London Bike Show 2017: Sonder Transmitter Carbon

by
March 6, 2017

We’re having a little trouble getting our heads around it, but apparently it’s been almost two years since Alpkit unveiled its new bike brand called Sonder. Where the heck did that time go??

First launched as an offshoot of Alpkit back in 2015, Sonder originally came about as a collaboration between Alpkit and Brant Richards of On-One fame. Since that launch, Sonder has gone on to release the production version of the highly popular Transmitter alloy trail hardtail, which earned itself a nomination in the 2016 Singletrack Reader Awards.

As one of Richard’s On-One/Planet-X protégés, Neil Sutton is now the driving force behind Sonder, and is looking to do very impressive things with the brand – particularly from a price-to-performance ratio. Case in point would be the all-new carbon version of the Transmitter, which we got a very close look at during the London Bike Show. Yes, this is a £699 carbon fibre frame…

sonder transmitter carbon hardtail 27.5 plus london bike show alpkit
The Transmitter Carbon is the newest mountain bike from Alpkit’s bike brand; Sonder.

The Transmitter Carbon is long, low, slack and fun. We’ve taken what we’ve learned from the original alloy Transmitter and evolved the geometry, we’ve extended the reach and the long and low wheelbase gives stability and control at high speed. The Transmitters are bikes that just fit in with hard riding. But mostly, they are to be ridden and enjoyed. Easy to ride and maintain, fast and lots of fun.” – Alpkit.

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The Sonder Transmitter Carbon Specifications

  • Carbon trail frame compatible with integrated tapered headset for a clean, low front end
  • Built for 27.5+ wheels
  • Recommended fork travel: 120-130mm
  • 65° head angle
  • Accepts up to a 2.8in rear tyre
  • Boost 148x12mm rear spacing for wheel strength and optimal chainline
  • Threaded 73 mm BSA BB shell for no-creak assembly
  • Chainstay mounted disc brake for clean lines and damage protection
  • Adventure cage compatible downtube mount
  • Internal cable routing with stealth dropper option
  • EN 14766 compliant
  • Available sizes: Small, Medium, Large
  • Painted or raw carbon finish
  • Frame RRP: £699
  • Bike RRP: £1499 – £3199
sonder transmitter carbon hardtail 27.5 plus london bike show alpkit
Based on the alloy Transmitter frame, the carbon version adds in some clever upgrades, including internal routing.

The alloy Transmitter has been gathering significant steam since its first release, and Sonder has been keen to capitalise on that momentum in the market. The obvious move was to produce the Transmitter in a carbon frame, so as to offer a lighter and higher performing option based around the same trail-inspired geometry and handling. Making full use of the material upgrade however, Sutton has implemented a number of key geometry and spec changes to the new Transmitter Carbon, which you can also read about in the press release from Alpkit about the new Transmitter Carbon.

sonder transmitter carbon hardtail 27.5 plus london bike show alpkit
Smooth seat tube junction.

One of the changes for the Transmitter Carbon is immediately obvious when you first see it. A shorter seat tube has been built into the carbon frame, which increases standover height and helps to improve compatibility with longer dropper posts – a feature that many riders are now looking for. The shorter seat tube and low-slung top tube give the Transmitter Carbon an almost BMX-style about it. Bear in mind that this black bike shown here is a Small size. The frame is also available in Medium and Large sizes, and you can get in raw carbon (black), or the rather fetching green and blue painted options (seen below).

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sonder transmitter carbon hardtail 27.5 plus london bike show alpkit
The thin top tube takes an almost direct route from the head tube all the way down to the dropouts.

With a lovely flowing junction at the top of the seat tube, the Transmitter Carbon offers an almost straight line between the head tube and rear dropouts, with an ever-so-slight downwards curve in the top tube. It’s all very elegant and swoopy without being over the top.

sonder transmitter carbon hardtail 27.5 plus london bike show alpkit
Semi-internal dropper post routing.

Cable routing runs inside the frame, including for the stealth dropper post. Citing the frustrations of routing internal cables around the tight bottom bracket junction, Sutton designed the Transmitter Carbon frame to partially route the dropper post line externally between the downtube and seat tube. The result is a more gentle bend in the cable/hose, and a much easier installation process.

sonder transmitter carbon hardtail 27.5 plus london bike show alpkit
Rear centre length remains at 425mm, and the Boost’d drivetrain maximises tyre clearance for up to 2.8in rubber.

Like the alloy version, the Transmitter Carbon frame runs 148x12mm Boost rear hub spacing, with a matching Boost offset drivetrain. This allows for a tight 425mm chain stay length whilst delivering clearance for 27.5+ tyres. Sutton states that you can fit up to a 2.8in tyre when in 27.5+ mode. You can also run 29in wheels, and while a 2.4in WTB Trail Boss tyre will fit, it will only just squeeze in there, so Sutton doesn’t recommend it.

sonder transmitter carbon hardtail 27.5 plus london bike show alpkit
The bottom bracket is a 73m threaded number, and the rear brake is of the 160mm post mount variety.

The compact back end is emphasised by the internally mounted rear disc brake calliper, which tucks in nicely inside the rear triangle. This placement has also allowed Sutton to thin out the seat stay tubes to offer a little more spring and vibration damping. Combined with wide tyres, the slightly slacker 73° seat tube angle (compared with the 74° and 75° seat tubes we’re seeing on comparable bikes) and the carbon fibre construction, it should offer a pretty comfortable ride for a hardtail.

sonder transmitter carbon hardtail 27.5 plus london bike show alpkit
The thinned-out top tube acts as a kind of leaf spring for added vertical give.

You can also see here just how thin the top tube is throughout it’s journey form the head tube to the seat tube. Unlike the beefy downtube, the top tube uses this thinner ‘leaf spring’ design to encourage flex for added vertical compliance. Or at least, that’s the theory anyway.

sonder transmitter carbon hardtail 27.5 plus london bike show alpkit
All complete Transmitter Carbon bikes will come with 27.5×2.8in tyres.

The complete bike that Sonder brought to the London Bike Show features 2.8in wide tyres from WTB, and a 3.0in wide tyre up front.

sonder transmitter carbon hardtail 27.5 plus london bike show alpkit
Slack and long; the Transmitter Carbon is a new-school trail hardtail.

The Transmitter Carbon’s head angle remains at 65° like the alloy frame, but the front centre measurement (that’s the distance between the bottom bracket and the front hub) grows a little alongside the longer top tube lengths used across the size range. This move helps to push the front wheel further out for enhanced high-speed stability. As an example of the increased wheelbase dimensions, a Medium Transmitter Carbon features an 1163mm wheelbase, compared to 1150mm on the alloy version.

sonder transmitter carbon hardtail 27.5 plus london bike show alpkit
A 40mm stem pairs to 740mm wide riserbars.

As it sits underneath the Alpkit umbrella, the Sonder Transmitter Carbon will come with a smattering of Love Mud components on the complete bike options, which helps to keep the sticker price in a more desirable bracket. Complete bikes will start at £1499 for the SRAM NX1 build, and range up to £3199 for the top-of-the-range model that features a SRAM XX1 Eagle 1×11 groupset and Rockshox Pike RCT3 forks. All complete bikes are built around 27.5in wheels with 2.8in wide tyres, and feature a 120mm travel fork, a 35mm stem, and 740mm wide riser bars. Only the two cheapest models miss out on a dropper post.

sonder transmitter carbon hardtail 27.5 plus london bike show alpkit
Want more pizazz than black? You’ve got a choice of painted frames too. Though they are heavier.

On display at the London Bike Show in the Alpkit booth were two other Transmitter Carbons, one in ‘Reef’ (or blue) and one in ‘Rocket’ (that’s green).

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sonder transmitter carbon hardtail 27.5 plus london bike show alpkit
Integrated tapered headset keeps the lines clean.

No special rubber plugs or plastic ports are used for the internal cable routing on the Transmitter Carbon frame – just a few good ol’ holes behind the frame that the cables and hoses pass through on their way into the downtube. Keeps it simple eh?

sonder transmitter carbon hardtail 27.5 plus london bike show alpkit
Ooh yes!

The Reef coloured Transmitter Carbon frame was a large size that features similar lines for the seat tube junction, albeit with a more conventional shape for the front triangle.

sonder transmitter carbon hardtail 27.5 plus london bike show alpkit
Sonder’s main man, Neil Sutton, is rocking a green Transmitter Carbon test bike, and he brought it to the London Bike Show.

The Rocket coloured Transmitter Carbon is actually Neil Sutton’s personal test bike. It’s running a RockShox PIKE RCT3 27.5+ fork on the front with 120mm of travel, and a 1×11 SRAM drivetrain and a RockShox Reverb dropper post.

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sonder transmitter carbon hardtail 27.5 plus london bike show alpkit
Prototype Love Mud carbon rims spotted on Sutton’s personal Transmitter Carbon test bike.

Getting a little closer to Sutton’s test bike, we had a good squiz at some prototype carbon fibre rims. Alpkit currently produce a range of different complete wheel options under the Love Mud brand, including the Hobo, Rumpus and Orbit wheels. However, all of those wheels only feature alloy rims. From what we can tell, it looks like it won’t be long before a carbon option will be joining the range…

sonder transmitter carbon hardtail 27.5 plus london bike show alpkit
More details to come…

Details are light-on at present, but according to Sutton, the Love Mud carbon prototype rims are running an internal width of 35mm, so a little narrower than the current Rumpus 27.5+ wheels, and likely suited to the new crop of plus-minus tyres around the 2.5/2.6in width. Compared to some other carbon rims, the prototype hoops that Sutton is rocking have a much shallower depth, likely to increase vertical compliance. Hubs appear to be the same as the current Rumpus wheels, which include forged alloy hub shells, sealed cartridge bearings, a 4-pawl freehub mechanism and interchangeable end caps. We’ll keep you updated as soon as we have more info on these…

In the meantime, you can check out our video tour of the new Sonder Transmitter Carbon from our time in the Alpkit booth at the London Bike Show. And if you’ve got any questions on the new bike, leave them in the comments section below and we’ll get Neil Sutton onto it for you!

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