berlinonaut
Veteran
- Location
- Berlin Germany
just as lumens can be misused and give a good numerical value for a light spreading its output all around, so can lux give a high value for a rather unusable keyhole pattern.
its nice if the light has a good and wide gradient concentrating the light further away.
the gvolt80 gives a such a light pattern, with reach and intensity comparable to your b+m. both are better with some fill-in in midrange. also for safety reasons i like the redundance of two separate front lights.
have taken away the dynamo lights (with led) on two of our brommies.
Regarding redundancy: I've never had a hub dynamo light failing on me. It is an upfront investment but fire and forget after that initial investment. Totally reliable. I've had battery lights failing on me countless times: Flat batteries, lights forgotten at home, lights falling of, lights deadjusting when hitting a pothole, lights becoming defect.
So in terms of reliability and comfort hub dynamo lights are literally lightyears ahead of battery lights, judging from my experience. In terms of weight battery lights tend to be slighly better but this obviously depends from the products involved - when using higher quality dynamo lights and battery lights that deliver a comparable output the weight difference is pretty neglectible. You may end up as low as a 50g advantage for battery lights (with a worse beam) that even turns into a disadvantage when carrying spare batteries with you.
Regarding the additional power necessary for the dynamo this ist totally neglectable with modern hub dynamos and unnoticable as well (the former Brompton-Shimano being an exception here as it is a very low-end model) - totally different from the bottle dynamos of the olden days.
I ride quite a lot in the dark, therefor most of my bikes that I use a lot have hub dynamos. However - suffering from the n+1 syndrome I can understand your issue with more bikes than would like to equip with hub dynamos for cost reasons. For a bike that get's ridden at night only occasionally I can live with battery lights personally. For a bike that get's ridden at night regularly (let alone almost daily) I'd always go for a hub dynamo.
Lumens are totally useless to compare lights as they only refer to the theoretical light output of the LED (which has nothing at all to do with the real world output let alone usable light or how well you will be able to see with this light). Lux is a bit better as it refers to the amount of light within a certain area in front of the bike - but it does not take the beam pattern into account. Thus lights with better/wider near view (desireable) may end up having lower Lux than those without.