Parametric bicycle computer mount adapter for a raised handlebar stem (FreeCAD).

I use an adjustable angle stem for the bike handlebar to raise it as high as possible. When my bicycle computer is mounted on it in the raised position, I cannot see any information on the screen. I know that the bicycle computer can be also mounted on the handlebar, but all the free space on the handlebar is used to mount other kinds of stuff when I'm in touring trips, so the stem seems to be the best place to mount the bicycle computer for me. This is why I made this adapter with a changing angle.

The model is completely parametric in FreeCAD. I made it for my noname bicycle computer. Its mount doesn't require full-sized 29 mm diameter tube to be mounted securely, so I made 15 mm diameter adapter to reduce weight. The length of the adapter is only 30 mm because I wanted to make it as small as possible. Bigger bicycle computers may require more space to be mounted, this is why you can easily adjust a few values in the spreadsheet to change it for your bicycle computer, for example, change diameters of the adapter tube and the stem clamp or change the length of the adapter. The clamp diameter should be just a little bit lower than the diameter of the stem to secure reliably.

DO NOT EDIT THE MODEL ITSELF, just edit the values in the spreadsheet, and the model will be recalculated automatically according to your new values.

The green values are safe to change for your needs. The red values are calculated using the green values automatically. There's no need to change the red values manually unless you want to get some non-typical shape and understand how to do it by changing the red values.

I used 2 mm thickness for the clamp to reduce weight. It seems to be reliable for PETG that I used because it is rather flexible and has good adhesion, so won't break. If you use other plastic, you may need to increase the thickness.

Tested reliable print settings for my PETG to reach minimal weight (9 grams for D25 and 6 grams for D15 adapters with clamps). You may use other settings if these are not good for your plastic.

Clamp:

Set 999 walls or 999 top/bottom to ensure 100% infill for the whole part. I used 110% flow and 0% fan speed to improve adhesion between neighboring lines (otherwise the lines may separate if you bend the clamp hard).

Adapter:

The tube is printed with 3 top, 3 bottom, 2 walls and 12% cubic infill. I couldn't break it when I stepped on it with my full weight and there won't be more load on in the real life, so I don't see any need in the excess of infill inside the tube. If you don't trust your plastic, better use 3 walls instead of increasing infill.

The tube-to-mount transition and several layers below it is better to print with 24+% infill.

The mount and several layers below it is better to print with 999 walls to prevent breaking it accidentally by clumsy movements as this is the most vulnerable part.

Use cubes with "modify settings for overlaps" in Cura to set different infill settings for different parts of the adapter as shown in the picture:

These recommendations are for long adapters with big diameters, as they will have too much weight if you use constant infill for the whole construction. For smaller adapters like mine (D15/30mm length) I recommend 20% cubic infill for the tube and 100% infill for the transition to the mount and the mount itself as it won't add too much weight within this volume but will increase reliability.

There are 2 versions of the clamp. The initial version is made of 2 separate parts. It is easy to fix securely as it uses 2 bolts and nuts. To further reduce weight and make it more neat I also made a single part clamp version that needs only one bolt and nut. It can be used with comparatively flexible plastic such as PETG that bends but doesn't break when low thickness is used as you will have to bend it to wrap it around the stem. Default thickness of 2 mm was OK for my PETG. But you need to find the precise stem diameter, otherwise one bolt will not keep the bike computer in the selected position securely. The version of the clamp with two parts is more universal and easy to install in this respect as it will be securely fixed by 2 bolts even if the clamp has a slightly wrong diameter.

Installation. 

The following instructions are for the two parts clamp version. If you use the single part clamp version, just skip redundant steps…

1) PETG is very slick. Make the rotating surfaces of the clamp and the adapter mount rough with a coarse sandpaper to prevent slippage.

2) Connect the two clamp parts and the adapter together with a M3 bolt and nut. Do not tightening hard at this point.

3) Attach your bike computer mount to the adapter tube with cable ties as if you attach it to the stem/handlebar.

4) Put the clamp around the stem and connect the two parts with another M3 bolt and nut. Do not tightening hard at this point.

5) Move the clamp up/down the stem and rotate the adapter tube to find the bike computer position with the best screen visibility.

6) Tighten the REAR nut (that is closer to the bike computer) to fix the bike computer position.

7) Tighten the FRONT nut to fix the clamp position. If it still rotates, you need to print another clamp with a smaller diameter or use a rubber gasket between the clamp and the stem. For me, it works great without gaskets.

8) Enjoy!

Any questions? Ask in the comments section. Photos of your bike computers mounted with my adapter are welcome!