ridden, such as Prime’s bargain carbon clinchers or Roval’s CLX 50.
There were, however, a few nuances that helped the Bora Ultra 50s shine a little brighter. First, there was the ride experience, which was preternaturally smooth in all regards; second, the wheels had a gentle ride quality that bordered on plush; third, the braking was ultra-smooth yet very effective; and fourth, the low overall weight really made for a versatile wheelset that I could leave on the bike for all but the windiest outings.
As a consequence, I not only enjoyed riding the Bora Ultra 50s, I started looking forward to the next outing. The wheels never disappointed me, and while I didn’t have to part with the cash, I started to feel like I was getting my money’s worth after just a few rides.
With that said, trying to dissect my experience was quite a challenge, since all of the various attributes seemed to come together to form something greater than the sum total. Nevertheless, some things were immediately obvious, like the quality of braking.
As I’ve already mentioned, the brake track of the Bora rims was incredibly smooth, as smooth as any machined alloy rim, yet the brake pads always managed to take a firm hold, at least in the dry. There was no vibration, harshness, or noise, and I found myself braking as late, and with as much confidence, as I would with an alloy rim.
This was not something that I fully appreciated for the Bora Ultra 35 wheelset during my initial review, probably because I was using less powerful callipers. Those wheels still serve the office, and going back to them, I found no difference in the quality of braking when compared to the Bora Ultra 50s.
Another attribute that stood out for me was how well the wheels rolled. There was no harshness to the ride quality, and in fact, they seemed to do a lot to quell vibrations from the road. I could do away with some of that plushness by switching to narrower tyres and higher pressures, but I’d rate the Boras as remarkably comfortable, not just for a 50mm wheelset, but in absolute terms as well.
That veil of quiet was not always welcome, though. When fitted to a carbon racing chassis like Chapter 2’s Tere, the Bora Ultra 50s complemented the overall feel of the bike. By contrast, the Boras toned down the ride quality of a steel and a titanium chassis too much for my taste, leaving me wishing for a little more feedback.
Underpinning the gentle ride quality was an ease that I suspect was a product of the balanced rims and the CULT bearings. Ceramic bearings have been celebrated for the power savings they can bring to wheels and bottom brackets, however the actual benefits fall firmly into the realm of marginal gains.
Interestingly, I couldn’t identify the same ease when riding a set of Bora Ones, so the CULT bearings may have had more to offer than the balanced rims. It was a fleeting nuance, to say the least, and it reminded me of my experience with Gokiso’s opulent Climber hubs. I wouldn’t put Campagnolo’s Ultra hubset in quite the same league, however it was very, very good. Is it enough to justify a 30% premium associated with the cost of the Ultra build? Hardly, but it does make the wheels feel a little more special.
The low overall weight meant the wheels weren’t a handicap in the hills. I was able to tackle all sorts of climbs without feeling weighed down by them, so I was never tempted to swap the Bora 50s out for something lighter. They always felt stiff and sturdy under load, and never really suffered from inertia when I wanted to lift my pace or attack the slope.
The only thing that limited the everyday appeal of the Bora Ultra 50s was the susceptibility to crosswinds. In light-moderate winds, I found the wheels reasonably easy to control and quite predictable, while strong gusts could tug on the front wheel with a fair bit of force.
In this regard, the Boras were no better or worse than any other 50mm rim I’ve ridden. I’ve had a lot of experience riding high-profile wheelsets, so I know what to expect, but for those that have yet to ride 50mm rims, a few weeks might be required to get comfortable with the wheels.
The Bora Ultra 50s remained smooth and comfortable at high speeds. Bombing down fast descents or winding the bike up in a tailwind, I was often unaware of the wheels, so it was easy to take them for granted. There were times when the Boras seemed to add to my speed, but that could have simply been a product of my enthusiasm. Having made the effort to measure the impact of other carbon wheels on my short-term speed and power, it’s clear that the influence of any wheel’s aerodynamics is marginal at best, but a sexy set of wheels can do wonders for one’s motivation.
Finally, the Bora Ultra 50s lived up to Campagnolo’s reputation for creating robust and reliable wheelsets. I had no trouble with the wheels coming out of true and the hubs remained smooth and free of play. That’s not enough to forecast the durability of the wheelset, but based on my experience with Campagnolo’s other wheelsets (including a long-term stint riding Bora Ultra 35s), I expect it will withstand everyday use without much trouble or complaint.
I received a set of Bora One 50s with Campagnolo’s new AC3 brake track a couple of months after I had completed my original review of the Bora Ultra 50. AC3 was specifically developed to improve braking in the wet. Where once the brake track was smooth, AC3 is textured with small arcs that have been cut into the resin.
Campagnolo’s AC3 brake track features a subtle texture created by a series of arcs etched in the resin.
That texture provides extra grip for the brake pads, and as a result, Campagnolo’s engineers had to make changes to the resin and the orientation of the fibres to contend with an increase in braking forces. Interestingly, no changes were made to the brake pads.
Unsurprisingly, the textured brake track added noticeably to the sound associated with braking. The previous 3Diamant treatment was smooth and silent under brakes; AC3, by contrast, produced a hum that increased in pitch with the force of braking to become a squeal.
This effect was very similar to Mavic’s Exalith brake track treatment, however AC3 doesn’t produce quite the same level of noise or vibration as Exalith. Indeed, AC3 retained most of the smooth braking sensation provided by 3Diamant (without a need to toe-in the brake pads).
Side-by-side, I found the pads seemed to have more bite on AC3 than 3Diamant. There were a few times when the extra grab surprised me and I found myself adopting a lighter touch when braking. That extra grab also inspired my confidence in the brakes in the wet, however there was still a small lag before the pads really started biting down on the rims.
I was able to perform a quick experiment to test the effectiveness of AC3, comparing the braking distance of the new Bora One 50s with a set of Ultra 35s with 3Diamant in both dry and wet conditions. I used the same bike and brakes for this test, which involved travelling at 35km/hr then measuring the distance required to come to a standstill. The results are shown in the figure below:
Comparison of braking distances for 3Diamant and AC3. One wheelset with each type of brake track was mounted to a bike that was accelerated to 35km/hr in dry and wet (raining) conditions. At a designated point, the brakes were applied until the bike came to a standstill and the distance was measured. This test was performed four times for each wheelset under both conditions. The results are plotted as average. Error bars represent the standard error of the mean. ** A paired student’s t-test identified a statistically significant difference (p=0.003) for AC3 in wet conditions.
In dry conditions, there was no difference in the braking distance for the two wheelsets. In the wet, there was some deterioration in braking for both wheelsets, resulting in ~30% increase in braking distances. Under these conditions, AC3 provided a marginal, yet reproducible, reduction (0.56m, 3.3%) in the braking distance.
At face value, these results fail to live up to Campagnolo’s claims for AC3 (up to 43% increase in braking performance over previous models), but after discussing the results with the company, it was clear there was a significant difference in the testing conditions. Campagnolo’s testing was performed with a significantly greater load (100kg versus ~85kg) at a higher speed (40km/hr versus 35km/hr); the company also concentrated on measuring the time taken to slow to 10km/hr rather than bringing the bike to a complete stop.
With this in mind, I’m satisfied that AC3 improves braking in the wet. Unfortunately, I didn’t have any other carbon wheels on hand to extend this comparison to other brands, but on the basis of braking confidence alone, Bora AC3 is the strongest performer I’ve ever experienced. Furthermore, it makes the Bora one of the few carbon wheelsets on the market where the quality of braking doesn’t feel like a compromise.
From the moment of its inception during the mid-90s, the Bora has been a dedicated racing wheelset to the point where Campagnolo resisted developing a clincher version until just a few years ago. Now buyers can enjoy the convenience of clinchers, and while it adds some weight to the wheelset, I’m sure the general appeal of the Bora has increased as a result.
At the heart of the Bora Ultra 50s is an ultra-smooth ride experience that is an absolute delight. It combines well with the relatively low weight of the wheelset and its gentle ride quality to shine in a variety of terrain. The ultra-smooth yet highly effective brake track elevates the Boras even further so buyers can enjoy the wheels almost every day. The only limitation is that the 50mm rims will catch the wind.
For those pondering what they might be missing out on by opting for the Bora One 50, it won’t be a lot, and for most purposes, the two builds will be indistinguishable. In fact, in practical terms, the Ultra build might be akin to adding pinstripes to a fully-worked race car, but there’s no denying the allure (or expense) that it adds to the wheelset.
There are, however, some downsides to this wheelset that deserve to be mentioned. First, there’s the exorbitant asking price. Second, the proprietary spokes are expensive and inconvenient to replace. Third, any other replacement parts are likely to be just as expensive. And fourth, the rim profile and bed width remains relatively narrow and out of step with current market trends.
Thus, the Bora Ultra 50 will not tick the boxes for every buyer, especially those concentrating on rim profiles that have been fastidiously refined to maximise marginal aerodynamic gains. In this regard, Campagnolo continues to steadfastly abide by its own vision and the result is a wheelset that eschews current trends yet provides a superb (but nuanced) ride experience that may be unmatched by any other 50mm carbon wheelset on the market.