Ja, when you share they road with others Over here i run at night on paths that are shared with cyclists, pedistrians, Joggers, horse riders, dog Walkers...etc... no cars or motorcycles. Most of the above use some form of Lights and reflectors, even the dogs have Lights on their collars and horses relfective tape... The cylists always have the brightest Lights and ineviatbly there is one whose light is so bright you cannot see anything once they get close to you and you are temporily blinded once they pass. I guess they are not Aware of the effect their Lights have, they probably think they are being smart for having such a bright light. Strangely I bet they dip their Lights when driving their cars at night., why should it be different when Cycling?
