The Science

Two questions drive every Coefficient handlebar: is it faster, and can you hold it comfortably hour after hour? The first question went to a wind tunnel. The second comes down to where the pressure sits on your hands. This page covers both.

Wind-tunnel tested against the Zipp SL-70 Aero

Coefficient benchmarked the RR against the Zipp SL-70 Aero, a popular and widely reviewed aero road bar, at the San Diego Low Speed Wind Tunnel. Cycling aerodynamicist Aaron Ross designed the testing protocol, and two test riders, Chloe Woodruff and Evan Pardi, rode both bars across a range of hand positions. The rider-by-rider results are published further down this page, along with the full test document, so you can read the data rather than take our word for it.

Why do your hands go numb on the bike?

Hands tend to go numb on a long ride when they stay locked in one position and pressure builds on the same part of the palm for too long. The most reliable fix riders and reviewers point to is simple: change your hand position often, so the load keeps moving. A bar helps when it gives you more than one comfortable place to hold, and a starting position that does not twist your wrists in the first place. For a fuller guide, see why your hands go numb when cycling.

How handlebar shape changes the pressure on your hands

Hold your arms out in front of you, palms down. Your hands settle with the thumbs slightly raised, not flat. A conventional straight bar top makes your wrists rotate away from that natural angle and hold the twist for as long as you ride. SWOPE, Coefficient's bar-top shape, combines 12 degrees of rearward sweep with 15 degrees of downward slope so your shoulders, arms and wrists sit in a more natural position. The figures hold up outside our own spec sheet: Cyclingnews notes the same 12-degree backsweep and 15-degree downslope in its AR review, and road.cc found the sloping, backswept tops removed the uneven wrist stresses of a conventional bar.

The shaped tops also give you several distinct places to rest your hands. Changing grip through a long day then feels natural rather than something you have to remember to do, and the load on your palms keeps moving instead of settling in one spot.

RR or AR: a difference in ride feel, not discipline

Coefficient makes two drop bars, and the difference between them is how they feel, not what surface they are allowed on. The RR is the firmer, road-leaning bar. The AR is the more compliant, gravel-leaning one. Both are built for pavement and gravel; choose by where you ride most and how firm you like the front of the bike to feel.

Independent reviews describe the same split. Comparing the two, Guy Kesteven at Cyclingnews found the RR more solid than the AR, with a little more vibration on rough surfaces, though never punishing over long distances. Riding the RR on a stiff modern road bike, road.cc reported great shock and vibration absorption on the hoods, even over extreme washboard surfaces. Impressions like these vary with bike and tires, but the pattern matches how the two bars are positioned.

What riders and reviewers say

An independent road.cc review of the RR found the sloping, backswept design removed the uneven wrist stresses of a conventional bar on long seated climbs, reducing forearm fatigue and shoulder tension. Cyclingnews described the position the bar tucks you into as "very comfortable, but also aero efficient". The Cycling Independent's reviewer put it plainly: "I've done four hours on this bar and arrived home more comfortable than I have in a few years." The shape has a race win behind it, too: Ian Boswell won the 2021 Unbound Gravel 200, the marquee race in US gravel, riding a Coefficient RR.

The research behind the shape

Coefficient studies its bar-top geometry in partnership with Cyclologic and its MotionMetriq lab, a cycling performance-science group whose work extends to the WorldTour. The aim is to understand why riders keep reporting a more comfortable, more planted position on the SWOPE shape, and to keep refining it from real rider data rather than marketing claims. The SWOPE bar-top shape is protected by U.S. Patent No. 11,505,275, "Ergonomic handlebar systems."

Which Coefficient bar is right for you?

RR: firmer, road-leaning

The RR is the road-first pick, and the bar Ian Boswell rode to his Unbound Gravel win. It comes in 36, 38, 40, 42 and 44 cm widths.

AR: more compliant, gravel-leaning

The AR is the pick for gravel and all-road riding, with a more compliant feel, and it is quick on the road too. It comes in 38, 40, 42, 44 and 46 cm widths.

Both bars share the SWOPE tops and are molded from Toray unidirectional carbon. You can see the full range of Coefficient road bike handlebars.

Common questions

What is SWOPE?

SWOPE is Coefficient's bar-top shape. It combines 12 degrees of rearward sweep with 15 degrees of downward slope, so your shoulders, arms and wrists sit in a more natural position.

How was the RR wind-tunnel tested?

Coefficient benchmarked the RR against the Zipp SL-70 Aero at the San Diego Low Speed Wind Tunnel. Cycling aerodynamicist Aaron Ross designed the protocol, and two test riders rode both bars across a range of hand positions.

Why do hands go numb on a long ride?

Hands tend to go numb when they stay in one position and pressure builds on the same part of the palm. The most reliable fix is to change your hand position often, which a bar with several comfortable holds makes easy.