Discussion in 'Off Topic' started by SimpleSimon, Feb 8, 2009.

  1. SimpleSimon

    SimpleSimon Active Member

    A guy I know here is a ham radio buff, and has quite a rig. He is putting up a new antenna tower, and has offered me his old one. It is typical antenna truss. face are 5 inches center to center between any two of the thee parallel tubes, and was built in two sections 12 foot each out of 3/4 EMT tubing and 1/8 rod making the angled cross bracing between each pair of main tubes - so the cross braces are welded to the main tubes every 10 inches along each tube.

    Antenna truss is incredibly strong stuff and will take really high side-loads. Full width on any one side, outside of tube to outside of tube, is 5.75 inches. Too clear that width, the BB width needed is right at 6 inches, then of course you have the crank and pedal width. I'm thinking about using it as the main beam for a tadpole trike.

    I'd like some input, please. Is that too wide to be practical for a BB? Suggestions, anyone?

  2. srdavo

    srdavo Active Member

    Interesting! Sounds plenty sturdy.

    Most tadpoles have the bottom bracket forward of the main frame.... a single tube (boom) & a normal BB would work. I mounted my boom & BB yesterday.... I'll post a pic later.

    20 20 heavy 3D.jpg I am basing my tad, 'loosely' on this design. The frame (my) is 8 & 1/4 " wide... my boom is a single tube.

    (compliments of Check out "Tips/Tools/Help"..... It's like a whole nother site...inside the site!)

    Having 24' of tower.... you'll be able to build 4 or 5 trikes.