11-9-2019
In the lead up to Veteran’s Day, campus has been eerily empty. With Miles out of town, I took the opportunity to design a crankset for the bike. The chainring fastens with a single bolt clamp similar to most BMX systems and has a locating flange concentric with the bottom bracket. This prevents the chainring from slipping under heavy loads and rotating around the clamping bolt.
The crankset is designed to get as near as possible to a planar chainline. The bottom bracket is unusually wide relative to the rear freewheel position, which eliminates most on-the-market products as viable solutions. Our design results in about 1-2mm of deflection along the chain span with a 3mm freewheel spacer, which is well within the functional limits.
Prior to milling the parts out of aluminum, a 3D printed prototype will be invaluable. Hopefully I’m able to get in contact with Junior and work something out with his large format CR-10. I’ve also designed rough molds that will be the basis for our fiberglass tank and seat cowling. More to come later!