broken frame

Are you planning to repair the frame or replace it? If its repair it then what is the frame made out of? Can you weld? Do you have access to a welder and what kind? Otherwise take your bike to a welding shop. Where the stays connect to the wheel dropouts fill in the weight reduction cut outs. Where the seat and chain stays meet at the wheel dropout you may want to cut a piece of flat bar to fit and be welded in there to reinforce the area.
 
Are you planning to repair the frame or replace it? If its repair it the
what is the frame made out of? Can you weld? Do you have access to a welder and what kind? Otherwise take your bike to a welding shop. Where the stays connect to the wheel dropouts fill in the weight reduction cut outs. Where the seat and chain stays meet at the wheel dropout you may want to cut a piece of flat bar to fit in there to reinforce the area. The first picture shows how I fixed a broken chain stay the second picture shows what it originally looked like.
 
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Risk you take when using something outside of what it was designed for. There is a reason why motorcycle frames use bigger and thicker tubing.
 
Some of the old Matchless bikes from the 50s had tubing not that dissimilar from bicycles.
 
Some of the old Matchless bikes from the 50s had tubing not that dissimilar from bicycles.

Bamford-AMC-Frame.jpg

yep sure looks like a bicycle frame... now if your talking about one of many that used a 98cc 2speed sachs you would not be far off the mark but not a Matchless frame.
 
tubing used on even a 98cc 2speed Sachs German made Wanderer .. Russian made Dnepr Kievlanin was 24.015mm X 2mm thick tube. The tubing used for a
single or twin cylinder was even much larger/thicker. Most bicycle tubing is .5 or .8mm the thickest is 1.5mm that is used for bottom bracket shells and headtubes.
 
some of the modern motorcycles still for sale at dealerships new and rolling out of factories are the same as whats used in bicycles... its usually not the steel itself, but the joins. or any heat affected areas. i have had a haro frame do a strange sort of spiral crack down the top tube, starting a few inches from the headtube...


on that note, ive seen lengths of 19mm bar get turned into drifts, only to find the bar had a crack running the entire length, that was only revealed when heated up redhot for the final stage, hardening the points. hi quality heat treating bar from a reputable supplier. it does happen.
 
29er frame tube set..
http://www.cycle-frames.com/bicycle-frame-tubing/29er-Tubeset-35-X-969-DT.html

thickest tubing 1.2mm

http://www.jpcycles.com/product/701-510
aftermarket Harley Davidsodson softtail frame 1.250 x >120 wall = 3.048 mm

that is at times more then 3X as thick as bicycle tubing and double that as there are TWO down tubes not just one and most HD motors have a top motormount besides the lower mounts and transmission mounts that tie everything togather to make it a more solid unit as compared to a chinadoll only using two mounts.. .. Now that the FACTS are right here tell me again how the tubing is the same???
 
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