Serfas TSL 750 Cycling Light Review


Last year we contacted a Serfas, a company who makes excellent cycling lights.  We told them we were going to be reviewing cycling lights and really wanted to check out their 750 Lumen Serfas TSL 750 Cycling Light and their USL-TL80 Tail Light.  These are Serfas’s top of the line USB compatible lights.  In 2011 we reviewed the Serfas’sTSL-500 True 500, which at the time, was their most powerful USB headlight.  In just 3 years, cycling light technology has advanced at a tremendous pace.  As a testament to this, Serfas now offers the TSL 750, an even brighter, more technically advanced version of their TSL 500 predecessor.

In February I had my Salsa El Mariachi stolen. This was the bike I originally used for testing the Serfas light.  Last night Kathleen broke out the Serface TSL 750 on my new purchased (Spot Rocker Single Speed). The light had been sitting in storage for about 5-6 months without charging. I expected the light would need to be charged, but what do you know, it still was ready to go.

Serfas TSL 750 Beam Pattern

There are a few things that make the TSL 750 stand out from earlier models.

  • First, the light comes with interchangeable lenses allowing you to swap a standard (Spot) lens for a wide beam (Flood) pattern lens.  We found the both have their uses, but our preference is the Flood lens for most cycling situations.  It puts out more light on the peripheral areas and isn’t as blinding when cycling at night with oncoming foot and cycling traffic.
  • Burn time hasn’t really improved over the 2011 model, but at each output level, the Lumen values are higher, making it much easier to see.  One area that is a big improvement is burn time for flashing.  With older models you would get around 4 hours, which in most cases would be fine for commutes, but the TSL 750 gives you and extra 2 hours.  Those who who just prefer the flashing mode, will welcome the extra 2 hours of burn time.
  • The 750 comes with a replaceable battery and an option to use the BAT-ADT Battery, that allows you to hook the light to an external battery.  This can extend burn time by a factor of 4.
  • Serfas has also redesigned the entire light and added better features to reduce heat, improve durability and overall performance.

The light has a low battery indicator, which turns from blue to red when there is approximately 20% power remaining.  Serfas uses what they call ram-air venting, which passes air through the light’s body reducing heat.  They also utilize a multi-layer heatsink to enhance cooling and maximize hi-lumen output.  The cooling does in fact seem to work rather well.  We ran the light for an hour on Overdrive and the result was the light was warm, but not too hot.

Serfas TSL 750 Cycling Light Overview

  • Max Lumens: 750
  • Interchangeable Lens for Standard (Spot 19 degrees) or Wide Beam (Flood 38 degrees) Patterns
  • Run Times and Lumens Per Mode:
    • Overdrive: 1 hour 30 minutes (750 lumens)
    • High: 2 hours and 40 minutes (480 lumens)
    • Medium: 3 hours and 20 minutes (330 lumens)
    • Low: 7 hours and 30 minutes (160 lumens)
    • Flashing: 6 hours
  • Charge Time with USB: 5 hours and 30 minutes
  • Charge Time (wall charger): 4 hours
  • Weight: 195 grams; 235 grams with bracket
  • Battery Type: 3300 mAh Li-Ion Battery
  • Replaceable Battery: Yes (*BAT-ADT Battery Upgrade)
    • BAT-ADT Battery Fits TSL-350, TSL-550 and TSL-750
    • Allows up to 4 times the runtime when used in place of internal battery and connected to BAT-4
  • Mounts Included: Universal Handlebar Mount; Universal Helmet Mount
  • Includes (USB) Charging Cable and Wall Adapter
  • Weight: Light only 195g and with bracket 235g.

Serfas TSL 750 Pug

Willie and Kathleen were pretty excited to see what was in the box from Serfas.  Of course Willie just wanted to eat the box. 🙂

Serfas TSL 750 Box

The Serfas TSL 750 cycling light comes in a really nice box.  Most of the technical information about the TSL 750 are written on the box, so you will know most of what it does.

Serfas TSL 750 Cycling Light Box 1

The box contains 2 compartments.  The first compartment houses the light body and bar mount.  The second compartment holds the USB charger, cable, extra lens, battery, helmet mount and directions.

Serfas TSL 750 Cycling Light Box 2

Serfas TSL 750 Cycling Light Box 3

Taking the contents out reveals all the components including the extra lens.  The True 750 came with the Spot light installed, but after testing it, we opted to replace the Spot with the Flood lens.  Charging time is fastest when using the wall charger (around 4 hours) vs using the USB hooked up to a computer (5 hours).

Serfas TSL 750 Cycling Light Box 13

The light mounts on the handle bar mount without need of tools.  Inserting the battery is also very straight forward, just slide it in and twist to lock.

Serfas TSL 750 Cycling Light Box 9

Above is the mounting area where the light slides in and locks into place.  Pushing downward on the unlock tab, releases the light and allows it to slide out.

Serfas TSL 750 Cycling Light Box 10

The quick release mounting bracket gives you plenty of diameter options to choose from.  There is a metal peg on either side of the strap, which can be adjusted by placing them in their provided peg slots.  While mounting system is tools free and a quick mount, we still find this type of mounting system not as easy as some other quick mount systems we have used.  That said, one advantage to this mounting system is its ability to swivel horizontally.  This can be very useful when riding trails with pedestrians and you don’t want the light to shine in their faces.  Shifting the light beam a few degrees to the right, doesn’t blind them when you pass.

Serfas TSL 750 Cycling Light Box 7

Here is the underside of the TSL 750, showing the mounting bracket.  The protective charging port tab can be pulled back to allow access to the micro USB connector.  The rubber tab is much beefier than the previous light we tested.  It appears much more durable and the rubber seems more robust.

Serfas TSL 750 Cycling Light Box 6

Here you can see some improvements to the airflow vents.  These help keep the unit cooler when the light is on.

Serfas TSL 750 Cycling Light Box 5

There is also side channel vents to also help keep the unit cooler as air passes from the front to the rear of the headlight.

Serfas TSL Light Open

When switching out the lenses, you will need to remove the battery, unlatch the micro USB port cover and then unscrew 4 screws which are located on the front of the light.

You will have the options of switching between the standard (Spot) lens or a wide beam (Flood) pattern lens.  The spot lens has a coverage of about 19 degrees and the flood’s coverage is 38 degrees.

Serfas 750 Beam Pattern

Serfas TSL 750 Cycling Light Box 4

Above is the comparison between the older Serfas 500 Lumens light and their redesigned 750 Lumens light.

Serfas TSL 750 Cycling Light Box 8

Here you can see the different light indicators on the top.  The 750 has a solid light display which is much easier to see than it’s earlier version.

BAT-ADT Battery


Serfas sells the BAT-ADT battery adapter for the TSL 750, which connects their their RB-LI-4, RB-LI-4+, BAT-2T or BAT-4T external batteries and can extend battery life up to 4 times longer.

Serfas TSL 750 Cycling Light Box 11

When we took the light out for our first test ride, there seemed to be a little bit of play in the mount where the light was attached.  This caused the light to shake during riding, which cause the light pattern to move up and down more than we thought it should.  After doing an evaluation to see if we did anything wrong during setup, it appeared not.  There was indeed a little bit of play that couldn’t be adjusted.  To fix this, we added a plastic shim, which eliminated the excess movement.  The shim by the way was cut from the plastic divider that came in the Serfas box.  Easy fix, easy solution.  Once the tweak was made, the light performed as expected without any shakiness.

Serfas TSL 750 Cycling Light Box 12

Overall Impression of the Serfas TSL 750 Cycling Light

Serfas has done an amazing job at making their lights even better and brighter.  More Lumens, means a much easier time seeing what is in front of you in the dark.  The ability to switch lenses is also welcomed.  We loved the beefier profile, but we are not sure this would be our optimal light for a helmet.  It’s rather bulky on the head and we feel it’s better served as a handlebar mounted light.  The ability to swivel the light either left or right while riding makes for more friendlier interactions when passing people head on.  You get less “HEY…Too Bright!” comments as you pass.

At maximum output (Overdrive), the TSL 750 is bright and gives you a lot of confidence navigating in the dark.  The High and Medium settings are also very useful at times and increase overall burn time.  The Low setting and Flashing are best used when lighting conditions are better and for being seen while in traffic.  We would opt for the Flashing mode while riding during the day or at dusk.  Once it’s dark, switching to High or Overdrive is optimal.

Be sure to check out the Serfas TSL 750 Cycling Light and other Serfas products including saddles, shoes, apparel, pumps and tires.

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About Author

Tom Crandall

Totally into multi-sports including triathlon, swimming, cycling, running skating and movement in general. Love to trail run and hang outdoors.

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