The Luu Extreme 4 isn’t the tidiest or brightest design, but you do get a lot for your money. The single 900-Lumen LED head comes with a selection of diffuser lenses to alter the beam spread.
Unfortunately the broadest spread cap causes a massive output drop to just over 50 lux and there’s a big black hole in the middle of the beam on the most focused setting.
There’s enough light for proper off-roading with the medium filter though and it’s good for the money. Run time is very generous too, and there’s a two-cell version available for £150.
The separate head unit, with metal clip holder, sliding shoe and quick-release mount make it too heavy for helmet use and prone to crash damage. Ours is still soldiering on with some tape and bolt reinforcement though.
For more information on how we tested this year's crop of lights, see our latest buyer's guide to mountain bike lights and Tested: 30 high-power mountain bike lights.