Techie Tuesday: The Emergence of the Electric Bike

Looking around for after-market batteries for my new MagicShine, as a 2nd 7.4v pack seems like a good investment, I noticed that Shimano has pushed their DuraAce Di2 electronic shifters down to the Ultegra 6770 level, and the price is ~ $1,500 street.

Since I have set up a charging station now right next to my bike, so I can plug in and charge the Garmin and the MagicShine, I was immediately curious as to what voltage the LION battery was that powers Shimano's shifters.

Electraglide in Grey

The Di2 system uses the same 7.4 volt standard as the MagicShine, and most other lights high-powered too I might add. That's nice, because the rather small Shimano battery lasts for hundreds of hours, so its not very power hungry, and with the same voltage, a stub with a Y connector to the MagicShine's battery would make the Shimano one redundant, and save some weight and drag.

Why would you want electronic shifting? Because indexed front derailleurs are a PITA. For every rear chain position there is a different front chain position, and a different shifting strategy depending on where you are and where you are going. The control inputs are also just taps, and you can tap through 10 gears in back without any delay or hesitation, and the front derailleur takes care of itself. 


This still leaves me with 2 AAA cells for the Planet Bike SuperFlash taillight, which I will be upgrading to SuperFlash Turbo. (I had to offset 2ft to the side and 4ft back to keep from getting blinded.by Steve's Thursday night. So much for the uber great tandem draft), and 2 AAs for the Planet Bike 1W Blaze in front. (could you PLEASE, make these all AA cells?)

Currently, the MagicShine runs on 7.4V, the Garmin on the 5.0V USB standard, and the other two lights on 3.0Vs. This is a mess. What is needed is an on-bike converter that uses clear, flat, urethane ribbon cables that have a Post-It Pads sticky glue and flat silver ribbon wire connecting everything with a pronged battery pack connector system that allows you to connect multiple packs together depending on power requirements. Obviously, this power management system should also charge everything from a single wall charger.

Looking at the emergence of the quad-bulb lights up front, and the effect of a 29.6v, 8-cell LION system in chopping the wire size to 1/4th of it's current size, I think bikes should, and probably will follow the example of aircraft, and develop higher voltage, lower current power systems.

Now if someone would just develop an on-bike generator that wasn't the size and weight of a cheap 11-36 mtb cassette....

C3 Aerobars Plus MagicShine

After a year of doing without, and making some very good rationalizations (like why do I need to ride at night, when I have all day to ride?), I finally pulled the trigger and ordered a MagicShine 900 lumen light with a 6Ah LION battery pack, helmet mount, and carbon fiber drop mount.


Planet Bike 1W Blaze and MagicShine 900

I decided to keep the Planet Bike Blazer 1W light on the bars until I'm sure the MagicShine is reliable, but as it turned out, having two is pretty useful anyway as the strobing Blazer marks me as a cyclist and not a motorcycle.

I also decided not to mount the light on my helmet, although that may change, I am still concerned about early reports that these lights were emitting so much radio frequency noise they were shutting down people's Garmins, and presumably, cooking their brains ala cell phones. I detected no problems with my Garmin, and it's mounted 5" away, but still being cautious.

(The evidence is very clear, although the cell phone mfgs are doing every last thing to suppress the studies, cell phones cause brain cancer when held against your head, so use a WIRED headset and don't end up a statistic. The last study I saw published came out of Scandinavia and was a 10yr study based on only a half-hour a day's use. That study showed a 6X increase in brain cancer ONLY on the side the user held the phone, and directly adjacent the ear.)

I wasn't sure if the drop mount, which clamps around the bar right next to the stem, has a 3" arm, and then a stub 1" round carbon tube about 2" long, would drop enough or be strong enough to hold the light in a stable way. It did, and I didn't even need to wrap the provided 3" rubber shim around the stub to get the light to mount firmly enough to prevent slippage.

Battery strapped on top of the top tube, resting on some foam shelf-liner. Nice cockpit view and the light isn't shining in my face.

I decided to just put the light right in front of the top tube, forward enough to not interfere with the cables with the handlebars turned in any direction. That turned out to be perfect. It stays cool, lights well, doesn't blind me with back-scatter, and seems about as aerodynamic a position as possible.

I could move it off to the right, as I am somewhat tempted to do, but as it is, the 6" of separation between the MagicShine and Blaze make the Blaze's strobe mode more visible. Otherwise it would just get lost in the flood of MagicShine light.

I went riding with a couple of friends from the Sacramento Bike Hikers Tuesday night, and they had their MagicShines helmet mounted so they could turn their heads and focus the light through turns and around riders ahead. Especially when I was in the middle, and offset 2ft to the right, this worked out very well.

My light provided constant illumination of the bike trail which allowed them to free-lance their helmet lights without losing sight of the trial's surface. Very nice for avoiding snakes. Counting 2 Blazes and 3 MagicShines we had over 3,000 lumens of white light ahead, and 7 tail lights behind mounted from mid-seatstay to helmet level. We were a flying Christmas Tree!

With the 3 of us riding together I was completely comfortable riding flat out - up to 25mph - with that amount of light. Riding home alone from the meetup site, the light was comfortable up to ~  20mph. Facing into streetlight going down a long hill I hit the brakes lightly to keep my speed down.

If I want to ride alone I will need more light to ride flat-out. The 4-LED MagicShine MS-872 Quad XP-G lighthead provides a perfect solution. It can be mounted on the drop stub, and my existing spot light moved to my helmet. With 1600 lumens it provides a full-width beam that lights the entire lane for at least 150ft - about 4 seconds at 25mph.

MagicShine MS-872 Quad XP-G Light employing 4 CREE LEDs

If you've studied the power consumption curves of LEDs you'll have noticed that as you push them harder and harder to get more light out of a single bulb, 2-3X as much power is dissipated as heat. Thus, one of the really great advantages of having 4 bulbs is that even on med-hi, it still puts out 900 lumens, and does so very efficiently. Good thing I got the big battery pack, as cranking out 2,500 lumens does take a toll on batteries, even LION batteries.

We had a lot of fun flying down the ARPT Tuesday night, and collected up a dozen or so riders who were riding with little or no light. By sharing the wealth of light, we collected a substantial paceline on the way from Sunrise to WBP, and at an average speed of 20.4mph.