The Four-Year Story of Fin Woods' DIY Carbon Enduro Gearbox Bike

Fin Woods, an industrial designer who lives in Mount Maunganui, just outside of Rotorua's Redwoods Forest, is one of those riders. The New Zealander set out to do something about it.





Woods' answer is a 170mm-travel, carbon fiber enduro bike that he designed himself. It employs a 12-speed gearbox from Pinion, along with a futuristic-looking suspension layout that combines a high main pivot, concentric axle pivot, and a low-slung shock compressed by a compact linkage near the bottom bracket.

It's an impressive looking bike that could easily be from a derailleur-less future but was actually designed in 2016, and the journey from sketches to a kinda-rideable prototype has been a bumpy one.

''For all of my life, I have had issues with derailleurs. So many rides have been ruined by snapped hangers, bent cages, broken cables, or all of the other problems that come with those bloody things,'' Woods told me. And then, back in 2016, when he was in his final year of university, Woods had to design and develop his own product. ''I had some different ideas for what I could do, but what made my decision was when I was going for a ride; I pulled my bike off the rack and the derailleur cable was snapped.''

That broken cable was one ride-ruiner too many, but the first step, he said, was to figure out why derailleurs were so pervasive, especially given the rate at which he was going through them.




He came to the same three conclusions others have: A lack of consumer knowledge, that many gearbox bikes are poorly designed or too bespoke, and the kicker is that gearboxes haven't seen anywhere near the development that derailleur-based drivetrains have over the past decades. ''Although not all solvable in a design project,'' he said, ''this is what defined the brief: A gearbox equipped enduro bike that was nicely designed, competitive with the derailleur-driven bikes, and I had a bit of stab of what bikes would look like in a few year's time.''

His project culminated in a proof-of-concept scale model, but Woods wanted something that he could ride, not just look at.



The Gearbox Mindset

Once you've had a few too many rides ruined by exploding derailleurs, having all those fragile bits tucked away safely inside a metal box surely seems like the better way to go. But the gearbox bike has never progressed past the point of wild-looking concepts and, at best, relatively low production numbers.

Opponents, including myself, usually cite cost, drivetrain inefficiencies, and how they can require a different shifting technique as the reasons, three strikes for many of us who haven't had the headache-causing derailleur issues that Woods has.





''It really comes down to the kind of riding you do in relation to drag,'' he counters. ''For flatter kind of riding, gearboxes don’t make too much sense. But as soon as you add a decent amount of gravity into the mix, their benefits really come into the light. The drag is actually super minimal in the lower end of the gearbox, so riding up is virtually unaffected by it.''


While I've probably written tens of thousands of words pointing out the negatives of gearbox drivetrains, for Woods, those are obviously outweighed by the positives.

''It’s funny, I’ve taken people riding that have barely ridden any kind of bike before, and they find the gearbox shifting much more intuitive and easier to learn than a derailleur,'' he says. ''People get stuck in their ways and find having to adapt a negative when, in reality, if they embrace it, they can open up possibilities in their riding not previously possible. It’s just a mindset thing, and not everyone lets themselves adjust,'' he added without actually using my name.





High Single-Pivot Suspension

While there are a handful of high single-pivot bikes to pick these days, from downhill sleds to burly trail bikes, that wasn't the case back in 2016 when Woods designed the Sherpa. So, how did he end up using this suspension layout four years before it became the up-to-the-minute way to do things? ''The gap between enduro and downhill bikes is constantly closing, and I wanted the bike to be ahead of the market, so I knew it would have to have downhill-influenced suspension,'' he answered.

Woods is referencing how a high-pivot layout provides a rearward axle path, something that's said to be a key ingredient when cooking up a fast bike. A rear wheel that moves back slightly can get out of the way of rocks and roots quicker than one that can only move straight up and down, thereby letting you carry more momentum over rough ground. When your races are three-minutes long and sometimes decided by tenths of a second, that kind of thing matters, and Woods wanted his enduro bike to have a similar focus.

But he says that he didn't want to take it too far: ''I like to call my suspension the 'not so high high-pivot' because if the pivot is too high and axle path too drastic, the bike can feel sluggish,'' he told me, with his goal being to have same baked-in pop and playfulness that a pure-race bike might not be inclined to offer.




But for a high-pivot design to work, the chain needs to be routed close to it to avoid too much drivetrain interference, often called "pedal kickback." This is when the suspension tugs on the chain and is prevented from moving freely.

Using an idler pulley, that funny looking cog that's nearly in-line with the main pivot, let Woods get around that, and he says that its small size helps to effectively eliminate any kickback: ''This meant I could set the anti-squat how I wanted without it affecting pedal kickback and rider fatigue, while also having it consistent through the whole travel.''

On a bike that's begging for questions, it's Woods' chain tensioner solution that most people ask about. Yes, that is a bungee cord holding it up. ''It’s actually the lightest and simplest way to keep it tight,'' he says, adding that he's happy he didn't design the torsion spring system he thought it would require.

The Fox air-sprung shock is compressed by a compact aluminum linkage that rotates just behind the bottom bracket. Its location helps keeps the weighty bits as low as possible on the frame, but it also leaves a ton of room inside the front triangle for water bottles and anything else you might want to hang off of it.






Manfacturing Challenges

Anyone who's tackled the kind of project Woods was diving into knows full well that the process can be a bumpy one. With his university work behind him and a full-time industrial design gig on the go, the next step was to figure out if he wanted to manufacture the frame himself or pay a professional. ''I was considering making it myself out of carbon, but thought I better get an expert in to do that aspect,'' he explained with obvious regret.

''But in the amount of time it took, I think I could have learned and done a better job.''


If it sounds like the process took the wind out of Woods' sails, it did. ''Originally, I had these big visions of starting my own mountain bike company, but after pursuing the design it’s made me have a bit of a change of mindset. Designing bikes is fun, but selling them is a different kettle of fish. The market is filled with people that don’t fully comprehend what they are buying and are fed yarns from whoever can yell the loudest, which is usually the big companies with big budgets making virtually no innovation and following what the smaller guys are doing anyway.'' He's certainly not the first to say it.


Woods set out to design an enduro gearbox bike that would show how much better things could be without derailleurs, but the process taught him about a lot more than just gearboxes. ''There’s such a lack of focus on fun in the mountain bike industry, which is a pretty big turn off as well. Everyone is bitching about the dumbest gear-related shit instead of enjoying themselves, which is ridiculous. It’s become so much more apparent through this project that a new bike isn’t going to make anyone a better rider. Just ride your bike and have some fun instead of weighing it and you’ll become a much better rider.''




Will we be seeing more from Sherpa Cycles? ''Right now, my focus is on shooting photos and video; it’s much more fun being outside than being stuck behind the computer. This might change again, who knows, just trying to have fun! In saying all of that though, if there was enough interest in the bike, it could become a reality to make a few of them.''

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Interested in more DIY stories? Jean-François Boivin's Insolent downhill bike employs a homemade shock made from parts of a Fox 40, while Ashley Kalym's single-sided carbon fiber linkage fork uses a leading-link design to deliver 160mm of travel. One of the most impressive finished products has to be Vladimir Yordanov's Sequence downhill bike that he made with help from Easy Composites.

Want to know more about Sherpa Cycles? Check out their Instagram page.