Can Somebody Please Explain Dynamo Lighting To Me?

[tyred]

I don't rate the B&M Dymotec. It's overpriced, noisier than the HR traction and the spring which holds it against the tyre seemed to give up the ghost on mine. It's the only bottle dynamo that I've used that actually failed and I own ones from the thirties which still work fine.

I'd say the Axa HR traction is the pick of the bunch. I must try to work out how to fit my spare one to my Brompton.

 

[JhnBssll]

Not to confuse matters, but regarding voltage stabilisers etc its worth pointing out that most modern "dynamo's" aren't technically dynamo's at all... Sorry if this isn't new info but I haven't seen it been stated yet

Dynamo's are mechanically commutated and produce DC current as you would get from a battery - the faster you spin them, the higher the voltage you'll see across the terminals. As a result, bulbs would pop if they were spun too quickly. External voltage stabilisers were added to limit the peaks and prevent this from happening.

Modern day "dynamo's" are actually magneto's, similar to the alternator in a car. They are not mechanically commutated and produce an AC current like you would get out of a plug socket (only much lower voltage). The AC current is then electronically converted to DC by means of a rectifier circuit. The electronics are housed within the "dynamo" casing and act to regulate the voltage as well so an external voltage stabiliser is often uneccessary.

The main advantage of the magneto over the dynamo is the lack of mechanical commutation. Since there are no carbon brushes to wear out keeping the bearings in order is the only maintenance required.

 

[MichaelW2]

I fitted a Shimano Ultegra grade dynamo disk hub in 2008. It is fit and forget. I use a b&m front lamp and smart dynamo rear lamp under the rear rack.
The only disadvantage of Shimano is that servicing is very tricky, it is easy to sever the metal tape conductor and hard to fix. Few shops will attempt it. How many of you have ever serviced yours?

 

[gazza_d]

Hub dynamos are by far the best solution. Fit and forget, always available, and (for me at least) no discernible drag. You won't regret it
Both of my Moultons have hub dynos for a year round commute.

Unless you have a wheelset, then the cheapest solution is to buy a ready built wheel from Taylor wheels. You can get a wheel built with a dyno from about 40 quid. I use Herrmans H One S front lights which are 75lux with a rear attached and they are really bright. You're best looking at the german/EU sites as they tend to have a much better selection & cheaper than UK.

I wrote up about my systems a while ago http://cyclingsouthtyne.blogspot.co.uk/2015/12/dynamo-lights-on-budget.html

 

[confusedcyclist]

Yes, another vote for hub dynamos. I specifically took up wheel building to build a hub dynamo for my commuter bike, I still ride with a backup battery powered LEDs in case of unexpected failure, but I don't sweat it if the battery dies. As others have said, hub dynamos are fit and forget and very rarely need fettling. In the last two years, I've only had trouble once when the cables become unclipped, I assume someone snagged them in the bike rack due to my loose routing (that'll teach me!). Oddly, hub dynamos don't seem that popular in the UK, I assume as cycling remains a 'leisure' activity for most, whereas on the continent where commuting is the norm, these systems are commonplace, their benefits are more obvious. I wouldn't want to ride on the TdF with a hub dynamo, but I wouldn't quibble about taking one out on a club run, especially if you have the option to reduce resistance to almost nothing by switching the lamp off. They are actually well suited to long distance rides, as there's no battery to worry about. They can also charge your gadgets...

As with all bike components, you can spend as little and as much as you like. Generally when deciding which hub to choose, you'll need to decide what to prioritise. You need to consider efficiency (i.e. less resistance when in power is drawn from the lamp, and more noticeably in better models, near zero resistance when your lamp is off), aesthetics of the hub/build quality or keeping costs down. Most modern hub dynamos don't have (user) serviceable bearings on both sides, so you'll want to opt for a more durable bearing construction (sealed) if you are concerned about that. However, cheaper hubs might have the edge here as you'll be less concerned about the cost of replacement when the time comes. Personally, I didn't want a hulking shimao hub on my pretty new surly, so opted for something a bit better looking, and more efficient to boot.

I have an SP PD-8 hub up front, an B&M IQ-X front lamp, and a B&M Secula LineTec Rear mounted to my seat post. I think these hubs are rated at about 40,000 miles, so at my mileage, it should last a decade. Truth be told, if I get 5-6 years out of the wheel, I'll be happy. I was going through a lot of USB charging lamps at £20-50 a pop. The front and rear lamps are excellent, among the best. You could pay a lot less for a perfectly functional lamp, but I do a lot of dark riding, so wanted the best I could afford at the time.

 

[Ajax Bay]

@gazza_d 's write up - thank you btw - included this link "This is a really comprehensive guide to dyno lights with shots of the lights in action"

 

[andrew_s]

The AC current is then electronically converted to DC by means of a rectifier circuit. The electronics are housed within the "dynamo" casing and act to regulate the voltage as well so an external voltage stabiliser is often uneccessary.

Not usually.
Bicycle dynamos put out AC, apart from one or two rare models.
Rectification wasn't needed for filament bulbs, and got included in LED dynamo lights to maintain compatibility.

Bottle dynamos often contain a voltage limiter (back to back zener diodes, usually) to avoid blowing filament bulbs at high speed, but many filament bulb lights also contained them. If neither the dynamo nor the light contained a voltage limiter, you needed to add one.

Hub dynamos are generally designed such that they give about half an amp, and won't give very much more current at all, but will give considerably more than 6V if it's required to push the half amp through the attached load, and you're going fast enough. LED lights have a fair amount of electronics inside, both to convert the dynamo AC into 3.5V DC for the LED itself, and to provoke a hub dynamo into needing to give higher voltages, and hence more power, to reach its half amp.
The current limit is because as you go faster, the AC frequency increases, and there isn't time for the magnetic field to build up to fully saturate the iron dynamo core before the next reversal (or something like that anyway).

 

[cosmicbike]

Had a minor brainwave tonight when I remembered the ICE trike came with dynamo lighting when I bought it from the member formerly known as @trikeman on here, but I removed the front as I took the screen off, I'm very much a fine weather trike-ist. Been in the garage playing, and I think the front is a B&M Lumotec IQ Cyo Senso Plus, and the rear is a Toplight Line Plus. There is a B&M bottle dynamo fitted to the rear wheel. A little time putting some temporary wiring together and then the wheels were spun up. Hey presto, we have light #
Both the front and rear have the 'standlight' function, and the front is a Senso version so it knows when it's dark apparently. Quite impressed with the light output from the front, which as far as I can figure is either 40 or 60 lumens.
Next step will be to remove from the trike, and bodge onto the commuter as a trial. If I like it then I'll look for a dynamo hub wheel.

Thanks for all the input folks

 

[mjr]

I suspect it'll be 40 or 60 lux, maybe ten times that in lumens.

 

[smutchin]

Quite impressed with the light output from the front, which as far as I can figure is either 40 or 60 lumens.

It'll be 40 or 60 lux, not lumens.

Lumens are a measure of light output, lux is a measure of illumination and tells you how much of that light output falls on a fixed point - IIRC German regulations stipulate a point 10m directly in front.

If you get one of those cheapo Chinese 2000 lumen lights off ebay and measure the beam with a light meter, you might find it actually gives less than 60 lux at that same point, but also scatters the same level of light indiscriminately in all directions, whereas B&M Lumotec lights have properly shaped beams so the light only goes where you want/need it. The IQ-X has a very noticeable cut-off at the top so you don't dazzle road users coming the other way, but is also wide enough to give excellent peripheral vision at the same time.

 

[cosmicbike]

I suspect it'll be 40 or 60 lux, maybe ten times that in lumens.

Yep, lux it is

 

[confusedcyclist]

Had a minor brainwave tonight when I remembered the ICE trike came with dynamo lighting when I bought it from the member formerly known as @trikeman on here, but I removed the front as I took the screen off, I'm very much a fine weather trike-ist. Been in the garage playing, and I think the front is a B&M Lumotec IQ Cyo Senso Plus, and the rear is a Toplight Line Plus. There is a B&M bottle dynamo fitted to the rear wheel. A little time putting some temporary wiring together and then the wheels were spun up. Hey presto, we have light #
Both the front and rear have the 'standlight' function, and the front is a Senso version so it knows when it's dark apparently. Quite impressed with the light output from the front, which as far as I can figure is either 40 or 60 lumens.
Next step will be to remove from the trike, and bodge onto the commuter as a trial. If I like it then I'll look for a dynamo hub wheel.

Thanks for all the input folks

SJS cycles sell all the mounts and bits, good luck!

 

[andrew_s]

...and the front is a Senso version so it knows when it's dark apparently.

As you've got a bottle dynamo, I'd recommend ignoring the senso setting. A bottle dynamo is noisy enough that you are only going to have it running when you want light, and the senso can't move the dynamo against the tyre or turn the light on when the dynamo isn't running.
Senso is meant for hub dynamos that are running all of the time. There is a suitable hub dynamo for an ICE trike, but it's expensive (£290 plus wheelbuilding)

 

[cosmicbike]

Bit of a thread resurrection. It's the middle of Summer, and who needs lights? Well I do , as I'm working nights at the moment and riding home in the dark. Afetr a flat battery moment I've had a fiddle. I ordered the bottle dynamo mount from SJS back in January, but have not gotten around to doing anything until today.
Bottle dynamo fitted, rear light fitted. I need to get the B&M IQ mount for the front light as it was on the front derailleur post on the trike.

All a bit heath Robinson, but it works. A tad noisy and I reckon I'll notice when it's on the wheel, but it's a tester. Rose bikes do a basic hub dynamo wheel for £60 plus a tenner to deliver, so if I like the idea I'll get one ready for Winter.

 

[si_c]

Bit of a thread resurrection. It's the middle of Summer, and who needs lights? Well I do , as I'm working nights at the moment and riding home in the dark. Afetr a flat battery moment I've had a fiddle. I ordered the bottle dynamo mount from SJS back in January, but have not gotten around to doing anything until today.
Bottle dynamo fitted, rear light fitted. I need to get the B&M IQ mount for the front light as it was on the front derailleur post on the trike.
View attachment 421026
View attachment 421027

All a bit heath Robinson, but it works. A tad noisy and I reckon I'll notice when it's on the wheel, but it's a tester. Rose bikes do a basic hub dynamo wheel for £60 plus a tenner to deliver, so if I like the idea I'll get one ready for Winter.

Definitely get the hub wheel. There is no downside - it's entirely silent and more efficient.