I think the rack you are using isn't quite what the Ile was designed for. If you compare it to a soma porteur rack, the support at the rear of the rack is only the width between the straps, so the clips don't need to be very tight to secure the bag.
It's not so much the tightness of the straps, more the tightness of the buckles, they just take a lot of force to engage/disengage.
Have actually grown to like it much more now that I've got used to it, but still wish the buckles were fidlock or something.
@Belagerent started
London Fixed Gear and Single-Speed is a community of predominantly fixed gear and single-speed cyclists in and around London, UK.
This site is supported almost exclusively by donations. Please consider donating a small amount regularly.
I think the rack you are using isn't quite what the Ile was designed for. If you compare it to a soma porteur rack, the support at the rear of the rack is only the width between the straps, so the clips don't need to be very tight to secure the bag.