Old Schwinn Road Bike Chop Chop Build

I thought some of you may be interested in what's going on with my Latest build - I am doing some radical engineering to rig up a swing arm dual suspension bike.

First, I started with a gigantic road bike that was given to me, set up for very tall riders. I chopped the head tube and the seat tube, removing almost 4 inches of tubing.

I'm going to affix a 1/2" axle perpendicular to the seattube with heavy welded steel. The swingarm axle hold a welded double sprocket offset about an inch that will feed the left side 36 tooth sprocket, anchored via clamshell on a 24" wheel. The swingarm width will be 7 inches, with my custom hub being 6 1/2" wide. The hub will ride on a 1/2" axle! It will take something to break that.

I am shooting for a 47" wheelbase.

I did some test fittings on the frame to get an idea of how it would look.

I'll need to dish out some money for sprockets, tube and tire, stepup drillbit (to put 5/8" bushing into swingarm), and two shocks to support the swingarm.

I will be running a 1' piece of heavy Duty unistrut along but slightly below the top tube/ down tube interface. That will hold a spring saddle and grab the top of the shocks.

 

[gary55]

I truly appreciate your concern but pictures can be deceiving. These channels are crazy strong, much stronger than any tube on a standard bicycle. I can't imagine the force it would take to bend one!

The weak points will be my welds, in particular the clevisses that I've welded to grasp the bottom of the shocks. I'll need to watch the Grade 8 studs that grasp the top of the shocks as well.

Everything is overdone. That's the whole point of this: max dependability, max trust.

I have no idea of the gauge. Just commenting on what I'm seeing. I would be happier if I were wrong and it held perfectly, and I hope it does. Not trying to be a dick head, Just don't see anyone eating it. Jake take it easy. I didn't pee in your cheerios.

 

[Timbone]

I have no idea of the gauge. Just commenting on what I'm seeing. I would be happier if I were wrong and it held perfectly, and I hope it does. Not trying to be a dick head, Just don't see anyone eating it. Jake take it easy. I didn't pee in your cheerios.

No worries. You didn't hurt my feelz. Part of posting is to receive feedback and I am way out of the box on this one. I truly appreciate the input. I want to leave nothing to chance. I broke an axle once that sent me tumbling - you are correct that this is to be avoided at all costs!

 

[gary55]

Cool, best wishes and I hope it works as anticipated. Rear suspension is a huge bonus. I wish someone would make a savior style frame for these bikes.

 

[Timbone]

I have a rolling chassis now, and attached a cool rear fender:

 

[Street Ryderz]

View attachment 79479 View attachment 79478 I have a rolling chassis now, and attached a cool rear fender:

that's pretty cool will the drive chain to wheel clear the cross braces on the swing arm?

 

[Timbone]

that's pretty cool will the drive chain to wheel clear the cross braces on the swing arm?

Good question! Yes, it's tight but with a bit of metal surgery on the topmost crossmember there should be plenty of room for clearance. Those are 12T sprockets on the swingarm axle.

 

[Street Ryderz]

Good question! Yes, it's tight but with a bit of metal surgery on the topmost crossmember there should be plenty of room for clearance. Those are 12T sprockets on the swingarm axle.

I hope it works out well for you should be a nice cushy ride.

 

[Timbone]

I hope it works out well for you should be a nice cushy ride.

Thanks! Today I did some downhill rolls. Very Cushy! It's light on the front end but it feels like a motorcycle with the long wheelbase: 50 inches! It's going to handle well.

The sketchy part is my offset sprockets. I'm using 9 very thin bearings carefully spaced inside the assembly. Can they take the force of the sudden slam when I pop the clutch? Should be able to but you never know!

Using channel for dropouts is a huge advantage because you can run axle tugs right thru the center. A thick fender washer is all you need to use on the back side.

 

[Timbone]

Though I would exhibit some photos of my rear disk brake adapter made to affix a 203mm rotor onto a 36T sprocket with clamshell device.

I welded three steel triangles and cut and threaded for the 3/8" bolts. Grinded and sanded both sides to where they would lay flat.

After carefully lining up the rotor, I decided to just hold the rotor on with nuts and bolts, loctited of course. I didn't have a tap for 5mm so I figured it would be the simplest solution.

The pics tell the story: everything looks great. It's very strong and sturdy, and the 13/64" holes are perfect for the 5mm bolts. I have bolts!

What I didn't consider: with the rotor bolted into place, there's no configuration that will all me to bolt the sprocket onto the clamshell adapter! Fail!

What to do? Knowing that the rotor holes were 13/64" - and that's the size I drilled the 6 holes - and being aware that's the size of drill for 1/4"-20 screw threads, I just tapped it all out. No nuts and bolts fastening - I'll use 6 shorty bolts and loctite them in.

I'm pretty happy with how this came out. Info from this board helped me a lot! Thanks!

 

[Deleted member 26224]

Man I really hope that seat tube is sleeved. Welding on a thin tube like what you've done above the u-bolt clamps weakens it a heck of a lot as well. And those u-bolts also weaken it a lot. Also replace that crappy fork, that thing will fail someday too. Not to be a dick, but I wouldn't ride that thing without a motor.