There is a clear warning. The board will start beeping like a m'fer. I live in Seattle and there are lots of hills that I go down. I usually make sure to charge the board to 90% instead of 100%. I agree that the brakes could be better - having the motor brake instead of an actual disc brake does sometimes cause a bad side-turning skid, but it's nothing that can't be dealt with diligently by knowing how to ride. I've never fell off due to the brakes.