November 10, 2023

Happy Friday,

There’s all sorts of fun armchair philosophizing to be done about the flaws in how we measure time (which, fun fact, is imprecise and more arbitrary than my brain is fully comfortable with), but the grim reality is that right now there are fewer hours of sun and daylight savings time is over, and that means biking in the dark. Let’s talk about dynamo-powered lights!

We don’t get into the weeds about gear upgrades on WABA’s website much because it can start to feel overwhelming and expensive for new riders, but if you’re reading this newsletter, you’re already in the weeds, so let’s go!

If you’re looking to make your bike more comfortable, there’s a simple trifecta of changes to start with: saddle (find one that fits you), then handlebars (find some that fit your body and riding style), then tires (bigger, softer for more shock absorption). 

Similarly, if you want to make your bike more practical for everyday use, there are three easy places to start: get a basket (you can stick anything in it, no special bag or attachment required), get some fenders (no more soggy stripe up your back!) and get a good set of lights. 

What makes a light good?

You can see where you’re going. This is not a given! Many bike lights, especially inexpensive ones, are designed as “be-seen” lights—they ensure that other people on the road notice that you’re there, but they don’t provide enough light to see where you’re going. Many of the trails in the region are unlit, and having a light that’s strong and focused enough to illuminate the path in front of you is important.

They don’t blind the people around you. If you search for bike lights on the internet, you’ll quickly encounter an arms race of lumens. Don’t fall for it! Lights that are just very bright don’t do a great job of illuminating your way, but they are good at  blinding other people on the trail in ways that range from annoying to unsafe. The key is a good asymmetric beam pattern that creates an even pool of light across a distance of road in front of you but cuts off at the horizon (like modern car headlights) so you’re not blasting extra light into space or the eyeballs of the people going the other direction. Peter White runs a shop in New Hampshire and has an excellent longer explanation here, as well as a fantastic resource showing beam patterns from a variety of lights. Some of the models are out of date, but the range in spread and evenness of the beams is illustrative. Until recently, it was hard to find battery powered lights with asymmetric beam patterns, but now you’ll find a few options at most bike shops.

They always work. Riding without lights at night is scary, dangerous, and illegal in most jurisdictions. I’ll be the first to acknowledge that I’m the weak point in my bike’s lighting system. Even the most reliable battery powered light isn’t helpful if I forget to charge it, or leave it in my coat pocket after removing it because I’m worried about it getting stolen. Enter dynamo-powered lights!

What’s a dynamo-powered light, and why are they so great?

Instead of a battery, a dynamo-powered light runs on electricity from a dynamo hub. A dynamo hub usually replaces the hub of your front wheel, and it has a small generator in it that’s powered by the rotation of the wheel. They’re a smidge heavier and draggier than a standard hub, so you might not want one on your racing bike, if that’s your thing. But on most bikes, it’s hardly noticeable. These hubs generate enough power to run front and rear lights. Nearly all dynamo powered headlights also have a capacitor in their circuitry so the lights stay on for a few minutes when your bike is stopped. 

Dynamo-powered lights don’t need batteries. If your bike is moving, they’re on. Never worry about batteries again! 

They bolt on to your bike. This makes them harder to steal, and less likely to get bonked out of alignment. And you can’t leave them in your other backpack by accident.

Most dynamo lights have asymmetric beam patterns that illuminate the road in front of you without blinding people in front of you. 

How do I get this setup, and how much does it cost?

A new front wheel with a dynamo hub and a set of good dynamo-powered lights will set you back at least a few hundred bucks in parts and another a couple hundred in labor, and can be much more if you like fancy wheel parts. 

Your preferred local bike shop should be able to order you a pre-built dynamo wheel that will work with your bike’s frame and brakes—or build one for you—and wire up the lights. 

If you’re confident with wire-strippers and heat shrink tubing, You can also buy a pre-built dynamo wheel online and wire the lights yourself. Make sure the wheel is the right size, and compatible with whatever brakes and wheel attachment system you have (through-axle, quick release, etc). 

If you have an afternoon or two to spare and want the complete DIY experience, the most affordable option is usually to buy the hub, spokes, and rim separately and build the wheel yourself. Not for the faint of heart or short of time, but also not rocket science. I find wheel-building a meditative and rewarding experience best accompanied by a pot of tea and an audiobook. Again, you’ll need to make sure the parts you buy are compatible with your wheel attachment mechanism and brakes. 

Oof, that’s a lot of time and money.

It is, and you can certainly get a great, reliable battery powered light setup for a lot less money.  If you ride regularly through the fall and winter, though, it’s worth considering as an investment in one-less-thing-to-think-about. No matter the weather or time of year, you can hop on your bike and know that you’ll be visible, and you’ll be able to see where you’re going. 

One neat thing about ebikes.

Most ebikes make this issue moot.—they come with lights wired directly to the big battery for the motor. 

Thanks for indulging this lengthier-than-usual bit of opining. In some future week we can dive into how we feel about tires.

Things to do this week:

A Fun Route Idea For the Weekend

Hop on the Silver Line to Reston and take the W&OD to Purcellville and back. The leaves are going to look nice out there!