A Closer Look at Haven Mercer's Mechanical Automatic Transmission Concept

Nov 28, 2023
by Jessie-May Morgan  
photo
UCI legal?

The bicycle drivetrain has seen a multitude of performance-enhancing changes over the last couple of decades, culminating in very reliable, easy to use options available over an astonishingly vast range of price points. We've seen the widespread adoption of narrow-wide chain rings that improve chain retention, clutch derailleurs that do the same (as well help keep things quiet on the trail), and the consolidation of the 1x system with wide range cassettes and climbing gears that, as my dad tells me, "you could ride up the side of a house with."

Then, there was the advent of wireless, electronic shifting, and the more recently introduced auto-shifting and coast-shifting features for eMTBs. More recently still, we've seen gearbox technology, which has been around for years, combined with an eBike motor in a single, sealed unit that does it all.

While all of these things are impressive, they are, arguably, somewhat incremental. It's rare that we see something completely left of field when it comes to the drivetrain. Hence, my interest having piqued in the last few days with the publication of Haven Mercer's patent on an "Automatic Transmission System for a Bicycle".

What we have here is a continuously variable transmission, meaning that the gear ratio varies between an upper and lower limit with no set number of gears to speak of; the number is effectively infinite. And, not only is the system fully automatic, it is also entirely mechanical. We got the details from the inventor himself.



I was delighted to hear that Mercer's continuously variable transmission is no mere concept. Indeed, he has created a working, rideable prototype.


And, he's taken it mountain biking. Indeed, his goal is to develop the system such that it works well enough for trail riding, reasoning that if it can cope with the demands of mountain biking, it can probably cope easily with the demands of road cycling, and so on. Fair enough.

How does it work?
The system is centered upon the ability of the chainring (for want of a better word) and rear sprocket to automatically expand and contract in response to varying torque inputs. Both consist of a number of pulley wheels distributed about the center of rotation, each supported on a linkage, the position of which is determined by a spring and the amount of torque applied in any given moment.

At the chainring, the mechanism is configured to bias the the pulley wheels to an extended position, such that they are each at their furthest point away from the center of rotation when there is no load on the pedals. Here, the chainring is in its largest effective size.

Before I continue with this explanation, it is essential to note that each pulley wheel sits on a one-way bearing. On the chainring, the pulleys can rotate clockwise, but not anti-clockwise.

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Credit: Haven Mercer
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So, when torque is applied to the pedals and the chain is pulled through the system, the last pulley to engage locks into the chain, effectively becoming a torque-sensing element. The more torque applied, the more the spring is forced to compress and, concomitantly, the smaller the effective chainring size becomes.

Indeed, as the torque-sensing pulley compresses, all of the others do so in unison. The fact that the pulley wheels are able to rotate in a clockwise direction, allows them to feed the chain through such that, as the distance between neighboring pulleys diminishes, the chain doesn't simply get ejected. The same is true for when torque is reduced, and the effective chainring size gets larger.

photo

The mechanism is reversed at the rear sprocket. Here, the spring and linkage system is configured to bias the sprocket towards its smallest possible size, with the pulley wheels closest to one another.

So, in an unloaded state, the transmission sits in its hardest gear. Stamping on the pedals forces the rear sprocket's effective size to increase, and the chainring's effective size to decrease, moving the system towards a relatively easier gear. As momentum increases, and the rider's torque input backs off, the rear sprocket will shrink, and the chainring size grow. The transmission automatically adjusts the gearing to the demand of the rider.

photo

Doesn't it have a built-in chain tensioner?
It occurred to me that it could be, theoretically, possible to run this system without the use of any chain tensioner. It's not so difficult to see that as the chain length requirement at the chainring increases, the chain length requirement at the rear sprocket decreases. While that is the case, the two are not equivalent.

Haven Mercer, inventor of this continuously variable transmission, explained that the system does in fact need not one, but two chain tensioners. That's because the rate at which the two ends expand and contract is different, and that can introduce undesirable chain slack along the upper and lower chain lines. The upper tensioner also doubles up as a sort of chain guide, which appears to be rather necessary given how violently the chain jumps up and down as it is fed into the chainring.

photo

Who is this alternative bicycle transmission for?
As I mentioned, inventor Haven Mercer intends to develop this transmission to the point where it's good enough for mountain biking, technical climbing and all. There are issues with the current prototype, the main one being that the springs are too light, and are thus too easy to compress under pedaling loads. Because of that, he says it rides a "bit squishy" at the moment.

It's easy enough to imagine that the perfect spring rate may not exist, or at least it won't be the same for every rider or every kind of terrain. That said, Haven plans to engineer it such that the springs are easily swapped out by the end user.

Another concern is the durability of the one-way bearings, not to mention the numerous durability issues that could arise from having so many moving parts.

Without riding it, it's hard to gauge how well it would work under any circumstance. However, the fact remains that this invention does eliminate the need for shifting, allowing the rider to pedal along without having to think about what gear they're in, or what gear they want to be in. The transmission would simply adapt to their input.

That could genuinely present an improvement in safety, particularly in the context of riding through heavy traffic. And, particularly for the individual who is a very, very occasional cyclist who is not tremendously well-versed in bike handling. The less that person has to think about, the more attention they can give to the road and other road users around them.

Author Info:
jessiemaymorgan avatar

Member since Oct 26, 2023
40 articles

195 Comments
  • 455 2
 Actually genius, but as a pinkbiker it is my duty to hate it
  • 142 3
 This is the way
  • 76 1
 ACKCHYUALLY...
  • 39 1
 @mcleodpulaski: TEK-NUH-KALLY...
  • 8 0
 @RusMan: This is the way
  • 16 1
 bikeretrogrouch.blogspot.com/2016/01/new-is-old-again-expanding-chainring.html Expanding chainrings is nothing new, but I think its kicking a dead horse. Trying to throw down power through a limited number of sprocket teeth is bad news.
  • 10 1
 Autobots, Roll Out!
  • 41 1
 AS AN ENGINEER......
  • 23 0
 Where do you shovel the coal in?
  • 7 3
 Rim brakes so fuck this
  • 4 7
 Nothing new, just a speed and torque sensitive clutch…..aka CVT
  • 5 0
 @BoneDog: Doesnt a standard chain/chainring only put down power on the first 5 teeth anyway?
  • 9 6
 What are the tolerances for above and below bumbling speed?
  • 1 1
 Is it, though? It just looks like massive drivetrain loss.
  • 4 0
 @onawalk: no.

Best way to visualize this is look at this ANSYS FEA drivetrain loading video and pause at the 5second mark.

- www.youtube.com/watch?app=desktop&v=PHt3zFHd-ZI

The amount of sprocket teeth which will carry the load is dependent on the loading angle of the chain. A larger sprocket has the force spread out more uniformly across multiple teeth, whereas a small sprocket, due to the load angle, only has a few teeth subjected to all the tangential force.

If you made a FBD of each chain link under load and consider the Tangential force driving the sprocket, and the Radial load squeezing the sprocket, it make sense right away why bigger sprockets = more uniform loading.

Also for smaller sprockets, each tooth does more work per revolution of the wheel = more wear.
  • 3 0
 @BoneDog: only time I'm making free body diagrams is when I'm getting paid to do so
  • 2 0
 @rivercitycycles: nothing new, just a CVT on a bike................
  • 2 0
 @BoneDog: Right, I got tired of seeing them in the patent files. I suppose they work, but after all these years, I think Browning was the only outfit that ever managed to sell a few, and that was decades ago.

I think there is an inevitable problem with this idea. As the chain ring turns, the chain rises up and down between the cogs. For a given setting, the gear ratio keeps changing, although not by much. Call it cogging. I think it would be irritating.
  • 2 0
 @garthpool: probably feel great if you had two prosthetic legs...
  • 2 0
 “As an engineer…”. (Followed my pretentious statement)
  • 1 0
 NOT really a new idea, but still a good idea! Also will have problems changing gear under loads
  • 161 0
 Love the simple design. May build one myself tonight.
  • 47 0
 Love the enthusiasm. May check back tomorrow
  • 18 0
 I’m halfway through my first 3D print of V1. May ride it tomorrow.
  • 69 0
 nice and simple...
  • 5 0
 And looks super smooth.
  • 64 0
 Hey bro, I heard you like chainrings and sprockets so we put chainrings on your chainrings and sprockets on your sprockets.
  • 9 0
 Xzibit in da house!!!
  • 1 0
 You make it sound so stupud...........ooooh
  • 62 0
 The MTB industry: we've nailed geometry, we've nailed suspension, we've nailed materials, there's nothing left to do except sell e-bikes.

Haven Mercer: watch this.
  • 14 1
 Apparently, the bicycle drivetrain still needs some over-engineering that isn't nailed down yet.
  • 44 2
 Obligatory "Why is anybody investing time into this instead of gearboxes" comment.
  • 33 0
 Automatic string driven gearbox please.
  • 6 3
 Because gearboxes are already fine the way they are.
  • 6 0
 @Murder-One: Automatic wireless string driven gearbox helicopter please.
  • 2 1
 Yes, this might actually be the one way to create something that has even more drag than a gearbox.
  • 3 0
 @FuzzyL: but it’s spring loaded, you get the energy back for free!!
  • 4 0
 @Ynotgorilla: Ah, I didn’t notice - that means this will kill the e-bike, right?
  • 27 0
 Anyone ever watch Krull? Copyright infringement.
  • 5 0
 Can they call it anything but the Glaive Transmission?? That movie is 40 years old...should be fine.
  • 4 0
 That was the first video I ever rented from the video store.
  • 2 0
 Crazy that I just saw a reference to that movie yesterday, for the first time in (likely) decades.
  • 2 0
 @JSTootell: It was also in my feed...
  • 13 0
 @tremeer023: obligatory what is a video store
  • 2 0
 @tremeer023: haha, me too. That and Beastmaster
  • 22 1
 If we're porting all the things that make cars boring next up is front wheel drive
  • 5 1
 If you're bored it just means you're not going fast enough.
  • 6 0
 It's a public road, not a drift track. And your granny's driving.
  • 2 0
 That's been around for a long time - christinibicycles.com
  • 19 0
 Somehow I feel the urge to go singlespeed.
  • 2 0
 Do it!
  • 2 0
 @RonSauce: I do have an old hardtail I could use and it would take almost no time.

Hmmmm.
  • 3 0
 @BarryWalstead: Look, obviously I didn't invent the singlespeed, and nothing I say here is going to be new information... Big Grin

But I converted my old CX bike commuter over to SS this fall, and it has been *incredible*- I never though a 10 year old, rim brake, aluminum cyclocross bike would ever bring such a smile to my face again, after riding all the new modern tech. There is something so satisfying about it.

I have an old Scott Scale frame that I started racing mountain bikes on it high school, and just realized that I have ~90 percent of the parts to set it up singlespeed. The only thing I need is a fork. Which means, I'm about to have 2 shiftable (lol) bikes, and 2 SS.

Try it, if you haven't before! Its so much fun, for so little investment!
  • 3 1
 @aks2017: Riding without clicking the shifter is indeed the smallest investment I can think of. And you can even keep it varied by using a different speed each day (just not on the same ride).
  • 5 0
 @BarryWalstead: dew it dew it dew it

Most fun thing I've done to a bike, climbs suck shit but take 1/4 of the time as you have to go faster or push and there's no servicing or noise.

Use a good tensioner for it, an original DMR STS or a clone of it would be perfect.
  • 2 0
 @tempnoo1: knocking a few thousand grams of unsprung rotational weight is pretty nice too.
  • 1 0
 @RonSauce: I counteracted that by going back to tubes lol
  • 14 1
 Given that I'm several years deep and thousands of hours into vetting the solid body interference of a complicated yet robust enclosed CVT gearbox of my own design... I applaud the crap out of Haven's effort. You have to be VERY motivated to try this kind of stuff. The comments in the thread give me some hope in an otherwise *dark* effort. I agree with the criticism that this design going to be hard to extract 500% range. It would be possible to have the retractable claws (to so speak) have an added order of complexity for the rear variable sprocket: like a human finger with two mid joints. The extra width required for the extra levers to do this would be just barely manageable in terms of Q factor. I'd like to see how this design handles sand and snow because it does looks vulnerable to fouling.

I'd like to know how the polygonal lumps in gain ratio - the straight sections of chain between contact points - end up feeling to the rider through the feet.

The solution to the "timing" problem of a variable sprocket is certainly intriguing on paper. Throw some dirt at this thing and do a wheelie with a slow motion camera.
  • 12 1
 The other problem not mentioned is gear range. This looks like it can vary between 58:30 and 44:40, maybe. Front ring can never be smaller than those eight 9 tooth sprockets can nestle together, which has to be fairly big (though you could maybe go to 7 or 6 of them and have it feel even less round), and there is a similar problem with the rear. Getting a range of even 200% will be very difficult, getting to 500% seems like a very big stretch.
  • 10 1
 "The transmission would simply adapt to their input."

No, this adapts to the output, not the input. Less friction on the output, hence less output power needed, makes it "shift" up. This thing would auto-"downshift" when you sprinted, which is not really what you want.
  • 3 0
 In theory I think it would just keep the force on your feet the same regardless of terrain or effort on your part. So if you want to sprint you would just pedal faster instead of harder and faster. I don't think it would work for more competitive riding but I could see it being a good cruiser transmission. I could see how you might be able to have some control over that though by changing the tension on the spring. That seems like a bit of a nightmare from an engineering standpoint though if you want to be able to adjust from the cockpit. It also already looks like a lot of rotating mass compared to normal gearboxes. cool Idea but I'm not sure the tradeoffs are going to be worth the benefits overall.
  • 1 0
 @Jsinisi: I know! He can incorporate a thumb actuated lever that would change spring tension
  • 2 0
 @Jsinisi: Yeah, that's what I said: sprinting (more input force relative to output; ie: accelerating) would cause a downshift, pedaling faster and easier, but not going faster. I don't think it would work for any bike: acceleration would be virtually impossible under most situations. There would be an upper limit on wheel speed depending on output force required, and that would be directly linked to the spring force. Without enough spring, you'd run out of cadence before getting sufficient wheel speed, but with enough spring to get useful speed it just wouldn't shift down. Interesting idea, but not really applicable to bicycles.
  • 20 15
 1x11 was so far the best drivetrain i had, 1x12 not so much....
"The bicycle drivetrain has seen a multitude of performance-enhancing changes over the last couple of decades, culminating in very reliable, easy to use options..." ..., untill eagle changed it
  • 28 1
 9 speed is king
  • 16 3
 11-speed XT > current offerings, but would happily take the same range with fewer cogs if the steps were right
  • 10 0
 @mior: 10s with a good chain is great as well.
  • 19 1
 My current 1x12 XT drivetrain handily outperforms every drivetrain I have had before it, including a SRAM 1x11 (2018 ish).
  • 8 3
 Curious: what exactly do you dislike about 12 speed?

I was pretty early to adopt SRAM eagle stuff and it worked great. Current generation Shimano XT and Sram Eagle and T-type have been completely flawless for me on a bike that sees proper enduro and some park riding.

There are several climbs in my area where I'd love a 13 speed - and that is despite being objectively quite fit!
  • 2 5
 @MartinKS: Funny, I find 1x11 to be the worst. Adjustments are really finicky and it always seems to end up rubbing on one or two cogs. Both 1x10 and 1x12 have been far more reliable for me. This is all with Shimano, SRAM may be different.
  • 12 0
 @mior: Advent X is king
  • 3 2
 12 speed XTR > 11 speed XTR and I loved 11 speed XTR
  • 1 0
 I like 1x12 over 1x11, with 1x11 being light years beyond 1x10.
  • 3 3
 1x11 with 11-50. Best drivetrain. Shit 1x12 only makes problems. 1x12 never would have been made if they brought 1x11 with 50 or more teeths.
  • 5 1
 Deore 5100 11 speed with 11-51 cassette the best value likely ever in a drivetrain. Can be had new for about $150 and performs beyond what I could have imagined an XTR system could ever be not more than 10 years ago.
  • 2 0
 @browner: hell yeah. Lent my bike out to a mate who owns X01 AXS, he came back saying my XTR stuff shifts smoother and cleaner every time.
It’s also 3 years older.
  • 1 0
 @psyfi: it's pretty good, but they should have gone a little more high-performance with the design. The cassette is a 600g boat anchor, and the shifter isn't as good as the old 11 speed XT from the 11-46 group.
  • 1 0
 @riish: it's also cheap I got cassette, chain, derailleur, shifter, f&r brakes for £650 in 2020
  • 2 0
 Actually, at the Shimano side of things I liked both 10speed and 12speed better than 11.
  • 3 2
 @KJP1230: 12speed is heavier and (in my experience) much more critical with the adjustment and more prone to straightness issues
  • 1 0
 @browner: yeah, compared to the prices of AXS and transmission it’s a steal. I min-maxed a bit and got an SLX crank/cassette, XT shifter, and XTR mech/chain.
Waxing chains, I’m going to get 3-4 years out of one cassette and 3 chains, riding 200-250 days a year. Which is a ridiculously low $/km ratio.
  • 1 0
 @riish: unfortunately, 200-250 days a year is not a great metric. That can be 5 flat miles in perfect weather, or 30 grinding miles in the mud. Both would have a very different outcome.

In my area, I get moderate grinding miles. But the weather is perfect, so get great longevity. My X01 12 speed cassette will last forever. And I haven't measured any chain stretch on any of my chains yet, I just rotate them at random.
  • 6 1
 Can you back-pedal? Seems like with one-way bearings all through the system that's a "no". I guess that's not a total deal breaker, but inconvenient, kinda like riding a coaster-brake. Why not just add/have a torque sensor tell the Di2 or AXS derailleur when to shift?
  • 10 1
 Back peddling is possible on any drivetrain via the rear hub freewheel. This mechanism wouldn't effect that.
  • 2 0
 @BarryWalstead: thanks for the reply. Do you think the whole system would shrink and "change gears" as you back pedal and are applying 0 torque, then it'll expand again as you pedal? Just wondering how "ratchet moves" we do on MTBs would work with this design. Thanks again for engaging.
  • 1 2
 @BarryWalstead: It says in the description that the bearings are one way, so to my mind you could freewheel, but you wouldn't be able to back pedal.
  • 2 0
 @commental: you don't need those bearing to spin to backpedal
  • 4 2
 @B-foster: "it is essential to note that each pulley wheel sits on a one-way bearing. On the chainring, the pulleys can rotate clockwise, but not anti-clockwise."
If the pulleys can't rotate anti clockwise I don't see how back pedalling would be possible.
  • 3 0
 I'll admit that I'm possibly having a huge brain fart though. :-)
  • 1 1
 @commental: Yeah, you'd have to have a freewheel in the front, too.
  • 5 0
 @commental: If the pulley wheels don't spin, then they act as a "solid" chainring or sprocket same as you would usually have. I'm assuming of course that there is a normal freehub in the hub. and the whole crank assembly spins backwards as would the freehub.
  • 9 0
 @commental: The pulleys rotation is opposite to the chainring rotation. When you apply power the pulleys are locked but when you backpedal, the chainring rotates anti-clockwise and the pulleys rotate clockwise. Yes you can backpedal.
  • 1 1
 @BarryWalstead: where does it say there's a rear hub freewheel? Each pulley freewheels, to have the hub do the same is superfluous.
  • 2 1
 @B-foster: Yes, I think I'm getting my head round it, but with the "chainring" changing in circumference with altered torque I wonder if there would be problems with the pulleys meshing with the chain if they can only rotate clockwise? I'm not going to lie, it's making my head hurt!
  • 3 1
 @clivem25: It doesn't say specifically in the description, but the reason for having a freewheel in the hub would be... to backpedal. Be a pretty crappy cycling experience if you could not.
  • 1 1
 @commental: I believe that's the purpose of the one way rotation pulleys, so the chain can stretch itself out and not bunch up
  • 1 0
 @B-foster: Yes, I think you're probably right. It's interesting watching the video using this method copied from a comment on another thread;

"A little known feature of Youtube: If you pause, you can then use the comma and period keys to go (respectively) backwards and forwards, one video frame at a time. Much more convenient than trying to pause at the perfect moment! Note that on an embedded video (such as here), you'll have to first close the "other videos" popup that appears when you pause."

If you watch the video using this method it's amazing how much the chain jumps at times as it engages (or not) on the first pulley at the top of the chain, As Jesse-May mentions in the article, the top tensioner acts as a chain guide. With the pulley on the lower tensioner being further away, and seeing how much slack there is at the bottom of the chain at times I could see it being far from smooth and pretty easy to drop the chain when back pedalling, especially off road.
Sorry if I'm going on a bit everyone, as you've probably all worked out by now, I'm not from an engineering background.
  • 1 0
 @clivem25: only if you WANT your chain to always be spinning and running on those tiny one way bearings.

And obviously you don't want that, so it must have a freewheel. This isn't rethinking every single bit of the drive, just the gearing.
  • 4 0
 bikeretrogrouch.blogspot.com/2016/01/new-is-old-again-expanding-chainring.html Similar designs have been out there for ages. Imaging trying to throwdown power on a chainring with equivalent of 6 tooth engagement. clunkyyyyy
  • 1 0
 Excellent link, thanks!
  • 6 0
 A stick somewhere in this thing looks like it would sew absolute havoc. Still, it’s kinda cool
  • 7 0
 Crank cowboy spurs
  • 2 0
 Can also be used for plowing
  • 6 0
 They used that in Spider Man 3
  • 7 0
 Dorks gone wild!!
  • 6 0
 More steam punk than sci-fi, but I like it.
  • 6 0
 Wow, neat! It's like the tourbillon of drivetrains.
  • 2 0
 Would this not consume considerable wattage by using rider input energy to compress all the springs? It takes energy to compress a spring, and also to keep it compressed even if it's not moving, no? Those springs don't look too insignificant.
  • 3 1
 166 comments at this point, and not a SINGLE mention of RUBE GOLDBERG??

You people are slipping!! lol

And using the word concomitantly?? Was that on your "Word of the day" feed, and you felt obligated to use it when there are a half dozen other words people have heard before and use often that would have got the point across..........
  • 2 0
 I came here to do exactly that, did a page search first for "Rube", yours is the only one that came up. I mean, did IQs just drop sharply while I was away? Big Grin
  • 3 0
 To everybody grousing about the use of "concomitantly", fret not, for the idiocracy is imminent. Oh, sorry, that should have been something like "you no worry, dumb time come soon".
  • 4 0
 This makes me appreciate the current bicycle drivetrain even more as it has existed for over 100 years!
  • 3 0
 That's pretty neat.

I don't get why the rear tensioner is so circuitous. Seems like a more traditional derailleur shaped tensioner would work fine back there?
  • 1 0
 I can see a version of this using an iris (similar to the aperture of a lens) to reduce the polygon nature of the chain around the device. It may also be possible to tension this using torsion which would simplify the design and reduce weight.
  • 1 0
 Reminds me of the perpetual wheel from 3 years back. Spring punk is alive.
www.pinkbike.com/news/the-super-wheel-claims-to-offer-power-assistance-without-a-motor-and-were-very-skeptical.html
Maybe a perpetual drive train and wheel together to end the need for batteries. But seriously, amazing engineering Haven. Very cool idea.
  • 1 0
 Maybe one for the engineer to explain.. but i'm trying to wrap my brain how this works in the real world- so I understand how it responds to torque to vary the gear ratio- but how does it respond to your speed increasing as you go?

I'm sure that this is obvious, but thinking from a practical sense of how we use gears- a certain amount of it is to reduce the effort of pushing our bodyweight + the bike up an incline, but also the other function is because our legs are only really useful at a certain cadence and as anyone who has ridden fixie would know- there is only so fast they can spin?
  • 1 0
 Yeah cvt's work great with the broad rev range of an engine. Not do sure with our limited cadence range.
  • 3 1
 This should replace my cassette not my chainring. " A" for effort, not sure there is any need for this system over current designs but i do love the look.
  • 3 0
 If someone approached me with that, I would IMMEDIATELY give them the launch codes.
  • 4 0
 No strings? Looks like it’s chained to the past.
  • 4 0
 I love this and hate it so much at the same time.
  • 2 0
 New word of the day: concomitantly - "at the same time; simultaneously."
As in, I am concomitantly working and scrolling through pinkbike.
  • 1 0
 So if you put more watts/torque it change the gear, must be weird to ride.

Also, I see bunch of people every year coming to Prague to see Astronomical clock, but I don´t think they want to see it on their bikes.
  • 1 1
 Cant we just get rid of the chain, make this much bigger and directly integrated with the front wheel. When pedaling hard uphill, would compress and shrink your front stack, when going downhill would expand and decrease your head angle. When hitting a rock would compress like a shock. Seriously - so many pinkbike problems solved!
  • 1 0
 Just imagine If WE put all the energy on improving gearboxx and making lighter gearhubs... How much money Sram and Shimano would lose??? And how good for the planet it will be?
  • 1 0
 You definitely need a bash guard to ride that thing ! Imagine casing a log or a stone, those amrs would bend like noodles ! Cool concept otherwise, problably more usefull in an urban/commuter usage than mtb though.
  • 3 0
 Looks like a dropped chain waiting to happen
  • 2 0
 It's a good idea, but this is a rough prototype. I'd love to see a cleaned up version of it.
  • 1 0
 That's gonna be a huge ass MOFO gearbox!
  • 2 0
 Attach it to the new Specialized prototype DH bike and you've basically got the ingredients for the next saw movie.
  • 3 0
 If the Marquis de Sade made a drive train...
  • 3 0
 This looks dangerous to operate and I like it.
  • 3 0
 Presenting the Circumciser 3000!
  • 2 0
 Bike 'engineers' will literally do anything besides develop a gearbox for the masses.
  • 1 0
 This...
  • 3 0
 Someone pass me the bong, I need to take closer look at this..
  • 1 0
 I thought of a prototype for this a long time ago but couldnt make it work properly. Its great to see something that actually works.
  • 1 0
 Ahhhh....the seemingly phyrric pursuit of a goal! no matter what form it arrives at. I applaud this maniacal experimentation, no matter how platypus-like it appears
  • 2 0
 Your move single speed guys!
  • 1 0
 Rohloff system..
  • 2 0
 Looks cool. Also looks an evil machine from that old movie 9.
  • 1 0
 Loved that flick as a adolescent animation fan/ stoner!
  • 1 0
 Someone broke out the 80's movies and got high:

images.app.goo.gl/T18LfmwA8essmPs17
  • 2 0
 concomitantly:

at the same time; simultaneously
  • 2 0
 For a whopping 200% range!
  • 2 0
 A single-speeder just died inside. That single-speeder is me.
  • 1 0
 Master of the flying guillotine. Huwaaaaa!!
youtu.be/w11jAtQrQHk?feature=shared
  • 3 0
 Holy Fuckery
  • 1 0
 All the kids' Christmas gift Lego sets are now being torn open by parents to build these things.
  • 2 0
 I LOVE IT! I would hate to get my ankle caught in it.
  • 1 0
 This is actually brilliant, but what happens when you want to pedal hard to go fast?
  • 1 0
 But if there's no gear cable, I can't route that through my headset! I'm out.
  • 1 0
 Can we please make stuff easier and more reliable instead of more complicated? That I would call innovation.
  • 1 0
 ok the crank.... but what about that hand pressed wheel resistance brake!!
  • 3 0
 LSD is a helluva drug.
  • 1 0
 We wanted some out of the box thinking around drivetrains. Now we have out of the box thinking about drivetrains.
  • 2 0
 Oh Sh*te, gotta replace bearings to my chainrings...
  • 1 0
 Consider how automatic transmission has ruined driving and the automobile in general... Had pass for me!
  • 1 0
 Let's invent a gearbox that is simpler, less delicate and, as far as possible, cheaper than current drivetrains.... lol?
  • 2 0
 Weird wild stuff, man.
  • 1 1
 I don't care that it weighs more than a high-pivot gearbox belt-drive with a Rohloff hub. I WANT IT!!!!!
  • 1 0
 NXT we'll be putting front derailers back on are bikes..
  • 2 0
 Landrider
  • 1 0
 Looks like a torture device
  • 1 1
 Nothing to see here... just a scooter (CV) transmission with a chain, instead of a belt.
  • 1 1
 Mmm... I have see it before!!! --> en.wikipedia.org/wiki/Buer_
  • 1 0
 Mad Max would definitely rock this groupset.
  • 1 1
 Imagine feeling that your viginity in such mortal peril that you actually install this on your bike
  • 1 0
 Ouch. Straight up dangerous LOL
  • 2 0
 Imagine the noise...
  • 1 0
 Have fun with that when you drop a chain
  • 1 0
 Gonna drop more chains than the slash
  • 1 0
 That crank looks like a medieval torture device.
  • 1 0
 Holy mother of moving parts batman.
  • 1 1
 Neat concept but completely impractical for mountain bikes. Maybe for use on a cheapo city bike.
  • 1 0
 This is insanely impressive
  • 1 0
 Come back when it's mounted to a Nicolai, then I'll listen
  • 2 0
 0% mud resist
  • 1 0
 Nice use of magic link spring
  • 1 0
 Wow, the Idea is kinda simple and default standards compatible!
  • 1 0
 How do you sprint with this thing?
  • 1 1
 . . . Just like most forms of Government, this design has too many moving parts ! ............
  • 1 0
 Holy chordal action batman
  • 1 0
 lol
  • 1 0
 CVT.
  • 1 0
 Indeed !
  • 1 0
 Square taper bb, I'm in!
  • 1 0
 Should be belt drive
  • 1 0
 Throwing stars ✨
  • 1 0
 Seems simple enough.
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