H-Bridge flyback diode selection?
The H bridge chip you are using has 1 amp capability (2 A non-repetitive). If you are using it correctly i.e. within spec then the diode you need has only to be rated about 1 amp. A 1N4007 is rated at 1 amp continuous and 30A non-repetitive so on the face of it it fits the bill.

As for your choice of H bridge, there are far better choices (dependant on the voltage supply). See this.