Greetings all,

I have just returned from a trip to Belgium and the Netherlands. Heavenly. Having been to ground zero for city bikes, a new project has been inspired, and I'm doing research. I've always used battery powered lighting in the past, but was exposed to all manner of human-powered lighting on my trip. Where my project is concerned, I'm wrestling with the idea of a bottle dynamo vs. a hub dynamo. I know this is a tired debate by now. Please bear with me.

I should say up front that I plan to use Sturmey hubs with drum brakes. There is an option for the front hub: a drum brake with or without dynamo. As Shimano and Schmidt don't offer drum brakes, they are not in the running. I have read that the Sturmey dynamo hub has components in common with Shimano anyway. So - do I get the hub with drum brake and dynamo? Or the one without the dynamo, and use a bottle dynamo?

On the bottle dynamo side I would be considering the B&M Dymotec 6. I am aware of the caveats of bottle dynamos - that they can slip in wet or snow or mud. That they can cause tire wear. That their whine or whirr can adversely affect an otherwise quiet evening ride (this latter point is, for me, the most significant.) Realistically, though, less than 5% of my riding is done after dark, and I live in Los Angeles, so rain and snow aren't an issue.

Hub dynamo pros:
clean appearance
quiet
good output even at low speed
less drag when in use than bottle dynamo

cons:
higher initial cost
requires rebuilding of wheel
whether light's on or off, always some drag (remember, SON is not an option)

Bottle dynamo pros:
lower initial cost
zero drag when not in use

cons:
noisy
more drag than a hub dynamo
can slip in wet weather
unattractive

These pros and cons have been debated ad nauseum, I know. Like many of you, I had been firmly on the side of the hub dynamo, until recently. There is one issue I haven't heard discussed at all, and that's longevity.

While I was in Belgium I stayed with extended family. At least 10 adult size bikes in the garage. All of them had lighting of some sort (by law.) One evening I asked to borrow a bike, and tried out all the bikes. Most of them had hub dynamos. Not one of the hub dynamos worked. The bottle dynamo on the old steel grandpa bike worked great. Now if you'd asked me beforehand to guess which one of these bikes had lights that didn't work, I would have bet on the grandpa bike.

I'm not saying that because of this experience I think bottle dynamos are more reliable than hub dynamos. What I am saying that hub dynamos aren't as reliable as everything I've read has led me to believe.

This puts a different spin on the issue. It's great that the hub dynamo is clean, well integrated, and quiet. But it's laced into the wheel. If it goes bad, it's a tragedy. To replace it will be expensive and a huge pain in the neck. If a bottle dynamo goes bad, it's merely an inconvenience. I can replace it in five minutes myself on the side of the road. It's cheap enough that I can have a spare on hand.

When the issue of replacement is considered, it makes the bottle dynamo look pretty good.

It would be great if someone could chime in and convince me that having found a group of 7 bikes with faulty hub dynamos was just a statistical aberration, and that hub dynamos are really reliable and long-lived. Or tell heroic tales of their old and wizened hub dynamo that keeps getting better and better with age.

I know my bike project would be cooler/cleaner/more whiz bang with a hub dynamo, but given the expense and what I now perceive as the likelihood of replacement, I just don't see how I can do it.

In your situation, I would just get the bottle dynamo and use tires (such as Schwalbes) that have a protective strip made for them.

Thanks for the reply. The way I see it, though, everyone is in my situation. Replacing a bottle dynamo every year or two isn't a big deal. Replacing a faulty hub dynamo every couple of years would be oppressive.

I'm not sure if they are still made but there is (or was...) the option of a dynamo that mounted near the bottom bracket and rolled against the bottom of the tire. Has most of the pros of the bottom dynamo but perhaps fewer of the cons.

To be frank, in your climate and your riding requirements and given the quality of SON (hub) and B&M (bottle) dynamos it is exremely unlikely that you will need to replace any sort of dynamo every couple of years or so. You can check on the Peter White Cycles site or his Google group and see what sort of longevity his customers get.

Peter White Cycles is importing the Sanyo bottom bracket mount dynamo. He lists it for $44 which is less than the B&M Dymotec 6. Should be a good option if it fits your frame. Supposed to be more efficient & quieter than a bottle dynamo.

What manufacturer made those hub dynamos? Are you sure the dynamos were broken, rather than the lights?

I've heard only good things about the modern Shimano, Sturmey-Archer and SON hub dynamos, and have heard no reports of them wearing out early. Really, what is there to wear out? They are made of permanent magnents and wire. The bearings will eventually wear out, but that would happen with any sort of hub.

Remember that Shimano makes a "Rollerbrake" (their trademark), which is basically a drum brake turned sideways, with many of the same pros and cons. The Sturmey Archer hub with drum brake and dynamo is a great deal, however, and I have read it has the same basic internal dynamo as the Shimano.

With your desire for drum brakes, I would go with the Sturmey Archer drum/dynamo hub. You will either need a new bike or new wheel anyway (unless you already have a front drum brake?), and the dynamo is a very small incremental cost in this case, not much more than a bottle dynamo. The bottle dynamo DOES have several moving parts which care be damaged or worn out. I think the hub dynamo will prove more durable, especially in Los Angeles, where the bike will be banging around in bike racks.

I've got a SON hub dynamo that is 3 and 1/2 years old, probably has 5000 miles and still running strong, never had a problem. I know that if you read the rando forums, that people get many more miles then that on them too. I've always heard very good things about the SON hub which is why I invested the money in one.

Thanks again everyone for your responses.

That's a good question. It could have been the lights. They were all Lumotec lights with Shimano dynamo hubs. I guess because the lamp worked on the grandpa bike I assumed that on the other bikes it must have been the dynamo at fault and not the lights.

I think corrosion could be a main culprit in spite of the fact the dynamos are supposed to be sealed.

The Sturmey Archer hubs are much better looking too, IMO. They have a more vintage-ish look. The Shimano roller brake isn't very pretty at all. There are a lot of stamped parts that scream "low-end". In addition to that, Sheldon Brown has this to say: "I particularly advise against using a front Rollerbrake, because the front hubs made for these brakes incorporate the infamous and wrong-headed "Power Modulator " mechanism which reduces the effectiveness of the brake." (Found it here.) The only problem with the Sturmey is that feedback about it is very sparse. The only significant thing I've found was this YouTube video, which was disheartening:


I'll be building this bike up from scratch. New wheels have always been part of the equation, so the cost of having them built is a fait accompli. My concern about the reliability of the hub dynamo is that I don't want to end up having the wheel rebuilt again in a couple of years.

At this point I've pretty much decided to go with the Sturmey 8 speed drum brake in the rear, and the Sturmey drum/dynamo hub up front. The dearth of reviews of the hubs has me more nervous about it than I'd like to be. If someone knows a good source of rider/owner reports, I'd love to know it.

I've heard great things about the SON hub as well. But as I've indicated, it's not in the running because it's not offered with a drum brake.

Thanks again everyone for your input.

Why not buy the hub generator then if it goes out use a bottle to replace it?

Allen

I'd bet the lights were out. The Lumotec brand has been expanded to include LED lights, but any Lumotec lights from a few years back would likely be halogen bulbs. Those bulbs only last 1000 hours at best, and can burn out or break under bad conditions. It would not surprise me if all those lights had burned out halogen bulbs, rather than bad generators.

I'm not sure of the brand, but this dynamo hub was used as part of a low-tech windmill design, so they must last a while: https://www.amazon.com/Boy-Who-Harnes.../dp/0061730327
https://www.bookbrowse.com/reviews/in...essed-the-Wind
If wind blows 8 hours a day, 1 year of windmill use would be similar to 10 or 20 year of commuting.

It would kill me knowing I was dealing with the extra weight and drag of the hub dynamo with no benefit.

I would say that, ridden at the same speed for the same number of miles, a hub dynamo should outlast a bottle dynamo by a large margin, AND should provide a higher quality riding experience during that time (no whine, no wear on tires, and much less drag).
However, all hub dynamos are not created equal, neither are all bottle dynamos. I've never used a bottle dynamo long enough to wear one out, although one (a Miller) did lose it's shiny chrome plating.
If a hub dynamo does burn out (which seems very unlikely)....the magnets are in the rotating hub, the stator windings would be in the stationary portion NOT laced to the wheel? So windings could be replaced without relacing, if you could order a new part from the makers.
Having said that...if you only ride at night for 5% of the time, even a bottle dynamo will last a very long time, and is very easy and cheap to replace if it does fail.
Or, you could just use rechargeable batteries and LED lights.

Curious why you are set on drum brakes? Not questioning it, just don't have any experience with them.

Excellent question. A while ago I was in Europe. There are lots of types of bikes there that I never get to see at home so I always had my eye out. There was one bike in particular that had a special elegance about it, and one of the things that contributed to the wonderfully clean lines of the bike was the lack of rim brakes. As I grow older I see bikes in terms of form as well as function. So I resolved a while ago that my next project would have drum brakes.

I think corrosion is as likely a culprit for the failure of these things as burning out or wearing out. (In my case, I'm not worried about rain, but I do ride near the ocean.)

I bet in three year time I'd have an easier time getting parts for a vintage dynohub than for one I bought today. Still, your point is taken.

Batteries? Pfft.!

i have a SouBitez bottle generator and i have had it for over 4 years and i got it for free on a bike that was on its way to the dump. it still works great
if the date on this web site is correct my generator is 40 years old

If you are buying a hub anyway ... go with the dynamo.