Universal Support Bolt

Hi. Got some Universal Support Bolts from Commuter cycle, but the bolt isn’t long enough to through the back of the pint size pannier for my wife’s bike. Do any of you know any alternatives or solutions to this. It’s pretty frustrating.

Are longer bolts possible? Maybe p-clamps?

I have both longer bolts and p-clamps if you need them, home all day.

The bolts are actually spot welded on to the clamp (pretty neat little design) so unless I re spot weld no good. I think I have a solution though, going to try it when I get home.
Cheers but.