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The Zipp SL-70 Aero handlebar is an expensive way to save some watts, but it certainly delivers on the stiffness and comfort front. Also, for an internally routed bar, fitting cables is a relative cinch.
Using a Computational Fluid Dynamics (CFD) program for the design, Zipp makes some decent aerodynamic claims for the SL-70 Aero's wing-like shape.
According to Zipp, a round-tube section handlebar creates a drag of about 0.74 newtons, which it found requires about 7.5 watts of effort at 30mph (48.3kph) to overcome. The SL-70 Aero creates just 0.11 newtons of drag, a saving of 6.4 watts – not massive by any stretch of the imagination, but if you're the type of rider who wants to get as much out of every gain going, not to be sniffed at.
Without a wind tunnel those claims are hard for us to verify, and in the real world there didn't feel to be a huge advantage when out for a hard ride.
What I can give my findings on, though, are stiffness and comfort; always a tricky balance to get right, but something Zipp has achieved.
Yanking on the hoods when riding hard out of the saddle there is absolutely no flex whatsoever, nor is there when you are braking hard transferring your weight through the handlebar.
It's the same when you're down in the drops. This is a proper racer's bar.
With a reach of 70mm and a drop of 128mm, it isn't as shallow as some more endurance style bars but nor is it so deep that only the most flexible can make full use of the drops.
The wing shaped top of the bar is actually quite comfortable to use, even with the majority of it being untaped. Zipp seems to have got the carbon layup right in a way that the SL-70 Aero is stiff but without being harsh, even on rough roads.
Like many aero bars, the Zipp doesn't have much room either side of the stem for fitting a computer mount or lights.
Some handlebars with internal cable routing can be an absolute nightmare to set up but the SL-70 Aero was a relative breeze thanks to what Zipp calls Rapid Routing. The holes are positioned exactly where they need to be to be compatible with all groupsets, and while the Zipp website only mentions mechanical brake/gear systems, a bit of a scoot round on the internet shows no issues with hydraulic hose use.
I was using the bar on a rim brake-equipped bike fitted with Shimano Ultegra 6800. All the cables passed through and exited without getting caught inside the bar. It's obviously more of a faff than externally routing them, especially if you have to remove all of the cables from an internally routed frame too, but it went a lot quicker and easier than expected.
Weight-wise, the Zipp is in the right ballpark at 236g for this 42cm size. The Ritchey WCS Carbon Streem bar is 248g, although it is a bit cheaper at £270 compared to the Zipp's £296.
Pro's Vibe Aero Carbon is slightly heavier at 261g and costs £299.99. It is aimed more directly at running Di2 internally, so routing a mechanical setup through the Vibe was nowhere near as easy as it was with the Zipp.
Overall, I really like the feel of the Zipp out on the road and got on well with the shape. And while the cost is high at nearly £300, it isn't massively overpriced against the opposition.
Expensive, but easy to set up and delivers a great ride and performance
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road.cc test report
Make and model: Zipp SL-70 Aero handlebar
Size tested: 42cm C-C
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?
Zipp says, "Zipp's SL-70 Aero is, in every way, a high-performance bar. This unidirectional carbon handlebar is packed with innovations for best-in-class fit, ergonomics and aerodynamic performance. With its wing-shaped bar top, the SL-70 Aero features Zipp's most advanced bar refinements while building on the trend-setting aero legacy of the VukaSprint.
The bar's distinctive wing-shaped top is designed using Computational Fluid Dynamics (CFD), the same software used to design Zipp® wheels. Our research showed that a traditional round-tube section creates drag of about 0.74 Newtons, which we found requires about 7.5 watts of effort at 30mph (48.3kph) to overcome. The airfoil developed in CFD that is used in the SL-70 Aero handlebar creates just 0.11N of drag, which means a savings of 6.4 watts over a round-tube section.
Beyond aero performance, the SL-70 Aero features a 70mm reach to allow proper fit without compromising stem length and steering control.
The 10-degree ramp angle to the brake hoods eliminates the need for up-rotated bars. The bar also provides ample wrist clearance for riding and sprinting in the drops."
I can't quantify the aero claims but it is a comfortable and stiff handlebar.
Tell us some more about the technical aspects of the product?
Features Zipp's Rapid Routing™ system, also used in the Vuka Aero system, for easy internal cable routing.
Compatible with all mechanical brake/gear systems.
Not clip compatible.
Available in Matte White and Matte Black finishes.
Sizes - 38cm/40cm/42cm/44cm centre-to-centre
Tell us how the product performed overall when used for its designed purpose
The bar offers loads of stiffness for performance riding.
Tell us what you particularly liked about the product
Comfortable hand positions; easy to run cables through.
Tell us what you particularly disliked about the product
A pricey upgrade.
How does the price compare to that of similar products in the market, including ones recently tested on road.cc?
The Zipp is at the upper end of those we have tested here at road.cc but not by a huge amount as you can see by the two I've compared them to in the review.
Did you enjoy using the product? Yes
Would you consider buying the product? Depends how cheap I could find them.
Would you recommend the product to a friend? Yes
Use this box to explain your overall score
A handlebar that can deal with any amount of power or force you can put through it, while also being pretty comfortable. Simple cable routing is a huge plus and helps to offset the high price.
About the tester
I usually ride: This month's test bike My best bike is: B'Twin Ultra CF draped in the latest bling test components
I've been riding for: Over 20 years I ride: Every day I would class myself as: Expert
I regularly do the following types of riding: time trialling, commuting, club rides, sportives, fixed/singlespeed,
With 20 years of road cycling and over 150,000 miles in his legs it's safe to say Stu is happiest when on the bike whatever the weather. Since writing his first review for road.cc back in 2009 he has also had a career in engineering including 3D-CAD design and product development, so has a real passion for all of the latest technology coming through in the industry but is also a sucker for a classic steel frame, skinny tyres, rim brakes and a damn good paintjob.
His fascination with gravel bikes is getting out of control too!