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Motorized Bicycle Welding, Fabrication and Painting - The Chop Shop Custom fabrication and projects, tanks, frames and more.

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Old 02-04-2015, 08:03 PM
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Davezilla Davezilla is offline
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Location: San Antonio Texas
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Default Re: how the **** do you do this?

I'll agree with using parts bikes since you can easily harvest a good set of horizontal drop outs from an old bmx frame and if you can weld and make up a jig, this can be pretty easy, but definitely practice practice practice, then practice some more...

If you got a welder and a plasma cutter, making drop outs can be done quick and easily, but I don't know what kind of equipment you have to work with. Even a band saw will work and save you a lot of time, but anything less than that and it's better to buy them pre made or harvest them from junk bikes.

I got some plans for making a motorcycle jig which could easily be applied to making a bicycle frame as well as a LOT of plans for forks like springer, leafer, and girder type, and same thing... they can all be scaled down to be used on a bicycle, it all depends on what look you're after and how well you need it to handle, but the girder type is by far the best handling type since it doesn't change the rake and trail as the spring compresses like the telescoping type forks used on most motorcycles, the reason most motorcycles use the telescoping type is to save on production costs, and they've been really advanced by using cartridges that control rebound, compression, nose dive on braking and really tight cornering etc, they can be made to work really well.

If a solid fork is all you're looking to make, there are severall designs to choose from whether it be a BMX type like the older mountain bikes use or a tripletree design which looks great and also offers good strength, but the steering needs some stops added to prevent tank dents.

But with a proper frame jig, you can easily set up the rake and trail to make the bike ultra stable or a bit less stabile in favor of faster turning capabilities etc...

Here's a site you can read all you need to know about frames, rake and trail, and which front end will suit your needs best... If you got building skills, the right tooling, and a good understanding about setting up rake and trail you can make a killer bike that'll be perfectly stable at any speed as well as excellent handling for whatever purpose you want the bike to serve...
Read the articles and download the plans etc... there are plans for frame jigs, tube benders and notchers etc that'll help you no matter what you want to build...
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Old 02-04-2015, 11:04 PM
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Gbrebes Gbrebes is offline
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Default Re: how the **** do you do this?

Originally Posted by jazz2561 View Post
Is the tube notched on both sides or just one side? How do you keep the dropout straight?
Hey Jazz,

I am not an expert, but as far as notching for a dropout, the way I understand it is you do not notch one side or the other, instead you are basically slicing a thin channel into the tubing that the flat dropout can slide snugly into. You will still have tubing on the side facing out and the side facing in.

As far as keeping it straight, some type of jig is the only way I can think of. if you can mount your frame perpendicular to a flat surface and the frame is plumb, then you could use a metal framing square to true up the dropout before tacking it in place.

Hope that helped a little,

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Old 02-04-2015, 11:09 PM
jazz2561 jazz2561 is offline
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Default Re: how the **** do you do this?

thanks Gbrebes, it does, im making my own dropouts for a 3/16 plate. I'm going to do a sketch to show the idea on how I thought about doing it.
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Old 02-06-2015, 01:23 AM
kdey777 kdey777 is offline
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Join Date: Nov 2014
Location: allentown Pa
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Default Re: how the **** do you do this?

ive done drop outs as an insert then spot weld and come back and put a nice dime thick bead around it. i gave myself about a half inch overhang ( guess that would be inner hang in this case) and that frame went through three years of dirt track and skate park teenage abuse and those dropouts were probably the only thing not broken on it at that point. as far as getting the frame straight its just a take it slow thing but dont get anything too hot. when you do you not only distort the work but put the integrity of the frames stress points into question.
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