I have SKS plastic fenders on one of my bikes and probably an SKS rear fender only on another bike. Both bikes have been used for multi-modal commuting with bus.

On the bus, the bikes ride in a rack up on front of the bus, out in the elements.

Both rear fenders have broken. The breaks start as cracks transversely across the fender. Other than the break, there are several cracks across the fenders.

I believe they are cracking and breaking due to the the constant wind loads they endure while on the bus. The bus commute includes approx 33 miles each way (66 miles per day) on an interstate with posted speed of 65 mph. I'm sure the bike is subjected to a lot of buffeting while riding on the front of the bus.

Does anyone else ride a bus at distances and speeds as this?

Would aluminum fenders hold up better, or not?

Suggestions?

Thanks.