Thank you for the advise.
Where can I buy one? Is there a difference between E21 and E21 R2?
http://www.amazon.com/dp/B0041NE8TG/?tag=cpf0b6-20
^ That?
The "R2" tells you how efficiently it turns electrical energy into light energy. A simple list of the most common efficiency bins looks like this, with the more efficient bins towards the bottom:
Q2
Q3
Q4
Q5
R2
R3
R4
R5
So, an LED of the R2 efficiency bin will turn more electrical energy into light energy than an LED of the Q2 efficiency bin.
There are two versions of the E21, both with Cree XP-E emitter. One has an XP-E R2 (unknown tint bin) and one has an XP-E Q4 neutral. The neutral will make things in nature look more realistic. For more information on this light, I highly recommend you read through this thread
here. It will answer many of your questions.
This picture compares the cool white (R2) to the neutral (Q4), both Cree XP-E emitters. The cool white will be marginally brighter. Different folks like different tints.
With respect to the bike light, you may want to read what others are using in the Bike forum. You could certainly use one flashlight for both, if you don't mind using the same light for general use and biking. But so this thread doesn't get too confusing, you may want to decide whether you want:
A) One light to cover general use *and* cycling
B) Two lights, one for general use, one for cycling
If the latter, then you may want to first settle on the general light, then pursue a biking light after perusing the Biking forum. People are always willing to help on this site, but it goes a long way if you show you did your homework and read in the appropriate forum first. :thumbsup: