Sunday, October 2, 2011

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 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....

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