Wayne, I'd like to add a third reason:
3. They are not user serviceable. Here's what I found on the Shutter Precision FAQ: *How often do SP hub dynamos require service?* SP hub dynamos employ sealed bearings that do not require service until the bearings are require replacement. We already have customers that have logged over 10,000 kms without any problems and we expect that under normal use the service life of these bearings should be well over 20,000 kms. Should they ever need servicing, they can be sent back to SP and replaced with new ones for roughly USD 30 including the cost of return postage. *Are SP hub dynamos user serviceable?* Alas, SP hub dynamos are *not* user serviceable and indeed we are aware of no hub dynamos that are based on manufacturer’s recommendations. *Any attempt to service a SP hub dynamo will **void its two-year warranty* <http://www.sp-dynamo.com/Support.html>*.* We have received quite a number of requests from consumers on how they might service their hubs even accepting that attempting to do so would void their two-year warranty. They accept this risk thinking that this would save the need to disassemble and rebuild the wheel. Unfortunately, the design of SP hub dynamos like that of many other brands requires disassembly of the wheel for bearing replacement. Furthermore, the delicate generator mechanism housed within the hub body must be re-calibrated to tolerances of less than a millimetre each time bearings are replaced. Failure to carry out this operation properly (which is likely without expert knowledge, experience and tools), will generally result in catastrophic failure of the generator mechanism after a period of use. SP engineers have considered making their hubs user serviceable (with much prodding from IDC at the behest of our technically savvy testers). But the expertise and equipment required to carry out recalibration of the generator mechanism each time the bearings are replaced presents a technical hurdle that SP engineers, and indeed all other hub dynamo manufacturers we are aware of, have so far declined to attempt. Did you catch the part about having to disassemble the wheel in order to replace the bearings! 20,00kms is roughly 12,000 miles. So every 12,000 miles you need to tear down your wheel, ship it off for new bearings, pay $30 + return shipping, and than rebuild your wheel. WOW. That combined with the initial buy-in makes dynamos a pretty expensive proposition. I suppose if you really need it than there is no substitute. But by comparison, just tonight, I replaced the original lithium-ion rechargeable battery in my USB-charged NiteRider Cordless 600 for a total cost of $10.99. This light was purchased in 8/2011. I use it light 5 days-a-week, year round on my early morning commute. With an initial cost of $108 it has proved to be a pretty good value. Matt On Wednesday, September 24, 2014 10:11:18 AM UTC-7, Wayne Mesard wrote: > > I'd like to anti-recommend the dynohub approach. I considered it when > building my Sam, but rejected it for a couple of reasons: > > 1. They're expensive! > 2. You pay the wattage tax whether you're using the thing or not. The > Interwebs say that the drag costs anywhere from 2 to 15 watts of additional > pedal power. That's not a lot. But it's not nothing either. > > Instead, I bought a USB battery ( > http://www.amazon.com/gp/product/B00IP1MQNK/), which I'm quite happy > with. That way I have backup power for all my devices, since they all > accept USB power (front and rear lights, GPS, cell phone, AfterShokz > headphones). With the money I saved, I could have bought five of them, but > one was more than enough. > > On my most recent tour, I had no problem keeping the battery charged by > plugging it in overnight and opportunistically at lunch stops. But just to > be safe, I also got a solar panel ( > http://www.amazon.com/Goal-Zero-11800-Nomad-Solar) which mounted easily > to the rear rack. Like I said, I didn't need it; but I was glad to have it > as a backup. > > Wayne(); > > > -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To unsubscribe from this group and stop receiving emails from it, send an email to rbw-owners-bunch+unsubscr...@googlegroups.com. To post to this group, send email to rbw-owners-bunch@googlegroups.com. Visit this group at http://groups.google.com/group/rbw-owners-bunch. For more options, visit https://groups.google.com/d/optout.
