Surly Corner Bar Review: Drop Bars For Mountain Bikes

Creating wonderfully weird and unique bike components isn’t anything new for Surly. The riser/drop Truck Stop Bar and the ever-popular Moloko alt mountain bike bar are just a couple of examples from the handlebar department. Their latest creation might just take the cake, however. In typical Surly fashion, the Corner Bar is constructed out of steel, and like the Moloko, it certainly isn’t the most svelte bar on the block. But the Corner Bar is quite unique in that it’s created for one purpose: converting a mountain bike to a drop-bar rig without having to switch the drivetrain and controls. We’ve been playing with one for a few weeks for this review.

Drop Bars on a Mountain Bike

First things first. Why would anyone want to put drop bars on a mountain bike? Good question. I suppose the answer in most cases would simply be, “Why not?” Otherwise, there are probably a lot of people experimenting with hand positions for the sake of comfort, or perhaps trying to make their bike feel as good riding to the trails as it does once on them. The latter might be a little more applicable to those who come from a road cycling background. Either way, we get a lot of questions about such conversions. And of course, with some tweaks to the stem length—typically a shorter stem, because mountain bikes are generally longer—saddle position, and other such adjustments, it’s possible to convert almost any hardtail or rigid mountain bike to a drop-bar rig. And, yeah, you can always toss one of the dozens of wild gravel-specific drop bars on your mountain bike, but that’ll likely mean needing to buy new shifters, controls, and other components if your parts bin is running low. Plus, many of the road/gravel drivetrains lack good low gearing. The Surly Corner Bar was created to help make the switch easier.

“If you have a mountain bike setup with a flat bar and you want to convert it to a drop bar, it’s not an easy or cheap conversion,” explains Surly’s Brand Manager, Paul Zeigle. “You have to buy shifters, brake levers, sometimes a new derailleur—because none of them are compatible. And the clamp size on a mountain handlebar and a road handlebar are different, so the levers don’t even fit the bars. So that’s one of the ideas here—how do we make it easier and less costly to convert?”

Surly Corner Bar Construction and Geo

The Surly Corner Bar is made from custom-butted 4130 CroMoly steel, coated with an E.D. black finish, and is constructed out of three pieces of tubing. It has two ~200mm bars that each have a single bend to make the dominant “in the drops” hand positions. These are welded onto a single straight bar that has forward bends at either end to simulate the hood curve. The Corner Bar has a 25.4mm clamp area that requires a shim for most modern mountain bike stems. Surly probably went that route to keep costs down and to provide a little more flex and compliance for comfort. The horns and drop diameter is 22.2mm to work with mountain shifter and lever clamps.

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The Corner Bar comes in three widths: 46, 50, and 54cm. Similar to traditional drop bars, those measurements reference the width of the bars from hood to hood. That said, according to Surly, the Corner Bar was built for comfort and control in two primary positions: the drops and the tops. Unlike standard drop bars, it’s not really designed for putting your hands on the hoods. The nubby hoods are actually more like horns and are used to clamp the brake levers, shifter, and dropper lever in place. However, there are workarounds to make them more like hoods in the wrapping process, which we’ll get to later.

When looking at the Corner Bar’s geometry, a couple of other significant numbers differentiate it from traditional drop bars. For one, the 94.2mm drop is 20-30mm shallower than most, and the 65.2° backsweep and 41.4° of flare is slightly more dramatic than the outsweep found on many other gravel dirt-drop bars. It kind of reminded me of the Woodchipper in that regard, although it doesn’t have as pronounced of a downward angle.

Fit and Installation

Any time you change a handlebar, it’s going to impact your bike fit. The Corner Bar is no different. Considering the dominant drop position of this bar, you’re essentially putting your hands and body in a different position than they would be in when using flat MTB bars. That’s exciting when you think about trying it, but it can also lead to fit issues, so as mentioned, the stem length and height may need to be adjusted. Fortunately, the shallow drop makes dialing in fit more approachable than it would be with deeper drop bars.

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The same goes for cable length. To preface, I didn’t really convert a mountain bike for drops, I converted a drop-bar bike to flat bars—I fitted my Cutthroat with some new, yet-to-be-released flat bars—and then swapped them for the Corner Bar for this review. With that said, the cables had been adjusted for flat bars, but I found they were a hair short for the Corner Bar, particularly when paired with a front bag. But, every bike is unique, so it’s possible your current setup will work better with the Corner Bar.

Speaking of bags, it’s worth noting that I tried a couple of bags on the Corner Bar, but haven’t gone out bikepacking with it yet. The distance between the hoods is about 47cm, so there’s plenty of space between the hoods to fit a larger bag. However, as mentioned, the cables are a little short, so forcing a bag in there against the cables is tricky. If left a little longer, they could go up and in front of a bag. A top-opener or handlebar harness system would be no problem. Bags such as the Bags X Bird offerings or Revelate Pronghorn come to mind.

Wrapping Up the Corner Bar

The Corner Bar can either be partially taped with grips installed on the drops or fully taped. I decided to tape mine. Like traditional drop bars, you start wrapping at the bar ends after installing the levers and controls. It was pretty straightforward, but it took a little trial and error to navigate the hoods and levers to get the tape neatly wrapped in that area.

According to Surly, the other way to wrap the Corner Bar is to use bar tape along the top and standard mountain grips on the bottom. This approach allows you to have larger grips for more padding, and it also leaves room for a little more creative freedom with the controls. And there’s a third method where you can use cut-up silicon grips to fabricate padded hoods. You can find details on that over on Surly’s Blog.

On The Trail

Surly sent the 54cm version for me to test, and I wouldn’t have it any other way. It’s wide and feels comparable to a modern mountain bike bar or the newer 520/540mm drop bars I’ve become accustomed to. Once on the trail, it quickly became clear that the Corner Bar’s design has a little more to it than simply making an MTB dirt-drop conversion easy. I immediately felt right at home in the drops. Their shallow stance and wide angle provide a very in-control feeling that puts your body in a more aggressive position than a flat bar would, but not the aero-tucked posture you might get from a normal drop bar. It also feels more steady and stable while descending than most drop bars I’ve tried. And, even with mechanical brakes, I found that the leverage and reach on the levers in this position were quite good, and easier to access than some levers on traditional drop bars.

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I regularly used three positions on the Corner Bar: the tops, drops, and palms resting on the bent portion of the long bar at the hoods. The latter actually worked pretty well for me when just pedaling along, but I could see adding a little padding on the horns to make it more comfortable. I could even actuate the brakes from that position, which was pretty impressive, though I’m guessing that wouldn’t be possible with all brakes. The Paul Love levers I was using are pretty slender and minimal and don’t have a lot of bulky parts to impede your hands. That said, getting an index finger and thumb grip around the hoods is slightly encumbered by the shifter lever. I used the AXS shifter and the big battery area caused it to get in the way a little, particularly when I was climbing and wanted to wrap a couple of fingers around it for leverage. This bar would be fantastic for a singlespeed, without a shifter lever, which would be great for climbing out of the saddle. I might also try moving the shifter under the junction to access it from the drops.

As for ride feel, the Corner Bar isn’t incredibly stiff or harsh, but it’s also not the most forgiving bar. It’s pretty heavy-gauge steel, and despite the thinner 25.4mm clamp area, I certainly wouldn’t consider it to be noticeably flexy or compliant. One way to remedy that is to use cushy grips on it. Neil did just that in his YouTube video review, which you can find below.

In our latest YouTube video, Neil Beltchenko provides his own take on the new Surly Corner Bar and sets it up on his Salsa Timberjack with the 50cm version with foam grips, hydraulic brakes, and a dropper lever mounted at the drop. Watch the full review here. And make sure to subscribe to our YouTube channel if you haven’t already done so.

• Model/Size Tested: 54cm
• Actual Weight: 737 grams (1.62 pounds)
• Place of Manufacture: Taiwan
• Price: $100*
• Manufacturer’s Details: SurlyBikes.com

*The Corner Bar will be available at North American dealers in early September 2021

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