To much fanfare, last month we teased the beautiful steel full suspension enduro rig that Tyler of BTCHN’ Bikes was cruising around with at Sea Otter in our event coverage. Aptly named The JERK, it’s a true stunner with a 29/27.5 mullet setup, standard 24mm bottom bracket single pivot, custom integrated bar/stem, wild paint, and so many other intricate details. Today we’re stoked to announce that BTCHN’ is launching a small batch pre-order for eight of these frames in a size run (S, M, L) and two suspension configurations. The engineering for this bike was complex and took Tyler and team a looong time to dial in. Below, Tyler goes into lavish detail about his design process and philosophy, so continue reading about this beautiful machine, how it came to fruition, and how you can get your hands on one!
The JERK from BTCHN’ Bikes is a raging, raucous enduro rig that gives zero fucks. You’ll likely experience an immediate head change when stepping aboard this bike. It will make you want to plow through anything with complete arrogance and give you the willingness to chuck yourself into anything that comes your way. This bike will turn the sweetest, the most mild-mannered person you know… into a complete Jerk. Now, I don’t condone being a jerk in your personal life, but I think it’s more than acceptable to embody the “asshole” within (while still maintaining proper trail etiquette, of course ;)) when careening down a trail on this rig. Go ahead – get yourself skinned up. You won’t regret it.
If you have a plastic bike in your quiver, especially a full suspension, I’d bet it’s not more than 5 years old. The lack of well-aged full-suspension bikes out in the world bikes really pisses me off. My business is built around creating high-quality bikes that are as beautiful as they are long-lasting. Mountain bikes are literally toys that we use to throw ourselves down mountains. So, why are we riding plastic bikes that can’t take a rock strike to the down tube, or a good crash into a rock garden? And another thing that pisses me off is that we live in a culture where consumerism is king and is literally the foundation upon which our capitalistic system is propped up. This has found itself deeply ingrained in the modern cycling industry and I’ve designed the JERK to be the antithesis.
This bike has all of the goods you’d want from a modern enduro slayer. It’s big, bash worthy, fast as hell, sexy, and designed with a modern geo; it’s meant for crushing the burly riding you’d find in the Sierra Nevadas of Northern California and beyond. But it’s also incredibly simple to service. It’s also STEEL! and repairable if your buddy happens to run it over with a truck. The main pivot uses the most common threaded external bottom bracket bearing, a BSA 24mm (Shimano Hollowtech) bottom bracket. This is likely the most easily sourced bottom bracket in the world. Many of us have the tools to replace a BB, and servicing the main pivot in this bike is no different. And that, I am really excited about and proud of.
Now, why would I design a reliable and predictable single-pivot suspension system? Why not build a VPP, Horst Link, or some other multi-link bike, you might ask? Well, this is primarily to reduce complexity, increase lifespan, and simplify serviceability. I’ll have a tech blog on my website soon that will go more in-depth on this topic. But in short, smaller bearings (which are used in multi-link bikes) are not as robust as larger bearings like that used in this single pivot system.
The Jerk is designed around a dedicated mullet setup and is optimized as such. This bike can be built as a 170mm or 160mm rear travel configuration, using either a 230×65 or a 230×60 shock respectively. The intention is to run a fork with matched travel to the rear. There will be more info in the tech blog regarding how the geo is affected by the different travel setups, but, in a nutshell: the 2 configurations allow the geo to be rather consistent between them.
This rig sports a 64° head angle and a 77.5° STA (Geo chart). Yup, it’s steep and it’s slack… maximizing its potential in both the ascending and descending realm. The single pivot design facilitates an intuitive predictability because of its “linear” kinematics (more in that in the blog too). You won’t find yourself wallowing deep into the mid stroke because you’re stuck in the ”U” of a digressive/progressive leverage curve you find in many multi link designs. Being one of the most buttery rides I’ve experienced, it also has an incredible connection to the ground mid corner. I have designed a reasonable amount of anti squat into this system as well which is lovely for when you jump on the pedals for that out of corner sprint, or nailing a big power move to clean a pitchy climb. So far, I’m absolutely tickled by its performance.
Starting as a simple 2D drawing in CAD, this has been a two-year project. I spent a lot of time playing with and analyzing kinematics. I started by throwing the pivot point all over the place in order to recognize trends for each quadrant where the pivot was placed in relationship to the bottom bracket. I ended up finding some beneficial, digressive anti-squat rates with the Instant Center placed behind the bottom bracket and… Bingo! Getting somewhere. I then set to brainstorming how I could get a progressive leverage ratio out of this simple single pivot. I experimented with shock mounting locations until I found “the one.” Haha. I landed on a position that lended a 16% progression through 90%+ of the travel. You can bet I was pumped to see some very tangible positives come out of such a simple (and often looked down upon) suspension system.
Like most aspects of my life, I created some unnecessary struggle by placing the lower end of the shock right in the middle of where a straight downtube would go. Great. I went through all sorts of weird-ass box-sectioned mounting solutions, split-down tubes, you name it. This was all in an attempt to keep more of the manufacturing process in-house. After many iterations, and none of them either elegant nor robust enough, I finally realized the necessity to have custom tubes bent. These downtubes are fairly light relative to their diameter and there was no way in hell I would ever be able to bend them with the tooling I have. These would inevitably have to be bent in batch quantities. This presented another hurdle, requiring a down tube design that could be used with an XS as well as an XL. After many emails, phone calls, and being turned down by what felt like every mandrel tube bending joint in California, I finally found a spot in LA that was game to do what I needed. After speaking with their engineers and my buddy Pete Olivetti about max/preferred bend angles with this material, I went back to the drawing board to optimize the design for manufacturing’s sake.
Gussets were a big part of the design element. Each frame size has an optimized gusset design for the head tube junction and lower shock mount. Last summer, two buddies who I used to work with at the bike shop, started an internship with me. They’re both seniors at Chico State in the Mechanical Engineering program and they brought the knowledge to take this project to the next level. We did a boatload of Finite Element Analysis on the frame and swingarm in CAD. A handful of revisions were made to the swingarm yoke until we found a solution that was not only stout, but easily manufacturable. Tube diameters were optimized throughout the design, including modeling ovalized and curved tubes where needed. We found that some additional triangulation was super beneficial in the swingarm when put in a torsional load. The front triangle found itself being almost equally entertaining to work through as we quickly found a glaring lack of a gusset near the BB/seat tube and pivot. The addition to that tubular gusset substantially reduced the localized stress that was sure to cause premature failure. FEA is powerful stuff.
I did a monster deep dive into gusset theory in order to understand their uses better, how they transfer loads, and how to mitigate stress risers. I came away from that research with a solid understanding of what keeps gussets from creating hot spots and ending up in failure of a different mode down the road. We then applied that understanding to our head tube gusset and shock mount design. Both went through their fair share of FEA and revisions until we felt the design was far more robust than necessary.
I am a small one-person shop. The benefits of living within a healthy and supportive community are not lost on me. This project wouldn’t have been what it is without the help and fiery support of so many friends, business partners, and craftspeople. Vibrant communities only exist when we put energy and resources towards them. Within capitalism, we get the opportunity to vote with every dollar spent. Thoughtfully spending our money on quality local goods, whether that be a Paul Component Klamper, or locally grown veggies from your weekly farmers market, is hugely beneficial to your community. It keeps your hard-earned money local, which empowers the homies you’re supporting to continue doing the work we all get fired up on. It also allows for all of the folks downline from them to continue to get support and facilitate robustness in our local economy.
Thanks for the time and for letting me share with you some thoughts, opinions (a lot of them!), and this creation, which I’m most proud of. If you can get down with any or all of this, check out my website for more details on this bike, geo charts, custom frames, handlebars, etc. This is my first foray into small batch production and I am only building 8 of these rigs in this first run. There will be a full size run available and the price will be $4500 for a frame, shock, and integrated bar/stem. I will be taking $2000 deposits up front through my website, which will secure your frame. At that point you will choose your colorway and expect frame deliveries to begin August 1st.
Bigggg props to my childhood homie Jade Elhardt Photography for the killer photos. You’re a boss!