What's wrong with dynamos?
 

Does anyone else notice that dynamos are a rare sighting while out riding? I just came from the bike shop where I dropped off a bike for service, and they indicated that they rarely see them. Is this because you lose a few watts? Just wondering why they aren't more popular for the convenience they offer.

Kind of like asking why the nerds in high school weren't cool. Dynamos aren't cool.

Useful, absolutely. But who want useful when you could have cool?

(Me, for one!)

I'm seeing more and more of them where I ride. They're the way to go IMO. :thumb:

This depends heavily on where you live. Around here in the Netherlands I think I see them on about 50-60% of bikes.

Road (racing) bikes however rarely have them as the people who ride those hardly ever ride them after dark or in cold or wet weather.

Not sure how they compare today's to the ones I remember, but they created a lot of drag when engaged. Other than that, I loved mine.

The other day when I stopped at the office, one of the other cyclist (mountain biker) came in and said that my lights were on-on my bike. I said it's ok, they are dynamo lights.

Then I had to explain what dynamo lights were, which he had never heard of.

Regarding your title, nothing is wrong with them. But manufacturers do not install them because new buyers do not ask for them. Not even on touring bikes where a dynohub for battery charging is desired.

When I built up one of my touring bikes in 2013, I put a dynohub on it but that was mostly to be used for charging up batteries with a USB charger. Set it up with dynohub powered lighting but that was a secondary priority.

And when I built up another touring bike in 2017, put one on for the same reasons, primarily for charging up batteries but also for lighting.

When building up a new bike with a new wheel, the cost of a dynohub and subtracting the cost of a regular hub makes the additional cost for a dynohub on the bike quite low. But if you already have a bike with a non-dynohub wheel, the cost to put a dynohub on it is the cost of the hub, cost of spokes and nipples, possibly a wheel build charge, and if you decided to keep your old wheel as a back up then you are buying new rim and rim tape too. Thus to upgrade a bike that did not have a dynohub on it, you are likely paying two or three times as much for the dynohub wheel. That is a big enough cost that not many people go for it.

My last bike tour (five weeks in Canadian Maritimes a couple months ago), I used battery powered lighting. My dynohub was exclusively used for charging up batteries for my GPS, phone, taillights, camera, and headlamp (for my head). I also had a headlamp (for the bike) that was powered only by USB cable, could use it by plugging it into my powerbank, but never used the headlight on the bike for all five weeks.

I admit I am probably in the minority when it comes to those that tour with a dynohub, most use the hub for headlamps too. Prior to this year I used dyno powered headlamps when touring but since I almost never turned them on, I decided to just carry a strap on battery light instead for my most recent tour. My most recent tour was on a bike with S&S couplers so I have to disassemble the bike to ship it, installing dyno powered lighting on the bike is one more headache that I decided to avoid when I tour on that bike, that is why I did not install dyno powered lights on it.

If you are a commuter, it really makes sense to have it for lighting. But if you buy a bike without a dynohub on it, it is not cheap to add it and also add the lighting.

So little drag that you can't tell when it is in use on the newest hubs. A good article on them was published in 2012, they concluded that the hub when turned on was equivalent to adding another 5 or 6 feet of elevation gain for every mile ridden.
https://www.bikeforums.net/electroni...son-tests.html

If I am riding 15 miles an hour, then it takes me four minutes to go that mile, I will not notice if I had to exert in a minute enough energy to climb another foot and a half.

Wow! They've come a long way from the one's available in the 70's that made a loud hum and created a substantial amount of drag. They were also cost prohibitive for the common man (or boy-me)

Dynohubs (not the old bottle dynos) are pretty sweet! It's very easy to forget that your lights are on during the day. :)

Are you asking about sidewall dynamos or hub dynamos? Sidewall dynamos are nice because they're light and fairly easy to install, but the drag is noticeable. I haven't tried the latest ones which are not as bad as the old ones.

Hub dynamos are great, but once installed are fairly expensive. You either have to buy a wheel with the hub or have a hub built into a wheel for you. I'm lucky that I can build my own wheels. Wheel building labor is around $50 or $60, and spokes are expensive when they're not with a pre-built wheel. Then there is the time to wire everything up. It's not hard for me, but paying for shop labor, it would add up.

But once you have them, you wonder why you waited so long.

Hub dynamos produce so little friction, you really don't notice it. I leave my lights on all the time because it can't hurt and could save me by letting someone see me before they otherwise would.

Even still, I think a lot of the reason they're not common in many countries is that people don't know how good they are, and not seeing many hub dynamos, they are not going to find out.

But yes, they are increasing here, slowly. I get a nice smile or nod when a knowing person sees me with mine.

https://lh3.googleusercontent.com/KT...w2044-h1532-no

Exactly. As you know, Tom, I've been searching around for just the right generator hub for my 1980 Raleigh Sports (I'm going to pass on the Nexus in the Gazelle; might even keep that bike intact), and it seems as if Google barely knows what a SRAM I-Light is, and even the Shimano hubs generally originate from Germany - where they seem to be popular and also appear to be required equipment that's policed - or Taiwan, where they originate.

I Googled the Shimano DH-3N31-NT manual during a search, and even that took me to the German Shimano page. Go figure.

-Kurt

I emailed Intelligent Design Cycle who make inexpensive handbuilt wheels with dynamos built in. They may not have wheels to sell for a few months because of tariff and administrative difficulties. :(

What's wrong with dynamos?

Nothing wrong with them. One reason we don't see many, At least here in Canada may be because they are not offered on many bikes. I would like to see it offered as an option, Or perhaps on 1 version of an existing line of bikes suited for them. Bikes one might use for touring for example.

Also with the introduction of LED lights and more efficient rechargeable batteries, We can install a very effective battery powered lighting system that is light and inexpensive. For most folks these work fine for commuting or recreation.

I've had a dyno hub on my commuting bike for years. When I replaced it to move to drum brakes (with dyno), I sold the old dyno hub quickly. Once folks realize what an advantage they are they have to have one. I see bikes with them every day, but still comprise less than 5% of bikes.

I have a dynohub on all of my bikes. It was a great addition to my riding, i don't have to worry about getting home before dark or charging lights. I always had a bike with a dyno back in the '70s and '80s. One of the Soubetez with a built in headlight. They weren't as expensive as batteries back then, this was before the advent of affordable rechargeable batteries

A lot of riders just don't know about them. But then again I see too many cyclists who don't seem to know about lights. It's that time of year.

I'd venture to say that : (1) for commuters, rechargeable LEDs have become so cheap, convenient and efficient that there is no point riding with a dynohub. (2) For touring, there could be an argument that dynohubs are a must for long trips. In my experience however, they add a degree of inconvenience when flying -- I've had issues twice. Battery banks have become cheap, convenient and efficient, to the point that they are reasonable substitutes for dynohubs. When you consider the cost of a good dynohub/USB charger/wheel building, and that the watts you get from the dynohub are taken from the watts that propel you forward, the case for a dynohub doesn't look that good.

Nothing is wrong with hub dynamos. Probably law requirements for bike lights are pretty easygoing were you live.

Here in germany estimated 95% of all city/touring bikes have a hub dyno (and before that every one had sidewall dynamo). But this was forced by law. Until a few years ago, every bike had to have approved bike lights, with a dynamo as power source, mounted 24/7. Only "race bikes with a weight less than 11 kg" were allowed to use battery lights, which were required to be at least in the bikers bag, even during a ride in bright daylight. Recent law changes removed the silly weight requirement and the need for a dynamo as power source. All bikes now must have lights mounted from dusk till dawn (or during a solar ecclipse..) only.


I agree, lights have become pretty cheap and bright, so the need for a dyno has lessened. However there are advantages of dynamo powered light over battery lights
1) you never have to think about whether your light is on the bike or not, you always have light
2) you never have to think about charging
3) Removable battery bike lights (left mounted on a bike standing still) tend to be stolen quickly
4) The newer generations of dyno powered bike lights (edelux, IQ-X, cyo premiums) provide fairly good light output.

Regarding hub dynamos:
The drag of a good hub dyno is not noticable when riding, a badly lubricated chain causes more drag. If you buy a new city/commuting bike, I'd always ask for hub dyno wheel. However, if you have to buy a new wheels, things become more expensive, unless you can build a wheel yourself (and use the exisiting rim).
There is a newer rim dynamo with efficiencies similar to the best hub dynos, however price wise with 150 Euros in a similar range: velogical rim dynamo

It looks like hub dynamo's operate at about 50% efficiency, Which is pretty much what I would expect. That being the case if 4w out requires 8w in. That's about an 8% loss of power. But the way bikes and aerodynamics work that 8%loss in power might translate into about a 6% loss in speed. About 2.3 minutes on a 15 km commute at 25 kph I estimate. Even less at 3w. And with no load they operate nearly as efficiently as conventional hubs. At least a decent one.



Pretty darned impressive if you ask me.

I think dynamos are awesome but I don't have one because:

• much more expensive than alternatives
• less powerful than battery lights
• extra drag and weight

There are very few battery lights that have a beam that's as good as many dyno lights though. So much of the power is wasted.

I have a set of their IDC Classy purchased before they ran into supply problems. Took my biggest tour to date coupled with a Sinewave Cycles Beacon, always had USB power during the day and unlimited headlight/taillight for the evening. It's the first set of wheels I have ever purchased that come out of the package perfect without the need to visit the shop for re-tensioning.

T

Certainly the hub dynamos, I haven't tried the bottle-type since I was a child (well before LEDs).

I thought it was a pretty damned good value before I saw the quality of the wheels. I paid $95 for a front wheel with Sanyo dynamo. But it's a truly handbuilt wheel with good and even spoke tension, totally true. I hope they can make a comeback, even if it means raising their prices.