Instead, frame tubes are precisely aligned into a jig and fixed in place until the welding is complete.

Fillet brazing is another method of joining frame tubes without lugs.

A few medium-quality bicycles used these steel alloys for only some of the frame tubes.

The pump took up the length of one frame tube and made a second bottle cage on the frame impossible.

However, the mounting posts for the bell cranks caused cracks in the main frame tubes.

One of the two frame tubes that run horizontally from the bottom bracket shell back to the rear dropouts.

Jigs hold frame tubes for tacking and alignment prior to welding.

Engine coolant passed through one of the frame tubes.

Coated in chrome, it is mounted directly to the upper frame tube.

More traditional bikes might employ airfoil cross sectional shapes in the frame tubes.