Fitted an XT e-type front mech to my on-one fatty to get a granny ring option, slight problem is the plate? moves an awful lot about 15mm between top and bottom ring. the plate is supposed to have a bolt to the frame but this arrangement doesn’t.
i dont think it will last too long getting that amount of flex. Any ideas on how to stiffen it up without adding much to the thickness around the BB.

I have one on my fatty. Added a bracket from a cyclocross roller clamp, and some washers and stuff to push against the plate to stop it flexing. Works ok.

I had this problem once. Used a clamp on the frame on the downtube to give the bolt something to fix to. From memory the clamp came from one of those wee pulley/roller things to reverse the pull of a front mech.

Would one of These fit?

cheers khani that looks the ticket. just need to find where to buy one of the buggers now.