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Schmidt Dynohub (SON)(9 posts)

Schmidt Dynohub (SON)mdehner
Jan 2, 2004 2:16 PM
Anyone here using this to power your lights, particulary for brevets and other long jaunts? I am wondering whether its performance justifies the cost.
re: Schmidt Dynohub (SON)Suds
Jan 2, 2004 3:36 PM
There is a good review here:
re: Schmidt Dynohub (SON)Heron Todd
Jan 3, 2004 9:01 AM
Disclaimer: I sell these, along with other lighting systems, as part of complete Herons (many of which are used for brevets).

This is my favorite lighting system. The drag is the lowest of any dynamo system whether a hub or tire sidewall system. Of course, you can completely disengage a sidewall dynamo when the light is not needed. The SON will still have a small amount of drag when the light is off, but it is not noticeable.

If you use an efficient European light like those from Lumotec or Schmidt, you get a surprising amount of illumination. The beam on these lights is very focused which means that you get a good view of the road ahead, but there is little spillover to see off to the side.

The hub is beautiful, and the workmanship is first-rate. I have about 3500 miles on mine so far with no problems. I like the fact that the light is always there in case a daytime ride gets extended into the evening hours.

The Shimano hubs are less expensive but not as efficient. They are getting better, however, and distribution in the US is improving. Whether you choose Shimano or SON, however, you'll have to search around for a dealer and maintenance support. I recommend checking out Peter White Cycles at for more information.

Todd Kuzma
Heron Bicycles
Tullio's Big Dog Cyclery
LaSalle, IL 815-223-1776
Todd, I really like your posts...Dave Hickey
Jan 3, 2004 11:07 AM
You are an industry insider but you clearly state that in your posts. It's really nice to read an expert opinion from someone that not only knows what they are talking about but is also clear that they sell the goods being discussed...

Todd, I really like your posts...Heron Todd
Jan 3, 2004 2:30 PM
Well, thank you Dave. I like your posts, too.

Todd Kuzma
Heron Bicycles
Tullio's Big Dog Cyclery
LaSalle, IL 815-223-1776
I do ...Trent in WA
Jan 3, 2004 1:34 PM
... as do most of the other folks in the Seattle randonneuring club, some of whom use it to descend mountain passes at speed, at night, with confidence. As Todd points out, it's the most efficient dynamo out there. It's also pretty bulletproof.

The SON driving one or two Schmidt or Lumotec headlights is pretty much the gold standard for brevet lighting here and elsewhere in North America.

I don'tcyclopathic
Jan 4, 2004 6:29 PM
Schmidt has almost religious following: for most who rave 'bout SON it is the first /and quite often only/ generator system they tried and it actually worked.

However, there're alternatives, new generation bottle generators are more powerful, efficient, cheaper. Check new Busch & Muller, and esp LightSPIN dynamo. They will work with any wheel, not just specially built. Not needing special wheel makes package cheaper, and using generator with aero wheel helps to offset generator drag: at higher speeds 32 spoke front wheel required for SON will generate as much resistance as hub itself.

I had been using LightSPIN for 4 years, done numerous brevets, daily commute, PBP, BMB, etc. On many occasions I had a chance to compare it to SON, and with 2 Union Basta lights, wired in parallel it had consistently outperformed Schmidt/Lumotec.

here's some info on LightSPIN:
I don'tHeron Todd
Jan 4, 2004 8:30 PM
I don't know of any bottle dynamo that is more efficient than the SON hub. The figures provided by LightSPIN for their dynamo are for the efficiency of their internal circuitry. However, I believe that they do NOT include the losses from the interface with the tire. Once these losses are included, you'll find that the hub dynamos are still more efficient.

That said, sidewall dynamos do have their advantages for sure. In many cases, they may be the best choice, and the current crop of bottle dynamos are MUCH better than the old models most Americans are familiar with.

If you are using your lighting system for brevets and other poor weather rides, I'd suggest getting a wire wheel as offered by B&M to reduce slippage in the rain. The standard plastic wheels tend to slip when wet. The wire wheels will accelerate sidewall wear so many folks will swap the wheels back and forth according to weather conditions.

Todd Kuzma
Heron Bicycles
Tullio's Big Dog Cyclery
LaSalle, IL
here's some info, take a lookcyclopathic
Jan 5, 2004 8:00 AM
DYNAMO TESTING by Velo Plus, Switzerland (

Für den Alltag und Reisen ist immer noch eine gute Dynamoanlage die sicherste Lösung. Hochentwickelte Dynamos erreichen extrem effiziente Wirkungsgrade von 67 Prozent. Um etwas Licht in die Dunkelheit zu bringen, lassen wir unsere Dynamos testen. Wir verwendeten die computerisierte Testanlage der Firma Schmidt in Tübingen. Diese aufschlussreichen Tests sind eine der Grundlagen für unsere Sortimentsauswah

For the everyday life, errands and urban commuting a dependable direct current generator dynamo is the most reliable solution. Highly developed direct current generators achieve extremely efficient operation of up to 67 per cent (LightSPIN). In order to bring some light into the darkness, we set up our direct current generator test. We used the computerized test plant of the company Schmidt in Tübingen.Schmidt is the maker of the SON Dynamo- their test apparatus shows the LightSPIN dynamo superior to their own product and all other currently available units.

Typ voltage over speed Efficiency rate %
10 km/h 20 km/h 30 km/h 10 km/h 20 km/h 30 km/h
AXA-Traction 4.6 6.0 6.5 32 29 21
Light SPIN 5.1 6.3 6.3 71 67 58
Union Turbo 5.0 6.3 6.6 37 33 25
Union Walze 86011 5.2 6.3 6.6 33 26 20
FER 2002 4.8 5.8 6.0 39 35 29
SON Schmidt 4.9 5.9 6.8 64 56 48
NX30 Shimano2 4.9 6.1 6.4 50 47 42
Dymotec S6 3 6.0 6.5 6.4 52 40 30
Dymotec 6 3 5.0 6.4 6.7 35 29 23

1-medium tension against tire,
2-w/o switch,
3-with rubber pulley cover

In addition it should be mentioned front wheel accounts for ~4% of total losses, or 10wt at 250wt output. (

SON generates additional drag in off position, and case study done by UK audax ( shows sizable time penalty on events like PBP.

Unlike LightSPIN SON doesn't have built in volt regulator, which shortens bulb lifespan.

With respect to sidewall wear and slippage in rain, yes it may be an issue if generator set up off-center. LightSPIN uses rubber cups and on my commuter tire has ~2500mi, and while there's some wear, it is acceptable. Generator doesn't slip in rain driving 2 lights one 2.4w and another 3w.