Originally Posted by
busted knuckles
I have a shutter precision on my big dummy. Its good. Its not as good as the son I have on my LHT. You pretty much have to be riding the bike to get full power to the lite, withe the son, walking will give full or close to full power. I have no problem with the SP, it is about half price.
Busted knuckles, what SP hub model do you have? The "S" series (SD-8, SV-8) hubs are designed to output 3.0w on 20" wheels (2.4w on 700c wheels), similar to the Schmidt SonDelux.
The "P" series (PD-8, PV-8) on the other hand, is designed to output 3.0w on 700c wheels, like the Son 28.
For an accurate comparison of the two brands, the models of both hubs would need to be known. In any case, I have not noticed any observable difference between the light output of the SP PV-8 and the Son 28 at either walking or riding speeds.
Originally Posted by
zacster
6v 2.4 watts, may be good enough. Don't put a taillight on with it though.
2.4w should be enough to power a headlight and taillight provided low power LEDs are used. Since less electrical drag is produced if less electrical output is produced, some riders use 700c wheels built with dynamo hubs designed for 20" wheels. According to Peter White Cycle's webpage, even German StVZO has changed to allow this.
A dynamo powered headlight must reach a certain brightness at a certain minimum speed. If you use a hub designed for 20" wheels to make a wheel with a 700c rim, that wheel will be rotating at a slower RPM at a given speed than the same hub in a 20" wheel, so the hub's output will be lower. With a halogen bulb headlight, the light would not reach the minimum required brightness until you were going faster than the law requires. But with LED headlights such as the Schmidt Edelux, Busch & Müller CYO and others, this isn't a problem. You can use a hub designed for 20" wheels in a 700c wheel and the light will be very bright at low speeds. Previously, it was illegal under German law for Schmidt to sell the SON20R in Germany for use in 700c wheels. But the law has been changed, provided the customer also buys a LED headlight. So now, Schmidt can sell the SON20R for use with 700c rims, as long as the wheel is used to power certain LED headlights that produce high output with very little power.
http://www.peterwhitecycles.com/schmidt.asp
I do find it interesting that the specs show this wheel is designed to output 2.4w on a 20" wheel, which means it would produce even less at the same speed on a 700c wheel due to lower RPM.