Introducing the Bunny Bouncer Floating Double A-Arm Suspension System

Posted by Ryan Gillespie on Sep 5th 2022

Introducing the Bunny Bouncer Floating Double A-Arm Suspension System


Other End-Of-Summer Updates From Our Busy Little Workshop!

  1. Sun Trip California
  2. The Magic E-Bike School Bus
  3. But Wait, You Don’t Have Running Water?
  4. Chris & Chungus Back Home In Boston
  5. Full Speed Ahead … Well, Almost
  6. Introducing The Floating Double A-Arm Suspension Upgrade For Organic Transit ELF - the “Bunny Bouncer”

Hello, and thank you for tuning into a long overdue update from Sol Mobil Electric Bikes — or, um, ‘Ryan the e-bike guy’ as I am known locally. I realized people have been asking what the heck I’m up to, since my cell phone had been broken all of last week. Well, the phone’s fixed, it’s a holiday today, and it’s raining, so I will take this opportunity to tell you all what the heck has been going on before it’s October again!

Read Time: probably too long

  1. Sun Trip California

As many of you know, I temporarily closed the shop for most of June in order to participate in the first ever Sun Trip California 2022. The event was a great success; though we didn’t quite cover the mileage we expected to as a group, we made many important discoveries that will undoubtedly lay the groundwork for successful future events - and all while having a really, really fun time out on one of the most scenic roads in the world. We fielded two bikes (red Stein trike, plus black Yuba Boda Boda), ridden by myself and Florian Bailly of the Sun Trip, as well as helped Carlin Comm and Oktay Ortabasi setup their e-bikes, since I sold them their motor systems. I intend to write a different post about this trip, plus the upcoming Sun Trip California 2023, at another time. Long story short, my return trip was delayed over a week because I contracted COVID 19 on the way back from California. I was actually ejected from an Amtrak train near Atlanta while en route back to North Carolina due to discovering symptoms of the virus while onboard the train, and was forced to spend about a week there before continuing home. Very fortunately for me, that is where I grew up, so my parents were kind enough to pick me up and help me out for that week (thanks a lot Mom and Dad!). I can only imagine our vaccines were doing their jobs, since surprisingly, neither one of them caught the virus from me that week.

Since I returned, we have been operating by appointment only until renovation work is completed on the retail space expansion. This has taken longer than expected, but that too was expected, since our new additional space is no ordinary e-bike shop: it moves down the road at about 55 miles per hour …

[pic of bus]

  1. The Magic E-Bike School Bus

Built in High Point, NC in 1998, and purchased right from the Forsyth County school system in Winston-Salem, our 35’ Thomas Saf-T-Liner is not-your-mother’s e-bike shop: it is about 250 square feet that represents the future of transportation technology every time it rumbles through your neighborhood. Right now, transportation & logistics is often the #1 source of carbon emissions embodied in the production of a new e-bike. We figured we might as well own that problem instead of hoping the rest of the world’s transportation infrastructure will figure it out for us one day. Over the last few years, we’ve learned that a lot of our Triad, Triangle, NC and Charlotte customers don’t particularly like hauling their e-bikes to and from the repair shop. While many e-bikes are light, and comparable in size to typical bikes, others we sell can be up to 130 pounds, or a trike, and present a logistical challenge for the customer. While some don’t mind coming to meet us with a pickup truck, that is not a valid option for everyone in our markets. I did the math, and figured that the experience of having your e-bike delivered, serviced, or repaired could be much improved by driving the shop to your bike instead of driving your bike to the shop. Sure, the bus only gets about 8mpg on a trip to Raleigh and back, but to be honest, that’s actually really good for a vehicle that large, and after stopping at only 2 or 3 customers over a weekend, it’s possible to actually burn less fuel in our bus than if we had all the customers drive to Winston-Salem separately. With the bus, we are able to meet & interact with local customers by parking it in front of our warehouse & storage space Tuesday through Friday, 10 am to 4pm, while still staying flexible enough to setup at events, pop-ups, and customer visits on weekends in the Triangle, plus Charlotte, as well as parts of the High Country including Boone, Hickory/Lenoir, and Asheville. We also utilize other warehouses in the area for certain types of fabrication & assembly projects, so having a mobile workshop and office made a lot of sense for those locations as well.

Though far from being fully complete, the bus has already proven its usefulness in a variety of situations, from ELF deliveries, to onsite diagnostics, repairs, and maybe even a bus party here or there … but it is also a ton of work to convert an old diesel bus into a workshop! It is hard to prioritize a project like this, important for the future, over projects for customers that are important right now … which brings me to the next update, which is a little closer to home.

Come see our evolving rolling retail experiment on Tuesdays-Fridays 10-4, plus or minus the events listed on our calendar. This September 11th, we will be setup at Gears and Guitars from 12-3, where you can join us in painting the bus. Come paint a picture of what you want the future to look like.

  1. But Wait, You Don’t Have Running Water?

People seem to be pretty surprised when I tell them I’ve been living in downtown Winston-Salem without running water for almost a year. I try not to mention it most of the time, but realized that this has become a little bit relevant here. I work from home often on Mondays (like today), as well as evenings and weekends, which is one of the big reasons I wanted a house in the first place. Less than a year after purchasing my first home (a small house east of hwy 52), the iron water main pipe in the front yard developed a leak, causing us to revert to using 5 gallon jugs from the shop’s LeBleu water machine for water. Myself, and my roommate at the time, Chris, quickly got used to this, weirdly enough, despite the major inconvenience this imposed. After all, we’re scrappy, and too busy fixing bikes to deal with that! Or are we …

The estimated repair cost was about $9,700 due to a high retaining wall and awkward angles, so I hadn’t been able to hire anyone to come fix it. Hell, if I had an extra 10k, I know exactly where I’d shove it - and I wouldn’t want it to be into a hole in the front yard! Homeowners insurance & a home warranty wouldn’t cover something outside the thermal envelope, and the city won’t cover something that’s across the line into private property. I had no idea how much of a time waster this had become until this past July 4th, actually, when I threw together the water pump system intended for the bus, and connected it to the washing machine inlet line and a 55 gallon drum so we could at least have running water. Though a temporary fix, this massively improved our water situation. Almost back to normal.

But far from perfect; to rely on this indefinitely, I needed to source a >1,000 gal water cistern, and start taking rainwater collection super seriously. A noble project, but one I don’t exactly have time for at the moment. Plus the city won’t like that solution. So myself and my awesome neighbor, who was giving us water from his garden hose, had some more beers after the Beers N gears monday night bike ride recently, and made a new plan: to simply dig up the pipe and look for the problem. I had resisted this idea up to that point because the plumber told me it’d be 10 feet down, and ‘almost impossible’ to get to. But wouldn’t ya know it, our simple minded pow wow was successful - after 3 hours of digging, I can now put my finger on the exact spot the pipe is freaking leaking from. I was expecting this to take 3 days, so it was a welcome surprise to find the problem that easily. A righteous fiberglass patch should solve this problem soon, and hold long enough for me to dig in a new PEX inlet pipe, meaning that now, the repair should cost much less, maybe 2 or 3 thousand instead of 10 after digging up the sidewalk & connecting the new line.

It’s been hard to prioritize this project when we have more pressing customer projects to attend to, but over time, the water situation has become more and more distracting. I am very happy to have finally found the root of the problem - literally - I believe the hole is partially due to a rogue weed I call a peanut butter tree (because that’s what they smell like when you pull them up). I found a big ass taproot right near the problem zone, and remember that root really taking over that area last summer.

This whole part of the blog really feels like TMI, until you realize that not having water has been incredibly distracting to the development of the company! Now that I’m through the worst of that, I’ll be able to focus on projects that need getting done, wires that need to be soldered, and orders that need to be shipped instead of struggling with this problem at home. I have been wanting to list the house on so that other people can use the backyard etc while on a bike tour, just as I did in San Jose before and after the Sun Trip this past June. But you can’t list your house on warmshowers if your actual shower doesn’t work that well!!!

  1. Chris & Chungus Back Home In Boston

Those of you active on the ELF facebook groups all know my friend Chris as ‘The Elf Guru.’ After Organic Transit went out of business, he became one of the only people in the online universe that would actually try to help you out with repair and maintenance issues on your ELF, since by that time, he had acquired 4 or 5 for himself, but struggled to keep even one of them in good repair. I had invited Chris to come to Winston-Salem, and stay as a guest for a month, partially to help me construct two new ELFs for the company that purchased the Organic Transit assets out of bankruptcy. But he liked it so much down here that he chose to stay after the project was over, and I liked the idea of renting out my spare room to a buddy. Over the last year, Chris has learned a lot about what it takes to build and repair ebikes, and I have learned a lot about what it takes to build and repair relationships with people who have physical and mental disabilities. But there came a point, after returning from the Sun Trip in July, where I very much required a more balanced and positive home environment, and realized Chris requires different things from his home environment as well that I really can’t provide. So we decided it would be best if he move back to Boston, and continue with the Computers for The Autistic Foundation, which donates recycled computers to autistic and disabled children. He can also help us out as a product rep now if someone in the Boston area is super curious about our bikes and things. Chris just left NC yesterday morning, so I took the opportunity to claim a new home office space, and ship a few orders that just were not getting enough attention :). Sometimes it’s the little things that are actually super important … Good luck back in Boston, Chris! If you are curious about ELFs or his organization, he’s always interested in setting up a meeting or phone call with you to discuss it further.

  1. Full Speed Ahead … Well, Almost

Now that the water situation is more under control, the bus is running well, and Chris has found his direction, we’re hitting that gear shifter and heading straight over the rainbow this fall. We’ll be catching up on some of the coolest projects ever to leave the shop, including a Sunn EV restoration for a local fresh juice company, putting the e-drive system into an electric Porsche 914, and making new iterations on the solar charged electric Stein Trikes Wild On-E we are currently developing. Did I mention we’ve also got more online products than ever before, including beautiful new bikes in stock from Monday Motorbikes? You’ve never seen a fat bike with this much swag, I promise. When I said ‘not your mother’s ebike shop’ earlier, that was total B.S., I actually sold my own mother a Monday Presidio and it was a hit! And her birthday was actually last Monday! A perfect fancy, yet rugged and fun surprise from Dad!

[pic of mom on monday]

There are other cool, new products as well that will continue to get fleshed out this fall and spring, including a solar powered briefcase/storage thing for cargo bikes, and more replacement ELF components. We’ll be visiting the Raleigh-Durham-Chapel Hill-Saxapahaw-HIllsborough-Wake Forest metro area more frequently than ever (wow, that’s a funny shaped triangle), and be making trips to the high country as well, including Boone. And, perhaps most exciting, we’ll finally make a permanent installation of the bus door with a possible revolutionary new technology. Seriously! I recently stumbled into some research being done in Indonesia that suggests bamboo can be used as an exceptionally strong hollow core material in the construction of composite sandwich panels. Well, I think we’re all about to find out if that’s true!I was given a roll of fiberglass, have a load of bamboo, and an order of infusion resin coming from Easy Composites this week. Oh, and a big chuck of acrylic that looks, to me, just like the window on a submarine. Wish me luck, people.

Though, admittedly, the Sun Trip and other distractions have placed unfair delays on a few orders, placed early in the summer, mostly for custom ELF parts. We have done what we can to get these people the parts they require as fast as possible or a refund, plus threw in a free set of ELF windows due to the continued inconvenience it had turned into. From now on, we will no longer sell you anything that isn’t listed on the website. If you ask for something that isn’t listed, I will want to force the product through the chain of tasks it takes in order to properly list it on the web store instead of simply generate a one time quote for price and optimistic availability of that part. That sounds obvious, but it actually wasn’t at first; often, I will quote local customers for parts that can be made in house or ordered in. While this is how I was able to get started, and it works for people in North Carolina, the process of hosting a product online now ensures that we will actually be able to stock and fulfill that order in a reasonable amount of time. Simply quoting the custom product, such as a torque arm or wire harness, and giving an estimated time of arrival, has become pretty difficult unless the item has been listed and inventoried in the online store. Since we have begun supplying parts to ELF owners and other e-bike enthusiasts online, some facets of the online retail experience are becoming a lot different than in person transactions, and this is admittedly a learning curve that’s hard to master by yourself. By the way, I am looking to hire someone to work on this end of the business with me as a sales manager. Sales + order fulfillment, plus bike shop tasks such as wheel builds, phone, and more. If you know someone in the area who may be qualified and interested, have them email us for details. Thanks.

  1. Introducing The Floating Double A Arm Suspension Upgrade For Organic Transit ELF - the “Bunny Bouncer” from Sol Mobil.

As if these few distractions aren’t enough, here’s an even more exciting, more distracting project I have been working on a lot over the last couple months: if you own an ELF, or are a member of one of the related facebook groups, then you have probably heard people talking about their front ‘Antlers,’ or king pins, as they are more commonly known on other vehicles. This is where the front wheels attach to the frame, the location where most people agree you would need to add suspension if such a thing was possible. I have seen some of the prototypes the company built in the past, and yes, it is possible. But practical? That was, and is the challenge. The following design is the result of a study into the questions “but what if I could design a replacement part to offer as much suspension as possible? Is it possible to add suspension to the front of these things?” I was already planning to make a short run of 5-10 sets of antlers for people who are stuck with aluminum ones, but if I redesigned this part to have suspension, I figured a lot more people would be interested, including myself, since it could potentially offer a massive performance upgrade compared to the current setup.

[Pic of bunny bouncer model]

Long story short, yes, it is! I believe I can give the ELF 3” of independent suspension travel on each front tire. I started out by modeling the existing antler on my ELF (#K37), plus comparing it to another as-built drawing Chris’s friend made for us at the maker space in Boston in 2018. Then I chopped the axle off of the rest of the part, and started looking into suspension options. What will move the axle the way we all want it to when going over the bumpies? How much travel can I fit when using a 24” or 20” front wheel?

I figured I could use a few inches inward from where this part rotates to design something, since there’s a lot of empty space in between where you pedal and the axle itself. And you would need to somehow attach everything to the rotating ‘antler’ itself, since the whole assembly would be moving independent of the frame (rotating as well as moving up and down).

So I drew up what I call the ‘floater,’ it’s the equivalent of the part of the bike where you would attach the a-arms - only on our bike (the ELF), they’re floating, since the only spot I could think to attach them to is on the antler arm itself. The ‘floater’ bolts into a square-ish piece of steel that has a proper steering tube welded into the middle. This is so we’ll get proper alignment in the lower bearing cup & race. Then it comes down in almost a P shape to give a few inches for the swingarms to bolt to.

Then there are two A arms that connect to the floater. For comparison, on a Stein trike and other trikes, they use ball joints to make the connection between the a-arms and the hub, but on the Bunny Bouncer, everything rotates, so these arms are more like H’s, and use more simple hardware, since the steering is taken care of separately farther up. I had first looked into doing a single, MacPherson style swingarm, but the tire would be swinging into the inner part of the fender all the time, and have a crazy amount of induced camber given packaging constraints. This meant I needed to try out a double a arm layout - sanity - before moving on to an even crazier sliding pillar concept … The first double a-arm layout showed it was much better, but it took 5 iterations to find an acceptable geometry for the system to work.

Satisfied with the geometry of a double a-arm setup attached to a weird shaped floating a arm bolted to the steel ‘new antler,’ we have the hub, which is machined aluminum. It holds the axle parallel to the ground when at 25% sag (your air shock should be set to sag from 0 to 25% of it’s max travel when you sit in the vehicle fully loaded). When fully extended in a bump or something (which is 25 degrees upwards in the lower a arm), the axle will sit about 76mm higher than it does at the sag point, allowing for about 3” of actual suspension travel where the tire meets the road. When fully extended, the camber of the tire goes from 0 degrees to 1.3, which is what I mean by ‘induced’ camber. Current ELFs all have about 3 degrees of camber all the time, which is great in turns, but not great when you’re driving down a flat road. The tire’s contact patch will remain the same throughout the length of travel since the upper arm is a bit shorter. Steering, compared to the regular antler, should remain minimally affected, since the contact patch & axis of rotation is staying the same. The 24” tire *shouldn’t* hit the fender, so we’ll find out once the first assembly is put together. 24” is the only size tire recommended for the Bunny Bouncer, since 20” is too small, and 26” is too big.

The axle that will be used in the prototype system is simply a 20mm stainless hex bolt from McMaster Carr, though we may go back to wanting to use a precision machined steel axle for future versions if the $20 bolt doesn’t work out. I want this to cost as little as possible as much as you guys do!

The air shock will come from DNM, the cheapest nice air shock I could find. I will be using the DNM AO-6 on the first two sets, since I already have them from previous trike experiments, but the subsequent systems will be designed to use the DNM A0-8RC since it looks like the AO-6 has been discontinued.

The ‘floater’ and double a-arms will be made from a new production system I call Bam-a-Lam, which means ‘Bamboo a la Laminate.’ We’ll be using aluminum where it’s required, and natural fiber composites where dimensionality isn’t as important. This part will use bamboo core, flax fiber and Entropy Super Sap epoxy resin, in addition to machined aluminum, to give it 3D definition & sideways strength. Those people in Indonesia are freaking smart! If this doesn’t work for some reason, we could definitely make these parts through another process (like metal 3D printing, or more machined aluminum) instead, but this design makes enough sense to try out once before moving on from it. I haven’t looked at carbon for this application because that would be expensive for a part designed to get beat on.

The first prototype of this new system will be mounted on my ELF for testing, then afterwards, I will want to ship these systems to 3-5 beta testers who can try it out & give feedback before we continue making them for people. I’ve made a few of the aluminum parts required, and have plans to make the rest soon.

But why is it called the Bunny Bouncer? Well, as Chris was leaving town, I thought he needed something he can use when biking with his pet rabbit Chungus. One of Chris’s favorite things to do around here was ELFing around with his beloved rabbit in the front of the ELF. While super duper cute, I always thought the bunny would love it if the ELF had suspension. 3” of suspension should make all the difference in the world when it comes to driving your ELF on rough roads, and I think that bunny will agree with me.

Anyways, if you are one of those people looking for an update from Sol Mobil, I hope you found it! We are getting into the fall swing full force with regular shop hours now back, even though the bus isn’t quite done yet, and are more capable than ever to fix your e-bike problem. Phone line is not always answered right away, but you will eventually get a call back if you leave a message or send an e-mail.

If you have a broken e-bike, we’ll fix it. And if you don’t have an e-bike, we’ll fix that too.

Thank you, everybody, for making my business your business. Stay in touch, and please come out to the shop or an event if you can!

  • Ryan Gillespie