My linkage was angle iron and a bell crank. There was no such thing as welding for us, and the only power tool we had was a 1/4" electric drill. Any larger holes were filed out after we rounded it with the bit as much as we could. I can remember when someone actually bought a Comet clutch for $10 dollars-until then everything was belt drive with a tensioner (if you were lucky-most things were push starts)
We also used to pound a wood roller from a reel-type lawn mower onto the shaft of an engine and clamp it to the frame of a bicycle right behind the seat. The roller would rub the tire and off we would go. Seems like we always came up with something fun to do about 2 weeks before school started again...