The Surly Corner Bar lets you add a drop bar to your mountain bike or hybrid while retaining all your existing levers, shifters, and drivetrain. If you want to turn your mountain bike into a gravel bike, this alternative to the best MTB handlebars is a cheap way to get aero and comfy.
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Surly is renowned for its alternative and often retro-grouchy steel creations, emphasising durability, simplicity and longevity. The brand has made interesting bar designs in the past, but the Corner Bar is on another planet.
Surly Corner Bar - Technical details
The handlebars are available in three widths - 46, 50, or 54cm (tested). The bar width is measured at the junction of the bar and end pieces.
Much easier to understand once you see it but what you get is a bar with a number of different hand positions (the whole point of drop bars) allowing you to reposition your grip depending on the speed, control, comfort, etc you need at any given time.
The Corner Bar starts out as a 25.8mm diameter CroMoly steel flat bar with a 31.8mm split shim to fit stems with removable faceplates. It then tapers each side over a length of 80mm down to 22.2mm, a standard MTB grip size. There's about 90mm of taper down to 22.2mm, then a whopping 150-ish mm of flat ‘tops’ as roadies call them. At the end of the tops, there is a 260mm ‘drop,’ which is welded to the top close to its upper end. That leaves 47mm sticking forward as a ‘horn.’
The 'drops' or lower grips are swept back at a sharp angle, aiming to replicate the sweep of a gravel drop bar, which is pushed outwards from the traditional vertical plane to broaden the leverage and allow a more-relaxed wrist angle in the drops. In this regard, they feel close-ish to how a Jones Bar works, with its radical backsweep.
The shim is 60mm wide, leaving you 10mm on either side to affix cycling computers, or other accessories before the gentle taper down to 22.2mm begins. The taper is pretty long, so you’ll get away with clamping stuff like lights and things that don’t need to be perfectly aligned here - maybe with rubber or tape under. As for weight, the bar weighs in at 792g including the shim.
The horns are where your controls mount. Once the brake and shifter clamp is installed there’s not much room to actually hang on but if your hands are large enough you can still feather the brakes with your last two fingers. You can purchase third-party handlebar extenders to increase grip or to clamp on gear like lights where they can clear luggage, but usual safety caveats apply.
Using standard bar tape you can wrap the drops, horns and tops with a single roll. The drops are 22.2mm in diameter, meaning you can also slide on a standard MTB grip on them. The issue here is it’s very unlikely you’ll be able to reach the end of the brake levers unless you slide the brakes up the drop instead of down onto the horns. In that case, your shifter might follow and need to be on the lower side.
There are certainly plenty of options to get creative, especially if you have shifters that attach to the brake levers. Some folks use the horn/drop to slide an original 22.2mm Rohloff or Grip Shift on - certainly not something you can do with a drop bar. You can also fit a much longer rubber or foam grip such as the ODI Longneck as opposed to a rigid or lock-on, to avoid wrapping the drops.
Surly Corner Bar - Performance
Changing from a flat or flattish bar to the Corner Bar will inevitably affect your bike fit. You may want to retain an upright position, in which case you might want a shorter or steeper stem, or both. You may be after a more-aero gravelly position, which the Corner Bar might give you using your existing stem
I prefer the brakes and shifter/dropper lever on the horn so when I use them my hands are wedged up in the ‘drops.' The 54cm version gives you mid-palm width of 640mm in the drops, so you're able to reach the levers. That's MTB bar width and thereby gives you plenty of control through rough terrain. I spent a happy six minutes descending Dunkeld’s Rake’n’Ruin red trail on my fully rigid 3-inch tyre fat bike and felt totally in control with a single finger on each lever. The bar ends measure a whopping 712mm in the largest size, which you might favour on long gravel descents off the brakes at the end of a tough day.
The tops act just like a road bar where you can bimble along without needing to use the controls and put your hands in different positions. There’s a considerable amount of space for a bar bag - around 40cm depending on how your cables exit the controls.
The drop is only 94mm - pretty shallow by drop bar standards, and the flare of the drops is over 40 degrees, hence their massive width. You’ll really need to watch doorways with this bar fitted. That short drop and wide flare translate to an easy move from the tops to give plenty of control when needed. What it means for your bike fit, stem choice, etc to get a comfy setup is another matter.
Surly Corner Bar - Verdict
The Corner Bar is a real Vegemite (aka Marmite) component. You’ll either see an immediate fit for what you want to do, or you’ll decry it as the ultimate folly and best way to ruin a perfectly good MTB. If you want to get a feel for drop bar multi-position choice on your MTB without spending a fortune on new parts, at £120 it’s a great option.