Wednesday, December 14, 2011

First impressions: SP Hub Generators PD-8 and PV-8 (updated)

Wouter Scholten's website is a great resource for all hub generator lighting issues. He extensively tests almost all models of hubs and lights on the market in real world settings, and he is also unusually well-informed with regard to the introduction of new products. A while ago, he wrote about a new player on the hub generator market, Shutter Precision Ltd. from Taiwan. As the name implies, they started as a supplier for digital cameras and then later moved into bike component manufacturing. While the company itself has little name recognition, they are (presumably) the suppliers for two better known companies, Velo Orange[1] and Supernova.

After having introduced their switchable dynamo (in my opinion a solution in search of a problem), at the 2011 Taipei Cycle Show SP announced what would be the lightest generator hub, the SD-8 (disc brake)/SV-8 (rim brake). These two hubs, however, only are rated to a power output of 2.4W in a 622mm wheel, making them not street-legal according to the German StVZO requirements. However, they also announced a slightly more heavy model rated at 3W, the PD-8 and the PV-8. The technical specs and the prototype tests by Wouter sounded promising, and when Wouter's shop, Gambiet Fietsen, offered them for pre-order in September I went in for two generators, one disc, one rim. The disc one will replace my Shimano DH3-N80 on the Cross-Check which I unfortunately messed up while trying to re-grease the bearings, and the PV-8 will be part of a second front wheel for Gunnar, finally allowing me to turn him into a real brevet bike.

The hubs arrived yesterday, at a total price of 180 Euro shipped. The actual wheelbuilding will have to wait for a little while longer, but I wanted to share some pictures and impressions.
PV-8 in its original packaging. I'm not sure if all the color and spoke count variants are or will be actually available.

The hub looks quite similar to the current SON 28...

...but it does have the same terminal as Shimano hubs

Here you can see the German K-certification wave, making the generator street legal in Germany

The weight pretty much exactly matches the claimed weight.

Both the disc and non-disc version of the hub match their claimed weight of 390 g and 410 g, compared to 440/460 for the new SON 28, 490 g for the Shimano DH3N80, and 399 g for the Supernova Infinity S (center lock disc mounts). Only the SONdelux at 390 g (rim) and 395 g (disc) can match this, but at a significantly higher price point.

SP claims that the new generators do not only excel in weight, but are also "the most efficient" generators (this refers to the 2.4W ones) and their product sheets has a couple of graphs that show the generators to be more efficient than the SONdelux. I'm somewhat skeptical about those claims and am very much looking forward to some independent testing.

Measuring the dimensions of the hubs is a bit tricky with the tools I have and I've only been able to find the manufacturer's numbers for the 2.4W version. Probably they're going to be the same for the 3W, but I'll confirm this with Wouter or measure myself. The bearings are sealed cartridges and I'm not sure if they are user-replaceable.

I think that's all I can say for now. Once I have the wheels built up and ridden them a bit, I will post an update.

Update 2011-12-16:
In the meantime I've found the website of SP's distributor, and their catalog lists the relevant dimensions as follows:
PV-8 PD-8 (non-disc/disc side)
Spoke P.C.D. 52mm  52mm/58mm
Flange diameter 60mm 60mm/66mm

They also have "replacement instructions" on their site that might contain instructions on how to replace the bearings. Unfortunately, the document is corrupted, though, and can't be opened. I've sent them an e-mail and we'll see if I hear back.

[1] If I remember correctly, the Velo Orange switchable dynohub got some bad reviews. At any rate, they no longer seem to sell it.
[2] There is also a 2.4W version, called SD-8/SV-8, suitable for those on small-wheeled bikes or those who don't care about the extra power/street legality in Germany.


  1. I'll be interested to hear how these do. I was very skeptical about the VO hubs, and I believe their weight was much higher too (there was a very large metal disc as the switch). My Shimano DH-3n80 is still going strong even after a shop mechanic yanked the wire out about a year ago when I asked for new bearings. The Cyo has taken a good beating too - scratches on the lens, and water spots from a cleaning mistake with the bike upside down. I think Santa is getting me a taillight for the system this year too.

    I saw a good comment about the power output of dynamo hubs that I agreed with: It would be ideal for us to have lights that reach full power closer to 12-15mph instead of 3mph, since that could reduce the drag even further. Or keep a similar amount of drag, but have a light with more output at the typical cruising speeds.

  2. Yeah, the broken cable is what happened to my Shimano, too. Unfortunately my soldering skills were not good enough to fix the issue.Soldering aluminum wire in a tight spot is hard.

    About power output: I honestly don't care about the little drag that modern generators create. If you do care, however, you should get one of the generators made for 20" wheels. They do exactly what you want: create full power only at higher speeds. The only problem is that with LED lights you will have to day with flickering lights at lower speeds. Not worth the saved 20g and 0.x W, IMO.

  3. I love my SP dynamos. I also have the PV-8 for the road and a PD-8 for my mountain bike, and my own home made light!

    There's a bit more on my MTB setup here:

    I got my SP hubs from IDC, who did a great service and speedy delivery:

    I'm getting a switchable one next for minimum rolling resistance in daylight

    1. Hi Rob, good to hear that other people have the SP dynamos too and are happy with them. I'm very curious to see how the hubs will hold up in the long run. I still have to wait for spring to actually test the one on my road bike.

  4. Thanks for the posting on the Shutter Precision PV-8. Had you had a chance to use the dynamo and do you have any updated thoughts worth sharing on it?

    Also I am curious as to whether you have any idea if the Supernova dynamos are in fact SP ones.


    1. Hi Andrew:
      I've had the PV-8 on my road bike for two months now. I've done probably 1000 km on it, including two 300 km brevets. So far I have zero complaints. The vibrations are less noticeable than on my Shimano DH3N80/72, they output enough power, the wheel holds up well. At this point the only question is how long they will last and how the bearings can be serviced. The disc hub which will go on my everyday bike I still haven't built up but I plan on doing it before winter arrives.

      Re Supernova: I'm 95% sure that the Supernovas are made by SP. If there are any differences in quality control or other aspects I don't know.


  5. detailed CAD drawing of the hub:

  6. Hi
    I used a SP PD-8 dynamo hub on a recent solo cycling trip across Europe. I cycled about 9000kms in total in -15 to +52 degree heat. I cycled in pouring rain and 100s kms in dirty and dusty tracks.
    I cycled in 13 countries in total over three months. My chain broke, my cassette broke and I had serious issues with my gears, but not one single issue with the dynamo hub.

    The SP PD-8 is a sealed unit and as such isn't really serviceable by the user, like most dynamos.
    I am no mechanic, so I wouldn't attemp to repair it if it broke, but maybe someone with better skills may find it easier.

    All I know for sure is that it has done about 9000kms of trouble free cycling and gets my vote for durability.

    1. Darron, that's great to hear! I don't have quite as many kilometers on my units as you do, but I also haven't encountered any issues so far. Thanks for providing feedback.