jetbike

I just got a new Shimano dyno hub (can't remember which one, but fairly cheap). It's not built into a wheel, so when trying to spin the hub on the axle with my fingers I notice a huge amount of resistance. Is this normal? I know that they do not spin as freely as a regular hub, but this is quite extreme. Do they 'break-in', can I expect this to improve, or is there something wrong with this one?

Thanks

bobbycorno

I've got two Shimano dynos (the ultegra-level one), and both feel "notchy" in the extreme when I try to turn the axle by hand. It's just the nature of the beast. Put 'em on the bike and ride, and there's no noticeable drag, until I turn the light on. Then my speed drops about 1/4 of a mile an hour. Big whoop. So, short answer appears to be you've got nothing to worry about.

SP

jetbike

Ta.

Noice.

Six jours

Even a nice dynohub -- ie. Schmidt -- is going to feel pretty bad when the axle is turned by hand. It's not as bad as it seems, though: notice that once you get past the "uphill" part, the axle will turn itself forward another few degrees. So it's not all resistance; the hub "gives some back" too. This is why the tests -- and the riding -- show that you don't actually lose a whole lot of speed.

bmike

the resistance is normal - but if it ever feels notchy / crunchy you may have a problem.
i just had to have a schmidt replaced due to corrosion getting into the seals. it was VERY hard to turn by hand, and made a crunching sounds as i would turn it...

Six jours

Was that one of the older ones without the vent?

bmike

not sure. peter white took care of everything after diagnosing it via email - and my lights quit.

CliftonGK1

The Shimano 3N71 is pretty efficient, approaching the SON28, but both of them still have a "staggered" feel when turning the wheel by hand. I just bought a SON28 this weekend, and while at the LBS I got to spin their demo wheel with a Supernova E3 attached. Even the SON28 feels "bumpy" or "notchy" when you spin it by hand. There's not really a break-in of the generator, but more that once you get the mass of bike and rider moving on it, that "notchy" feel disappears.

Ashen

Whoa, which local shop has an E3 I can shine around and compare with other lights? This I must try.

CliftonGK1

Sammamish Valley Cycles over here in Redmond. They have a Mavic OP CD laced up to a SON28, and right now they have an E3 on it. They'll switch it out and let you compare it to other demo lamps.
The E3 was bright enough that in the middle of a sunny day, with the lights on in the shop, there was a considerably bright spot on the carpet just from a quick hand-spin of the wheel.

(They also have an overstock no-box SON28 36h for $225)

jetbike

Another Dyno-newb question. The hub is Shimano DH-3N70. I wanted to run two lights, low down on the front rack/fork area, rando-style.

I see this has only one socket to connect a light to, does this mean I can only run one light?

Many thanks in advance.

spokenword

you run a primary and secondary and you wire them in series. Peter White's page has some slightly useful instructions for wiring dual E-6s and setting up dual headlights.

Though, really, the dual headlight setup is rapidly growing obsolete. All the bleeding edge randonneurs nowadays use single Supernova E3s or the Edeluxe. Hell, even my girlfriend's single IQ Fly gives my dual E6s a run for their money.