Agree with Falchoon, we need to know a little more info. A budget is needed, but what type of riding and how long will you be out is important. Are you doing mtn bike riding at night or commuting on the roads? Will you need light for half an hour or for 3 - 4 hours at a time? Is it important that you light up your path or do you just want to be seen in traffic? Also, are you more interested in replaceable batteries or do you want a self contained USB rechargeable light? The more info you give the better answers you will receive.