I used a large hose clamp for my sturmey-archer drum front on a solid fork, maybe a smaller screw type hose clamp will work for you? Unscrew it until you can pull the band from the screw unit, wrap around brake arm AND fork arm of your choice and tighten. Test for a block under hard braking, then tighten again. Check it periodically, if it comes off you're in for a world of hurt...