A company called Lumos makes an increasingly popular helmet, the Kickstart, that incorporates LED lights: white ones facing forward, red ones facing the rear, and amber ones on the front and rear “corners” of the helmets that serve as turn signals. (You trigger the turn signals via a remote control that you attach to your bike’s handlebars.) The lights work well—though you do need to remember to turn off the turn signal once you’ve completed your turn, as there’s no “blinker” sound to remind you—but we see a fundamental problem with incorporating such technology in a helmet. Bike helmets are, by design, “one and done”: That is, a helmet is meant to be replaced if you hit your head, even if it appears to be undamaged. (What you can’t see is whether or not the foam liner has been fatally compromised—that kind of damage will be hidden by the outer shell.) However, after having sunk $200 into a helmet with turn-signal electronics that can’t be transferred to a new helmet (so far, they can’t), you might understandably be reluctant to discard it just because it might have some invisible damage. And Lumos offers no crash warranty or discounts to soften that financial blow. (The helmet does now, at least, come in two sizes; at first, it came in only one.) Lumos makes four other helmet styles—including an even more expensive helmet called Matrix, which has a programmable LED sign on the back—but they each come in only one size, and the electronics can’t be transferred to a new helmet should you need to replace the old one. (Some models are supposedly available in a MIPS version, but at an up-charge of $30 or $40.)