Monday, November 19, 2012

Lighting 2012: Helmet Mount for Headlight Pt II

Like historians, who didn't know to number "The Great War" until the next one came along, labeling it WW-II, I find myself needing to update my helmet lighting again after just a short time.

I was ordering bar tape to match my new saddle and needed to order a few extra bucks worth of something to get free shipping, so decided to splurge and spend $37 at Amazon for a Fenix E25 2xAA cell flashlight.

I almost sent it back when it arrived, because it looked too big. Too big for the mounting system, and too big for the top of a helmet. In the end though, a frontal area only 26% that of a MagicShine was appealing, so I cut it out of the package and tried it in the mount.

Whoot! It fit. Just barely, but it fit. Tight enough I aligned one of the groves in the hand hold area with one shoulder of the clamp on the bottom, but it fits quite nicely. Even with the extra thickness of a star and cut-washer set of lock washers, the bolt was long enough I could get it started by squeezing the clamp shut lightly while starting it in the threads with a screwdriver.

Two layers of Velcro straps go on either side of the Volt's "V". Note topside position of the 3-position switch, sealed by the grey rectangular patch on top

Note how the back half of the shoulders on the shoe are cut away to improve the fit

The retention tab, covered by 2 layers of Velco straps, in addition to the Velcro stuck to the shoe and helmet, provides excellent front-to-back stability.

Light is mounted slightly behind the center of gravity to allow angling it up enough to point it well up the road when in the aerobars

Minimal frontal area and low-profile mount makes this aerodynamic, silent, and keeps the weight from shifting the helmet around.

The E25 is a little long. An E35, powered by a single 18650 LION cell would be better, but the price is close to that of a Cygolite then, and this mount doesn't allow you to slip the light off when riding in daylight. It does allow you to walk into "Bertha and Bubba's Bait Barn" anywhere in the US and buy AA alkaline cells on double centuries.

The involvement on the inside of the helmet is minimal, and being a soft mount, doesn't compromise the structural integrity of the helmet's protection in any way I can detect.

This shoe got covered with an inch of soft-side Velcro which added a lot of stability when interfacing with the scratchy side Velco stuck to the helmet

The "Velcro" comes in rolls, and isn't Velcro, but a Chinese rip-off with smaller loops and hooks. It is just a bit stretchy, which really helps when doing a soft mount like this. The Fenix LD01 is pictured here for scale.

I had already futzed around with the Velcro on the mounting system before trying this, but note that the new approach is cleaner and more stable. The changes to the system are as follows.
  1. I cut the shoulders off of the shoe about half way from back to front to get a better straddle over the helmet's raised "V"
  2. I ground the shoe's retention pip off on some concrete (crude, but effective) to make the shoe completely flat
  3. I covered the flat part of the shoe with a strip of self-adhesive soft-side Velcro to interface with the scratchy-side Velcro already stuck to the helmet top
  4. I ditched the red Velcro strap running side-to-side as the mount is completely stable side-to-side now without it
  5. I added a 2nd layer of front-to-back mini-Velcro, running one layer on the right side of the Volt helmet's leading "V",  and one layer on the left side
  6. I added a star lock washer against the plastic of the mount, and a cut-washer type lock washer against the bolt head. This keeps the screw from unscrewing itself when you work the tilt mechanism back and forth when transitioning from the blocks to aerobars and back.
In the end, what made the decision to keep the E25 easy was it's extremely tight beam pattern -  1.5ft @ 25ft, and able to paint reflective signs at over 5 blocks. It lit up the dozens of trash cans in the bike lane on California Ave for 2 blocks ahead, and almost blinded me when I accidentally bounced the beam off of a 4x4' yellow speed caution sign.

I also appreciated that it was very easy to point away from oncoming riders on the ARPT by pointing it at the shoulder 20ft ahead, knowing that almost no light was spilling out into the oncoming rider's eyes. I had no difficulty at all seeing where I was going, even looking into lighting in the 2,000 lumen range from multiple bikes riding in a paceline. It's that bright! (rated at 156 meters, and it's all of that)

In talking to endurance riders, those that ride double centuries, Brevets, and 500+ mile rides, as well as devoted night riders and commuters, one thing comes up again and again. The battery life of headlights should be at least 2X your greatest need on the highest setting. The alternative is constantly 2nd guessing yourself about how much light you can afford to use, fearing complete darkness. The more challenging the ride, the less welcome this constant nagging thought becomes.

I'm going to try a single 18650 cell flashlight just for grins, as it will be smaller and should last longer, having 1 X 3.7v X 3,000mAh or 11.1 watt-hours of energy stored, v.s. 2 X 1.25v X 2,700mAh or 6.75 watt-hours of energy, and will be lighter as well.

In the end, everything is going to be powered by 18650 LION cells, because this is what electric cars, like the new Ford C-Max Energi are using. CygoLite uses these in removable packages in many of their lights, but as yet, you can't walk into a gas station in a remote area and buy them like AA cells. 

If you give up on a battery solution for the duration of the ride, then by all means go with batteries that are readily available along the way. The 1st time you are humping a bunch of dead batteries up the side of a mountain 10-12 hours into a double century, this will become abundantly clear.