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Sour steel Double Choc enduro & Cybercrank prototypes

We already knew that Sour loves building bikes in steel, but a couple of new prototypes suggest they aren’t stopping at regular old hardtail mountain bikes and gravel bikes anytime soon. It’s not our first glance at the full-suspension Double Choc, but now we get an up-close look (and video of Timo Pritzel backflipping it!)  And those Cybercranks? Let’s just say that a modern direct mount tubular CrMo steel crankset would have a lot of applications both from gravel to trail…

Sour Double Choc steel enduro prototype

We’ve been catching glimpses of this steel full-suspension Sour mountain bike since the end of 2020. Its overall form appears to not have changed much since those first trail-ready prototypes… but the level of riding it’s been put through has definitely continued to evolve.

That’s because this particular bike has been in the hands of German freerider Timo Pritzel since the start of development. And gone from trail riding on it and hyping people to ride bikes & do yoga… to now alternately treating it like a slopestyle or bike park bike.

Tech details… What do we know?

Sour Double Choc steel 143mm travel enduro bike prototype, linkage-driven single pivot URT

The made-in-Germany steel Double Choc prototype features a single pivot suspension layout with a shock driven by a separate linkage and a rocker arm. Those two shiny silver elements are the only bits not made of steel, instead CNC’d just across town from Sour in Dresden by Actofive.

Sour Double Choc steel 143mm travel enduro bike prototype, big bearings

The bike pivots exclusively on oversized bearings, and there’s a lot of them up top to keep this thing moving smoothly, giving the bike Sour prototype 143mm of rear wheel travel.

Sour Double Choc steel 143mm travel enduro bike prototype, BB box

Down below, it’s a more simple setup, featuring a classic BSA threaded bottom bracket at the back of a boxy dropped section that ties together the lower shock mount with stainless steel reinforcing, a dropped downtube to make way for the low shock position (and piggyback shock clearance at full travel), and the no-frills single pivot at the base of the 2-part seattube.

Sour Double Choc steel 143mm travel enduro bike prototype, IS brake

Out back, the welded oval chainstays and round seatstays come together with a nice machined Boost thru-axle dropout, an IS disc brake mount, and a tidy little brake strut brazed in between the stays.

There’s still plenty left unsaid from Sour, other than the fact that the bike is mostly dialed-in and pretty much refined… all in Sweet Steel 4130 CrMo…

Sour Double Choc steel 143mm travel enduro bike prototype, Sweet CrMo

In fact, Sour had originally expected to release the new bike to consumers as early as last year. But instead, they decided to go all in on German frame production, shifting from frames made in Taiwan to frames welded and brazed in Saxony, just outside of the city of Dresden where they are based.

That Homegrown shift gives them more flexibility, while keeping prices affordable. But it has been a major move in the days of an ongoing pandemic (some of their custom small parts are still produced overseas for the moment). They are building production hardtail mountain bikes already in Germany now…

Sour Double Choc steel 143mm travel enduro bike prototype, complete

But the all-new Sour Double Choc full-suspension bike is a bit more complicated to produce, so they are prioritizing the more straightforward bikes at the moment. That said, this Sour prototype isn’t exactly on the back burner – it’s just getting a lot of extra product testing days in before you’ll be able to order your own Double Choc.

Timo Pritzel backflipping it

Besides the fact that this prototype I took photos of clearly still has trail grime in its nooks & crannies, Timo Pritzel has made clear that his bike is being properly trail tested.

This isn’t some ‘non-ridable sample’ prototype.

This is the prototype they are using abusing to dial-in suspension kinematics and to make sure it will stand up to the most demanding riders. Apparently, after a couple decades of flipping bikes in the air from those benchmark early New World Disorder films and Crankworkx competitions to today… Timo was itching to get some new upside-down riding shots.

Sour Cybercranks steel prototype direct mount cranks

Sour Cybercranks tubular chromoly steel direct mount crankset prototype #11

Now a bit back down closer to earth… Sour had another prototype hidden in plain sight at Eurobike. It appears to be prototype 11 in fact.

It’s been a while since I’ve seen a new tubular chromoly steel crankset on a mountain bike, so maybe Sour decided it was time to change that.

Sour Bad Grany Gates belt drive MTB bike

We already got a glimpse of these prototype Cybercranks on this rad Sour Bad Granny modern MTB klunker helping to celebrate 15 years of Gates Carbon belt drives.

But a closer look reveals some cool detail.

Sour Cybercranks tubular chromoly steel direct mount crankset prototype, naming

We’re going to have to assume the hand-scrawled-on name of the back of these Cybercranks doesn’t suggest that they are internet-connected or anything. Maybe it has more to do with the original Greek origins of control. These definitely will help with that.

Sour Cybercranks tubular chromoly steel direct mount crankset prototype, DM bolts & spider

What’s really unique about these welded tubular steel cranks though, are their standard 3-bolt direct mount interface. Sure, this setup has another machined 4-bolt spider to mount the Gates belt ring.

But 1x mountain or gravel bikers could easily bolt up a single direct mount chainring for a great-looking setup combining retro-style small diameter chromoly crank arms with a precise modern narrow-wide 1x ring for the latest 11/12/13-speed drivetrains.

Sour Cybercranks tubular chromoly steel direct mount crankset prototype with Gates Carbon belt drive

Now, there’s even less info available now on this Sour prototype tubular steel direct mount Cybercranks crankset. But if they can build a full-suspension steel enduro bike in their German workshop, surely they can weld together a few steel cranksets too, right?

We’ll keep on Sour to see how long until your gravel bike can get some modern steel cranks.




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    • I hate to burst your bubble, but the Sour Double Choc steel enduro prototype is just another overhyped disappointment. Ive seen it in action and its far from being a beast. Dont believe the marketing hype, my friend.

    • Are you serious? Those prototypes are nothing but hype. I highly doubt theyll live up to the expectations. Dont get your hopes up too high, my friend.

  1. Those bikes may look impressive, but looks can be deceiving. Ive seen plenty of flashy prototypes that turned out to be disappointing in reality. Lets hold our excitement until we actually see them in action.

  2. Eh, they might look tough, but looks can be deceiving. Ive seen sturdier bikes that could eat those prototypes for breakfast. Dont believe the hype, my friend.

  3. Wow, those Sour steel Double Choc enduro & Cybercrank prototypes are out of this world! Cant wait to see them in action!


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