Dynamo Hub & Lighting

November 26, 2015   dynamo_lighting

I just added a thing to the database in the form of a dynamo bicycle hub and accompanying lighting.

I made my last big investment in my bike commute just over a year ago, when I bought clipless pedals and some new rain gear. The pedals paid off when the winter rains started: No more sliding off the pedals on hills, and an improved sense of overall efficiency regardless of the weather. Dedicated bicycling rain gear was so much more comfortable than the improvised stuff I'd tried to use the winter before.

This year there's no need to replace any of that, and I'm about to start biking to work again just as the weather takes its turn, so I decided to address the one thing that's been bothering me for years, which is lighting.

I started several years ago with the basic "AA-powered, bought-it-at-Fred-Meyer" Bell lighting kit. The headlight fell off its mount and smashed all over the pavement (thankfully during the day), so I bought a nice USB-rechargeable light with an aluminum case to replace it. That was a big step forward, if only because the light was much nicer and it was great to be able to just plug it into a USB cable and charge it up during the day at work or overnight at home.

The problem with rechargeables is mostly down to how good you are at remembering to charge them. I did a pretty good job of that, but after one evening when my lights gave out on an unlighted stretch of the Springwater I ended up buying a set of cheap blinkies that took button batteries as a power source and tossed them into my bag as a backup.

I never really warmed up to that rechargeable as a light. It was too bright when at its brightest setting, not quite bright enough at its lowest setting, and I always found myself fiddling with it because it cast a wide beam that always seemed to be blinding people going the opposite direction. I couldn't point it low enough to avoid doing that without compromising its usefulness on dark stretches with a lot of people walking around without reflective clothing.

Dynamo hubs provide a way to power lighting without the need to change or charge batteries. Revolutions of the front wheel generate the electricity, and the lights are semi-permanently wired to the hub and bolted on to the frame. Since there's no need to take them on or off, and since their design is tightly linked to their use in a market where they're mandated for all bicycles (Germany), they can be placed more sensibly than a handlebar mount, down closer to the ground.

It's easy to find information about them and how they work, and there are very few brands to sort through here in the United States. They're much more common in Germany, and that's where the major lighting brands are from.

Getting the Lights and Dynamo Installed

Unfortunately, they're a bit of an undertaking to buy and install here in the States: You can't just walk into any bicycle shop, pick the parts off the shelf, and troop home to stick them on with a socket set and 30 minutes of your time. Rather, you can do that, but you also need to know how to rebuild and true your front wheel with new spokes.

I ended up having to get my set installed with parts from three places. My local bicycle shop stocked the hub I wanted, and they could get the headlight from another local store, but they couldn't get the tail light in a decent timeframe. They were also more than able to handle building the wheel and wiring everything up. I ended up poking around in a few local shops to get the tail light so that I could avoid going through Amazon or another online retailer. Even local shops that offer this sort of lighting have supply issues. If you're particular about the color of the light housing, for instance, expect things to take some time.

In my case it took about nine days to get from dropping the bike off to to picking it up. I wasn't in any hurry (I just needed it all ready by next Monday), and I didn't mind waiting if it kept my business somewhat local. If you want to do this and don't want to be off your bike for a week, you'll probably want to have your local shop verify they have all the parts, let them order what they need, and drop the bike off when everything has been shipped.

I had the shop handle all the wiring and mounting, placing the light down close to the front wheel.

First Ride

I rode my bike home from the shop last night. Most of the ride was on the bike path, some was on a busy street with a bike lane.

I was wondering how long it would take to have some sort of illumination once I was rolling. The hub produces 6 volts of current at 3 watts, but I didn't know how fast I'd need to be going to get things going. As it turns out, the headlight and tail lights started blinking as soon as I started pushing the bike through the store. Getting on and pedaling through the parking lot was enough to get a steady light going from both. It wasn't bright, but it was enough to be seen. By the time I was out of the parking lot and on to a bike path, the light was steady and plentiful.

The light set I bought uses capacitors to provide some illumination even when stopped. The first time I had to stop it dimmed considerably but persisted (enough to be seen, though I wouldn't gamble on it and would expect reflective gear to do more good), and the next time I stopped it stayed pretty bright for as long as I stood there.

The lighting itself is plainly much better designed than the light cannon I used to use: There's a sharp ceiling to the area it illuminates, so I'm more confident it won't blind oncoming bicyclists.

If you bike a lot at night I'd encourage you to think about this a little: You don't need lights that blind other people, you need lights that ensure you're seen and can see. To read the packaging on some lighting, you'd think the goal is to force oncoming traffic to pull over and for oncoming pedestrians to throw themselves in a ditch to preserve their eyesight. I'm pretty sure that's the wrong answer, no matter how good or reassuring it might feel to you. Even if you never mix with automotive traffic, this matters. I've been in situations on the Springwater at night where an oncoming cyclist's bright lights kept me from being able to safely keep my eyes forward and look out for pedestrians on the path. That lowers our collective safety, including the people with the bright lights.

Looking Ahead

These lights are arriving just as we settle into the post-Thanksgiving rainy season. I liked what I saw of them last night, but I didn't see enough to judge how they'll work long term: I didn't see any other bicyclists or pedestrians out on my short ride to judge how well the lower mount point worked in practice. I just know I've seen similar configurations in the past and envied how much non-blinding light they seemed to provide. It'll take a few commutes to see how it all pans out.

Things is © 2015 Mike Hall.