New Bike: The Rear Frame

Measuring up the frame - this is getting the size for the front part.

Marking the frame centreline for drilling the headtube holes

Cutting the front part square

 

Drilling the head tube bearing holes

And filing them.......

 

and done - well one side at least.

Rounding the front part of the frame. I did it manually for the most part but used an angle grinder at the end.

3D printed frame separators and M8 Tee Nuts

Transferring positions from the back part of the frame to the front for drilling small holes.

The cool tool! The front bolt keeping the frames together is a low-profile M8 allen bolt because clothing gets caught in it if it is a higher bolt. I put the tool to undo it into the other bolt which is underneath the bike.

Rear bottom bracket assenbly consists of YST bottom bracket, 2 custom castings, 2 spacer bars and 2 spacer bar retaining studs.

 

Ta Da.....

The.......

Finished Frame

 As mentioned in my last post, I have been building a bike for a few days now. I'm trying to document it in some detail but I do have bits and pieces of old bike around which lets me skip forward a few steps. For this 2-part rear frame, I had most of the back part built and only needed to saw an end off, drill a few small holes and fit parts. But I made the front part from scratch, and this involved marking positions for, hole sawing and filing holes for the head tube bearings.

This work was fun and not too hard, about 10 hours work in getting this made. 

Update July 26

Over the last few days I have worked on attaching the back wheels to the rear frame as well as making the front frame. Here is the process of adapting shafts and making spacers for the rear wheels. The wheels were too narrow for the shaft, and simply shortening the shaft is no good as that would make the outer bearing sit on a recessed bit of of the shaft. Who designed the shaft? What were they thinking? (Oh that's right its me!) Anyway, I made appropriate spacers with a pipe cutter, marked up the shafts for shortening, shortened the shafts on a lathe, retapped the shaft thread, and finally fitted it all up. Pretty good now! Wheels are from MR Recumbent trikes and an 89mm aluminium square taper unicycle crank set is from the Australian branch of Unicycle.com

 

Marking the shaft protrusion before trimming shaft to length

Spacer cutting. This leaves a big burr on the inside - I filed it quite roughly to get the right inside diameter to suit the shaft.

After retapping the shaft is done

Turning down the shaft length

Done!

and done, the turned down shaft matches the bearing face

Assembly with YST bottom bracket, unicycle cranks, frame and bottom bracket holder.

Full assembly, for more details see here .