Lighting. Damn it.

peugeot late 40's headlamp

I have not been a huge fan of generator lighting.  Part of the reason is that I am loathe to do anything that would reduce the efficiency of my pedaling efforts.  And, I usually only have to ride at night during the winter months when the daylight is scarce.  Since my commute is 30 to 40 minutes each way, battery powered lights work fine for me.  Guilt can be assuaged by using rechargeable batteries, and further assuaged by using a solar powered charger.

The other reason may be that my few experiences with generator lighting involved very inefficient bottle generators on old clunky bikes that belonged to friends and that I would occasionally borrow to ride as a child (my own childhood bikes were generator-free).  While I was busy contemplating how the generator worked, I would get more and more fatigued trying to ride up the hill to my house.  These devices put way too much drag on the tire, so I banished them to my minds’ nether-regions for decades.

Adding fuel to my flame, generator lighting is also often part of the standard equipment on a production hybrid or city bike, with poorly designed too-bright optics, which are sold to the enthusiastic masses, who then point their lights straight ahead, proceeding to blind all oncoming traffic.  I cannot tell you how many times I have been blinded in this way, one time from behind by a rider who was naively drafting too close at dawn, with her big bright light aimed horizontally, and when I looked behind to set up for a 3 lane left hand crossing, her light literally shocked and blinded me to such a degree that I nearly lost control of my bike. And I could not see past her light to the traffic I would soon try to cross.  Needless to say, I missed that turn.

Recently, I needed to install lighting on a few bikes I was working on, all of which used sidewall driven generators.  That got me thinking about installing lighting on my Meral, since I have begun using it as my primary commuter. I thought long and hard about that, and researched the pros and cons of bottle generators vs. hub dynamos.  I even explored a new technology – the rim driven dynamo built by Velogical.

Soubitez sidewall dynamo

Soubitez sidewall dynamo

If you are not an electrical engineer, dealing with the set up of a bottle dynamo can seem challenging.  First of all, it is very difficult to find wiring schematics and instructions for sidewall-driven generators.  These, I learned, are not technically dynamos, which generate DC power, but  magnetos, which generate AC power.  The only vintage shop manual in my collection which had more than a passing mention of generator lighting was Glenn’s New Complete Bicycle Manual, which is actually one of my favorite manuals because it has extensive guidance on rebuilding internal hubs.

Reading through Glenn’s guidance (who, in my mind, I refer to affectionately as “Dr. Glenn”), it is not hard to accept the old saying that mechanics do mechanical things and electricians do electrical things, and never the twain shall meet.

In days gone by, pretty much all bicycles were steel, and could be grounded with a simple contact to the bare frame or some other steel component.  This fork mounted dynamo on the Peugeot Mixte 650b that I recently restored is a good example of that:

Ducel fork mount dynamo

Ducel fork mount dynamo

The horizontal screw at the mount point provides the needed ground for this system.  As I was setting it up, I didn’t worry about much of anything as I wired up the lighting to this dynamo.  Thoughts of resistors, amps, volts, ground wires, and wattage never entered my brain.  And, after I connected the wiring, everything worked perfectly.  In fact, this little dynamo puts very little resistance on the sidewall, and I had fun riding around on this bike with my lights blazing.

But, that is a vintage system which requires only 1.8 watts at 6 volts.  Enter the new times, where 3 watts and 12 volt systems are the standard. (Question:  what are watts and what are volts – don’t ask me!)

Do you need resistors, double wires, and ground wires?  How do you set up a new system?  As I mentioned before, I seriously considered setting up generator lighting on my Meral, and toward this end I purchased a front wheel which featured a Shimano Deore LX hub (model DH-T670-3N), mounted to a Velocity Synergy 650b rim matching my existing rims.

Shimano Deore LX generator hub

Shimano Deore LX generator hub

I sourced a headlamp and tail lamp from Harris Cyclery and proceeded to test the system prior to mounting to my bike, to make sure I understood the wiring requirements. Once I figured out how to make the wires connect properly to the hub, I was able to mount the wheel into my truing stand, give it a whirl, and watch the lights illuminate my shop.  I even generated enough power to engage the standing lights, which remain on when the bikes is not moving.  But what really shocked me was the amount of resistance in the hub whenever I switched the lamps to the “on” position.  I had already read about these hubs having their cones being too tightly adjusted, which turned out to be true, and had fixed that.  Yes, these hubs were adjusted way too tight from the factory.  After that, I expected to experience only modest resistance when engaging the lights.  Not so.  Not so at all.  So I mounted the front light and installed the wheel into my Meral just to see if I was panicking for no reason.  As it turned out, the resistance in these hubs with the lights engaged is totally unacceptable to me, and I immediately switched back to my original wheel and battery powered lights.

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I am still interested in rim driven dynamos, and in generator hubs which have less resistance than the Shimano hub I tested.  Those are spendy options.  So for now, I will happily re-charge the batteries for my lights on all my bikes, and sleep well at night.

11 thoughts on “Lighting. Damn it.

  1. You really feel that much resistance?

    I’m the opposite of you. I don’t feel resistance from my generator hubs, but then again I’m not riding light bikes and I don’t care too much about performance. And I like to have dynolighting on all my bikes, if possible.

    I know the SON hubs are supposed to have the least resistance of the lot, but yeah, spendy. I’ve been hearing good things about the Shutter Precision ones, though, and pricewise they are more in line with the upper-end Shimano offerings.

    • Hi Sean, yes this particular hub has more resistance the any of the bottle dynamos I currently have on bikes in inventory. There’s virtually no resistance when the lights are turned off, however. I have seen a few studies where certain Shimano hubs perform much more poorly than their competitors, so maybe this model something of a lemon.

      Even so, I really want to make the point that users of generator lighting are often trying to “be seen” rather than “to see”, and are thus misdirecting their headlamps, which can be dangerous to oncoming traffic. I have been using blinky lights which can also be seen from a side view, and those are effective at being seen. But I have lately become aware that the blinking can cause seizures in certain people with epilepsy and other conditions. So, I have stopped blinking for now…

      • It’s actually Shawn, but whatever. 😉

        I think I have the same Shimano hub on my Crested Butte, a Deore, the one that QPB was putting on the pre-built dyno wheels they’ve been selling recently. And no, I haven’t noticed a change in resistance between the non-dyno wheel and the dyno wheel. But as I said previously, I’m a fat ass riding heavy bikes, so these things wouldn’t effect me as much as others.

        As for the “see/be seen”, I’ve also come to a different conclusion that you. While those who buy bikes that have factory-installed dyno systems might fall into the “be seen/poorly adjusted beams” camp, I think the majority of folks that go through the trouble of spending the time and money to install dynamo systems on their bike are more into the “see” camp, and want their powerful beams pointed downward to see the dark roads.

        Yeah, the blinking mode for front lights is just bad. It’s a carry-over from the era when LEDs weren’t that powerful, and it was definitely more a “be seen” thing. There’s a reason why German made headlamps never have a blinking mode. (And also why they don’t do rear blinkies as well.)

  2. I don’t notice the Shimano dynohub at all on my Toer Populair, but then the Gazelle is so massive that I hardly notice the roller brakes working at speed either !
    I have some 70s Sanyo Dynapower gen. sets that fit behind the BB under the chainstays. I would like to compare these with the sidewall style one day. Probably the effect varies with different tread patterns. It’s more the strange whirring noises that sometimes get on my nerves with tyre dynamos .. at the moment it’s batteries on my lightweight bikes, as with you.

      • Yes Nola, I have a couple of Sanyo sets lying around – one of then I bought new many years ago. The dynamo with these sets doesn’t always fit all stay types though.
        Incidentally, I’ve just had to remove the front wheel of my Gazelle to replace a spoke and noticed the resistance that ypu mentioned. It’s amazing that I can’t feel it when riding !

      • If you want to sell one of your BB mounted dynamos, just get in touch with me via email. My address is noted on my wordpress avatar. The hub’s “notchy” feeling is normal, but the resistance with the lights on is quite a bit greater. It will be fun to explore other options.

  3. Have you seen the research Bicycle Quarterly has conducted about generator hubs? Interesting data, when comparing one hub to another.

    I use a Sanyo generator hub on my Boulder front wheel. Spinning the wheel by hand I can definitely feel the resistance, but I don’t notice it at all when actually riding. You know what they say though: YMMV!

    • Yes, I have seen that study and one that was done a bit earlier. There does seem to be quite a bit of variation in performance among the various hub selections. For riders who need the security of seeing at night, it does make sense to go with some kind of generator power, but I am still curious to see if the rim driven dynamo by Velological will ever take off. It’s very tiny and unobtrusive, and can be added to any bike without the expense and weight of a new hub and wheel.


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