i think the mean usage among all bike sharing systems is much lower

Weighted average? Citi bike has 15k bikes and claims to have served over 120 million miles, although they don't know the true mileage because they just use the grid distance between stations. That's closing in on 10k miles per bike, ignoring whatever number they've needed to replace, and bike-of-Theseus philosophical questions.

yeah but you can't ignore the replacements, i guess share bikes frames draw a bell curve with a peak of around 5 years