The hook wasn't a problem; the rubbing of the mudguard strut against the back of the pannier was. The strut being soft aluminium and being in the firing range of road dirt, quickly eroded until I put a clear PVC tube around it. The back of the pannier likewise was damaged somewhat. That said, I traveled the absolute worst possible roads on it - Kangaroo Island, maost roads were gravel, with corrugations from car suspensions, which exercised the Birdy suspension maximally, plus the gravel kicked up exercised the pannier-strut interface under this severe condition. Overall, the Birdy handled it fine, and I found when going faster than 20km/h, the suspension soaked up the corrugations almost completely.