I use blinky red lights when I ride day or night, as I often am riding in traffic and every bit of visibility helps. The main thing you want is one with high lumens output. 100 lm and 150 lm are both plenty bright. They are USB rechargeable. I pull a small section of the strap out of a hole on the back of my helmet and clip it on there. When I fasten the helmet the light tightens to the helmet.
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Great location and at night can be easily seen a block away. However, if it must be mounted on your bike, you can take the reflector off the back of your rack if you have one and buy a small L shape bracket to attach with a nut and bolt through the rack and make a holder for it. Brighter lumens = more visibility. They seem pricey but are so convenient and you don’t have to mess with batteries. Cygolite is a good brand. (Snapshot only)
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