Category Archives: Frame building

DSC_0236

An all carbon bike?

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.

It’s not always plain sailing

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!

Panda progress

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: