Crank Arm Door Handles

I have always had the idea to use bicycle crank arms as door handles, as they seem perfectly shaped for that purpose. When I finally had my own dedicated bike cabinet, I decided to mount my spare crank arms onto the doors, to be used as door handles.

It is not a straightforward task to mount the crank arm onto the door, as there is no readily available mounting option. I decided to create my own 3D CAD for the adapters, and got it 3D printed! With the right design used, the crank arms can be securely attached to the cabinet doors.

My idea is to connect both ends of the crank arms to the door, and this requires a pair of adapters to work. See the pictures below for the design.

Two 3D printed parts are needed. The left adapter screws into the thread, while the right adapter is to match the Hollowtech spindle splines.

The spindle splines makes it more secure, although I think a circular shaft of the right diameter will work as well. I made a little square cutout at the back surface, in case I need to pry off the part later.

3M mounting tape pasted at the back, and trimmed to match the shape of the adapter.

Fits nicely! Need the correct length so that...

...the plastic Crank Arm Fixing Bolt can be screwed on properly.

Notice that I am using the old type of Crank Arm Fixing Bolt, which has a smaller M15 thread instead of the later M20 thread. This is so that I can make the wall of the adapter shaft thicker for the 3D printed threads. If I used M20 threads, the shaft walls of the 3D printed part will only be 2 mm thick, since the spindle outer diameter is 24 mm.

You can also make the design solid, or cored out from the back. Or just leave it as a hollow interior without fixing the bolt, just that it will not look as neat. You can just tighten the two clamp bolts lightly to fix the crank arm to this adapter.

On the other end, where the pedal thread is, another adapter is designed. 

3D printed adapter at the pedal axle thread. For left side crank arms, the pedal threads are left hand threads.

As each crank arm has a different Q-factor, the adapter needs to adapt to different distances from the cabinet door. A screw thread enables the adapter to be inserted at different depths.

Adjusting the adapters so that they will rest flat on the cabinet door. Both adapters will be pasted onto the cabinet door together with the crank arm.

Crank arms mounted onto the cabinet doors! Ultegra R8000 on the left side, Dura-Ace R9100 on the right side.

These premium door handles look nice and shiny!

I have a spare Dura-Ace R9100 left crank arm, as I am using the 4iiii power meter version on the bike.

Overall view of the bike cabinet and new door handles.

Testing to see how an old Dura-Ace 7800 crank arm will look.

Swapped to different crank arms after 2 years. The 3D printed adapters have held up surprisingly well with no issues at all!

By sheer luck, the crank arm door handles managed to avoid hitting the Omnidesk when the cabinet doors are opened.

I am really pleased with the crank arm door handles, as it makes the bike cabinet really unique. It enables me to put the extra crank arms to good use, while displaying them at the same time. The longevity of the 3D printed adapters have surprised me as well, as they are still working fine after 3 years.