We just got a tip from reader Selvan about a dual-purpose bicycle that can be used for transportation as well as for energy production. Using a stand that fixes the bike in a stationary position and a pedal power attachment that can be fabricated from widely available parts, the DPB can be used to power numerous small‑scale mechanical devices such as grain threshers, grinders, water pumps, electrical generators, and furniture making tools. Because the bike is low-cost and pretty simple to fabricate, it’s ideal for developing nations.