Wood Bike 2

I got into wood bikes recently. I made Wood bike 1 and then have been looking on the net and elswhere for ideas for number 2. I found one on this site that I loved https://www.instructables.com/id/Bent-Plywood-Bicycle/ . This bike and others inspired me to make my own bent bike. I am fairly competent with tools and have a lot of bits and pieces in my shed.

It took me 3 full days and cost about $100 and a donor bike. I have a bit of tidying up to do but its pretty much finished.

First I got a bit of ChipBoard big enough to fit the bike on and make my  bending jig. Then I put my bike on it and traced the frame with a pencil. Once I had an outline I used a bendy bit of yellow plastic to work out the curves that I like. I used a couple of screws to hold it into place while tracing

I had a $20 donor bike and decided to copy the frame geometry. I think its a fairly good bike but its about to cease to exist. 

I went to the hardware shop and found a 4 x 8 sheet of 4mm Hardwood bracing ply. Also 2m of 20mm x 45mm pine to make my bending jig.

The pine I then cut into +\- 150 mm pieces as the uprights on my jig. I then screwed them to my jig with 2 big screws each and some glue. They have to be fairly strong because thats what the first layer will be clamped to.

The pic below is just a pic of the jig with a mock up bend just to see if I had enough clamps. Wel as it turns out I dont have enough clamps- YOU CAN NEVER HAVE ENOUGH CLAMPS.

Today I drew the shapes i want  on one piece of ply and screwed 5 together. Then I cut out the shape with a circular saw and a router for the tricky bits.

I laminated the both sides separately . As I'm using steel for the connections I can laminate in 2 halves and dont have to do them in one go.

 I used 5 layers of 4mm ply and that got me to 24mm total thickness.  I used PVA white glue as it's cheap and I had some. The glue was painted on thick till the complete surface was covered and then I just clamped them on one by one. After about an hour each time I just stuck some screws in from the back to hold the last piece in place, took the clamps off and glued another one on.

The right way would probably be to wait a day between layers. Its amazing but after the 3rd one I released all the clamps just to see what would happen and it kept its shape. This is the first time I bent wood and although I know it works it still blew me away.

Its all drying in the shed overnight.

The curves were released from the mould today. There was a lot of sanding and planing and routering but I finally got them smooth.

I used and electric plane and a belt sander.

I also started working on the steel bracket that will connect the top and bottom curves to the steering head.

This is the part where I chop up the old bike to get the bits I need. I would wear gloves, glasses and ear protection as a minimum when working with a grinder. 

Firstly I cut the dropouts off. Thats the bits where the back wheels connect to the frame. Save them for later.

Now I started cutting out the bottom bracket with the seat tube still attached. I use a 125mm angle grinder with a 1mm cutoff disk. It slices like a hot knife through butter. Then I cut the steering neck out as well, while removing brakes and cables and things as I run into them.

In the last photo is the result of what I had left over. It took about 1 hour to grind all the welds off and smooth it all over. I then hit all the grinds with a bit of grey primer as i live at the beach and it will rust almost over night.

Today was a big one, about 7 hours on the bike. I had some bits of 2mm plate so I cut some pieces out to make an attachment bracket for the steering head. After lots of cutting, grinding and halfround filing I was ready for welding.

All my angles were worked out very loosely by holding all the pieces on the ground and tracing it on the floor with a pencil, then transfer to paper. I then cut out the paper and transfered to steel plate for cutout.

So I cut the 3 pieces out and welded them all together to the steering head tube.

For the dropout brackets I had to do some Blacksmithing. First I drew it up roughly on the ground again and transferred to paper.

Now remember when I cut off the dropouts before and told you to save them for later. Well this is later. I cut out the shape out of plate and bent, blowtorched and hammered till I had these brackets. I then welded it all together and also welded the dropouts on.

I probably should have approached this more scientifically but...

A bit of primer paint after welding is always a good idea.

This is where I started screwing things together. I used 20mm wood screws for testing but I now replaced them with 6mm bolts with nylocker nuts. I had to do a fair bit of trimming on the frame to make it all fit. The wheel hit the sides and I had to adjust the brackets a bit. I didn't spend too much time measuring things I just kindof made it up and adjusted where needed.

Other than that it all went together nicely.

For the seatpost I drilled a 28mm hole in the top beam. On the bottom of the bottom bracket I welded a mounting plate that you can see in the second photo. I forgot to take a photo as I made it. I then stuck the seatpost tube through the hole from underneath and screwed the mounting plate to the bottom beam.

I am making a little wooden box to cover the ugly bottom bracket. I still need to do another couple of coats of varnish and back brakes and front derauler. Other than that the bike is done and very strong.

I then put all the bike bits on and it was test drive time. I had to stop a couple of times for adjustments but it felt very strong. At first I let the seatpost slide through the top beam so all my weight pressed on the bottom beam only. It was nice and springy but not in a good way. There was no shock absorbtion and it didn't improve the ride at all just very bouncy. I didnt like it so I put a couple of screws in to stop the seatpost from sliding. The bike now feels solid to ride and I gave it heaps of testing: Up and down pavements, wheelies, stoppies, top speed down the road , 150kg load test. Its all holding up.

Some photos and one of woodbike1 as well.