Bending/stretching Aluminum frames?

[rich56]

I have a Trek Rail that I'd like to replace the coaster brake with a 3spd Shimano hub. That calls for widening the chain stays. I know its done on steel bikes. Will a aluminum frame tolerate some bending?

 

[Uncle Stretch]

Man thats a good question. I know aluminum is pretty unforgiving. You can usually bend it once and then after that it will break. Good luck.

 

[bicycleguy]

Bending aluminum frames "cold" usually never ends well, if you use some heat it usually helps but it destroys the paint.

 

[user 135]

The good news is you should not have to bend your frame at all. The OLD(over locknut dimension) of the Nexus 3speed should be the same or very close as the coasterbrake hub that came on the Rail. You can spring apart the frame a little bit and that should not be a problem.

http://www.sheldonbrown.com/frame-spacing.html

I would not bend aluminum at all.

 

[deorman]

A regular freewheeling 3-spd Shimano should slide right in. but some old coaster brake Shimano 3-spds are indeed nearly an inch wider than 1-spd coasters. I would not even consider trying to force them into an aluminum frame.

 

[Korporal]

Once aluminum has a shape, it likes to keep it. I can almost guarantee that bending the stays will lead to cracking the frame.