History on frame style

[AlphaWolf25]

Hey yall, im trying to find history or information on rigid frames that has X or / style braces in the rear legs. What do those called, their purposes. I only know one thing which was built for race. I am building a chopper and I’m debating to add those to my frame. But id like to learn more about it. Any information would be great! Ive attached pictures.

[rockman96]

They're called gussets in the drag racing circles. Their purpose id to prevent the frame from folding under high power.

[JBinNC]

Check out vintage hillclimbers (20's and 30's) and you will see the origins of those reinforcements.

Jim

[flatman]

The Harley WR factory racers had a vertical bar on the hardtail, same with Indian sport scout. Like JB said the hillclimbers had a brace also. Several of the factory (HD) hill climbers in the 20s had a HORIZONTAL brace running from the axel plate to the seatpost.

[Tater66]

The pic on the left is reminds me of some of the frames I saw in the early 80's. Weekend racers would start with struts to eliminate the shocks. As they gained horsepower the next step was to weld gussets made of tubing to the swingarm. Most guys could weld but fabbing axle plates was not really in their wheelhouse. Another trick was to cut the engine cradle in the front and use a bottle jack to push the frame/engine down an inch or so. Weld in some extension to lower center of gravity. That was used on a Jap 4 cylinder unit engines.