The Polo Bike is a practice in welding and manufacturing a tube frame with an unusual design.
The Polo Bike is a frame designed for playing bicycle polo. The use of 26″ (32-559) tires and removing the seat tube allows the rear axle to be placed closer to the bottom bracket compared to regular single-speed frames. The wheelbase is short and the weight of the player is just in front of the rear axle. The result is nimble handling while the relaxed 72 degree angles keep the steering calm. The bike looks tall and short, but it is made to fit a 180 cm player with an effective top tube of 560 mm.
The Polo Bike is TIG welded from stainless hollow sections. The square sections for most of the frame are 25 x 25 x 1,5 mm while the chain stays and seat stays use a 20 x 20 x 1,2 mm profile. The head tube has a wall thickness of 3 mm and the drop outs are machined from 5 mm material. The austenitic stainless steels used are EN 1.4301 (Type 304), EN 1.4404 (Type 316) and an experimental heat of a low-nickel copper alloyed stainless steel similar to EN 1.4372 (Type 201). The filler wire was of the type 316 and Argon was used as a shielding gas. The frame was welded using constant currents between 25 and 55 Amperes depending on the material thickness. The surface is left raw with some of the weld caps ground flush and some of them TIG-dressed. The frame is 4 kilograms and indestructible.
Acknowledgements: We wish to thank Outokumpu Stainless Tubular Products for providing the tubes to us, the welding technology lab at Aalto University and SolidWorks Corp.