DIY Recumbents - Atomic Zombie

opik_bidin
Posts: 968
Joined: Sun Jun 24, 2018 5:45 pm

DIY Recumbents - Atomic Zombie

Postby opik_bidin » Tue Jan 15, 2019 4:35 pm

from this site: http://www.atomiczombie.com/

I'll post some

http://www.atomiczombie.com/newsletters ... anFWD.aspx

A Zombie inspired Front Wheel Drive Lowracer

Homemade recumbent project in England

BY IAN W. SWINDELLS (SWIZZ69)

I'm sitting to write this a day after being paid a huge compliment. A friend upon seeing the bike for the first time exclaimed, "Wow!" and asked, "Isn't that what they call..." furiously searching for an appropriate descriptive, "...a C5?" And this, just a week after taking part in a discussion of that very machine on the Atomic Zombie Forum!

Image

An insult to many quite possibly and whilst the lowracer may be one wheel, an electric motor and a sleek body shell short of a real Sinclair C5, having been a 9yr old fan of Sir Clive's creation back in 1984, to now have built my own recumbent cycle and have it even loosely compared...well, you get the picture.

I'd been toying with the possibility of owning a recumbent for a good chunk of the last decade after finding Velo Vision magazine. A chance online discovery of modern velomobiles led me to a Dutch company who sold the Alleweder velomobile in kit form along with plans for a 20/26 'bent.

Image

Searching further online for bike plans led to Atomic Zombie's website and whilst none of the bikes at the time suited, the notion that people were building their own kept me interested. Every return visit to the site revealed a new model and when the Warrior was released, Atomic Zombie really had me hooked. Here was a serious bit of kit!

Image
Being from the UK though, one concern I had with a tadpole trike was how it would cope with the ridiculous barriers the cycle paths have over here. The Netherlands we are not when it comes to bicycle infrastructure, so low racers started to look appealing as a compromise. A production machine getting good reviews at the time was the Raptobike which had front wheel drive, a feature that made sense on a layout that placed much of its weight over the front wheel and a similar bike available, the Zox, had a square tube frame.

Image
I had purchased a set of six plans a while back and felt liberated by the instructions within that gave some really straightforward how-to's. Looking at the Zox and thinking laterally from the plans, for no reason other than that familiar square tubed frame, the Zombie inside my head said, "Aha, I can build that."

So, I bought some 40mm mild steel box section, did a fag packet sketch, printed out some of the angles on A4 to use as a measuring guide and set to work.

Image

As Joseph Whitworth discovered, accuracy is everything in engineering. A low racer frame starts at the boom before curving its way around the front wheel under the rider’s derrière to end at the rear fork. Creating all those angles whilst keeping the frame following a straight line can only be done with some form of jig, something us home builders don't have the resources for.

As most Zombie builders will have discovered, a half decent bench vise will suffice as a jig for each joint as you can clamp two pieces of square tube together in perfect alignment. Whatever angle you have mitred into them, two flat sides of the tubes will always be in line with one another, and for the same reason the joint you make at one end of a length of tube will be parallel to the joint at the other.

Image

That's how all the main tube angles on this frame were done - mig welded in a bench vise. The front and rear forks were set up and tacked together on a flat surface and once checked for accuracy, clamped tight in the bench vise to be fully welded without warping out of alignment.

Being front wheel drive meant that a conventional fork wouldn't be wide enough for a rear wheel hub to fit. After making a pigs ear out of trying to modify an old mountain bike fork, forum user Stormbird came to the rescue with a couple of plans he had for a Zox style bike along with a raft of photographs. Along with the AZ plans, this gave me the confidence to stop dithering about and just build some from scratch using the steerer from the scrap fork, some hefty rear dropouts off the donor frame and some rectangular tube.

Image

With a completed frame and forks a critical point in the build process had been reached. Yes, now I had to spend some money. After failing to bend some plywood into the shape of a bucket seat without it going c-c-crack, I took the easier option of buying a fibreglass one from Ocean Cycle as used by several recumbent manufacturers. The next deep breath to take was in ordering a set of wheels.

Being a Dutch Bike rider I love Sturmey Archer drum brakes. They are weather resistant, almost maintenance free and just plain old nice to use so a custom wheel set was ordered from Practical Cycles with sturdy black rims, the 26" rear wheel having a 70mm front drum hub. For the driven 20" front wheel I specified a 70mm drum hub with screw on freewheel, as rumour has it the cassette version they offer is difficult to service.

Image

Having the wheels custom built was an expense but worth every penny for those brakes. For this rider, nothing comes close to a good set of drums and as a bonus they look superb, too. Compared with buying new wheels with disc brakes, they are actually pretty good value as everything comes included except for your choice of brake levers. It’s been good to read of some support for them on the Forum with a Warrior builder choosing some for his build also. Anyway, with the fork fitted and the wheels bolted on, the pile of bits now looked like a bicycle and a pretty sleek one at that.

A long tandem stem was found (the sort that clamps the Stoker’s handlebars to the Pilot’s seat post), but as 1 1/8" steerer tubes are slightly smaller than the nearest diameter seat post, a solution was needed to give a closer fit. Thinking laterally again, a trip to our local builders warehouse yielded a straight copper pipe fitting that with just one cut down its length with a hacksaw made the perfect shim! A set of town bike handlebars and lever/shifters off an old mountain bike put some icing on the cake, and with what started as a short and shaky first ride led on to almost 100 miles of dry weather road testing during which I became confident enough to crack on with getting it finished.

Image

Two old chromo plastic mudguards (fenders) were fitted, the front being trimmed for chain clearance and both of them being extended with mud flaps repurposed from the bottle of an Eco brand of washing up liquid! On the rear went a lightweight Pletscher rack. A 'bar end' rear view mirror was hacked to fit as a motorcycle mirror would, helping greatly in traffic as craning your neck around to look behind in the recumbent position is less than ideal.

A kickstand was lengthened and a bracket welded on for it below the seat base; its position near the front of the bike suiting the weight distribution. In fact it's so sturdy, as a party trick I can sit with both feet in the pedals, wobble to tip the bike fully upright and pedal away whilst flicking the stand up by hand. This cannot be done showing off after a beer though. Don't ask!

Image

The only real learning curve has been in trying to increase the maximum speed I can ride it at without the handlebars wobbling, due more to nerves I think than any flaw. For the first few miles, 15 mph was where the shakes began. Whilst it runs out of gears above around 25 mph, it will freewheel downhill at over 30 mph now with no issues.

A visit to a BHPC meet at Darley Moor race circuit during the summer saw Stormbird and another spectator take a ride on it, both of whom did fine, Paul in particular getting the hang immediately and giving its handling the thumbs up. Slow speed handling is good meaning that hill starts present no problem, and up steep wet or steep loose surfaces I've found that the best way to avoid a loss of traction is to adopt a smooth pedal stroke.

Image

So, has it been worth it? Yes, of course. The result is a perfectly sound recumbent low racer that looks good, rides good and is practical to boot. It's taken me shopping, on 30 mile rides out around the cycle paths and canals of Manchester, has provided interesting conversation with interested passers by and will hopefully take in a few nights of camping next year. The build process has been thoroughly enjoyable and whilst as a bicycle it will never replace the Dutch Bike in my life, I wouldn't hesitate to do it all again and at some point probably will!

This being a Dad project, both my young daughters haven't had the chance to get involved beyond offering their opinions along the way, changing gradually from, "What on Earth?" to proudly telling their mates, "Our Dad made that!" The process of building it has hopefully been a quiet inspiration to both of them who have seen a bicycle created from dust.

They are enthused enough to want us all to build a small boat together next year to use on the nearby narrow canal, as it'll be something they can be involved in from start to finish and get to use for themselves. For their future, I'm encouraged by the female contingent on the Forum where I can offer a certain prolific electric trike builder to them as proof that this home brewing lark isn't just for the fellas.

I have no problem recommending Atomic Zombie to anyone that asks about the bike as despite it being my own creation, Brad and Kat's superb plans provided the kick start and answered so many questions along the way, as did the wonderful members of the Atomiczombie online community.

John Lewis
Posts: 1391
Joined: Tue Oct 02, 2007 7:12 pm
Location: Albany. 400km South of Perth

Re: DIY Recumbents - Atomic Zombie

Postby John Lewis » Wed Jan 16, 2019 12:15 am

I have built several Atomic Zombie bikes.
Delta Wolf Delta trike.
Marauder LWB.
Street Fox Tadpole.
They were all fun to build and work well.
The way they are designed makes it easy to add you own ideas and alterations so I have in fact done that.

I have also built several from this site. AD Carson's Recycled recumbents.

https://sites.google.com/site/recycledrecumbents/home

My favourite is the Mk2 but I have built several Mk 1's for others.

Another good one was the Bentech SWB and I built two of those.
Sadly that site seems to have disappeared but perhaps the plans are still out ther somewhere.

opik_bidin
Posts: 968
Joined: Sun Jun 24, 2018 5:45 pm

Re: DIY Recumbents - Atomic Zombie

Postby opik_bidin » Fri Jan 18, 2019 9:04 am

John Lewis wrote:I have built several Atomic Zombie bikes.
Delta Wolf Delta trike.
Marauder LWB.
Street Fox Tadpole.
They were all fun to build and work well.
The way they are designed makes it easy to add you own ideas and alterations so I have in fact done that.

I have also built several from this site. AD Carson's Recycled recumbents.

https://sites.google.com/site/recycledrecumbents/home

My favourite is the Mk2 but I have built several Mk 1's for others.

Another good one was the Bentech SWB and I built two of those.
Sadly that site seems to have disappeared but perhaps the plans are still out ther somewhere.
That is great and looks fun, I've don't have the resources to build bikes on my own, just spreading the word

http://www.atomiczombie.com/Tutorial%20 ... e%201.aspx

Simple SWB Recumbent

Image
Here is a very simple 20 inch wheel short wheelbase recumbent bike that you can build in a few hours using nothing more than a kid's bike and a few lengths of round tubing. This project makes a good starter recumbent and is a good experimenter's platform for those who want to try out various seating positions and angles. The completed bike doesn't weigh much more than the bike used as parts, and can be stored in the same space as a regular bicycle. Of course, this simple project lacks many of the more advanced features offered in our DIY Plans, but you could always add your own modifications to expand on this project.

Image
You can build a 20 inch wheel short wheelbase recumbent from practically any kid's bike or BMX bike. You will need to start with a working cycle or at least one that has functioning wheels, cranks, and a transmission system. The rear wheel should have a multi-speed freewheel so that you can have multiple gears, but you could also build the SWB around a coaster hub and just make your bike single speed. If you want to climb a hill or reach any decent top speed, then you will need a rear wheel that has at least a 5 speed freehub.

Besides a working 20 inch bike, you will also need a few feet of round tubing. You can cut up another bike frame for the tubing, or just use some thin walled electrical conduit (EMT) for this project. Basically any square or round tubing with an approximate 1.25 inch diameter and a wall thickness similar to bicycle frame tubing will work. The other part shown in the photo is the bottom bracket and crankset that will be placed ahead of the front wheel. You can cut the bottom bracket from another frame since the original bottom bracket will be unused and left on the frame. For more information on bottom bracket sizes and assembly, see the tutorials on our main page.

Image

This simple recumbent bike is made to fit the rider, so it has no adjustable seat or bottom bracket. For this reason, we will make the seat first so that you can later use your body as a measuring system in order to determine the optimal placement of the cranks for your leg length. Chop off the top of the seat tube as shown in the photo and then find another 12 inch long tube that can be welded over the top of the cut-off seat tube. This tube will become your seat back tube, and it will support the back of the seat as well as set the recumbent angle of your seat.

Image

The angle of the seat is completely up to you. Anything from 25 degrees to 35 degrees (taken from the horizontal ground) will work. If you lean your seat back too much, then you will have to hold up your head, and if you set your seat to far forward, your knees will have to bend a lot while pedaling. Try a 30 degree angle and make only tack welds on the seat support tubing until you can sit on the frame and see if you like the angle. On a project like this, it is easy to make adjustments, and since your frame parts will differ from the ones shown here, you will need to experiment.

To support the seat, the 12 inch long seat tube is welded to the top of the cut-off seat tube and then braces with any small tubing such as a seat of seat stays cut from another old frame. When you are testing your seat angle, you can get away without the bracing as long as you don't put any hard pressure against the back of the seat. For riding though, you will definitely need the seat tube bracing.

Image

The seat will be held to the frame by a set of tabs that have holes drilled for woodscrews. Any 1 inch wide 1/8 inch or similar flatbar can be used to make the seat mounting tabs, and they are made 6 inches long so that there is about 3 inches of material on each side of the frame tubing to mount the seat. Weld the seat mounting tabs to the frame so that the woodscrews will fasten each part of the seat in the approximate center of each board.

Image

The seat mounting tabs shown here are welded to the frame so that each seat board will be held to the frame by a set of woodscrews. If you are not yet sure of your final seat angle, then leave out the seat back support tubing until you have had a chance to sit on the frame and see if your seat angle is comfortable. You could also make an adjustable seat back by hinging the seat back support tube and installing some kind of clamp that will allow the seat back support tubing to be moved along the frame and then locked into position.

Image

The seat is made of 3/4 inch thick plywood and foam as shown here. Feel free to make your seat any width and height you like, but for a reference, I like to make my seat base 10 inches wide at the back, 8 inches wide at the front, and 10 inches in length. I usually make the seat back 10 inches wide at the back, 8 inches wide at the top, and 12 inches in length. To further enhance the seat, another top section can be added to support your upper back, but for now, this basic seat will get you started.

For seat padding, I used a firm 1.5 inch thick foam that has been cut to fit onto the plywood seat boards. You will need to install your seat padding before moving on with the frame design.

Image

Fasten the two seat boards together where the meet using a pair of bent L-shaped shelf brackets so that your seat becomes ones ingle assembly. You can then glue the foam to the plywood using some spray adhesive. The shelf brackets will be strong enough to hold your seat boards together yet still allow some give if you want to force the seat into another angle later as you make modifications to your bike. Once your seat is made, fasten it to the frame by using the four woodscrews through the seat mounting tabs installed on the frame.

Who is online

Users browsing this forum: No registered users