Dynamo Hub Help?
01-06-12 | 02:24 PM
#1
Thread Starter
Senior Member
Joined: Oct 2010
Posts: 149
Likes: 3
From: Berkeley, CA
Bikes: 1988 Miyata 615, 1985 Team Miyata
Dynamo Hub Help?
Hello everybody,
I just received in the mail what is my first dynamo-equipped wheel, built on a Sanyo H-27 hub. When I opened the box and spun it in my hands I was greatly disappointed to find that it feels like crap: the rotation is so "bumpy" that it only spins for a few seconds before coming to a halt and I'm almost certain that I'm going to feel the vibration through the frame once the wheel is mounted. I know this is a low-end dyno-hub and it's not going to spin as well as a Schmidt or a good Shimano one, but is it really supposed to be this bad? Can this hub be adjusted in the same way that a conventional cup-and-cone one can? Or did I waste my money on a lousy wheel?
I just received in the mail what is my first dynamo-equipped wheel, built on a Sanyo H-27 hub. When I opened the box and spun it in my hands I was greatly disappointed to find that it feels like crap: the rotation is so "bumpy" that it only spins for a few seconds before coming to a halt and I'm almost certain that I'm going to feel the vibration through the frame once the wheel is mounted. I know this is a low-end dyno-hub and it's not going to spin as well as a Schmidt or a good Shimano one, but is it really supposed to be this bad? Can this hub be adjusted in the same way that a conventional cup-and-cone one can? Or did I waste my money on a lousy wheel?
01-06-12 | 02:41 PM
#5
Old. Slow. Happy.
Joined: Jan 2010
Posts: 1,797
Likes: 1
From: Boulder County, CO
01-06-12 | 02:44 PM
#6
Thread Starter
Senior Member
Joined: Oct 2010
Posts: 149
Likes: 3
From: Berkeley, CA
Bikes: 1988 Miyata 615, 1985 Team Miyata
That's interesting. I wasn't aware that the amount of drag was affected by the light being on or off. But then, that's not surprising considering that I have absolutely no understanding of electric circuits.
Thanks for the reassurance guys. I was starting to feel ripped off, which is an all-too-familiar bad feeling. And my apologies if this had been covered before. I never encountered it when I did my pre-purchase research. Everyone just said "minimal drag, minimal drag..." so I was surprised to feel the extent of the "notchiness".
Thanks for the reassurance guys. I was starting to feel ripped off, which is an all-too-familiar bad feeling. And my apologies if this had been covered before. I never encountered it when I did my pre-purchase research. Everyone just said "minimal drag, minimal drag..." so I was surprised to feel the extent of the "notchiness".
Last edited by jar351; 01-06-12 at 02:47 PM.
01-06-12 | 02:48 PM
#8
Senior Member
Joined: Aug 2008
Posts: 4,134
Likes: 192
From: Somerville, MA and Catskill Mtns
Yes to all the above. Normal feel for off the bike. Once on, you won't feel the notchiness, but it still won't spin as fluidly and free as a regular hub. But once riding, you won't know the difference.
01-06-12 | 03:32 PM
#11
Wookie Jesus inspires me.
Joined: Mar 2011
Posts: 2,215
Likes: 4
From: Seattle, WA
01-06-12 | 03:39 PM
#12
Senior Member
Joined: Dec 2011
Posts: 90
Likes: 3
From: Toronto
As all have stated, notchiness is normal. I think Peter White does a good job of summarizing what the notchiness is and why you needn't worry about it:
Taken from here.
*Apparently the bad word filter doesn't like the verb defined as 'delay or hold back in terms of progress, development, or accomplishment', so I've replaced it with a non-offensive synonym.
At the risk of sounding repetitive, I like the Sanyo H27. I've driven it up to 50 kph+ in a motorized testing jig and not noticed any problems with vibrations.
Originally Posted by Peter White Cycles
Schezbzflat! My hub feels notchy!
When you hold the wheel or hub in your hand and turn the axle, you'll feel a lot of resistance. There are 26 poles and 26 magnets in the SON28 hub (fewer in the SON20). That creates 26 points around the hub shell that the axle wants to settle in, and a corresponding 26 points where the axle doesn't want to be. In the transitions between those points, the axle wants to turn in one direction or the other, to find the point where it wants to settle. As you ride, the hub turns relative to the axle, and 26 times in each rotation of the wheel, the hub wants to turn one way, and then the other, theoretically speeding you up and slowing you down, 26 times per rotation. At speed, the effects of these two forces almost completely cancel each other out, leaving you with extremely low drag overall. It's only when you don't have a lot of mass (your weight) and inertia (your speed) that the effect is to actually slow* the rotation of the hub axle. So there's no reason to be concerned about the way the axle feels when turned by hand.
When you hold the wheel or hub in your hand and turn the axle, you'll feel a lot of resistance. There are 26 poles and 26 magnets in the SON28 hub (fewer in the SON20). That creates 26 points around the hub shell that the axle wants to settle in, and a corresponding 26 points where the axle doesn't want to be. In the transitions between those points, the axle wants to turn in one direction or the other, to find the point where it wants to settle. As you ride, the hub turns relative to the axle, and 26 times in each rotation of the wheel, the hub wants to turn one way, and then the other, theoretically speeding you up and slowing you down, 26 times per rotation. At speed, the effects of these two forces almost completely cancel each other out, leaving you with extremely low drag overall. It's only when you don't have a lot of mass (your weight) and inertia (your speed) that the effect is to actually slow* the rotation of the hub axle. So there's no reason to be concerned about the way the axle feels when turned by hand.
*Apparently the bad word filter doesn't like the verb defined as 'delay or hold back in terms of progress, development, or accomplishment', so I've replaced it with a non-offensive synonym.
At the risk of sounding repetitive, I like the Sanyo H27. I've driven it up to 50 kph+ in a motorized testing jig and not noticed any problems with vibrations.
01-06-12 | 03:40 PM
#13
Senior Member
Joined: Aug 2008
Posts: 4,134
Likes: 192
From: Somerville, MA and Catskill Mtns
Yes, in terms of output, there's no significant difference. But in terms of resistance or drag, there is. The Sanyo and the low-end Shimano (3D-xxxx series) have more drag than the higher end Shimano (3N-xxxx) and other dynamos (Son, e.g.). I don't know about the SRAMs.
01-06-12 | 03:44 PM
#14
Senior Member
Joined: Aug 2008
Posts: 4,134
Likes: 192
From: Somerville, MA and Catskill Mtns
Personally, I think all dynamo hubs look pretty good. Even the low end Shimanos have a nice satin finish, while the high end ones and the SONs and the VO hub have a polished finish. To me, they're all nice.
01-06-12 | 09:43 PM
#16
Half way there
Joined: May 2011
Posts: 1,109
Likes: 1
From: Durham, NC
Bikes: 69 Hercules, 73 Raleigh Sports, 74 Raliegh Competition, 78 Nishiki Professional, 79 Nishiki International, 83 Colnago Super, 83 Viner Junior
I have the Shimano 3N72 with about 300 miles on it so far. I had the same reaction as you at first - "this doesn't feel right". I will echo all others in saying you won't notice it when riding. You will enjoy the freedom from batteries and chargers, though
What lights are you planning to use?
-G
What lights are you planning to use?
-G
01-06-12 | 11:16 PM
#17
Insane Bicycle Mechanic
Joined: Mar 2008
Posts: 10,168
Likes: 1,135
From: other Vancouver
Ditto to all of the above. I have two dynohubs- a Shimano and a Schmidt- and they feel horrid when turned by hand. This is unnoticeable when riding. I feel some vibration at speed, though.
__________________
Jeff Wills
Comcast nuked my web page. It will return soon..
Jeff Wills
Comcast nuked my web page. It will return soon..
01-07-12 | 01:14 AM
#18
Thread Starter
Senior Member
Joined: Oct 2010
Posts: 149
Likes: 3
From: Berkeley, CA
Bikes: 1988 Miyata 615, 1985 Team Miyata
I gotta say, it's great to get so many opinions on the matter. Now I can't wait to try out my wheel. It'll be a while, though, as I still have to settle on a light to use (and then order it). Anyone have any strong recommendations? I'm looking for something simple that won't break the bank. Doesn't have to have a standlight but should be compatible with a rear light should I decide to wire one in at some point. I ride mostly in urban areas that are fairly well lit so it doesn't have to be super-bright, just enough to illuminate the pot holes.
01-07-12 | 01:44 AM
#19
Senior Member
Joined: Oct 2008
Posts: 1,620
Likes: 187
From: Frankfurt, Germany
Bikes: Focus trash find commuter, Eddy Merckx Corsa, BP Stealth TT bike, Leader 720 TT bike, Boardman Comp Hybrid drop bar conversion, Quantec CX budget cyclocross build, SerottaNOS frameset ready to build up!
Pretty sure that all front lights are designed to be wired up to a rear light too. I have a b&m halogen light on my commuter which is ok. Spending more on an led front dynamo light brings a noticeable increase in performance. The guys on the commuting forum are the experts on lights.
01-07-12 | 01:48 AM
#20
Velocommuter Commando
Joined: Nov 2007
Posts: 2,683
Likes: 38
From: Houston, Texas
Bikes: '88 Specialized Sirrus, '89 Alpine Monitor Pass, two '70 Raligh Twenties, '07 Schwinn Town & Country Trike, '07 Specialized Sirrus Hybrid
I gotta say, it's great to get so many opinions on the matter. Now I can't wait to try out my wheel. It'll be a while, though, as I still have to settle on a light to use (and then order it). Anyone have any strong recommendations? I'm looking for something simple that won't break the bank. Doesn't have to have a standlight but should be compatible with a rear light should I decide to wire one in at some point. I ride mostly in urban areas that are fairly well lit so it doesn't have to be super-bright, just enough to illuminate the pot holes.
01-07-12 | 01:50 AM
#21
Thread Starter
Senior Member
Joined: Oct 2010
Posts: 149
Likes: 3
From: Berkeley, CA
Bikes: 1988 Miyata 615, 1985 Team Miyata
Pretty sure that all front lights are designed to be wired up to a rear light too. I have a b&m halogen light on my commuter which is ok. Spending more on an led front dynamo light brings a noticeable increase in performance. The guys on the commuting forum are the experts on lights.
01-07-12 | 01:58 AM
#22
Thread Starter
Senior Member
Joined: Oct 2010
Posts: 149
Likes: 3
From: Berkeley, CA
Bikes: 1988 Miyata 615, 1985 Team Miyata
These look pretty good, although I'll admit I always get lost somewhere between lux and lumens--who calculates this crap?. Do you know whether these have an option to mount on a front rack? Certainly something can be rigged up, I'm sure, but it'd be nice if the light were designed with this option in mind.
01-07-12 | 07:04 AM
#23
Freewheel Medic
Joined: Oct 2005
Posts: 13,578
Likes: 3,329
From: An Island on the Coast of GA!
Bikes: Snazzy* Schwinns, Classy Cannondales & a Super Pro Aero Lotus (* Ed.)
I just ordered one of these newbies to the generator field, the Sunup Eco. The best I can tell you can only find them on ebay. I used my ebay bucks to lower the price to what I felt was a reasonable $80 shipped.
__________________
Bob
Enjoying the GA coast all year long!
Thanks for visiting my website: www.freewheelspa.com
Bob
Enjoying the GA coast all year long!
Thanks for visiting my website: www.freewheelspa.com
01-07-12 | 07:48 AM
#24
Membership Not Required
Joined: Jan 2005
Posts: 16,853
Likes: 18
From: On the road-USA
Bikes: Giant Excursion, Raleigh Sports, Raleigh R.S.W. Compact, Motobecane? and about 20 more! OMG
I have 6 bikes with generator hubs, 2 with bottom bracket generators and 3 with sidewall generators. Dyno hubs rock, even the 40+ year old Sturmey Archer (which don't put out 3 watts, more like 1.6 watts) I use a variety of lights, but use LED's on the bikes that I have to ride at night.
The best LED lights for the buck IMHO are from B&M. The least expensive is the Lumotec Lyt ~$45usd. LED's don't have to have the tail light wired in like the halogens do. Supposedly it will shorten the life of the LED some, but no one has stated by how much.
All dyno hubs are going to feel a bit notchy when they are spun by hand, even on the bike. Some like the SON it is not as obvious. But for the price of a SON you can buy about 5 Sanyos. Nothing against the SON it is a great hub and there are many applications where it makes sense. For a commuter for shorter distances the Shimano or Sanyo is the way to go.
Aaron
__________________
Webshots is bailing out, if you find any of my posts with corrupt picture files and want to see them corrected please let me know. :(
ISO: A late 1980's Giant Iguana MTB frameset (or complete bike) 23" Red with yellow graphics.
"Cycling should be a way of life, not a hobby.
RIDE, YOU FOOL, RIDE!"_Nicodemus
"Steel: nearly a thousand years of metallurgical development
Aluminum: barely a hundred
Which one would you rather have under your butt at 30mph?"_krazygluon
Webshots is bailing out, if you find any of my posts with corrupt picture files and want to see them corrected please let me know. :(
ISO: A late 1980's Giant Iguana MTB frameset (or complete bike) 23" Red with yellow graphics.
"Cycling should be a way of life, not a hobby.
RIDE, YOU FOOL, RIDE!"_Nicodemus
"Steel: nearly a thousand years of metallurgical development
Aluminum: barely a hundred
Which one would you rather have under your butt at 30mph?"_krazygluon
