Socket Drive

To further show the specialization needed in flatland, Flatware has gotten its own Twombolt Crank. The Flatware Twombolts have a few features that set it apart from the regular Twombolt. First and most obvious is the shorter size, 160 mm arms. The arms are thinner and butted differently to save as much weight as possible, on an already ultra light crank.

The most different feature would have to be the Socket Drive system . Socket Drive is a way of attaching a sprocket without using a bolt. Flatlanders use increasingly small sprockets, which infringes on the traditional bolt location on most cranks. Instead of hacking super tight tolerances, we decided to eliminate the bolt altogether.

The 9 sided shoulder keeps the sprocket from spinning, and keeps it tightly fixed to the crank arms. It also saves weight and eliminates the use of tools to remove or install the sprocket. Socket Drive requires special sprockets that fit the 9 sided shoulder, with a 9 sided hole. The Rhode Island sprocket is Flatware’s 7075 aluminum 22 and 20 tooth sprockets that only work with the Flatware Twombolts.

If you’re a manufacturer that’s interested in using the ROYALTY FREE interface, please download the spec sheet for dimensions and tolerancing specifications and feel free to use the drawing to produce your own Socket Drive sprockets. Dimensions for making the crank’s sprocket boss will also be posted soon.