How Much Do Dynamo Hubs Really Slow You Down?

And is dynamo drag too much? Let's run the numbers.

Like my videos? Patreon supporters get early access to my films and exclusive access to my Q&As:

RELEVANT LINKS

0:00 - Intro
1:08 - Component Overview
1:55 - Rider Simulations
2:34 - Data Source
2:54 - Hub Drag (No Connection)
3:38 - Light Drag
4:25 - USB Charger Drag
5:13 - My Charging Setup
5:55 - Summary

[peroperic]

This guy doesnt do videos for the money or fame, in his reviews its just pure passion. Love Your work sir 😎👍💪

[ichbrauchmehrkaffee]

As a daily cycling commuter, dynamo lights are the only way to go for me.
Especially during the winter, I spend a lot of my riding time in the dark, so I absolutely need good lighting on my bike.
Because I don't have to worry about charging my lights, that makes the dynamo not only more convenient, but also more reliable and practical.

[natbarmore]

Very interesting comparison. Previous to this, the two data points I was going off of (and why I have a dynohub) were:
1: my SON dynohub, when off, has less resistance than all but the very best racing hubs. We measured this by: flip the bikes over, give the wheels an equal-force spin, and then see how long until the wheel stops spinning, the bearings and construction are so much better in the SON hub than in most non-dynamo front hubs that it will spin longer, despite the added magnetic resistance. It just goes and goes and goes. And that certainly matches my on-bike perceptions: when the hub is off, I don’t feel a thing, and I can coast a long time if I’m in a good tuck.
2: I definitely notice the dynohub kick in. I have automatic lights, so it sometimes turns on in the middle of a ride, like when I go under a bridge. That said, the resistance with the lights on is still /way/ less then the semi-knobby tires I use in winter, and the difference between dynohub on and dynohub off is also much less noticeable than the difference between tires at 60 psi and same tires at 80 psi. Mostly, I notice the subtle vibrational hum coming up through the handlebars, not any additional resistance.

[harindergill]

Depth of research, crisp and clear description, and pure, unadulterated passion = a treat of a video. Thanks!

[rotormotored]

Your videos are very well made. Your attention to detail indicates to your professionalism.

[nrdesign]

Compared to my ancient side-friction dynamo on my old bike, the hub dynamo always wins.

[peterwhite]

Very nice video. One minor point. At the end of the video you say the Cyo headlight, introduced about 12 or 13 years ago is half the brightness of the IQ-X, which is true. However the Cyo Premium, which was introduced 7 or 8 years ago is 80 lux, vs 100 lux for the IQ-X. So anyone buying a current Cyo headlight is most likely buying a Cyo Premium, which is almost as bright as the IQ-X. The difference is enough to be noticeable if you're riding side by side and have the lights aimed exactly the same, vertically. But even a small difference in aiming the light will have a more significant difference in the beam's brightness on the road.
That being said, if you're riding in traffic at night in the rain, you never have enough light!
Peter J White
Peter White Cycles LLC

[stevenwiedel]

Nerd out to your [our] heart’s content! Good real world information from someone who knows-

[ebbiketrip]

Idk how I have missed this channel. Great video and certainly gives me food for thought. I am just thinking of using it to charge my battery banks. Seems more dependable than using my solar wing and hoping for good weather. Thanks for the well researched info. Ride safe!

[trannel]

Awesome. I opted for the B&M IQ X and Son hub :D Holy moly. this is a detailed report. Thank you!

[marcotngsn]

THIS is awesome and very informative. Will be watching your videos a lot.

[coastaku]

In my city, we have a bike share system and all of the bikes there use Hub Dynamos to power the integrated lights, I don't really have an issue using them and having the lights is a great safety feature

[paulbusek]

As always, another superbly researched and presented video. Your work is very much appreciated and I thank you broadening my cycling knowledge!

[antoniomaglione]

Dynamo on a bike make much more sense nowadays with high efficiency LEDs. I recall when using a two 6 V 10 W Sylvania halogen bulbs setup (the bulbs with 30 hours lifetime). While with the LED the dynamo uses 1.5% of the total pedal power, with the halogen illuminator I went up to 10% of pedal power (for the same luminous flux). For time critical runs, we added a 6 V 10 Ah lead-acid battery, which provided 2 hours of light at 20 Watts, or 4 hours at 10 Watts.
Thanks for the video...

[stevencowles]

Really interesting, I'm just getting the parts together to rebuild an old bike from my shed to use as a commuter and now think that a dynamo hub and lights will be the ideal answer for me.

[konstantinwilleke]

Great video, thanks a lot! I do think though that you overestimate the w/kg output of the average bikepacker. This number will vary massively across cyclists of course, but I do think that 2 w/kg average for bikepacking is quite a big overestimation. To comfortably pedal that for 5+ hours, the cyclists threshold should be 3.5 - 4 w/kg, which is higher than that of most bikepackers (pointy end of ultradistance racers excluded) - closer to the range of competitive cyclists.
I'd be with you in the uphill case - 2w/kg are produced when going uphill a 5% slope. But on the flat road, your results could be a bit misleading.
That being said, your content is fantastic and I really appreciate the effort in sharing your knowledge! Cheers from Germany.

[jacobashton]

Thanks for more great content, Alee! I've always been curious about just how much of a difference dynamos make. It's surprising how many ultra racers use them given that overnight time penalty you mentioned! Guess that's another reason to sleep at night 🤣

[Bunny-Power]

With a little tiny bit of drag you get to see more on the rides 😉
I love my SON with the Edelux and the B&M E-Werk on my Fatbike.
And I have to wait for my buddy all the time anyway, so that drag does not bother me at all!

[lightracer]

Love my son and my klite. First real test was the Pioneer 400 in September and it worked flawlessly and I easily charged stuff as I rode. Keep needing-out!

[Rino-bicycle]

Thanks for the reviews and information, today things cost so much and there are so many choices, not always easy to try them all.