The Gemini Duo is ideal for helmet mounting as it it provides a lightweight head, very similar to the Lupine Piko 4. It throws out a nice 1208 Lumen beam pattern for a run time of 1:30.


  • Price: $230
  • Claimed Lumens: 1500 Lumens
  • Measured Lumens: 1208 Lumens
  • Measured MTBR Lux: 118 Lux
  • Lumens per $: 5.25 Lumens
  • Lumens per gram: 3.82 Lumens
  • Time on High: 1:30 Hours
  • Charge Time: 2:00 Hours
  • Mounted Weight: 316 grams
  • Category: High End


  • Such a small yet bright package
  • Configurable battery options makes for a custom setup for on helmet battery mounting or long run time
  • Excellent craftsmanship with a solid company supporting the product
  • Versatile mount allows it to be mounted on the helmet or bars easily
  • Excellent switch action. Good programmability options
  • Clean optics and consistent beam pattern with no hot spots


  • 1208 measured Lumens is lower than 1500 Lumen claims
  • Looks a lot like the Lupine Piko
  • Green switch light is always on and is quite bright


Mounting is a very simple helmet strap and a rubber band system. The band allows the light to be tilted up and down easily. The helmet mount is on near the front of the helmet so it is pretty low profile and doesn't stick up so high where it can get caught in low-hanging branches. Because of the band mounting system, it can be mounted on the bars too.

Mtbr Light Meter Measurements

This light measured 118 Lux on our ambient light measurement facility. The light output measurement is performed by placing a Lux light meter beside the light. Both are pointed at the ceiling (five feet above) of a dark room. This measurement uses the ambient light produced by the bike light.

Integrating Sphere Measured Lumens

This light measured 1208 Lumens in an integrating sphere. Claimed Lumens by the manufacturer is 1500 Lumens. The Lumen-hour graph below shows how the light performs over the first three minutes of its battery cycle.

Compare all Lumen Tests here »

Tunnel Beam Pattern Photo

The location is useful since it has walls and a ceiling that can display a bike light beam pattern. The walls have a lot of graffiti on them and actually show detail when they are lit up by a light with a wide angle. Cones and targets are set up with the far target set up at 120 feet.

Compare all Tunnel Beam Patterns here »

For more information visit

Return to 2014 Bike Lights Shootout Main Page »

Related Links
2014 Tunnel Beam Pattern Comparisons »
2014 Mtbr Lumen Tests »
2013 Bike Lights Shootout »
2012 Bike Lights Shootout »
Mtbr Lights Reviews »
Mtbr Lights Forum »

Do you own the Gemini Lights Duo 1500? Help us become a better resource and write a review!