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Old 05-14-2016, 02:53 AM
Motorized Bicycle Elite Member
Join Date: Jul 2010
Location: CA
Posts: 1,747
Default Re: Cracked chain stay

Originally Posted by beginner01 View Post
Well $hit. new frame huh. I fixed it for now doing the pipe over it, welded it shut then used a torch to form the pipe to it and weld it. Ran outta wire to weld the license plate mount, but it will be like a brace/gusset when it's welded. Been wanting to do a full suspension cruiser build maybe will do it on this one, then I could cut off the entire rear triangle. Would it help to switch to a 24" with a fat tire for suspension?
I had to make a manufactured rear wheel Whizzer clone sheave fit. It was that my home made washing machine pulley I made some 50 years ago on another rig, was available then and of strong steel.

Back then, I could find in pressed stamped steel. The white metal type of today is not going to last very long I found out. To fit the only China Girl part on my Briggs bike, I had to widen the chain stay on the side of the sheave.

I ground away 1/2 the thickness of the area the sheave was rubbing. It was only a small spot with a length of 2 inches. Then I put a couple of plates of steel welded to the area where I notched on the chain stay. The bike I use only offroad doing trail riding.

The bike weighs 130 lbs and myself a light weight about the same. No problem have I seen it cracking, but I also added gussets at area of the drop outs.

I can respect the idea that fixing a spot where possibly fatigued metal may be along a length. If that is the case a weld could break at the areas at the ends of the welded fix.

Wet suit material I have had professionally repaired where instead of gluing and stitching just the area that wore out, they cut away a swath 3 times the size of the worn through area and attached the repair material at a point where the suit material was not so worn. Replacing the full length of the chain stay on the broken side or both sides might be the equivalent of the wet suit repair idea.

If you have to get another frame of the same, and also if you had modified that frame to work with the bike as current can be difficult.

One thing for sure, if you are concerned and get another frame at least that very complex shifting with multiple clutches you made is already done.

To add strength beside gusseting, putting something in replace of the metal seat post tube, that even if not used for a seat, would I think be adding useful. Area just forward of the rear wheel fit something there.

Great you have the bike back and are working to get it in shape.

Last edited by MEASURE TWICE; 05-14-2016 at 03:04 AM.
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