Building your own custom fat tire bicycle can be difficult, but rewarding. A fat tire bicycle is ideal for extreme terrains given the durability of its frame as well as the tires that are its defining aspect. A fat tire bicycle is bulky to take to the beach or on vacations, but worth the effort to ride on different terrains and discuss your handiwork with other bike enthusiasts.
Parts and Tools
You can use parts of several bikes to build your frame to your desired size. Check for other parts you may need while stripping other bikes. Arrange the parts for your fat tire bicycle on a flat piece of cardboard to get an idea of how they will fit together and how the bicycle will appear when complete. Use conduit benders to shape parts of the frame to your required size. Use an angle grinder and a grinding stone to shape the metal parts of the bike as needed so they fit into place according to your specified design. Use flap wheels to remove galvanizing on the metal frame parts prior to welding because welding galvanized steel can be dangerous. Use a 120V stick welder to connect each metal part in the bike frame. Use the wheels from an ATV as the wheels for your fat tire bicycle because of their large size and the four-bolt pattern of the rims, which is ideal for stability.
The front and rear axles should be made of at least 1-inch solid steel to accommodate the stress from turning the fat tires. The swing of the crank must be sized so that your feet will not touch the rear swing-arm frame when you pedal the bicycle. Use a standard gear hub as the transfer hub or jack shaft between the bottom bracket alignment and rear tire alignment. Position the jack shaft behind where your feet would set as you pedal to avoid touching it. Mount a solid steel disc brake, similar to what you would find on a go-kart, onto the rear axle. Mount a chain ring onto a sprocket adapter and use spacers to keep the two clear of each other. Mount a front derailleur on a seat tube to accommodate the higher drive train angle necessary for the fat tires to easily rotate. Add a chain tensioner to the drive train if there is no axle adjustment or derailleur to keep the chain tight.