OK then, this is Day #3, the putty is completely hardened and will be brought into it’s shape today. I have rasped it down with a lightly curved very rough rasp. It’s done quite quickly but as you need to rasp down as much putty as possible to get a lean and slick bike frame it is primark (what a wonderful word) that you haven’t been too generous on day to, as I have been on this UTA bamboo bike frame.
Most of the work gets done with a rasp. You need to model the joints into a homogenous shape, as they will be covered with flax cloth on the next day and all you do now has a big effect on what your frame will look like in the end.
After rasping everything down, I have smoothened the joints with sanding paper. Again! You can see that it’s important to use as few epoxy-putty as possible and as much as necessary, as you need to take down as much als possible. Don’t wrorry, the joints will get big enough with all the flax fibre we’re putting on it on day 4…
For the next step you need to bey very brave! To get an interal cable duct into the frame you need to drill a hole into your carefully modeled fram. It felt wrong – extremely wrong, when I did this for the first time, but the holes don’t get in there by themselves…
The cable duct needs to be routed as sraight as possible. I did this with a drill (8mm) in the beginning and the fine tuning with a round rasp.
The alloy tubes I have used needed to be bent a little bit and are now suck through the holes in the frame. For this Rafa bike fram I have only used tubes for the brake and an extra one for the rear light cables, but for other bike frames you can add several cable ducts in all bamboo tubes. The tubes are then getting sealed with epoxy putty again, which needs to harden over night again.
This was the 3rd day. All went rather quick and all was easy and fun actually!
If you don’t want any inner cable ducts, you can continue with day 4 directly without drilling holes in your bamboo bike frame, as day 3 usually only takes about half a day. Of you can go out and tell all your friends how much fun it is to build your own bike! You may not need internal cables. Fixate them with zip ties or get creatine and do it in some diffent ways and maybe your next bike will have internal cable. Who knows…