*Clever* alternative chain tensioner, but...

[Danneaux]

... I'm not entirely sure how secure or long lived it would be.
http://www.bikerumor.com/2014/06/30/moonmen-launch-their-first-bike-the-m00-a-bmx-inspired-titanium-fat-bike/
Clever as all get out though.

Best, 

Dan.

[jags]

they went to a lot of trouble just to keep a chain tensioned 

[Andre Jute]

They've just created a new adjustment problem, keeping the frame ends parallel. On the other hand, if they have some clever way of achieving this and holding the position before tightening the locknuts, some people may consider this a cleaner design than anything that went before. The question arises though whether the extra weight is justified by appearances alone.

[mickeg]

Having just gotten home from a 890 mile bike tour with a frame (non-Thorn) that was too flexible, I would be very nervous about a frame that is partly threaded together with anything less robust than S&S couplers.

[jags]

where did you go.

[macspud]

... I'm not entirely sure how secure or long lived it would be.

From what I can see, not very long lived at all.
There is no form of articulation at the ends of the chainstays or at the ends of the seatstays to counteract the changes in geometry caused by the variable length of the chainstay, that means when the chainstay is lengthened using their tensioner there will be a lot of bending force added to both chainstays & seatstays. I would expect fatigue to set in fairly quickly.
Then as Andre says there's the problem of keeping the frame ends parallel.
My first thought is that this is the worst solution to the chain tensioning problem that I've seen so far.

[Danneaux]

Inclined to agree,  Mac.

Best,

Dan.

[mickeg]

Having just gotten home from a 890 mile bike tour with a frame (non-Thorn) that was too flexible, I would be very nervous about a frame that is partly threaded together with anything less robust than S&S couplers.

where did you go.

Astoria, Oregon to San Fransisco, California.

[Andre Jute]

From what I can see, not very long lived at all.
There is no form of articulation at the ends of the chainstays or at the ends of the seatstays to counteract the changes in geometry caused by the variable length of the chainstay, that means when the chainstay is lengthened using their tensioner there will be a lot of bending force added to both chainstays & seatstays. I would expect fatigue to set in fairly quickly.

That bike is an accident waiting to happen to someone. Makes you wonder what they did with the fork that is "revolutionary" and didn't tell you about...

Bike design is conservative for a very good reason: any conceivable gain is marginal and the cost of failure (hospital bills or worse) is disproportionately high.