I've used this for 5 group night rides and would advise anyone riding for 1.5 hrs or more to get a light with a longer lasting battery. Contrary to what the description says in the first paragraph: "For instance, it's plenty adequate for an evening of ripping singletrack." Its NOT adequate for more than +/-1 hour of ripping singletrack in a group ride situation. Strava showed 1':55" of elapsed time and 1:31 of moving time. The light sputtered out before the ride was done. I think its typical for mountain bike rides to have breaks and regroups, so one would expect a 1.5 hr ride to have a longer total elapsed time. The problem is you really need the full power/ 750 lumens for the whole ride and this does not have the battery power to sustain that.