Project Z – Full Suspension Prototype

Ever since the early days of Myth Cycles, it’s been my goal to make a full suspension frame. Myth is based in Durango, Colorado and the mountain biking culture here is driven by having an inordinately high number of phenomenal athletes. Racing and sponsorship is a big part of the scene, and because of that, the handbuilt bicycle market locally is actually quite small. Steel handbuilt bikes are many things, but purebred racing machines, they are not. Since there’s such a high influx of this year’s and last year’s version of the biggest brand name’s bikes going to sponsored riders, the used bike market here is also chock full of what the industry considers standard for a mountain bike. Aluminum, carbon, full suspension, terrible geometry, and complex linkage systems with 22 separate bearings that need replacing every year.

The funny thing is that we actually have a ton of fantastic terrain for riding hardtails. Much of our mountain biking and trails were established in the 80s and early 90s, when mountain bikes were just starting to incorporate the idea of suspension in forks. Many of our trails aren’t the most gnarly progressive trails you’ve ever ridden, but they’re great fun and frankly, perfect terrain for a hardtail with modern trail geometry.

Still, there is also a ton of riding here that is great full suspension riding. I have always wanted to make one because I believe they definitely have a place in any mountain biker’s quiver, and they just serve a different purpose and riding style. I also believe that steel is the best material for bicycles, and what they’ve been doing over in the UK for the last 10 years with duallies has been very inspiring. I believe it’s time someone released a well designed, thought out, tested, and proven steel full susser for the American market.

I’ll start by saying the basic design is not that special or unique in any way. The basic idea has been around since the dawn of bicycles, and even some of the finer points are similar to designs that are being built and ridden every day in Europe. But as with any design, the devil is in the details.

Project Z is a single pivot design, with a yoked shock that allows the pivot point to be in front of the effective shock attachment point, giving it a progressive leverage ratio instead of a digressive one. It’s simple, with only 4 bearings in the whole design, which have been selected because they were the largest, strongest bearings that will fit in their respective locations. It incorporates no complex linkages, and as such has a linear leverage ratio that acts simply, and makes it very easy to tune and ride. The material is steel. In most places, 4130 aircraft steel that is strong, durable, stiff, has excellent fatigue life, and has a ride quality completely unmatched by any other material. And most importantly, the geometry has been chosen specifically for the type of terrain that a bike of this amount of travel shines in. Steep, fast, challenging trails that have the rider pedaling on long uphills, and charging fast on long downhills.

I first started designing the bike over two years ago, when a friend of mine (and neighbor at the time) started bugging me about building a full susser. He’s a talented local rider who’s background was in downhill racing, and who owns a suspension tuning company here in Durango called Diaz Suspension Design. It was in countless long talks with Diaz about suspension design and what is important and what isn’t, that guided my process. A single pivot design is incredibly simple, but it’s amazing how easily it can be gotten wrong by paying attention to the wrong parameters.

So, this is the result. The first one. Project Z.

Any time you build the first one of anything, all you can think about by the end is all the things you’re going to do better next time. This was no different. Fortunately, due to thinking about this project long enough before hand, this bike is not only completely ridable, but it turned out far better than I was expecting. It pedals uphill well, descends great, it corners shockingly well, and it’s actually not very heavy. The basics are as follows:

Specs: (geo unsagged)
Travel: 145 rear/ 160 front
Seat angle: 76
Head angle: 65.5
Reach: 480
Front Center: 824
Chainstays (actual): 444
BB drop: 20

Suspension parameters:
Leverage ratio: 2.75 to 2.55
Anti squat in a 30/36 climbing gear at 25% sag: 116%

The biggest difference between this design and ones like it already available in Europe, are how the swingarm gets its stiffness. One belief I have is that duallies handle better with long chainstays, and this bike is certainly giving me evidence to support that. There is a bit of extra room in the swingarm, and it gives me space to use a different way of preventing swingarm flex. One of the reasons I haven’t powder coated this bike is that I started out with less bracing in the swingarm, and I’ve been adding more in between rides to see how it affects flex. I still have one final piece of bracing to add to test the final design, but so far it’s already very stiff.

Perhaps the biggest surprise about this project has been the final weight. The frame weighs just about 8 lbs without a shock. For a size Large, that was not what I was expecting. Fully built as you see it, the total is 32.5lbs. And my build kit isn’t particularly light. I believe that what it comes back to is the simplicity. Few bearings, no crazy CNC’d linkages, and a design that highlights the best build qualities of steel, add up to a bike with a pretty average frame weight. But I’m not building this bike to be light, I’m building it to be the last mountain bike you need to buy for a long time.

There are already so many details I’ve redesigned to be better in the second prototype. The short term goal for Project Z is to crank out a few more prototypes and get them under riders who are hard on bikes to try and find it’s weaknesses. The long term goal is to have the design ready to sell by January of 2021. Don’t hold me to that, but it is my goal. If you’re interested in riding one, either in the short term or long term, shoot me a line via the Contact Page and we can discuss it.

Want to be the first to see new builds, and hear updates from Myth Cycles? Scroll to the bottom of this page and subscribe to our blog via email, and you’ll be notified of any new posts as soon as they happen.

Leave a Reply