Hub dynamos

[tgame]

I'm delighted with the front wheel hub dynamo on my Agattu. Spinning the wheel by hand I don't seem to find any resistance at all. Is there significant drag with them when the lights are not in use?

 

[flecc]

No, it's negligible on the Shimano hub. It's a great product, and infinitely preferable to tyre wall dynamos. The only objection is that it adds some weight to a bike.
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[Ian]

In practice the drag is virtually nil. If a hub dynamo is rotated when removed from the wheel it feels slightly jerky but this does not tranlate to drag as the jerks are actually alternating periods of resistance and assistance as the poles pass the magnets, and when smoothed out by the wheel acting as a flywheel the net result is zero.

 

[mk1]

When the lights are off I doubt there would be any noticeable drag.
It appears though that the Pro Connect lights work direct from the battery, so which would be the most efficient system of the two when the lights are on?.

Martin

 

[flecc]

I think the hubdyno is the better when all factors are taken into account, since using the main battery subtracts from the range. How much will depend on how good the lights are of course, and I suspect that weight saving was the priority for the Pro-Connect, so the loss was deemed acceptable.
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[tgame]

I've been trying out the lights on the Agattu again this evening and I've found them really first class. I rode for a mile or so along a small unlighted road to see how they would perform, and I found that it was perfectly possible to see where I was going safely at the gentle speeds which I use, although anyone riding fast would probably need something rather brighter. The rear light is very visible indeed, and gives a feeling of safety. The fact that some electricity is stored so that the rear light can remain on for a while when stationary is a real safety measure and gives one a lot of confidence.
There must be some drag from the dynamo when the lights are on but I was not able to detect it although I did try several times.
Yet another fine feature on this splendid bicycle.

 

[cliff]

Thanks for that Tony; it's good to know that the lights are up to scratch as I intend to commute on some unlit roads in winter. Your post led me to check the B&M website and a little more research located the even brighter B&M Lumotec LED lights in the UK and some positive reviews.
Cliff