The Solarforce unit is a flashlight body with no guts. It accepts a "P60 drop in" which are available from multiple sources with many different LEDs and control circuits. P60 drop ins are also available with higher power LEDs but then heat dissipation becomes a concern. It is a versatile setup. The light module and tail switch are both replaceable and available from the source you llinked to which guarantees the light can be fixed if it does fail. This is NOT true of most other styles of LED lights.

For bike headlight use I would suggest a orange peel finish drop-in as it gives a bit broader beam, better for headlight use IMO. Up to you if a single mode version is adequate. The multi mode ones are more versatile if you want to use it as a flashlight off of the bike too.

Also Ultrafire batteries work fine so far for me and they are about the most reasonable priced ones available. Do buy "protected" ones.