Hi, does anybody have a link for a 15mm thru axle chain keeper/dummy hub?
15mm, sure you don't mean 12mm?
I was just going to get one of these or similar for the rear axle
https://www.ebay.co.uk/itm/323782726092
But there are other random things
https://www.ebay.co.uk/itm/380953163787
https://www.ebay.co.uk/itm/333163808699
I just use a piece of plastic waste pipe over the axle, about the same length as the spacing minus a bit so it can rotate. On a qr hub instead of sitting on the axle directly I have a 135mm length of metal tube (actually a hanging rail from a wardrobe) and a spare qr, the dropouts hold the wr rail and the waste pipe sits on that.
Pennies
I use a Park DH-1 which works well with QR and 12mm for both workshop and travelling. If you really do have a 15mm back-end, I'd fabricate something with a bit of pipe and a spare axle.