I wanted to add a default sport to an existing bike. However, the save button was greyed out, making it impossible to save the changes. The UI didn't display any reason for why saving was not possible. After testing a bit, it turned out it was because the weight was invalid (1 kg) (When I first created the bike, 1 kg was accepted). When you try to save, it should for example jump to the invalid weight field and clearly say why its not valid.