There were problems with the Bugaboo Bee stroller earlier where the wheels could jam and cause the stroller to potentially tip-over. Representatives from Bugaboo stated that the problem was fixed months ago.
According to UK’s MadeForMums.com:
Replacement wheels were sent out free to those who had bought and registered their Bugaboo Bee Plus in the past year. Those who were experiencing “shuddering” from the front wheels were advised to lock the wheels, until the plastic bearings were swapped for the “tried and tested” metal version.
It is reported that with the new metal ball-bearings, independent tests conclude it is now safer and more nimble. Therefore, just check that you have the updated version before you make a purchase.