Can you fill us in with a source, i.e. an English or Chinese newspaper article to back up this rumor?

If they did something like this, then the next question becomes enforcement. To use Guangzhou as an example, they first did a ban with times, i.e from 8am to 5pm, then it was a full-scale ban with a huge propaganda campaign for people to stop riding their bikes and turn them in at various check stations around town. These bikes were then launched onto a truck and carted off to the scrapyard.

If Shanghai is serious about doing something like this in summer, then they would need to provide a full-scale enforcement plan which I've heard nothing about and would take considerable planning to arrange.