Originally Posted by
Unca_Sam
you're not the only one with a suggestion for a seatpost bag, but the OP specified that he's using a carbon seatpost. I'm not sure I'd want to introduce those forces there.
Good tip though!
I only read his first post.
I wonder now what his bicycle frame material is? If it's steel or aluminium I'd consider putting an alloy seatpost on it so he could then use a large seat bag or a handlebar bag mounted as I showed.
Cheers