Bike Check: Auckland Cycle Works' "Kind of Like a Rearward Pivot URT" Experimental Prototypes

Jun 28, 2022 at 10:50
by Alicia Leggett  

"All the good photos" by Jerry Tatton @JWDTphotography

The bike world runs on out-of-the-box ideas. How else would we have reached the point we're at today, with dropper posts, mixed wheel sizes, high pivot designs, and all the other wackiness we now take for granted and that makes our lives easier? Even mountain bikes themselves were born from cruisers that some renegades decided to retrofit with balloon tires (the details depending on which branch of mountain bike origin folklore we believe).

Our entire sport owes itself to nonconformity, and for that reason, it's always exciting to see a truly left-field idea come to fruition. A little while back, we found the webpage for a fascinating project that we've been watching, created by British bike shop owner Gary Ewing, who fits all the criteria for a top-notch tinkerer: he's creative, intensely curious, and seems to have an endless supply of what if questions. In 2021, when he had more free time than usual amidst the pandemic, he decided to draw on a conversation he had nearly two decades prior for inspiration to create a bike.

The current edition, the Marra, is the result of lots of experimentation.

In about 2002, Ewing was on a ride with endurance cycling legend Mike Hall and asked Hall about a bike he'd designed and built for an A-level school project. All Hall said, Ewing recounted, was that the bike design was "kind of like a rearward-pivot URT."

URT - unified rear triangle - bikes emerged in the '90s to try to balance pedaling firmness and suspension performance. By moving the bottom bracket from the frame's front triangle back onto the swingarm and putting the main pivot up away from the bottom bracket, engineer and cyclist John Castellano managed to create a system that was firm while pedaling out of the saddle but provided active suspension while seated, which was the gold standard at the time. For a variety of reasons - including the already-scary-by-modern-standards bike geometry becoming increasingly sketchy under braking forces and while descending - URT was retired about as quickly as it rose to prominence, and the bike world largely moved on. (Find a deep dive into the URT story here.) Still, Ewing says he believes in exploring concepts and wasn't convinced that the URT theory had been fully played out.

When we discovered his project, one sentence in Ewing's description stood out: "The discredited URT (unified rear triangle) design looked like an unfixably bad idea, but I wondered: if combined with other things that also appear to be bad ideas, what's the worst that could happen?"

If that's not an intriguing approach, I'm not sure what is. Enter Ewing's aluminum prototypes.

As a starting place, he wondered if perhaps a URT bike with a rearward virtual pivot motion and dramatically rearward axle path could help control some of the negative characteristics that had undone the URT design in the '90s. He built his first two URT test configurations not because he thought they would work (he was clear that they probably wouldn't), but because that seemed like a good place to start the experiment.

We at Pinkbike hear from many, many people who believe their idea is the next great thing that's going to change mountain biking forever. Spoiler: those ideas often don't live up to the hype. In contrast, it was quite refreshing - charming, even - that Ewing approached his project with pure curiosity and without grandiose claims.

"I started this whole project thinking that I’d make something that was vaguely like Mike’s idea, as a fitting tribute to him, that I’d learn a whole heap of new skills, and I’d get a bonkers thing to hang on the wall of my shop and an interesting YouTube vid," he wrote.

There's a lot to look at here on the first prototype, even with the exciting part all covered up. The bike wasn't even exactly supposed to work, so it wasn't a big deal that the seat tube angle came out dramatically wrong. "I knew this was just an experiment," Ewing explained. Plus, he could problem-solve to make the effective seat tube angle rideable.

For the first experimentation and design, Ewing built his initial models using Lego Technic, not the CAD programs used by most builders, because he likes the ability to make quick changes and engage with his designs hands-on, even if the process has a bit less finesse than computer-based systems. Plus, as someone who grew up toying with Lego Technic models of all kinds, he's plenty familiar with that style of tinkering. For initial proof of concept, his way worked great, he said.

He did have to learn some CAD modeling and made quick progress with the Fusion 360 CAD program to get the linkages CNC’d, he said, but realized he could spend two years full-time on that side of the project and still be only a mediocre CAD designer. "It soon became clear that CAD is a whole universe of learning and knowledge, and that I’d be better off finding someone good that can do this for me," he explained.

When the Lego models took shape in the real world, to Ewing's surprise, the first prototype performed pretty well... sometimes. Pedaling hard in a high gear "required motion sickness tablets," he said, but the bike was a surprisingly quiet pedaler in low gears and the braking performance was better than expected, compared to the head-angle-steepening and wheelbase-shortening effects under braking - resulting from extension of the rear shock - that marked the historic URT bikes. Still, it needed some big changes, so he hacksawed it and re-assembled it into the second prototype, which was a bit better, he said: "The very rearward axle-path made it blisteringly and effortlessly fast on smooth singletrack. The awful kinematics of the URT design meant the suspension didn’t cope well with lumpier terrain, yet the braking performance was surprisingly good."

Prototype two. "Better than proto #1, but proves beyond any doubt that the URT concept should be left to rest in peace."

The remains of proto #1 were still in there somewhere with proto #2. "For this proto, I only paid for strong welds," Ewing said. "Pretty ones cost extra!"

It wasn't the bike he wanted to ride, so Ewing had all but committed to putting the project to bed when he had what he describes as a true eureka moment - he figured maybe some of the characteristics he liked about the bike could be retained if he just moved the bottom bracket to a more standard position. Based on how the suspension linkage moves, he figured he could put a high pivot idler on the lower linkage that could be easily moved forward, backward, up, or down - within seconds, he said - to fine-tune the bike's pedaling and suspension performance.

From the first design... the current one.

Starting again from the ground up, he built a bike that he's calling the Marra, which features 190 mm of suspension front and rear and already has a patent pending on the suspension design. Through some more experimentation with his idler concept, he discovered that - surprisingly - the idler position that allowed for the easiest pedaling was also the position that best optimized the shock performance, he said. As for the actual measurements, the current model has a 480mm reach, a 645mm stack, and a 63-degree head angle.

He's not surprised that the bike performs well on the descents, thanks in part to an axle path that's dramatically rearward for the first half of the shock stroke but nearly vertical for the rest of the stroke. The chainstays lengthening only through the top of the stroke means that the bike should retain a fair amount of playfulness, he explained, though he's still not quite satisfied and wants the chainstays to be a bit shorter. Even so, a recent trip to Les Gets reaffirmed his suspicions that he's onto something, he said, with the bike pedaling efficiently and descending comfortably.

The next parts of the story: Ewing says he'll keep refining the Marra and plans to play with some shorter-travel top links. He's also been working on a 120 mm carbon bike that he was hoping to race at the Glentress Seven race - a seven-hour trial by fire - but unfortunately he's been sidelined by injury for the time being, and that was an ambitious deadline for getting the bike finished anyway, he said.

The short travel edition is nearly ready to move into the physical world. Ewing suggested the label #neverbackdowncountry, which I think is downright amazing.

Hopping the other direction in travel, he's also sketched a downhill version that's almost identical to the current Marra but uses an extra linkage that alters the kinematics, making the shock stroke more linear at the beginning and more progressive at the very end for coil shock compatibility.

Looking even farther ahead, Ewing also hopes to one day make an e-bike. At the moment, though, he has plenty to keep him busy, with his suspension design patent decision approaching in August, plans to race the Marra at the Tweedlove Bike Festival in September, and a stand booked at the Bespoked Handmade Bicycle Show in October.

And we know that whatever he does next, he'll be following his curiosity, testing his intuition, and giving the bike world something new to talk about. Which is exactly what I want to see.

Follow along at, Instagram, and YouTube.

The bike is right at home on choppy descents, Ewing said. He's planning to keep experimenting.


  • 99 2
 I sat for a while and pondered should i really just head for the comments section at 17.56 GMT and see what the 5 comments are or should i wait and actually read the article that someone has spent a good few hours writing , see i think i have become a comment section whore , flawed by my inpatience and requirment to see what others think SO , I READ the entire article in all its glory and discovered NOT A SINGLE MENTION OF HOW MANY WATER BOTTLE MOUNTS screw you guys
  • 21 1
 Lol. With how this bike is hacked and welded together I'm sure this guy would have no problem fitting 10, 15, maybe even 30 zits, I mean bottle mounts, on this frame.
  • 79 0
 Great effort. 6 more pivots and I think he would have nailed it.
  • 1 0
  • 3 0
 @jclnv you so evil
  • 2 0
 That was my r3action too!
  • 1 1
 op doesn't even know what a pivot is.
  • 38 2
 Definitely nURT a Session.
  • 5 0
 Judging from the pics, even this psychopath decided URT is still the stupidest design in history.
  • 2 0
 @BenPea: if there weren't for "psychopaths" you'd be living in a cave, caveman
  • 36 3
 Thought it was an Orange prototype when I saw the welding
  • 4 2
 They do love old technology
  • 26 0
 In a shocking development, the refined version does away with the URT. Who could've seen that coming?!
  • 1 0
 My brother still rides his Mantra, although mostly as a townie these days. I rode it a few hundred feet on a steepish dirt road. Stinkbug effect is no joke. Couldn't wait to get back on my bike, no way I would ride that thing on singletrack unless it was pancake flat. Good riddance.
  • 20 0
 How many links do you want?

  • 16 0
 I don't think you even paid for 'strong'
  • 7 0
 Ya.. As much as I respect the builder, pretty welds ARE strong welds. Consistency, same travel speed, same dip of Al filler into the puddle, same arc length, same tungsten angle will result in a clean pretty strong weld. The starts and stops, different puddle widths of the welds... idk maybe its just me

Has anyone ever seen a broken Nicolai?
  • 2 0
 @trumbullhucker55: i guess you shouldnt take it to seriously. might just be a joke Wink
  • 16 0
 He's going to add headset cable routing in the next version, just you wait
  • 13 0
 I love the underwear to cover up the interesting stuff. A big brand should do that, have a rider race with some briefs covering up the fun bits Wink

On the bike you perv
  • 15 0
 Needs a curved dropper post
  • 1 0
  • 4 0
 Dropper circle
  • 4 0
 That's a funny idea. A curved dropper could work as long as it arcs with the same radius all along (like a section taken from a circle). I'm not sure if there's a rational reason for building one, but in the spirit of this article, someone should definitely build one.
  • 14 2
 i-Track suspension lawsuit inbound in 5...
  • 2 0
 Was just about to say that, loving my craftworks enr i-track..
  • 3 0
 if the bikes are never for sale theres no infringment.
  • 1 0
 @HeatedRotor: not only australia. I'd expect Hugh to have protected it in other markets given Intense was testing his suspension
  • 2 0
 @spaced: They weren't 'testing his suspension', they had to run a logo (just like Neko), because the idler was 'link mounted'. That's the patent. As long as it's a single pivot or the idler is front triangle mounted (doesn't move relative to the front triangle, so coaxial to a link is kosher), then it's fine.

You can buy i-Track development services, but the stickers on the Intense are there because of the position of the idler. As far as I know (Neko confirmed that in his videos for his bike for example).

Given what kind of a bike the i-Track proto is, I SINCERELY doubt Intense would go for a simple horst link if they bought their services.
  • 8 0
 Protos from the insane solo mad scientist type builders are a special kind of ugly. That's just fine though because they have no need of any marketing sneak peak advertising BS like big brands try to do. It works and you learned something? Home run. Screw the aesthetics.

I had a ton of Lego technic stuff that i loved so hell yeah on using that for mockups.
  • 8 0
 That involved some serious Backward thinking... Ya, I got nothing for a good pun.
  • 3 0
 I always have questions WHY? will it provide more than 10% ( or whatever) benefits over current platforms?
It is always cool to see improvements in bike design, however, I believe modern sus quite dialed, compared to other areas of the bike design.

for fun - sure it makes perfects sense
  • 1 0
 10% would be huge, it's more likely to be 1%
  • 3 0
 I guess most of y'all are too young to remember that Giant actually made a prototype VPP/URT/pull-shock mashup for John Tomac in 1996. The internet seems to have totally forgotten about it short of this one pic that unfortunately has a sketchy looking URL. The second (more reputable looking) link is the article it is from if you scroll just past halfway down.
  • 8 3
 I've ridden it, it's pretty good!
  • 1 0
 Well, good lord…I suppose I got to doff my cap to him for doing what he’s done. But, I mean, well, let’s put it this way, Ancillotti built a Mtb over 30 years ago and it won a world championship. About 10 years later it won another one and the same design keeps winning enduro and downhill races and championships to this day. Keep it simple, the rest is mostly marketing bs.
  • 1 0
 Back in the stoneage, when Trek released the Y (TF you do that) bike, I got into some flame wars on the stoneage internet of the time with people about it being the stupidest, most obviously flawed design ever. Man, if you read those exchanges but didn't know the year, you'd think it happened today. I soooo wish I could find some of those kooks and tease them something fierce. Maybe if I go explore the Mojave and look for some remote permanent Airstream camps...
  • 3 0
 Jesus h how long did it take to have an argument on the internet back then on dial up
  • 2 0
 @Compositepro: LOL! 9600baud was screaming fast for posting to Usenet. Big Grin
  • 2 0
 Looks like a… ahh… nevermind.

But always great to see a new approach, let us know when the short travel version comes around.
  • 5 0
 needs a gearbox.
  • 3 0
 Is the underwear to "protect proprietary design" or is it just to cover the shame of building a URT bike?
  • 3 1
 I like all the holes in the shock mount plate (2nd pic) Great way to reduce weight & make the bike feel lighter..
  • 6 0
 @sportstuff: Speed holes
  • 13 0
 @FaahkEet: drillium
  • 3 0
 Prototype 1 should be called The Peyronie’s Disease
  • 1 0
 That's a Hardtail rider's nightmare. Still, nice to see people pushing boundaries. Not my cuppa tea, but hats off for trying!
  • 2 0
 Cool approach. Just fool around. See where it leads. And don't be afraid to totally switch paths when necessary.
  • 2 0
 So kinda like a kludgy Haro Sonix.
  • 2 0
 Haro Sonix - that was an FSR w/ the Horst link near the bb. It was a free bike but real unsightly. Gave it to ex-wife’s new husband….
  • 1 0
 @NWintheUSA: No, it was what happened when you cross breed an URT with a DW-link.
  • 2 0
 Love the Peyronies seat post!
  • 3 0
 fugly as eff
  • 1 0
 Seen it in Morzine a couple of days ago... It looks crazy but I love it haha
  • 4 3
 As long you don’t have canyon weld your bike, you’ll be good.
  • 1 0
 I absolutely love the monstrosity of welds and pivots. Wink
  • 1 0
 TIL Auckland isn't only the largest city in New Zealand.
  • 1 0
 Im sitting here in Auckland going wtf. Move over here mate.
  • 1 0
 Are the Y-fronts a nod to Trek's infamous Y-frame URT bikes?
  • 2 0
 I feel sick
  • 1 0
 Should have just made a carbon sintesi bazooka just..
  • 1 0
 lol like they say...trash is trash
  • 1 0
 Love to see GAMUT cilos stems still floating around.
  • 1 0
 Don't EVER stop!
  • 1 0
 Keep it simple stupid!
  • 1 0
 Holy chain slap...
  • 1 0
 This is so cool.
  • 1 0
 So many Bearings....
  • 1 0
 Ewing, cool name
  • 1 0
 pure precision
  • 1 2
 Welded by Orange

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