I bought a £17 Cree light off ebay .... I use it in pitch dark cycle paths every night and I only use it on the low setting (it has 3 settings) .... I use the headband and I don't want to 'faff' around with a rubber band every time want to take it off the handlebars

on low, it's superbright like a Volvo bus headlights on bright.... This has been one of my best buys this year