Tubing Help

[Chopper]

Ok here's the deal, this is my new frame which I had a frame manufacturer build to our specs for the prototype. From here on out we have to make it ourselves obviously. I am trying to decide if I can make the rear hoops on a pro-tools bender and a large radius bender. I know the radius can be made on the roller but can the sharp bend that ties in to the seat area on the top hoop and the bottom frame rail on the bottom one be made on the pro-tools bender? The radius looks awfully tight and to make it with one piece like this I dont know. I called and spoke to Brian at Pro-tools and he said,"I dont want to tell you yes and I dont want to tell you no, so I guess he doesnt know either. Since this is/was a motorsports site, i know a lot of you have experience in race car chassis and cages so this is the best place to ask. Any and all help with specific recommendations on making these just as they are in one piece for each hoop would be appreciated. I have attached the photo. Thanks.

[lramberson]

Chopper need more info to supply the right answer.
1) Type of tube & thickness you are using?
2) Distance between A & B? So estimated radius can be figured.
3) Are the items you are adding for structural rigidity or visual appeal?

[Chopper]

1. Tubing is DOM 120 wall
2. Length of bend near seat is 4 - 4/2 inches
3. Structural integrity just like in the picture

Thanks again.

[dyn88]

the radius by the seat upright area is deviating. It apears to be a wide radius that was mitered to the proper fit. Much like when you bend an exhaust pipe and cut it parralel to the tangent to give it a more appealing look. Hope this helps.

[Chopper]

Its kind of hard to see in the picture, but the hoop section ties in to the main backbone and then there is small section of tubing that connects the backbone to the hoop. The rear hope section is all one piece and I dont know if I can make that with just a roller and a pro-tools bender? Thanks for all the input.

[snow]

Hello Chopper

Usually for a "proto-type", you would get a blueprint or schematic.....or at least a detailed set of bending instructions......telling you length of tube, radius of die, bend start points, etc......

These questions could and should be answered by the people who built the prototype...........on the other hand, if this is just a one-off bike to them, they may not have recorded the info and may not want to share it even if they did........since you are fixing to become some of thier competition........lol

It is hard to tell from the pics........but it looks like common dies were used to me.........I would guess a 5 inch radius on the slightly bent tubes and a 3 or 4 on the tighter bends........

Common dies for the pro.........or the hossfeld......

Go with the hossfeld......

Good Luck