I found a disc brake and sprocket combo for a #35 chain . I dream about this for more standard chains but am considering trying this on my next build for a left side mid drive im working on. https://www.ebay.com/itm/Mini-Bike-REAR-CALIPER-BRAKE-Kit-FOR-35-SPROCKETS-WITH-WELD-TABS-FREE-SHiP-/131305930796