Bonded

Tubes are glued into cast aluminum lugs. Generally produces a somewhat flexible frame.

Brazed

Metal tubes (usually steel) are adjoined by melted brass solder without the aid of lugs. Very expensive, usually used for custom frames.

Lugged

Tubes are either brazed or soldered into metal lugs. Useful only for regular tube shapes, so it's becoming more and more uncommon. Conventionally found in steel, aluminum, and carbon fiber bikes.

MIG-Welded

MIG-welded bike frames are less common than the closely related TIG-welded bike frames. Short for Metal Inert Gas, MIG-welding is used on aluminum and steel-tubed bikes.

TIG-Welded

Used to construct steel frames and done so with tungsten electrodes. Commonly found in mountain bikes and road bikes.

Welded

A common method for titanium, steel, and aluminum bikes in which argon gas is used to fuse similar materials into a single frame. Welded frames offer a great combination of light weight, strength, and affordability.

Monocoque

NASA often designs rockets using the monocoque method, because it places almost all of the stress on the outer shell. Bikes constructed this way are usually made of carbon fiber, sometimes with aluminum. They are light and offer the biker control over the ride. This method differs from most others in that no major joints are glued. Instead, a single piece of material is molded into the frame. Monocoque bikes are generally best for long, flat rides.