Were the bikes under the library bridge ever actually tagged to identify and remove abandoned bikes, as it was announced that they would be? The stand is often pretty full, and RAL Estates told me that they would not be buying another Sheffield stand. They provided one of the wheel rack variety instead, despite my drawing their attention to the advice against them at https://www.broxap.com/cycle-parking-guide-planning-completion/types-cycle-parking/ . So it would be worth ensuring at least that all the bikes parked at the Sheffield stand are actually in use. This can legitimately include occasional use at lunchtimes, so a bike can be in use but nonetheless always there overnight, but even so there is at least one that has been in the same exact spot for long enough to raise suspicions.