But you signal with the hand that faces traffic: If you ride on the left, you signal with your right arm, and if you ride on the right, you signal with your left arm. At least, that's the rule in the US (where you may ride on the left on a one-way street).   I've never ridden a bike in the US with the brakes reversed: On all, the right-hand brake controlled the rear brake. However, when I let people ride my bike in Tanzania, they almost inevitably crash the first time they use the brakes - they've never been on a bike with that configuration before. So here are two countries with different traffic directionalities corresponding to clear differences is brake setup. Now, nearly all Tanzanian bikes are made in China, as are a good number of US bikes (Schwinn, for example). So China must be selling right-rear bikes to the US, and left-rear bikes to Tanzania (or more likely East Africa).     