Brompton Dynamo Package

I've been riding my Brompton at night to avoid the extreme heat we've been experiencing here in Southern California this summer. I decided to invest in a dynamo system but I don't ride enough to justify the price of a Schmidt SON. So I decided to buy a system based around a Shutter Precision dynamo.

 https://www.perennialcycle.com/shutter-precision-upgrade-dynamo-package-for-brompton.html

For almost $400 (after tax and shipping) I got...

• New front wheel built around a Shutter Precision SV-8 dynamo hub, with rim tape
• Busch & Muller IX-SX front light and mount
• Busch & Muller Toplight Line Plus tail light
• Wiring and zip ties.

Although the photo on their website shows all the pieces separate, some assembly had already been done for me. I got the black one to match my bike.

The rim tape was already on the wheel and the through-axle was installed. The front light was wired. The rear light cable is cut for a light mounted on a rack. I don't have a rack so I chose to shorten my cable.

These were my installation steps, which took about an hour.

• Turn the bike upside down, deflate the front tire and remove the wheel.
• Pull the tire and tube off the wheel and put them on the new wheel.
• Install the new wheel with the connector on the right when the bike is the right way up
• Remove the front brake from the frame and discard the front reflector and mount
• Put the front light and mount in the same place the reflector was
• Reinstall the front brake and make sure it still works correctly
• Inflate the front tire
• Plug the front light into the dynamo and use a zip tie to hold the wire in place
• Spin the wheel to make sure the light is working
• Remove the rear reflector
• Plug the rear-light wire into the spade terminals on the front light
• Route the wire along the rear brake and gear cables using zip ties as needed
• Shorten the wire if needed and expose 1cm of bare wire each
• Push the exposed wires into the two holes at the back of the tail light and slide the black lever over to lock them in. Polarity is not important.
• Install the tail light where the reflector was
• Spin the wheel again to make sure the tail light works too

You have the following parts left over. If you have more or less, check the installation steps again.

• Original front wheel with rim tape and locking nuts
• Front reflector and mount
• Rear reflector

Note: The new front light mount is wider than the old reflector mount and doesn't quite fit the frame properly. I used a vice to slightly narrow the new mount so it fitted better.

The dynamo feels very notchy (I assume it has 8 magnets from the name) but it's not fair to compare a dynamo on the 16" wheel and a 27" wheel because the larger wheel has a much greater moment of inertia. The truth is in the ride. More on that later...

So I went for a 14 mile ride up in the mountains and I have to say the SP dynamo seems to have more drag than the SON. I'm not sure how much of this is the smaller wheel and how much is the cheaper dynamo, but it's noticeable. It's also possible that I was dragging because I was at 7000' where there's way less oxygen. Let's assume there was some drag and we don't know how much. Maybe I'll try it again at sea-level.

The front light has a beam pattern that is optimized for mounting 30" above the ground. Because the Brompton mounts the light 18" above the ground, the near-field is brighter than it would ideally be although it's not a show-stopper. Other than that, the beam pattern is lovely and I could see road hazards up to 100' ahead if there weren't too many other lights around. That gives me five seconds notice at 15 mph. The light also lets photons escape to the side, which is a nice safety feature, although reflective tires work better.

The light rubs on the bottom of the front bag that my friend, Greg, made for me which is a bummer. However, my Suntique bag works fine so that will be my new go-to front bag. The photo's below show the bags with the reflector, but you can see why Greg's bag rubs the light. If your bag partially obscures your reflector, it will probably rub on a front light.

Suntique does not rub :-)

Greg's bag rubs :-(

The tail light is a Toplight Line Plus. I have the Brake version on my road bike with a custom seat-stay mount so I already like this light. It's actually one of the things that attracted me to this package. It's big and bright and has a wide viewing angle. I pair it with a Cygolite spot tail light which is very bright but has a narrow viewing angle.

Overall I would say this is a good dynamo/light package at a reasonable price. I have a far more expensive dynamo/light set on my road bike because I frequently ride all night on it, but that will never happen on my Brompton. Installation was easy and all the parts worked properly.