I've used this design for half a year now (10 kg bike and stone wall) and didn't encounter any problems. But depending on the material of your wall and the weight of your bike, it might fail to hold your bike.

Material

• two wooden poles (35 mm diameter)
• two 6 mm diameter screws (and probably dowels)

Print Settings

I've used CF-PLA, but most other materials should also be fine.

The Bigger Parts

• needs to be printed with tree supports enabled.
• 6-8 walls and 25% infill
• 0,2 mm layer height

The Smaller Parts

• no supports required
• 100% infill
• 0,2mm layer height

Assembly

First, insert the wood into the bigger part. This should require some force, so you might need a hammer. Drill holes into your wall at the correct locations and screw the smaller part to the wall (the wider side facing into the room). Then, take the assembly from the first step and slide it onto the screwed in parts from the top. It should be tight agents the wall. Carefully try to put some load on the woods and see if it holds up.

Feedback 

Please let me know what you think. Is there anything I could improve or should I upload different diameters? I would love to hear your thoughts.