A while back my awesome LBS gave me a box of carbon tubes and lugs and said “You’re the right person to give these too!”. And with that I had 4 frames to build, one of which I’ve completed. Take a squizz:
The process wasn’t a simple one. Here’s what I did:
Bonded all carbon tubes and dropouts together
Sanded and filed those back.
Drilled and riveted front derailleur clamp
Drilled and set water bottle bosses
Drilled custom internal cable routing
3D printed custom rear brake boss
3D printed cable stop for front derailleur cable
Masked and handpainted the colour stripes with enamel paint
Flat black enamel spray followed by 3 coats of gloss enamel spray.
What does this mean for bamboo? Well, I don’t know at this stage. It’s certainly easier working with full carbon, pre-made tubes! Maybe there’ll be another bamboo bike made soon… only time will tell.
Today my 4th frame, the recently finished The Samurai, underwent my quality assurance testing that I do on all frames. The video below details the test and shows that the frame is strong and passes the Australian Standards for Frame and Fork Assembly. Stay tuned for a time-lapse of the parts build!
The Samurai, my fourth frame was going well until I discovered that the seat-tube had developed some cracks around both the bottom bracket and where the seat-post sleeve inserts into it.
Luckily I hadn’t yet carbon fibered up either of those joints so I’ve been able to cut out the offending tube and will replace it with one that’s hopefully not so prone to cracking.
The cause of the cracking is probably due to the consistent cold temperates in the workshop overnight and that without coatings of epoxy bamboo will naturally dry out and become brittle and crack. It’s also due to the steel seat-post sleeve insert changing temperatures at different rates to the bamboo, causing the bamboo to crack.
Interestingly both the cracks were in places that would have been covered with carbon fiber and they probably won’t have propagated any further, but I couldn’t take the risk of that not being the case and don’t want to let a mistake roll out the door.
Below are some pics of the cracked seat-tube both before and after I’ve cut it out. It was interesting to see the different levels of adhesion (or lack thereof) of the epoxy to the various materials. It’s mostly only mechanically bonded to both the steel and the bamboo, making it very important to roughen up the surfaces to ensure a good bond. The aluminium bottom bracket is painted in a specific etch primer (the white paint), but it doesn’t seem to have chemically adhered properly to it. I’ll have to investigate why!
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!