Generator Hub- What is Normal?
04-25-23, 01:43 PM
#1
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Generator Hub- What is Normal?
I bought a set of vey lightly used rando type wheels with a Shimano Alfine generator hub. When I turn the axle by hand, there is a definite "cogging" feel from the hub. I realize generator hubs must have a bit more resistance, but is cogging what I should be feeling? This is my first experience with a generator hub. Also, does it matter what side of the wheel the wire should originate from?
04-25-23, 02:17 PM
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I bought a set of vey lightly used rando type wheels with a Shimano Alfine generator hub. When I turn the axle by hand, there is a definite "cogging" feel from the hub. I realize generator hubs must have a bit more resistance, but is cogging what I should be feeling? This is my first experience with a generator hub. Also, does it matter what side of the wheel the wire should originate from?
04-25-23, 02:54 PM
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That's normal. Both my SON and my Shimano 3N70(?) have that notchy-ness. Get on the bike and ride it, and you mostly won't notice it. Mostly, because there's about a 2 mph window on both bikes where I feel a bit of a buzz if the light's on (which it always is).
That notchy feeling makes truing/re-truing the wheel a bit of a drag because the wheel doesn't spin as freely as a standard hub. But, again, it's not a bother while riding.
That notchy feeling makes truing/re-truing the wheel a bit of a drag because the wheel doesn't spin as freely as a standard hub. But, again, it's not a bother while riding.
04-25-23, 03:46 PM
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Some dynohubs are reversible and some aren't. I'm not sure what would be the difference.
The cogging is normal, it happens when the magnets line up with the windings.
The cogging is normal, it happens when the magnets line up with the windings.
04-25-23, 04:47 PM
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As the armature turns past magnets, that causes the odd feel, which is normal for a dynohub.
You mentioned it is a Shimano hub. Be advised that Shimano hubs are grounded to the fork. That usually does not matter at all, but if either of your lights is grounded to the fork or frame, if it does not work you may have to reverse the wires to the light that does not work. It took me a few hours to figure that out when my light did not work on one of my bikes.
I have heard both that it does not matter which way the wheel turns, and that it does matter. Since the norm is to have the the plug on the right (drive) side of the bike, that is how I did it on all of my bikes.
If you are interested, I described how I wired my rando bike for lights at:
Wiring up a dyno powered lighting system with USB charger
You mentioned it is a Shimano hub. Be advised that Shimano hubs are grounded to the fork. That usually does not matter at all, but if either of your lights is grounded to the fork or frame, if it does not work you may have to reverse the wires to the light that does not work. It took me a few hours to figure that out when my light did not work on one of my bikes.
I have heard both that it does not matter which way the wheel turns, and that it does matter. Since the norm is to have the the plug on the right (drive) side of the bike, that is how I did it on all of my bikes.
If you are interested, I described how I wired my rando bike for lights at:
Wiring up a dyno powered lighting system with USB charger
04-25-23, 08:10 PM
#6
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Thanks Guys! I couldn't respond earlier (babysitting grandkids) but you've taken a load off my paranoid mind. It makes perfect sense. This rando stuff takes a bit of learning curve. All the things that seem cool to me now are the things I would have cringed at in '73 (lights, racks, wide tires, wide gearing). Little did I know that the Motobecane Grand Record I bought that year would be the bike that ticks almost all the rando frame boxes.
04-26-23, 01:26 PM
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I was using a rather nice bottle dyno before I got my SP hub dyno. I was worried like you after spinning the hub in the hand but after the wheel build and on the bike? So much better. My new normal.
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