Author Topic: hub generators  (Read 4929 times)

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Offline commuter

hub generators
« on: January 05, 2011, 07:34:10 pm »
I'm going to be building a bike soon and am wondering about hub generators. Is there a noticable drag with this type of hub? Are some better than others? Can a phone, camera or GPS be charged by these hubs or are they just for lights?

Offline rvklassen

Re: hub generators
« Reply #1 on: January 05, 2011, 08:20:51 pm »
I'm going to be building a bike soon and am wondering about hub generators. Is there a noticable drag with this type of hub? Are some better than others? Can a phone, camera or GPS be charged by these hubs or are they just for lights?
Yes, yes, and yes.

I have a Shimano generator on my winter bike.  Combined with studded tires and 80' climb over two miles (i.e. not much climb) it feels like I'm riding an exercise bike.   

Peter White's site has comparisons of the amount of drag for three (?) different hubs, of different manufacturers.

IIRC Peter also has information about adaptors to charge things rather than powering lights.

Offline Fred Hiltz

Re: hub generators
« Reply #2 on: January 05, 2011, 09:35:22 pm »
See also 15 posts here, found by typing "generator" into the search box above.

Fred

Offline Pat Lamb

Re: hub generators
« Reply #3 on: January 05, 2011, 09:40:14 pm »
Is there a noticable drag with this type of hub? Are some better than others?

Yes, you can notice the drag.  No, it doesn't make any difference.   :-\

I've got the Shimano [whatever]-72.  You can feel a buzz around 17 mph with the light on, I presume when the overvoltage protection is switching on and off.  After a few months, I decided to test it.  Up a nice little hill, stop on the white line at the light near the top and coast down.  Max speed, 26.7 mph with the light on.  Re-test, 27.1 mph -- it makes a difference!  Oops, the light was still on.  Up again, 26.8 mph with the light off.  Right in the middle of the light-on error bar!

I said the heck with it and went for a nice bike ride.

Offline driftlessregion

Re: hub generators
« Reply #4 on: January 05, 2011, 09:53:35 pm »
Two great sources of information are Peter White Cycles http://www.peterwhitecycles.com/schmidt.asp and Bicycle Quarterly http://www.bikequarterly.com/VBQgenerator.html.

Offline ducnut

Re: hub generators
« Reply #5 on: January 06, 2011, 07:43:03 pm »
Bicycle Quarterly http://www.bikequarterly.com/VBQgenerator.html.

Bicycle Quarterly, Winter 2010 issue, compares the Shimano DH-3N80 hub to a SON delux hub. They found the Shimano vibrated noticeably more than the SON and that it required about twice as many watts to power it. Given BQ's result and Peter White's opinions, I'd definitely go with the SON hub. My next set wheels will be from Peter and have a dynamo.

Offline Pat Lamb

Re: hub generators
« Reply #6 on: January 06, 2011, 09:25:00 pm »
Bicycle Quarterly http://www.bikequarterly.com/VBQgenerator.html.

Bicycle Quarterly, Winter 2010 issue, compares the Shimano DH-3N80 hub to a SON delux hub. They found the Shimano vibrated noticeably more than the SON and that it required about twice as many watts to power it. Given BQ's result and Peter White's opinions, I'd definitely go with the SON hub. My next set wheels will be from Peter and have a dynamo.

You might as well fill in the blanks from the link; the Shimano sucked up 1.5 W more at 30 kph (18 mph) than the SON.  I doubt that would be significant as long as you're not racing, and certainly not significant if your touring is loaded.  I drooled over the Schmidt SON, but I couldn't justify the price difference.  Peter White's cheapest SON wheel is about $440, while velo-orange.com got a wheel with the Shimano hub to me for less than half that.  YMMV.

Offline ducnut

Re: hub generators
« Reply #7 on: January 07, 2011, 01:19:01 pm »
while velo-orange.com got a wheel with the Shimano hub to me for less than half that.

So, does it vibrate, as claimed?

Offline Pat Lamb

Re: hub generators
« Reply #8 on: January 07, 2011, 06:38:20 pm »
So, does it vibrate, as claimed?

Define "vibrate."  I noted up thread that there's a buzz starting about 17 mph with the lights on.  I notice it more when I'm coasting than pedaling (probably because when I'm pedaling over 17 I'm pushing hard to stay with a group), and it diminishes at higher speeds.  There's nothing to hear.  The first time I felt it I was wondering if there was something wrong with the bike, like a fender out of its socket rubbing against the tire.  I think it's getting less noticeable with time and miles, but I couldn't swear to that.  Light off, no effect.

I'll state what I merely implied before: it's your choice and your decision whether the slight drag and mild buzz is worth an extra $250.  I might have said "yes" if I were doing long randonnees of >300 km, but since my night time rides are either 40 miles or 10 mile commutes, it's not worth it to me.

Offline ducnut

Re: hub generators
« Reply #9 on: January 07, 2011, 07:34:39 pm »
So, does it vibrate, as claimed?

Define "vibrate."  I noted up thread that there's a buzz starting about 17 mph with the lights on.  I notice it more when I'm coasting than pedaling (probably because when I'm pedaling over 17 I'm pushing hard to stay with a group), and it diminishes at higher speeds.  There's nothing to hear.  The first time I felt it I was wondering if there was something wrong with the bike, like a fender out of its socket rubbing against the tire.  I think it's getting less noticeable with time and miles, but I couldn't swear to that.  Light off, no effect.

In the BQ article, they stated that after two consecutive all-night rides that their hands were numb and tingly. I gathered that it was pretty significant. Total test mileage was 1560 miles. Seems that your experience is/was more favorable. I'll give it more thought, when I'm ready to buy a wheelset.

I'm just looking for a more permanent solution than the battery-powered LED headlights (I run 2) I currently use. I've had two crashes, because the lights weren't bright enough for me to detect the nature of the surface I was approaching. I ride a lot of country roads and they have a tendency to have loose gravel sections. Some are really loose and deep. My lighting deficiency causes me to limit the duration and direction of night rides. I think with the added power of the hub and the ability to power a more substantial light system, I'd be safer. I don't need to be breaking anything, bike or body.

Thanks for your feedback.

Offline RussSeaton

Re: hub generators
« Reply #10 on: January 08, 2011, 12:04:46 am »
In the BQ article, they stated that after two consecutive all-night rides that their hands were numb and tingly. I gathered that it was pretty significant. Total test mileage was 1560 miles.


To put it bluntly, Bicycle Quarterly was making this stuff up.  The Shimano generator hub does not vibrate.  I've used it on PBP as well as several thousand miles of brevets.  It functions quite well.  No resistance is noticed while using it.

http://www.starbike.com/php/product_list.php?prodcatid=28&lang=en&Hersteller=&Kategorie=Std+100+mm&Lochzahl=32&filter_submit=GO

Starbike has the Shimano DH-3N80 for about $95.  While the Schmidt is $230.

Offline pptouring

Re: hub generators
« Reply #11 on: January 09, 2011, 09:23:59 pm »
Is there a noticable drag with this type of hub?

I'm going to say NO!

Are some better than others?


Not sure, I can only speak about the SON28 that my wife and I have and they rock!

Can a phone, camera or GPS be charged by these hubs or are they just for lights?

Not by themselves, but you can get something like the E-WERK that will charge and/or run your GPS, camera(s), phone, or just about anything that uses USB power. I run my Garmin eTrek, charge my cell phone, small video camera, and iTouch and run my lights at the same time. Great device to use with your hub and it will work with the Shimano hub too. 

Offline pptouring

Re: hub generators
« Reply #12 on: January 09, 2011, 09:40:42 pm »
I can say that we have a couple thousand miles on our hubs and never have we noticed any sort of vibrations. We run our lights all the time and I normally have the GPS turned on at the same time. Also, I've had my ride to just over 40MPH (going downhill of course). 

Offline bikerdan

Re: hub generators
« Reply #13 on: January 10, 2011, 03:40:01 pm »
I just built up a Salsa Vaya and we put a Schmidt SON 28 disc in the front wheel.  Other than the $300+ cost, I am absolutely blown away by this thing.  Try as I might, I can not detect a difference with lights on or off.  I am running Busch and Muller Lumotec IQ CYO R Senso Plus in the front and Toplight Line plus in the back -- also fantastic and amazing lights.

If you turn the axle with the wheel out of the fork you notice notchiness and wonder what you just spent $300 on.  Drop it into the fork, though, and it rolls and rolls.  Peter White (I think) describes this as 30 pulls and pushes that almost cancel out.  Turn on the light with the wheel spinning, and it noticeably slows.

Like I said though, riding the bike, I don't see how you can ever tell.  No noise or vibration at all ... just lights you never have to worry about!

-Dan

Offline bikerdan

Re: hub generators
« Reply #14 on: January 12, 2011, 11:00:07 am »
On the topic of resistance, Peter White has very specific drag/efficiency information on this page:

   http://peterwhitecycles.com/shimano3n70.asp

 Specifically, calls out the Schmidt as 64% efficiant, requiring 1.5 watts and the recent Shimanos as 53% efficient and requiting 2.2 watts.

Overall, it's probably worth your time to read all of Peter's site and mull it over for a while.

-Dan