Getting the Bends?

[handyandy1100]

Ok, perhaps it's silly question time again.
Is it possible to bend a tube in a bike frame without cutting or welding anything?
Specifically, a man's bike frame with a straight top tube, can it be bent to resemble the top tube of, say, a vintage Snyder fastback?

To make something like this:

Look something like this:

 

[The Renaissance Man]

I suppose it's possible to bend it somewhat but it wouldn't bend smoothly from end to end because the ends are set it place. Plus even if you were to bend it, it would pull the head tube and seat tube closer together which would change the geometry. But hey, frames like that are cheap so you don't have much to loose by trying!

 

[handyandy1100]

That's what I was thinking, the head tube would get pulled back towards the seat tube.
Thanks.

Sent from my SM-G920V using Tapatalk

 

[horsefarmer]

Maybe if you heat the top tube and apply enough heat to soften the metal and use a jack to apply force? I have to try that...

 

[Indyjps]

How are you going to hold it, if you could secure the tube the rest of the frame will bend to accommodate it.

The frame youre looking to create has arched seat stays as well that give it the nice flowing design.

Not trying to dissuade you, just dont see how to do it without cutting and welding -without significantly moving the other points on the frame. Headtube angle etc.

 

[handyandy1100]

How are you going to hold it, if you could secure the tube the rest of the frame will bend to accommodate it.

The frame youre looking to create has arched seat stays as well that give it the nice flowing design.

Not trying to dissuade you, just dont see how to do it without cutting and welding -without significantly moving the other points on the frame. Headtube angle etc.

I think I've already dissuaded myself.
Thanks!

Sent from my SM-G920V using Tapatalk

 

[GuitarlCarl]

Don't give up so easy. A little tweak to the head tube just rakes your forks a bit and that's a look we're always chasing. But to bend it in the frame... Hmm... I'm thinking a hydralic jack wedged in by the bottom bracket pushing against the top tube may just work. You should probably have some kind of "buck" or form to push into the top tube and secure the frame down to a table or working surface somehow. A nice hefty bar to insert into the head tube to lift on probably wouldn't hurt. I'd test the idea on an old frame. But alloys and steels are all different for different bikes so results may vary. Thanks for the idea!

Carl.

 

[horsefarmer]

I'm thinking of using an old car bumper jack between the BB and the top tube.

 

[LukeTheJoker]

Please let us know how it goes if anyone does try it!

 

[Indyjps]

If we're throwing out ideas, I bend forks in the trailer hitch receiver on my truck. Safety chain loops take each fork leg, or use the main receiver and keep them even.

Any open end tube thats secured and a bar can be a forming device. Fence posts, telephone poles, just need a good anchor. A comealong, a chain, a telephone pole and a truck, you can move any tube you want.

A bar in the headtube and apply pressure then a bumper jack in the middle of the frame??? Could move both at the same time, or buckle the bottom tube. Be careful, if the welds let go.