The purpose of the bashring is to provide protection to the chain and chainring from impact.  

The design of this bashring uses 4x fixing points and symmetrical design, so that if the bashring gets worn or damaged on one side, it can be flipped 180 degrees to continue providing protection, increasing the lifespan of the part. 

After completing the initial design, it was prototyped by 3D printing in PLA. 

The part was fitted to the bike and then tested. The clearance to the crank arm was ok and the protection to the chainring was enough to prevent it from being hit, without being too big and reducing the ground clearance significantly. 

Once I was happy with the prototype, a two part mould was designed. This had to incorporate appropriate draft angles and corner radii. To provide compression to the part, the position of the split line had to also be carefully considered. 

The position for the split line was fairly high, with 3/4 of the finished part being within the female mould. This would make removal tricky, so extrusion screws were incorporated into the design. 

To remove any visible extrusion screw marks, the existing bolt positions designed into the finished part were used. There would be a solid volume of carbon to push against once the part is set, which would be drilled out later when finishing the part. By using this location for the extrusion screws, it avoids any visual imperfections on the finished part. 

The next step was to print the male and female moulds and prepare them for moulding. 

Wax was used to backfill the open cavity where the extrusion screws were and mould release agent applied to the remaining surfaces.

The female mould was then packed with carbon fiber and resin and left to cure. After curing, the mould was split and the part removed. Any flash was sanded away and the fixing holes were drilled out to their required size.

The final step was to polish the part, fit to the bike, and use! 

Thanks for looking!