Answer Question
A helmet light should be at least 700 lumens to get good night vision while mountain biking on single track. So a good light for the Troy Lee A1 or A2 helmets that isn't too expensive would be the NiteRider Lumina 750 Boost light, along with the NiteRider Lumina Helmet Mount Strap.
For a bit more brightness on the trail go with the NiteRider Lumina 950 Boost light.
In addition to this, pair your helmet light up with a handle bar light like the NiteRider Lumina Micro 600 Bike Light for the great night vision riding.
Which is better...Stan's NoTubes vs Orange Seal Tire Sealant?
What is the best trunk rack for mountain bikes?
What is the Best Digital Bike Tire Pressure Gauge?
What are the best mountain biking gloves?
Why is a creeky noise coming from my bottom bracket when peddling?
What are the Best Mountain Biking Sunglasses?
What is the best single bike hitch mount rack?
What lightweight bike lock can I use while at a bike park to lock up my bike?