I've taken mine on some really technical rocky trails and never had the socket head screws come loose. Mine came with star lock washers and I crank them down tight.
There is a possibility that neither the 91 or 121 will fit perfect, The best plan is to get the bag and sit it on the rack and measure the distance from behind the stem clamp bolt to the bag rear face. Subtract 5 mm for the part that bolts to the bag and you have the size. Pick the one that fits this distance best. Since it rotates on an arc you can move it a bit to get the right fit. ~mike Carlsbad Ca. -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To unsubscribe from this group and stop receiving emails from it, send an email to rbw-owners-bunch+unsubscr...@googlegroups.com. To post to this group, send email to rbw-owners-bunch@googlegroups.com. Visit this group at http://groups.google.com/group/rbw-owners-bunch. For more options, visit https://groups.google.com/d/optout.