The top dog in this series is the the True 750 for $160 but the this sibling, the True 550 can be had for $140. The other advantage besides fitting it in the budget is the run time increases to the coveted 2-hour mode in the highest setting.

Instead of sticking with the light chassis from last year, Serfas stepped it up with a brand new, more robust chassis this year. The new one seems bigger with more cooling fins. It has air ports in front near the lens that serve to funnel air through the heat sink and cool the light down at speed.

This light also has a removable battery that can be replaced on the trail for 'infinite' run time. The battery is encased in a proprietary plastic carrier to keep it protected and less prone to shorting out.

A unique feature with this light is that the lens is replaceable, so the optics can be focused or wide. The optional lens is included in the package and it is a very useful tool for optimizing one's setup. One could run a wide beam on the bar and narrow on the helmet for example.

Beam pattern is good, as it has a spot and a nice wide halo around it. The case and switch ergonomics seem excellent, as there is a positive click when activating the switch. There's three light modes and a flashing mode to scroll through before the light shuts off. Another way to shut the light off is by depressing the switch for about 2 seconds.

One thing we noticed with this light is that it stayed cooler than competitors during our bench test in front of the fan. That means that it has excellent heat dissipation qualities and it will not only protect the circuits better, but it will also stay brighter longer under hot or non-moving conditions.

Packaging for this light is top-notch with a host of accessories included in the box. One handy accessory included is a USB 110 volt charger. While all other manufacturers assume you have a USB charger already and cut costs by not supplying one, Serfas supplies a pretty nice one in the package.

So even though the Serfas True 550 is not the cheapest in the 500 Lumen category, it is actually one of the better values around.

There are three lights in this family with the 750, 550 and the 350 Lumen version. And since they all share the same chassis and battery, the 350 stays very cool and runs the longest at 3:30 in the highest setting.



  • Price: $140
  • Claimed Lumens: 550 Lumens
  • Measured Lumens: 577 Lumens
  • Measured MTBR Lux: 55 Lux
  • Lumens per $: 4.12 Lumens
  • Lumens per gram: 2.46 Lumens
  • Time on High: 2:00 Hours
  • Charge Time: 4:00 Hours (Wall adapter included)
  • Mounted Weight: 235 grams
  • Category: Flashlight/Commuter


  • Excellent light output and beam pattern
  • Optics are replaceable for a wide or narrow beam pattern
  • Good switch action and logic
  • Light stays cool even at high power and some airflow
  • USB charger is included
  • Great value at $140
  • Battery is replaceable even on the trail if one has a spare.
  • Bar and helmet mount are included


  • Some may consider it bulky for a self-contained light.
  • The True 750 is really the better option for only $20 more.


Handlebar mounting is done with a quick release mount that works quite well once snug. It can be aimed left to right. The quick release lever is non-intuitive at first, as it seems to be reversed. Mounting on different diameter bars is a bit tricky as two pins have to be aligned in the right holes to get the proper bracket size.

The helmet mount is included.

Mtbr Light Meter Measurements

This light measured 55 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 577 Lumens in an integrating sphere. Claimed Lumens by the manufacturer is 550 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 »

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