Dynamo hub adjustment

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Wildcat

Wildcat

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I picked up two of these Shimano generator hubs and laced one up to check it out. They both have the same rolling resistance. The vid shows how they roll. I would like to have them roll much better, but I know they are probably generating electricity. I didn't get any connectors with them, maybe why they were so cheap. I can't find the connectors anywhere so I can hook up a light. I looked on the web, but there's a lot of disinformation out there.
I'm hoping someone here has firsthand knowledge of these hubs.
Two questions:
Is there a way to get better rolling resistance?
Where can I find connectors for the hub contacts?

 
What are the hub model numbers?

Their first gen hubs were pretty weak. At one time Peter White cycles had some comparison tests of the models available then. The early Shimano (NX30) had far more drag when 'off' due to a bad stator design. Not worth buying or trying to use.

I have 3 of the second gen (3d71) which work quite well. I initially built up wheels in 700 race, 700 wide and 26" mtb figuring I would just put them on what ever bike I was going to ride that night. But they stayed put on 2 of my touring bikes, Trek 520 (700c wide) and my Gary Fisher (mtb). With no electric load the drag is not even noticable when riding. The electric drag load is generally proportional to the power being requested. They were designed to output a max of 3 watts at normal riding speed. Not a huge amount. You can't be running high power headlights with them. 3 watts is the max target. None of those 20 or 30 or 60 watt lights. I took one on my cross USA ride and kept the headlight on at all times during the day when on roadways. I have a Sinewave Converter (regulated 5 volt usb charger port) that I used to power the mp3 player when on trails. Basic saftey rules, no earbuds when on the roads, lights always on when on the roads. I had a friend tell me he could see my headlight from a couple miles away during day time. I could slightly feel the drag. My guess was I was giving up about 1/2 mph which would add about 10 minutes to a full day's ride. Some rough numbers, humans output about 100 watts to ride at an easy speed. Pro racers are in the 500 watt range at race speed. By comparison a 3 watt hub generator is pretty minor. It takes a lot more effort to push knobby mountain bike tires. Far less drag than those awful bottle generators that have 50 watts of mechanical drag to produce 3 watts of electricty.

There are generator specific head lights. IMO, the Shimano is quite poor. The main issue is it has a secondary LED in the lens that runs up and over the light which messes up your night vision. I have the Planet bike LED headlights on the bikes now. They have a capacitor in them so they stay lit when you stop moving for a bit. The LEDs put out a lot more light per watt. And they don't burn out if you go down a hill to fast. Don't waste your time with incandescent bulbs or Krypton gas bulbs. Peter White carries some very nice generator specific lights like the E3

We did get an early SON for my wife for her midnight century rides and ultra races. The version with the black tube body that was more prone to water infiltration. It's quite expensive but was the best overall. Built up in 650c and since sold off as she when back to 700c bikes. There are many other brands now.

Could be the bearings need a repack. The 3d71 hubs have shimano's high end bearings. Some of other brands have sealed cartridge bearings. Those can be over tightened depending on the axle design. It's quite easy to destroy a Shimano hub (rip the wires out) if you allow the connector to turn on the axle when adjusting the bearings. That hub looks to be in new condition so it's probably to factory spec.
 
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rickpaulos said:
What are the hub model numbers?

Their first gen hubs were pretty weak. At one time Peter White cycles had some comparison tests of the models available then. The early Shimano (NX30) had far more drag when 'off' due to a bad stator design. Not worth buying or trying to use.

I have 3 of the second gen (3d71) which work quite well. I initially built up wheels in 700 race, 700 wide and 26" mtb figuring I would just put them on what ever bike I was going to ride that night. But they stayed put on 2 of my touring bikes, Trek 520 (700c wide) and my Gary Fisher (mtb). With no electric load the drag is not even noticable when riding. The electric drag load is generally proportional to the power being requested. They were designed to output a max of 3 watts at normal riding speed. Not a huge amount. You can't be running high power headlights with them. 3 watts is the max target. None of those 20 or 30 or 60 watt lights. I took one on my cross USA ride and kept the headlight on at all times during the day when on roadways. I have a Sinewave Converter (regulated 5 volt usb charger port) that I used to power the mp3 player when on trails. Basic saftey rules, no earbuds when on the roads, lights always on when on the roads. I had a friend tell me he could see my headlight from a couple miles away during day time. I could slightly feel the drag. My guess was I was giving up about 1/2 mph which would add about 10 minutes to a full day's ride. Some rough numbers, humans output about 100 watts to ride at an easy speed. Pro racers are in the 500 watt range at race speed. By comparison a 3 watt hub generator is pretty minor. It takes a lot more effort to push knobby mountain bike tires. Far less drag than those awful bottle generators that have 50 watts of mechanical drag to produce 3 watts of electricty.

There are generator specific head lights. IMO, the Shimano is quite poor. The main issue is it has a secondary LED in the lens that runs up and over the light which messes up your night vision. I have the Planet bike LED headlights on the bikes now. They have a capacitor in them so they stay lit when you stop moving for a bit. The LEDs put out a lot more light per watt. And they don't burn out if you go down a hill to fast. Don't waste your time with incandescent bulbs or Krypton gas bulbs. Peter White carries some very nice generator specific lights like the E3

We did get an early SON for my wife for her midnight century rides and ultra races. The version with the black tube body that was more prone to water infiltration. It's quite expensive but was the best overall. Built up in 650c and since sold off as she when back to 700c bikes. There are many other brands now.

Could be the bearings need a repack. The 3d71 hubs have shimano's high end bearings. Some of other brands have sealed cartridge bearings. Those can be over tightened depending on the axle design. It's quite easy to destroy a Shimano hub (rip the wires out) if you allow the connector to turn on the axle when adjusting the bearings. That hub looks to be in new condition so it's probably to factory spec.
Click to expand...
Thanks for the info. Mine are an HB-NX32 and an HB-C051-D.
433090817_984371076639135_5366206828828575734_n.jpg

Probably the earlier models you mentioned. If loosening the cones and making sure the bearings have grease doesn't help, I may try to gut the hub and not worry about having a generator. I don't do any night riding so they would just be for looks.
 
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Sometimes if the wheel is not true it will miss shape the hub I've had similar issues with drum breaks
 
I looked at that same video earlier to see which way the large part turns to get the guts out. I got all the small stuff, but I don't have a wrench big enough and couldn't hold the hub shell well enough to turn the armature thing.

The spokes aren't tightened up, I let the guys at the shop do all that, I just lace them up.
 
"I got all the small stuff, but I don't have a wrench big enough and couldn't hold the hub shell well enough to turn the armature thing."

When the hub is spoked up, the rim is your leverage. Kinda like removing freewheels which is nearly impossible to do from just a hub.
 
rickpaulos said:
"I got all the small stuff, but I don't have a wrench big enough and couldn't hold the hub shell well enough to turn the armature thing."

When the hub is spoked up, the rim is your leverage. Kinda like removing freewheels which is nearly impossible to do from just a hub.
Click to expand...
I have a 80's suntour hub in my parts that I can't get the cluster off, I cut out all the rusty spokes before I tried to remove it.

On these hubs, I tried with the black one, not the laced up silver one. I'll take it to the bike shop to see if they can break it free. Then if it's a good roller, I'll try it with the laced up one, with a new big adjustable wrench! More tools!
 
The secret trick to getting freewheels off hubs is to spoke them to a rim so you can use the rim for leverage. You only need about 6 spokes, they don't even need to be the correct length or tensioned. Just all the same size and equally spaced. Ditto for taking the generator hub apart.

Another lesser trick is to bolt a long steel bar to a hub assuming it has large enough holes in the flange. More chance of breaking an aluminum flange. About a 3 foot bar works well. I have one (angle iron) that I use to remove threaded on brake discs.

I've seen hubs destroyed by trying to put them in a bench vise (doesn't work) or using a couple pairs of vice grips (doesn't work). Metal jaw plumbing pipe wrenches will chew right through aluminum or chrome plating. The plumbers strap wrenches are useless on small diameter objects.
 
Some of that rolling resistance is "false", or worse than it seems. Hard to describe but the magnets in the hub make it feel notchy as heck in the hand, and the video you posted shows how that looks. Once you get the weight of a tire+tube on there it will feel less so. And then again once on a bike and riding you'll feel it even less than that.

With the good condition yours appear to be in, I kind of doubt there is any bearing trouble inside, I think it's just the way dynohubs feel. At least in my experience. I've owned several Shimano, a SON, and an SP. They all feel this way to one degree or another, though to be sure some are actually lower rolling resistance.
 

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