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.