My largest rear cog will be a 23 though, the large/large should be easily doable. I think if a short cage Shimano light action can handle it with the huge freewheel, the NR might be able to cope with a 13/23. If it doesn't work out I may consider it. The bike is a P-15 however, and came with the triple. After seeing what they go for, there's no way I could afford to get a replacement should I decide to make it original again. I could, but my wife would take my wallet from me, and put me on an allowance. lol.,,,,BD