Bamboo Bike #3, dubbed The Panda by its eventual owner is nearing completion. I’ve laid up 95% of the carbon fibre and just need to do some final cosmetic layers and then lots of finishing. Then comes the tricky things like brake holes, derailleur mounts and cable stops. Then some clear coat, then some testing!
Bamboo Bike #4 isn’t far away either. The head-tube’s been wrapped and the rest is scheduled to be done next week.
Here’s a few progress pics of The Panda:
all layed up, just needs sanding back
still a few more layers to go, then lots of sanding
they’ll be polished up to a mirror finish
kinda went overboard on the filleting, but it should be super stiff
needs one more cosmetic layer and a bit more sanding
looking pretty messy at this point with all the tape, but rest assured there’s beautifully scratch free bamboo under there!
I’m using expanding filler foam on this frame as lightweight way to make the joints more curvaceous (and thus stronger). It’s super easy to sand back and shape and doesn’t take long to set.
I’ve done the initial wrappings of the rear end and head-tube with 12K carbon fiber tow. So far it’s taken 90metres of the stuff! I’ll cover these in 1-3 layers of woven carbon fiber cloth then 2 layers of clear coat. Job done.
Today I’ve put the first of the final touches to the frame – a carved bamboo head-tube Cognitive logo. It’s a bit simplified, but that’s ok as it will probably change down the track anyway.
The only things left to do now are two more layers of carbon on the seat tube and then to unwrap all the tape, sand it back properly, and add some final clear coat as a protective varnish layer.
I’m continuing to wrap the bottom bracket joint today. I’ve now done a total of 9 layers, which I’m pretty sure will be enough for a sturdy and stiff BB.
After wrapping up each series of layers in cling wrap and PVC tape I place it inside my homemade autoclave. It gets up to 80 degrees C in there, with just a regular old hairdryer. 30-40minutes is all it needs at that temperature to cure the epoxy enough that the wrapping can be removed. It will continue to cure at room temperature over the next few days.
this is what happens when you forget to poke holes in the wrapping tape.
a hairdryer stuck into a carboard box.
The headtube’s pretty much done so I’m now starting work on laying up the bottom bracket area. It’s a much more complex shape to work with, which made the template cutting all the more fun. I’ve figured out a better way to make the templates is to wrap smaller pieces of cloth around each part, then stick them together with tape, then cut strategic slits to remove it from the frame. Then lay that all flat and trace over it to make one bigger template. I also add areas of overlap around where the slits were cut to add strength to those areas.
Here’s some pics of the finished headtube and the first layer of the bottom bracket: