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Coefficient Cycling's RR handlebar is a drop bar with an aero top, but also some specific ergonomic shaping, and an integrated GPS mount. There's some weight penalty, but it's comfortable, effective and, when well-configured, very easy to live with.
Like it or not, a rider comprises around three-quarters of the system drag of rider and bike, so anything you can do to optimise your position (as well as clothing, helmet, and so on), should benefit your cycling efficiency and save you energy.
Assuming you already have a good position on your bike, it is usually possible to adopt a more aerodynamic body shape on a conventional drop handlebar. With training, it can be maintained for a reasonable time, but with greater hand and forearm support it's possible to remain aero for longer, which can only be a benefit.
At first look, Coefficient Cycling's RR bar challenges what we're used to, but it retains a conventional handlebar's essential positional reference points, and plays around with the bits in between.
The stem clamps to a short round section, which actually aligns perfectly with the bend into the drops, except that instead of joining the two points, the RR bar extends forwards, creating the arrow-shaped loop that supports the integrated GPS mount, while each side of the tops begins from an elevated position, sweeping downwards and rearwards to the drops.
It's this aspect that Coefficient Cycling has patented as 'Swope', meaning sloping, sweeping bar tops. It's claimed to relax your upper body and improve respiratory and neuromuscular function. The slope is 15 degrees, with 12 degrees of back sweep, and the drops have 7 degrees of flare.
The RR bar is constructed from Toray UD carbon fibre and is supplied with your choice of easily swappable GPS mount for Garmin, Wahoo, Lezyne, Polar, Cateye, Bryton, Joule, Hammerhead, Magellan and Mio. The underside of the GPS mounting bridge is also drilled for a proprietary GoPro mount, and I expect a light could be fitted there too, although there's likely to be an adverse effect on aerodynamics.
The 313g weight of our 42cm test handlebar includes the rubber grommets and bungs, a GPS mount, plus a pair of cable guiding tubes on each side.
It's available in 38, 40, 42 and 44cm widths, and the width at the drops is 2cm wider for each size. The flat aero tops are respectively 43mm, 45mm, 47mm and 49mm wide.
Fitting is straightforward, with useful graduated markings on the central mounting portion for alignment, and a textured surface which has prevented any sort of slippage with the stem clamp correctly torqued.
I fitted it to a BMC SLR01, with first generation eTap, meaning I only needed to route the brake lines through the bar. The entry holes behind the levers are generously large and well placed for easy access, and using a Park Tool IR 1.2 internal routing kit, guiding the brake lines to the rear-facing exit holes was simple too. There's ample room for gear cables to pass through, and the exit port includes a rubber grommet with two slotted holes to support cables, preventing abrasion and rattling.
This routing aligned perfectly with the BMC's ICS stem, which includes internal routing beneath a cover underneath it, and ensures clean lines.
Deciding on the correct position for the levers was a tougher prospect. My first attempt placed them too low, but a small upward shift created a much more supportive surface from bar to hood, and more relaxed arms and shoulders. The short forward throw from the tops to the drops is angled slightly upwards, which is where I went wrong. Tilting the bar up would have ruined the drop position, and reach to the levers, but my final result felt spot on for me.
Shortly after the bend into the tops, there's a step, which gives you the option to stop taping there, as I did, for a smooth transition into the slightly bulkier tops, or continue further should you prefer.
I chose some 2.5mm thick tape which was, on reflection, a little too thick and stiff to easily wrap around the acute (less than 90-degree) angle after the hoods. It's on, and it works, but something a bit more supple would ease the process.
The position on the hoods is very comfortable and suited to most riding, with great shock and vibration absorption even over extreme washboard surfaces.
I ride in the drops a lot, and set my bikes up accordingly. With an ergonomic compact 127mm drop and 77mm reach, the RR bar felt extremely comfortable when maintaining a tuck for extended periods. Below each lever, a cut-out, stepped section about 25mm high creates a useful place for your thumb to rest, assisting grip, lever reach and comfort, and very slightly decreasing frontal area.
Pedalling on the flat or climbing while gripping the tops showed me the benefit of the Swope design. On long, seated climbs I'm always aware of uneven stresses on my wrists when pulling on a conventional handlebar, but the sloping, backswept design of the RR completely banished that, reducing forearm fatigue and shoulder tension. Even untaped, with track mitts on, the carbon tops proved grippy enough.
One of Coefficient Cycling's headline claims covers the potential for the RR bar to provide a central, extended aero riding position, using the GPS bridge section. According to Coefficient Cycling, the RR bar still complies with the UCI's recently tightened handlebar regulations, and as someone who still owns (but can no longer use) Cinelli's Spinaci Light extensions, this feature was certainly appealing to me.
On the flat, I placed one hand either side of my Garmin, dropped my forearms and shoulders, and pedalled. My road position is quite aggressive – not quite Adam Hansen-esque, but well stretched out, with a 120mm stem and a healthy saddle-to-bar drop – but immediately I needed to angle my elbows outwards to avoid clashing with my knees. My elbows were then in almost the same position as if my hands were cradling the hoods, with horizontal forearms, a position that is far easier to sustain because of the grip on the hoods.
I found I could get lower and decrease the knee clashing by curling one thumb around the base of my Garmin, with the other hand on top, and letting the fingers hold onto the leading edge of the bar. Obviously, I wasn't actually gripping the GPS, but did have a reasonable purchase for control. This was more comfortable, but still far from a TT position, with elbows still splayed out somewhat.
The limiting factor is forearm support, as this position relies on your shoulders and core strength for stability. With practice, it becomes easier, and it's definitely faster than riding in the drops, but lacks the grip and control of having flat arms holding the hoods, and you're further from the brakes of course.
I really like the integrated GPS mount. Compared to even the sturdiest K-Edge mounts, the screen isn't subject to vibration, making it easier to read faster. It should certainly appeal to users of larger devices, which often overwhelm slick but spindly out-front mounts. There's no data on any negative aero effects of a slightly proud GPS unit atop the aero bar tops, but I suspect the practicalities outweigh any extra drag.
The RR costs more than most other aero road bars, but offers something unique as well, which helps justify the extra to an extent. That said, it is cheaper than the Vision Metron Aero which now has an RRP of £429.95.
Since fine-tuning my position on the RR bar, it's become a favourite because of its impressive comfort and enhanced hand positions. I tortured myself in some fairly contorted positions throughout years of time trialling in the 80s and 90s, and these days I welcome improvements that do legitimately increase my physical comfort on the bike, as I know it'll pay me back in the long term.
Although expensive and a little weightier than most, and not the huge game-changer I was hoping for, the Coefficient Cycling RR has no real disadvantages when compared with other aero road bars, but does offer some uniquely useful positives.
Ergonomic, go-faster aero bar with unique looks and some tangible benefits
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road.cc test report
Make and model: Coefficient Cycling RR Handlebar
Size tested: 42cm
Tell us what the product is for and who it's aimed at. What do the manufacturers say about it? How does that compare to your own feelings about it?
Coefficient Cycling says:
The Coefficient RR handlebar is purpose-built for riders that race frequently on pavement and/or gravel.
Ideally Suited For:
Road Racing & Chasing City Limit Signs
Aggressive Gravel Riding & Racing
ITU Draft Legal Triathlon Racing
Tell us some more about the technical aspects of the product?
Coefficient Cycling says: "The RR's patent pending integrated computer bridge is not just a perch for your favourite data capturing gizmo, it offers hand placement options to powerfully and comfortably lift you over a steep climb AND/OR stretch-out and narrow-up to bridge a gap or breakaway from the pack. Designed within UCI and ITU rules, the RR will change your cycling experience for the better. The RR Bar is Shimano Di2 compatible. It not only accepts the bar end junction, it includes exit holes for remote shifter buttons in four locations (2 each side) on the underside of the tops."
The carbon construction is perfectly neat and tidy, with grommets and plugs to support cables or fill holes.
Once suitably fettled, the RR is an ergonomically accomplished handlebar, with some positional options that set it apart from almost all of the competition. It can take a little extra setup and training effort to exploit its benefits though.
It's a well-made carbon bar, and so far has given me no reason to think it'll have any unusual durability issues.
With its additional loop, broad, flattened tops and built-in GPS mount, at 313g the RR bar is unsurprisingly heavier than a light aero road bar, but allowing 30-40g for an out-front GPS mount halves the difference, and in some cases negates it.
Throughout my testing time, on a stiff, modern road bike with 25mm tubeless tyres, I was never aware of any road buzz. Under maximum load some welcome flex is noticeable, but it's never intrusive. Ergonomically, the RR bar is excellent.
There's no escaping the price tag, as £379 is a lot in anyone's wallet, but there are an increasing number of sculpted aero road bars nudging £300, which don't offer as many hand positions. And it's cheaper than the Vision Metron Aero...
Tell us how the product performed overall when used for its designed purpose
After my initial rides I made some adjustments, which perfected my position and allowed me to enjoy the full potential of the bar. On solo fast-paced rides, and the odd Strava segment chase, the RR performed admirably, and the result was some personal bests.
Tell us what you particularly liked about the product
I liked the integrated GPS mount, and the hand position options, especially the tops and drops.
Tell us what you particularly disliked about the product
Finalising the lever position took two attempts, and taping the bar around the very tight top turn took some care.
How does the price compare to that of similar products in the market, including ones recently tested on road.cc?
It costs more than most other aero road bars, but offers something unique as well.
Did you enjoy using the product? Yes
Would you consider buying the product? If I was in the market for an aero bar for a suitable bike, I'd certainly consider it.
Would you recommend the product to a friend? Yes
Use this box to explain your overall score
The RR bar has a look that challenges what we're used to seeing on a bike, and some may struggle to see past that, but it works well as an ergonomically sorted cockpit option, offering improved comfort in some positions over standard bend bars, and the integrated GPS mount is very useful. Overall, I'd say it's very good.
About the tester
I usually ride: Specialized S-Works Tarmac SL6 with Campagnolo Super Record 12s My best bike is: BMC SLR01
I've been riding for: Over 20 years I ride: Most days I would class myself as: Expert
I regularly do the following types of riding: road racing, time trialling, cyclo cross, commuting, touring, club rides, general fitness riding, mtb, Riding with my children, using both a child seat and trailer bike