Sonder Transmitter Carbon 2017 Mountain Bike Review

Sonder Transmitter Carbon 2017

Reviews / Hard Tails

Sonder 5,120

At a Glance

Sonder is a relatively new bike brand from British outdoor experts Alpkit; they have been turning heads since launched at the London bike show in 2015. The well-reputed Brant Richards was involved at the beginning, and now Neil Sutton holds the reigns of this exciting brand as it brings with it a rapidly expanding line up.

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The Transmitter has been on the scene for a couple of years now as an entry level plus size alloy hardtail, and due to its popularity, Sonder decided that a carbon version would be a nice addition to the family for 2017. Unlike the other hardtails in their range which are more geared up for adventure cycling and bike packing, the Transmitter is here to tackle mountain biking in its purest form, from trail centres to big all mountain adventures with an emphasis on providing the rider with bucket loads of fun.

To increase the fun factor the new carbon Transmitter is not only considerably lighter due to the material it’s made from but boasts a longer reach for extra stability, and a shorter seat tube to allow longer dropper posts and give better standover clearance. For riders taller than around 6ft 2in the XL alloy version is your only choice as the carbon model stops at size L due to the excessive costs of using the required carbon moulds.

For those who like to build their own bikes the frame can be bought for £749. Otherwise one can choose from five different full build options ranging from £1499 (SRAM NX and Rock Shox Recon fork) to £3199 (SRAM XX1 Eagle and RockShox Pike). Our test bike was the SRAM GX/Revelation build which is priced in at £2249.

One thing that is clear from the off, this is a great looking hardtail. The striking aesthetics of the frame are enhanced thanks to its clean straight lines, which are kept free of any cable clutter due to the excellent internal cabling system (there are full-length pipes bonded inside the frame that you can just slide the outer all the way through).

The top tube resembles more of a blade than a tube; this is here to add both lateral stiffness and vertical compliance to find that sweet spot between agility, stability and beauty. The tube junctions are silky smooth, as are the curves on the stays and around the bottom bracket.

The frame is available in blue, green and raw carbon (which is pretty much black), all of which I think looks good with the eye-catching decals. The frame weighs in at 1,130g (Large), which means a saving of 700g over the alloy Transmitter chassis and significantly more compared to most steel hardcore hardtail frames.

It’s great to see that the bottom bracket is threaded for external bearings, avoiding all the short life, creak and other issues associated with press fit systems. The 148×12mm Boost rear axle slots securely and neatly into the fully replaceable drive side dropout.

Our test bike was fitted with a set of RockShox 29er 120mm Revelation forks (to allow for the plus tyres), although Sonder have now changed these to 130mm on all models. These forks have recently undergone some improvements and now boast a 35mm chassis and are easily as good as previous Pikes.

The excellent SRAM GX Eagle 12 speed drivetrain and RS Guide brakes add some real quality to this particular build while the rest is rounded off with Love Mud bars, stem, seat and wheels. These wheels are dressed in a set of WTB Ranger tyres, a 3.0 up front and a 2.8 on the rear and are set up tubeless. In theory, the Transmitter could take a 29er wheel, but this would seriously limit the tyre clearance as well as raising the bottom bracket height which would affect the ride performance.

On The Trail

Before my first outing on the Transmitter Carbon, I was a little bit dubious, to say the least. Picking it up I was impressed with its low weight (approx. 28.5lbs with pedals) but wasn’t convinced it would stay in one piece. If I was to give it a testing on par with previous test bikes I’ve had, especially with that low profile top tube and a short travel front fork. Neil Sutton inspired me with confidence, however, ensuring me that the build quality is second to none and that the geometry has been drawn up to cater for more than just your average XC riding. This guy sure knows his stuff, so I embarked on my first ride with a bit more confidence in the machine.

This first ride involved a big old carry, which was so enjoyable due to the low weight. At times I forgot I even had a bike on my back, this was a good start. Pedalling uphill on easy terrain feels positive, direct acceleration comes from pedalling, and as long as the tyre pressures are right, then the ride is surprisingly supple and comfortable.

The SRAM Eagle 12 speed gearing has a great range and allows you to plod away on long climbs, conserving energy for the descents just like the good old days when bikes had derailleurs up front and a selection of chainrings. On the more technical slow speed climbs I found that the front felt a bit light and wondered a little, no real surprise here though with fairly short chainstays (425mm) and slacker than average 65-degree head angle. The plus size tyres do however provide heaps of traction, particularly on dry rock where you’ll struggle to spin out.

Once you point downhill you can’t help but immediately accept the slight compromise in its climbing ability; this bike is a little ripper. It comes alive on smooth flowing trails, the combination of a high front end, well-positioned bottom bracket, slack head angle and short rear triangle encourages a rowdy riding style.

The newly revamped RockShox Revelations are silky smooth and complement the bike perfectly while the short stem and wide riser bars keep things direct and responsive. It pops onto the back wheel so easily which makes pumping and manualing a heap of fun. The short 120-130mm travel range means that geometry doesn’t vary too much when cornering, so attacking berms feels confidence inspiring, and with the lightweight and stiff feel to the bike, it encourages you to either unweight or even manual out of the corners with added gusto.

The seat tube has been shortened which allows you to keep your weight closer to where it wants to be on a hardtail, a good move for sure. Take this bike to any smooth flowing trail centre, and it will help you to improve your riding, it just seems to encourage a bit of style and flare as well as encouraging you to ride faster.

At high speeds on easy terrain, things feel pretty stable thanks to the big profiled tyres and a reach, which has been increased from that on the aluminium version. I’m a reasonably tall rider at 6ft 2in, and am of the general opinion that all bikes should seek out a longer reach/wheelbase in their design and feel that the Transmitter could certainly go even longer again.

When the trails start getting really steep and technical the Transmitter can cope fine thanks to its slack head angle but it will require the rider to stay alert, and on the ball, it feels a little less forgiving than some ‘hardcore’ hardtails but is still impressively capable for a short travelled plus tyre carbon steed.

The newer models with a 130mm fork will likely feel a touch more sturdy on the steeper stuff. The stock WTB Ranger tyres have their limits and simply don’t have enough grip or strength to tolerate the more gnarly terrain. I swapped the tyres out for a thicker side walled pair with a more aggressive tread pattern which allowed me to push harder in search of the bikes limits, while being able to run the tyres at the recommended lower pressures.

Running lower pressures also makes the general ride feel a lot gentler and supple, this is important on those longer rides. Tyre clearance on the stays was fairly minimal with the more aggressive tyre, but thanks to the Boost set up keeping things stiff when cornering, I never noticed any frame rub.

Plus size tyres can work great until things get sloppy and muddy, then they just don’t work properly, so it’s worth mentioning that the Transmitter can be set up with a longer travelled 150mm 27.5 fork and a more modest 2.6in tyre which will keep the angles nigh on exactly as they should be. This is great to hear as it keeps the options open to those that like the plus game and those who prefer a more standard set up. Alpkit are happy to chat over the phone and recommend the best build set up for you too if you are unsure of what you want.


This is an impressively solid and well-balanced bike to come from a manufacturer so new to the game. Wherever you take it you will have so much fun it’s off the chart. Taller riders would benefit from a longer size, but for most this is a great bike that can do everything, from pump track and trail centre shredding to all mountain adventures.

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This review was in Issue 51 of IMB.

For more information visit Sonder


By Charley Oldrid
Charley Oldrid is a man who spends a lot of time in the saddle. A highly experienced Mountain Bike Guide, having led trips all over world riding the finest trails he can find. His personal riding style can only be described as wild, getting sideways isn't an option on a ride with Charley, it's mandatory. If anyone can find the limit of a test bike, it's him.

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