This is a Fixperts project we participated in, where we teamed up Zion Halfon, who has wrist disarticulation and wanted to ride his mountain bike, we've designed a tool to help him do just that, and made it public so anyone with a similar amputation will also be able to use the tool and hopefully ride bicycle with ease.
Step 1: Bill of Materials - Objects Used
Step 2: 3D Printing
3D print the file attached to this document.
Recommended settings: Print in ABS/PETG
0.1 layer thickness
Support structure at 60 degrees
Step 3: Cut Rod End
Make sure your rod end is at the correct length so both hands of the future bicycle rider are at the same distance from the handlebars of the bicycle. Zion needed 5 cm of the thread of the rod end with the length of the main body.
Step 4: Cut Bigger Steel Rod to Correct Length
In order to fit into the main body without sticking out and risking an injury, cut the 12cm diameter solid steel rod to be 4.5 cm from end to end, and sand the edges so they are not sharp
Step 5: Drill Hole for Securing Pin
Measure 1 cm from one of the edges of the 12cm diameter steel rod and drill a 3 cm hole that goes all the way through to the other side (sanding the edges optional for easier insertion of pin).
Step 6: Place Cut Parts Into Place
Insert the rod end into the back of the main body, with the hole concentric to the holes in the top and bottom(we found it easier to do when the main body was laying on a table), and push the 12 cm steel rod through all holes, making sure the hole you made is facing backwards - towards the hole in the main body.
Step 7: Secure the Pin
insert the 3 cm steel rod into both holes(main body and bigger rod), and cut into desired length(possible to leave some sticking out if you want to take everything apart, could also glue it in place so it wouldn't move).
Step 8: Insert Stainless Steel Washer
At the bottom of the main body there is a slot right on top of the hexagonal hole, slide the stainless steel washer into place and make sure it stays there for the next step.
Step 9: Place Cam Lever in Place
Make sure the handle is at the top (as in the picture), and push the cam lever through the holes of the main body, making sure it went through the stainless steel washer.
Step 10: Screw Nut to Secure
Screw the hexagonal nut around the cam lever thread, only enough for it to not fall and push it into the hole at the bottom of the main body, then continue screwing cam lever while holding the nut in place, don't close too hard because there are still adjustments to make.
Step 11: Remove Hook From Prosthesis
If your transradial prosthesis came with a hook fixed into it, screw it out and store somewhere, if there is nothing screwed to the end, continue to next step.
Step 12: Connect Everything to the Prosthesis
Screw the entire assembled body with the rod end to the prosthesis screw, where the hook was before, make sure to leave one turn free, for pronation and supination of the arm, and lock the lever of the cam lever for the next step.
Step 13: Fit to Your Own Bicycle Handlebars
Push the object to the handlebars to see if it goes in with the lever of the cam lever closed, if it does not, or is too hard, unscrew and lock the lever and try again, until it is possible to push it to fit around the handlebars and pull out of it. Should be firm enough so it is possible to ride with it, but not too loose so it'll come off.
Step 14: Simply Ride Your Bicycle
And you're more than welcome to watch our video of how it was made: