Thinking of getting a 5-mode flashlight for my bicycle mostly for daytime riding in flashing mode. Seems like most flashlights run in high mode while flashing. A couple of questions:

1. What's the minimum lumens recommended for this purpose?

2. In flashing mode (high mode), how much longer will I be able to operate the battery before a recharge? The one I'm looking at has a runtime of 2 hours in high mode.