Replace v-brakes with rim caliper brakes with no center hole: adapter? - Bicycles Stack Exchange
BMXmuseum.com For Sale / U Brake Adapter #227 FREE SAME DAY SHIPPING.
Cheers.US Bicycle V Brake Adapter Converter to Caliper Brake Adaptor for Folding Bike Road Cycling V-Brake Mounting Holder Part Accessories - Walmart.com
U-Brake Service | Park Tool
DIA-COMPE+Br-990+Boomerang+Freestyle+BMX+U-brake+Front+Brake+Adapter+Plate+Black for sale online | eBay
406 451 Folding Bike Road C Caliper Brake Conversion Adapter Aluminum Alloy Front Rear Brake Extension Mount Black Red Silver - AliExpress
Amazon.com : RUJOI Disc Brake Conversion Kit, 1Pcs Disc Brake Adapter Bracket Fitting Frame Mount Cycling Holder,1 pcs Alu-Alloy Threaded Hubs Disk Adapter for Bike Brake Rotor with 6 pcs T25 Bolts
BMXmuseum.com For Sale / NOS Fishbone U Brake Adapter