ISCG05 Bash Guard

While mountain biking, I’ve scratched and bent a few chainrings. Feeling the need to protect my overpriced Sram 32t chainrings, I designed a simple durable bash guard made specifically for my Evil Offering V2. Evil and Rocky Mountain bikes as far as I know are the two large brands which use two tabs to mount any bash guards instead of the traditional three on the ISCG05 standard

A piece 7075 T6 Aluminum billet was milled to form the plate which bolted onto the bike. Slots were added to adjust the angle and coverage of the bash guard. Custom 1/2″ – 20 bolts that are are hex boarched to 1/4″ were also made on a CNC lathe.

Using FEA anaylsis, I found that having zero gap between the sacifical bash and the metal mount would allow for the impact to the transfered to the bike the most effectively; a gap would have transfered the force to the mounting screws and then to the frame. From FEA, I concluded on the infill and wall thickness of the 3D print.

The sacifical bash is 3D printed on a MarkForge using Onyx filament — micro carbon fiber filled nylon — with kelvar reinforcement on the outside layer. To make the spares, I alternatively used Fiberon™ PA612-CF15.

The bash guard is stout. My chainring and bottom bracket are thanking me.