The Wood Chopper

Joined
Jun 14, 2020
Messages
13
Location
Oregon
This is the sequel to my cold molded plywood ebike. "Long, low, and slack," I heard. I really love the original bike, but COVID makes you crazy and I started to get curious. Total project cost was around $50 for the plywood and other little bits, but all the components just swapped over from the first bike like changing a suit of clothes. I decided to forego the fiberglass this time around for lack of epoxy in the house, and I can't say I've noticed a difference yet.

Overall time from design to finish has taken me about a week. It was so quick because I solved all the little random unexpected problems during the first build, but it's a problem because this was supposed to be my winter project.

I took it on a test ride today, and it's definitely a different kind of ride. Not as nimble as the wuddbike, and I have to watch my toes on tight turns, but pretty nice and easy otherwise, especially with the springs in the seat.

A kid at the skate park yelled "Nice bike!" as I went past, which is really what I was going for.
 

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The beauty and the danger of a wood bike is you can keep adding as much stuff to it as you have screws and scraps. Here's a little buddy seat I built for my boy. The bars and upholstery come off an old lawn chair.
 

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Well done! Even if someone doesn't like this particular style, this is a great example of how you can affordably make a bike frame with any style you like.

There are a few bikes from Rans with the same posture that I like, but the cheapest one is VERY expensive.
 
Latest changes:

-- Added fiberglass skin to the outside of the frame, which stiffened it up significantly. This removed the minor flex I was getting when I'd waggle the handlebars while at a stop. It also just adds stoutness to the rear "legs" so I don't have to worry about cracking the frame on a bad pothole.

-- changed handlebar to high rise so I can ride reclined with full leg extension. I think it's technically a "semi-recumbent" now.

-- added a metal crossbar under the frame and behind the pedals to act as foot pegs for standing while riding. Geometry is just right to be able to stand upright with hands right in front of my navel. Can steer with my hips.

-- Cut a tailbone hole in the padding of my seat, which solved the bruising problem I was having with this riding posture.

-- added a wood front fender because fall is on its way. I just soaked a thin strip of plywood in the tub, strapped it around a garbage can for a day, then epoxied the result.
 

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Looks like you made your plywood cut pattern using the projector? Brilliant! :thumb:
 
This is why i love this forum, the weird and wonderful creations people make.

I don't understand why anyone would ever think making a bike from plywood is a good idea, but you've done it and the execution looks fantastic.

How fast is it?
 
mxlemming said:
I don't understand why anyone would ever think making a bike from plywood is a good idea,

When the only tool you have is a jigsaw....
 
"Overall time from design to finish has taken me about a week."
"A kid at the skate park yelled "Nice bike!" as I went past, which is really what I was going for."
"The beauty and the danger of a wood bike is you can keep adding as much stuff to it as you have screws and scraps."


Looks like a fun project and a fun bike! :thumb:
Plywood is so darn strong, I find myself wondering just how much material you could remove and still have an amply strong frame. Resolving that question might need a third experimental build...
 
Cheers everyone. There's some truth to the "when all you have is a jigsaw" comment. I've also done a lot of work on cold-molded boats, so fiberglass is a familiar friend. Mostly though, I'm just too cheap to buy a frame with the riding geometry I was curious to try.

I did a lot of learning during this build, but if I had to do it again I bet I could probably keep total project cost right around $1,000, with the motor and battery constituting about half of that. It depends on how lucky I get with the combination of components on a craigslist donor bike.

I'm still not sure how much the thing weighs, but I can lug it around reasonably well by grabbing the rear seat's handlebar. As it is now, it can get up to 28 mph carrying both me and the boy without trouble, but I tend to cruise sub-25.

I've thought about cutting speed holes in it, but I did a calculation at one point and decided it wouldn't be enough weight savings to make much difference. It's possible I could have gotten away with 3/8" plywood instead of 1/2" and let the fiberglass do more structural work. Maybe I'll try it this winter for science, but I'll need to dream up a new shape to try first.
 
One problem with cutting all them holes, it would create drag. Well if you went fast enough.
I would go with the Art angle. It looks good and stands out. I would go for looks. People like the look of wood. Pleasing!
 
One question on behalf of everyone who is eyeing their wood pile and thinking of builds. Did you use any particular type/grade of plywood, or just a sheet of what you had on hand? I could imagine going whole hog with a sheet of beautiful Baltic birch marine ply, equally could imagine just using a sheet of basic crappy plywood sheathing. What did you use?
 
On the plywood grade question, I used 1/2" birch ply from Home Depot. I chose it because it was hardwood and didn't look to be riddled with voids. Plus, I wanted an attractive surface since I knew I didn't want to paint it. Marine ply seemed overkill, and I sealed the end-grain with epoxy, plus there's the structural support from the glass. I personally wouldn't choose a crappy plywood source when the cost difference is a couple tens of dollars. I'm cheap, not crazy.

Also I should point out that the curved battery area is only 1/8" ply. There's a battery notch cut into the large sheets, which allowed me to not have to bend the wood as far to accommodate the battery's width in between the crank/headtube and the rear dropouts.
 

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