Need a rear frame loop 1" OD

Just as the topic says, Looking for something with approximately a 4" radius bend.

Build one

Thanks for the constructive comment. I'd like to save myself the time and hassle of building a die.

I've got essentially the same problem as you, finding someone who has a bender that can handle small tube. If you know of any race car folks in your area find out where they are having frames made. Also, and this may or may not work for you, find the center-stand from an old Honda and you will discover that with about a half hours time spent with a grinder you can liberate a very nicely bent U-shaped with extending legs piece of 1" tube from it that is about 8" wide between the tubes - to put is simply, just what you're looking for.

Where are you located?

I'm in Iowa