Custom Bicycle

Thanks! Yes, a show bike. It will be hard to pedal with the 14" wide crankset!
Question: I need to attach the crank spindle end shown previously to a new shaft. I have ground the spindle to .625 and it fits into a corresponding hole in the end of the 20 mm shaft. What is the best method to do this without distortion? I could TIG it but I am afraid of warping it. I am considering TIG brazing with Silicon bronze or Silver solder with a small Ox/Propane torch. I am not sure the Ox/Prop torch can get these large pieces hot enough to braze.

It's almost time for a ride!

Robert
 
Last edited:
If you take your time tig welding will work well. Do a few tacks around the shaft let it cool down completely, then do a few more let it cool down as before it make take several hours but I don't think it will warp or bend if you consistently repeat till the parts are welded up. I would not rush it or use water to quick cool that would encourage a warp and metal changes from heat and cold. You could use the tig braze with your rods but use the same process.
Good luck it does look cool , BIG banana seat with backrest . I use to build lots of bikes in the sixties and seventies , we didn't have money or even a WELDER , but free bikes from the dump , I had all kinds of fun , three person , trailers , long trikes . Oh the memories .
 
So I decided to TIG braze the ends of the crank spindle:

33963689114_695e423dcc_h.jpg


Here you can see one end as brazed and the other after a few passes with the lathe to clean it up:

34645395692_b4ba5bad97_h.jpg


Looks great!:
33941236774_8adb16027b_h.jpg


Not so fast...total failure! I was shocked but the braze joint failed after applying moderate torque. I can't believe it or explain it. I suspect that melting of the steel caused the formation of brittle intermetallics resulting in a weak joint. You can't alloy bronze with steel and know how strong it will be. Soooooo...now to try to get off the bronze and use conventional TIG to weld the ends on.
More in the saga later.
Robert
 
Sorry to hear robert, I was really looking forward to hearing your success story. Tire really looks awesome.
Looking forward to more updates!
Rich
 
Is the tire on back direction marked? Not trying to had anymore work but it looks backwards like a tractor tire , I'm not sure it may be made that way for rain wet roads I'm asking. It really looks good waiting to see next step.
Is the crank connection with the rod just flat and welded to each side? If yes your going to need to v it and build up the weld and then turn in your lathe to size. If it's made to slide into the shaft you could pin it and weld , several ways you can or could do it still.
 
Last edited:
The tire is mounted backwards. I was hoping no one would notice! The crank spindle ends sit in holes bored in the ends of the shaft 3/4" deep. I plan to just weld the perimeter.
Robert
EDIT: It was intentional. For bicycle applications you are supposed to run the tire backwards. ; )
R
 
Good ol' TIG.

34684916362_b9c94469ca_h.jpg


Then on the tool post grinder. I had to take down the weld beads so they would fit through the bearings.

R
 
Is there a back brake ? Rear disk brake would be slick
 
You must log in or register to reply here.
Back
Top