Tossing and Tortured 'Till Dawn

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Wednesday, November 04, 2009

REV: Sigma Karma Pro Headlight

I’ve been riding the Karma for far too long not to have written it up. Apologies, Sigma.

The short version: Nice work indeed. This style of light is the way of the future for commuting, and I enthusiastically endorse it.

Longer Review: Sigma has been known in the US market for their durable bike computers with manuals containing quirky German-to-English translation. They’ve also had a wide range of lights, but it seems like recently a new designer stepped up to the plate. The Karma was my first experience.

Images of the light alone don’t do its size, or lack thereof, justice. Both the emitter and battery are TINY. Together, they weigh only (have to dig out my gram scale.)

The lithium-ion battery pack combined with the efficiency of a regulated LED is great. The light lasts about 4 hours on high, as claimed and tested by yours truly. At the end of my four-hour, round trip, commute, burning on high, the Karma JUST began to run out of batteries. On “economy” mode, Sigma claims sixteen hours, but I was not about to test that! The new model features a flashing mode as well, but my demo was not so equipped.

An excellent balance between weight, brightness, and battery life, the Karma is designed as a commuter light.

Just how bright is 75 Lux? Rating lighting systems against one another is challenging. Sigma use “LUX” to rate their lights, Light and Motion counts Lumens, and Cateye shows rankings in Candlepower. Without getting into physics, I will say that the Karma is quite bright, but not “portable sun” bright.

The beam is quite narrow; it will illuminate your lane, but will not light up the lane beside you. The Karma feels designed as a helmet-mounted light, which works for me, as it allows you to announce your presence to automobile cross-traffic.

For backroads in complete darkness, I found myself wanting a little more light. Sigma offers a high-quality, waterproof splitter cable that lets you run a pair of lights off a single battery. Now, I'm guessing it was intended for handlebars, but, I ended up with frog eyes!

With both lights on high, flying down Peasley Canyon way at thirty-five miles an hour, I’m not outrunning my lights, and reflective surfaces on both sides of the road flare up at me. The single battery still lasts more than my whole commute, and if I needed to recharge at the office, the included rapid-smart-charger brings a dead battery to full charge in about two hours.

This is a far cry from the overnight-recharges and ninety-minute run time of NiCd Halogen lights of the past!

Fit and finish are great, and includes lots of little tricks: it includes both a helmet mount and a fairly tricky handlebar mount that ratchets on with a single pinch. The emitter shell is a machined aluminum cylinder, and the power button is fully sealed – it’s about as watertight as a sport wristwatch. That’s essential for commuting in the Pacific Northwest.

Also included is a multi-directional quick release battery mount that affixes to your handlebar, stem, top tube, or helmet. The battery is light enough that it’s not uncomfortable on the back of my helmet, or you can use the included extension cable and drop the battery in a jersey pocket.

Sigma is also standardizing their batteries across their range, and the L-ION packs
can be used with a number of other lights. It’s nice not have to play the “which battery goes with which light?” game, or carry multiple chargers with you to races or events.

Disadvantages? The on-off switch is a little quirky. To activate the light, you double-click the switch. Single clicks cycle through the high-low-economy-flashing modes, but will not return the light to “off”; this requires a press and hold for two seconds. I’d rather have the option of a squeeze bulb on the extension cord to activate the light. With two on my helmet, I find myself fumbling with soaked gloves or cold fingers to adjust both lights.

Of course, most rides will be shorter than the total battery life for most riders, so you’d just pick your desired brightness at the start and turn it off at the end.
I like the quick-release handlebar mount, but today’s bikes are coming with an increasingly strange array of handlebar sizes, so I’d like to see a “mountless” O-ring option for the light on bars – this works quite well with lightweight emitters like the Karma, and Sigma use a similar setup for their tail lights.

Summary : With light weight, long battery life, and water tightness, the Karma is an excellent choice for commuters who want to step up from Alkaline-powered lights. Alone or in tandem, it could make a good night-riding light, but more firepower might be necessary for 24-hour mountain bike racing.

Addendum No, I'm not going to take the light out in the dark and attempt to take a picture to show how much illumination it produces. That shows more about the camera than it does about the light...


  • At 4:48 PM , Anonymous Anonymous said...

    Gram scale?
    What are you a drug dealer?!

  • At 1:29 PM , Anonymous Anonymous said...

    I suggest the Cygolite Mitycross 350.


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