need bike frame advice

[Wishes]

I am trying to fit a wheel on a ebike frame upper support arms of the rear wheel triangle, are not wide enough. The bottom ones are. But the top ones have a slight curve inwards to them that make it too narrow for the tire I'm trying to squeeze onto this ebike frame.

Having absolutely no experience at bike frame building, in fact I am good with the electricals, I suck at the mechanical aspect of things.

I was wondering if it is possible to bend these out? Can you do that to a bike frame without structurally compromising it?

See below

And in this picture you can see the bottom supports don't have that bend. I think I need only 5mm.

 

[wesnewell]

If they're steel, I'd have no problems driving a 2x4 or steel pipe in between them to spread them apart. I've done it to widen the dropouts on every bike I've put a motor on. If aluminum I wouldn't do it.

 

[e-beach]

Put a magnate to it to see if it is steel or aluminum. As WesNewell stated above, steel is easy to flex. Aluminum snaps back unless it cracks Pull it open at the dropouts. Some around here use a piece of "all thread" rod and a couple of washers and nuts to stretch the dropouts apart. They lay the all thread across the dropouts and crank the nuts open. Others use small car jacks to crank the dropouts open. On both of my builds, one steel and the other one aluminum I just used my arms to pull them apart. If you have a friend who can help you pull the dropouts apart, that can work also. One of you on each side.

If it still rubs, then your frame is too small for the rim or your tire is too fat...

 

[Wishes]

I just did the magnet test, it is definately steel. I will try prying it apart then. Thanks for the advice all.

Wishes

 

[Zerogain]

Yes, it's possible to widen the dropouts to fit the motor in. Sheldon Brown has a good guide, which also shows you how to check that you've spread the frame evenly on both sides:

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

 

[wesnewell]

There's probably better ways, but I think you just want to widen the part where the tire fits and not really the dropouts as much. I'd take a 2x4 and wedge it in there with a mini sledge hammer and then bend the dropouts back to where you want them.

 

[Wishes]

There's probably better ways, but I think you just want to widen the part where the tire fits and not really the dropouts as much. I'd take a 2x4 and wedge it in there with a mini sledge hammer and then bend the dropouts back to where you want them.

Worked wonderfully. I got the wheel to fit. There is no room to spare. I think I will work on making a bit more room for it as I find it somewhat tight. But the thing fit. Thanks everyone for your advice. Now its going to the welders for some re-enforcements.

Wishes