Frame bending

[skyl4rk]

I have a greenline cruiser similar to this one:

I would like to cut the bottom tube in front of the bracket, and bend the tube so that it is closer to the wheel. Then weld in a motor mount.

How hard is it to bend a tube? Do I need to be careful not to kink it? Should I make some kind of a bending tool or can I do it by hand?

 

[BarelyAWake]

We've this pipe bender where I work and it's completely useless, the points of contact are so far apart it kinks the tubing every time regardless of OD: Northern Industrial Air/Hydraulic Pipe Bender — 16-Ton | Pipe + Bar Benders | Northern Tool + Equipment We've (me and a buddy) have been yappin' about giving this one a shot, a roller/mandrel tubing bender that is reputed to make nice bends in tubing w/o flat spots or kinking: Woodward Fab Tube and Pipe Bender, Model# WFB2 | Pipe + Bar Benders | Northern Tool + Equipment

...but be warned of a coupla things - "pipe" benders are typically ill suited for the comparatively small OD & thin walls of bike tubing, "tubing" benders are usually better, used by racing car drivers to make chromoly cages, where things like flats & kinks are simply not allowed. The problem is while the above links are for affordable benders, the dies for tubing benders are rarely included and get pricey quick - but they usually include one die of your choice w/purchase... Ya might have some luck diggin' around & llokin' through the links ere in GH's thread: http://motorbicycling.com/f36/huge-list-frame-builder-suppliers-24414.html

There is a buncha DIY solutions like cutting your own (stationary) dies out of hardwood, even packing the tube with sand & capping it off before bending it etc. Try "DIY tubing bender" in google and ya will get a ton of returns...

BUT - while I've played w/metal for a good long time - I'm new to the bike frame fab game & I'd love some feedback from our fabricators too



BTW - should ya decide to go the packed sand & endcap route, if ya use heat - make sure your sand is DRY & have pinholes in the endcaps or you mighta just made yourself one heck of a steam-powered pipe bomb

 

[Tinsmith]

For what it's worth a tubing bender is the only way to get the job done right, and one worth having ain't cheap. Any other method (pipe benders, sand, etc) will still tend to flatten out the tube when it's bent. A gradual bend less so, but it might be worthwhile to find a fabricator in your area with a bender and draw out a profile of the desired shape and just pay to have it done. Just the dies for 1" tubing are around $200 for the bender a friend of mine has. Good Luck! Dan