Frame idea.

Discussion in 'Photos & Bicycle Builds' started by Timbone, May 29, 2016.

  1. Timbone

    Timbone Active Member

    I scored this very big brazed Schwinn frame from a neighbor who knew I liked bikes.

    This frame measures 23 inches from bottom bracket to the top tube and has a 8" head tube. I'd like to hack this frame up and make it something special. I have a threaded suspension front fork ready to go.

    My goals would be a 48" wheelbase, with the pedal bottom bracket 11" above the ground. To get the frame down to size, I plan to chop 3" off the head tube and the seat tube. The discrepency in tube angles may allow me to lay the frame back a bit, making for more motorcycly trail.

    How to reconnect the tubes after the chop? Might just fab a piece of tubing over the head tube sections and solder it. Maybe MIG weld it. Still thinking.

    I want to leave the seat tube unconnected. Fill the gap with a stainless steel coupling and stick it with two 1/4" Grade 8 studs. Would still be solid and would allow the vibrations a place to go.

    I have a cool design for a swing arm! Done some preliminary tests. I'll have a solid axle with a bushing to allow movement. I'll hack off the seat and chain stays and run metal back over the wheel for a cafe racer style seat. The swing arm will connect to the upper frame via small shock absorbers. Full suspension! The trick is to center the swing arm axle with the motor drive sprocket.

    Maybe I can fab my own custom shock absorbers. I have two springs that would be perfect for the task...

  2. butre

    butre Well-Known Member

    ideally you would braze or weld the tubes to reconnect. solder isn't going to hold it.
  3. Timbone

    Timbone Active Member

    I can't argue with that. Head tube takes a great deal of abuse.
  4. Hello Moto!

    Hello Moto! Active Member

    Sounds like a cool project. I'd be interested in seeing the process as it unfolds. Keep us posted if you get it goin man.
    Timbone likes this.
  5. Frankfort MB's

    Frankfort MB's Well-Known Member

    I have 2 old jc Higgins I was about to cut one up to try a dual suspension since one of the bikes the wheels are messed up. The other one the wheels are good but the fork is bent and bottom bar I think might be bent. Got them both plus an old BMX bike for cheap so why not lol
  6. skyash

    skyash Active Member

    i have been thinking of 2 wheels at the front 1 at the back for maybe sliding or off rode .like a tadpole motor bike just 2 forks on the outside of the stock ones ?
  7. libranskeptic

    libranskeptic Member

    Interesting, albeit heavy, concept.

    If you welded each outer suspension fork to an arm of a wheelless center suspension fork, you would have double, independent suspension on each wheel.

    I rode in the cab of a truck, which itself was on the bed of another truck, on the roughest road imaginable, and was like riding a cloud.
  8. Timbone

    Timbone Active Member

    IMG_0279.JPG IMG_0276.JPG
    I actually hacked this frame up just for fun. Took off 3 3/4" . Using a MIG welder with flux core wire (less than optimal I know), I welded some support steel inside the new seat tube and tacked it together.

    This weekend, I plan to do a complete bead around both cuts, then grind down smooth. I'll beef up the head tube with a metal collar. As for the seat tube, I will grind down those welds and build out a circumference of 1 1/2" inches so that a muffler bracket can hold down the rear of the engine.

    I think I have my swing arm design. I think a 3/8" fixed axle will be strong enough to support. It will be a complicated build with flat stock intersecting roundstock. I'll do a double sprocket offset so that the final drive comes from the swing arm so no issues with chain slackening and tightening.

    My front suspension fork is 26", so I'll plan for that. 24" on the back with 36T sprocket.
    Last edited: Jul 4, 2017