Dynamo lights yey or nay?

Last year I built up a wheel with an SP PV8 dynohub, like this one http://www.sjscycles.co.uk/sp-dynamo-pv-8-front-hub-32h-prod29696/ I bought it on ebay from the far East, I can't remember how much, but less than UK shop prices. I've got it paired with a Philips light from Rose http://www.rosebikes.co.uk/article/philips-led-front-light-bike-light/aid:489003?gclid=CMDTusKO9roCFZMDOgodJnAAzw I'm very pleased with the combination. Not as bright as some of the battery powered lights, but still quite impressive. The hub rolls very nicely and there is hardly any of the slight jolting you can get with dynamo hubs when moving slowly. In a completely different league to the old bottle dynamos. One of the best looking dynamo hubs too.

I commute on some dark roads, and it is bright enought to avoid pot holes, badgers and the like. For me the main attraction is not having to worry about forgetting to charge the battery, or leaving the lights at home.

AndyH01 wrote:

Do dynamos offer value for money over battery powered alternitives, appreaciate no batteries to fail however especially bottle dyamo could fail and need replacing.

These days, dynamo lights don't offer great value compared to battery lights, especially when you can buy some eBay special for £20.

However, dynamo lights are much more convenient. No batteries to mess around with, generally well designed lights that put the light where it needs to be. Battery technology has been left rather behind the curve of LED technology and you've got lights that'll put out loads of light, but only for a couple of hours; whereas a dynamo system will keep going all night long.

I've not got experience of bottle dynamos other than in hazy childhood memories, but dynohubs are very cost-effective these days. Shimano hubs have a great reputation and are very good value - I know of many people doing big miles on them and I wouldn't hesitate to use one nowadays - I run a couple of Schmidts, but they are pricey.

Lights - I like the B&Ms. I have run a Cyo for a couple of years on the Audax bike - it's now on my commuting bike. Great light for the money, really is.

As others have mentioned - shopping on the German sites may well help as the lights, in particular, can be a bit cheaper.

As mentioned, Spa are also worth checking out for their builds - one of my dynohub wheels was built by them, and it's given me no trouble at all.

My Schmidt Edelux dynamo light puts out something like 200 lumens, and lights up the road about as well as my Magicshine MJ808, which is a claimed 900 lumens.
It does this but putting almost all of the light on the road that you are riding onto, whilst the Magicshine both spreads the light all over the verges and overhanging trees, and isn't as bright as it says it is (450-500 lumens when tested). I would expect that the 500 lumens that the Moon XP500 claims is also considerably inflated.

There are new "premium" versions of the B+M Cyo & IQ Fly lights out in Germany, which are both brighter (80 lux vs 60) and with a wider beam. The price has remained about the same, with the non-premium versions being reduced in price (£35-£40). These newer lights don't seem to have reached the UK yet, with the old versions still being sold at full price. My Schmidt (above) is quite old, and the non-premium B+M Cyo is almost the same power.
Whilst more light is always nicer, it is perfectly possible to ride at relatively normal speeds with only 15 lux, which is about as good as it got back before bottle cage rechargeable lights started coming in the late 90s (Lumicycle, Cateye Stadium HID).
Wet roads are always going to be a problem. Even with car headlights you can't see the actual road surface well.

Bottle dynamos are fine for what they are meant for - providing light for about town utility riding. They don't usually slip unless asked to provide more power than the standard 3W, they are badly fitted, or there is some form of lubrication on the tyre (mud or snow). For winter club rides, the noise and extra drag compared to a hub dynamo are enough to put most people off. The other drawback is that they can damage lightweight tyre if not fitted correctly. The clamp-on mounts work fine on relatively heavy steel frames, but I wouldn't put one on a good bike.

Shimano hub dynamos are officially non-serviceable on the connector (right) side, though it is possible if you take care and don't do it very often. RHS service requires bending the connector wires to disentangle them from the cones, and they will only take so much bending back and forth before breaking. Service on the left is as for any other Shimano hub, except that you can't take the axle out. What you'd normally do whilst servicing the left side is to push the axle in a bit to expose a gap on the right side that you can squirt some extra grease into with a grease gun, and leave the right side otherwise alone.

Schmidt SON hubs are not user serviceable at all - they go back to Germany if required. The guarantee is 5 years, and mostly they don't need any service within that period. I've got an original version that has been in use since March 1998 without service, and which is now on its 5th rim.
SP hubs are also not user serviceable (I believe), and the last I heard there was no service facility in Europe and guarantee issues were being dealt with by handing out a replacement hub (with you or the shop having to sort out the wheelbuild).