A bump sensor would be fine I guess, except for the fact that the FRONT TIRE gets absolutely NO weight on it so it NEVER LIGHTS UP.

A bump sensor would be fine I guess, except for the fact that the FRONT TIRE gets absolutely NO weight on it so it NEVER LIGHTS UP. And the rear tire doesn't make a solid disk of light, it's more like a sporadic circle. It just looks ridiculous on my bike so I took them off...for now.Honestly, can someone just invent a friggin' valve LED that STAYS ON!? I don't care about saving battery at stop signs, I care about looking like Tron!! When I'm done riding for the night I'll take the batteries out, seesh. You would think they'd invent that FIRST!? Then all this fancy shamncy night and motion detection. And God forbid I ask for an on and off switch... (o_O)2 Stars because they're super cheap (material wise too, that's not metal...it's shiny plastic.) so it's not like I'm losing out on a bunch of money, and also they're pretty darn bright when they do light up. This product is amazing I only had to go 8mph on my bike (average cruzzing speed for me is 15) and there supper bright I love them if they happen to break I wouldent hesitate on buying morePros: bright, looks coolCons, cheep plastic They don't fit one of my bike's valves, which is just an ordinary one for a road bike (it's the smaller valve compared to like a mountain bike). They also turn on by themselves and won't shut off wasting the batteries in them. They're cool...if they even turn on and stay on when you're riding, which was another problem with them. Was disappointed with product when i first tried them out. Could not get them to light up under any conditions. After unscrewing one of them realized there was a piece of paper between the batteries and contact that has to be removed. Not shipped with any directions that inform you of this. Work great now, however they dont have a light sensor as advertised so they light up in the daytime which will shorten battery life. I bought these lights for my Grandson for Christmas and he is having fun with them showing off to his friends that don't have them. I think they would be a good thing for anyone that rides at night to let the people in vehicle be aware of where you are. Do not work on presta valves. It would have been very helpful to know that before I wasted my money. Very cool product. Attach to the valve stem of your bycicle Inertia of wheel motion turns on the light. Nice safety feature for night riding as it makes a perfect lighted circle. Standard valve on Forte XStra tires. Doesn't work. Don't know if I need to change the batteries or what. Bummer. My favorite color is blue. I love how these work on my bike and how brite they are. Attracts the attention of drivers at night so I feel a lot safer riding. Ok, as you may have heard you get what you pay for.Lights are not of good quality. I unscrewed the lights to put air in my tires and after screwing lights back on they did not work anymore. So I returned them for a complete refund. 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