Extra rear LED light - large diameter?

[dim]

I know it wasn't what you asked, but I'd look at this the other way round; having one large, dynamo light, I'd choose a bright, intense battery light for a second. It's worth having a second just as back up and as the most common failure in dynamo systems seems to be wiring, it makes sense for the back up to be a battery light.

fully agree .... lots of very good USB charged tail lights such as the Cygolite ... run both the rear dynamo light and the USB light at the same time .... even in the dark, you are never sure if your rear dynamo light has malfunctioned (unless you check or unless someone else tells you while you are riding)

but there's also the new USB Lupine "ROTLICHT MAX" for 105 Euros

https://www.lupine-shop.com/en/led-lightsets/taillights/1675/rotlicht-max



up to 120 hrs runtime on blink mode... fully adjustable with some nice features such as G-Force brakelight if you ride in a group etc

2W 160 Lumens
G-Force sensor for brakelight
Brightness sensor
4 different and adjustable beamlevels
Charging via Micro USB
CNC machined housing

https://www.lupine-shop.com/media/pdf/30/69/75/RotlichtMax_webo5Q813O3H4ZLL.pdf

on my wishlist for when I go touring or ride long Audax .... might get a family member to buy me one for Christmas

[LittleGreyCat]

The B&M Toplight Line Plus is one of the best rear lights for visibility and is itself pretty large. Whether the Spanninga Elips is significantly better, I don't know; I've seen both but never side by side. It certainly won't be significantly worse but I doubt it will be different enough to really make it worthwhile. If you want another large dynamo-driven light it probably is as good a choice as you'll get.

I know it wasn't what you asked, but I'd look at this the other way round; having one large, dynamo light, I'd choose a bright, intense battery light for a second. It's worth having a second just as back up and as the most common failure in dynamo systems seems to be wiring, it makes sense for the back up to be a battery light.

I do have an intense battery LED as backup but only as backup. I see no need of it if my dynamo light is working as it is rechargeable and would cause additional hassle if I used it as my main light.

As originally stated I am looking for an additional LED rear light, which I can add on or leave off depending on circumstances. I am not looking to replace my current rear light.

Mounting would have to be flexible, as one idea was to attach the light to luggage when carried and I have panniers and a rear rack bag. Which I don't usually use together.

From the information so far the concept of a second, auxiliary, LED dynamo rear light doesn't seem to be a mainstream concept.

One thing that I have noted is that the online details of the lights don't seem to give the wattage to enable me to calculate/guess if I have enough output from the dynamo to drive any given combination.

[pwa]

I know it wasn't what you asked, but I'd look at this the other way round; having one large, dynamo light, I'd choose a bright, intense battery light for a second. It's worth having a second just as back up and as the most common failure in dynamo systems seems to be wiring, it makes sense for the back up to be a battery light.

Good point. If you are having a second rear light, make it one that is entirely independent of the other so that if a problem affects one it will not affect both.

[squeaker]

but there's also the new USB Lupine "ROTLICHT MAX" for 105 Euros

105 euro and it's held on with a rubber band

(Hope the g-force sensor is better behaved than the Cateye Kinetic X2 Rear light which goes 'stoplight' on typical minor road surfaces...)

[dim]

but there's also the new USB Lupine "ROTLICHT MAX" for 105 Euros

105 euro and it's held on with a rubber band

(Hope the g-force sensor is better behaved than the Cateye Kinetic X2 Rear light which goes 'stoplight' on typical minor road surfaces...)

this is Lupine not cateye ...

top quality and regarded my many as the very best .... expect to pay £1000 for a front light from them

[slowster]

Battery back up lighting makes sense, although for the front the criterion of whether the light is to be seen by or to see by on unlit roads will probably make a substantial difference to the cost and bulk of the light. Moreover, whereas rechargeable lights are the obvious choice where battery powered lights are the primary form of lighting, for emergency back up lights which can use disposable lithium batteries with a very long shelf life, and which can be carried in luggage and quickly fitted to the bike, seem like the best option to me. I would want the back up front light also to be suitable for fixing a puncture or mechnical in the dark, e.g. possibly a head torch like the Petzl Zipka.

As originally stated I am looking for an additional LED rear light, which I can add on or leave off depending on circumstances. I am not looking to replace my current rear light.

Mounting would have to be flexible, as one idea was to attach the light to luggage when carried and I have panniers and a rear rack bag. Which I don't usually use together.

From the information so far the concept of a second, auxiliary, LED dynamo rear light doesn't seem to be a mainstream concept.

One thing that I have noted is that the online details of the lights don't seem to give the wattage to enable me to calculate/guess if I have enough output from the dynamo to drive any given combination.

Since you have the B&M Toplight fitted to your pannier rack, the obvious, easiest and simplest solution is to fit a B&M Secula Plus light to your mudguard, and power it as I have described above by a short section of cable from the Toplight's second set of connectors. Once fitted there is no need or point in being able to take off and re-fit a Secula Plus: it's unobtrusive and does not weigh much - a case of fit and forget.

I've got a Toplight and a Secula Plus fitted to my tourer. Like you I was unsure about the adequacy of the power for both lights, but I could not find a definitive answer so I just went ahead and fitted them both anyway. To check the result I went for a short one mile ride in the dark to charge up the capacitors which power the standlight function and then got off and had a look at the lights, and I was very pleased with the visibility of both.

I've already described above how to connect a Secula Plus using the supplied wire and connectors. I would add that I would choose the mudguard mounting version, not the seatstay mount version. You just need to drill two holes in the mudguard to fit the lamp. If your mudguard is made by SKS/Bluemels and has a small square reflector, then you simply remove the reflector and fit the Secula Plus using the existing holes. Note however that if your mudguards have a triangular reflector like the one shown in my post here, that is a permanent riveted on fixture, and you would have to mount the Secula Plus above it.

[LittleGreyCat]

The advice from "slowster" is good if I was looking for a permanent extra central rear light.
I may even end up doing it.

However the start point was looking for an optional (not permanent) rear light to probably go on a rear pannier to give more width to my rear light profile.

Something like the Secula Plus might well do the job (probably in seat post mount version).

The picture I had in my head was something circular and probably up to 10 cms in diameter whereas most lights seem to be designed as oblong to fit neatly onto the standard fitment on a rear carrier, or onto a mudguard (as with the Secula Plus).

It is looking as though nobody makes one specifically for bikes (as the proposed fitment is non-standard).

[Bmblbzzz]

It sounds as if you're looking for something that will be visually similar to the old Ever Read Night Rider.

[LittleGreyCat]

It sounds as if you're looking for something that will be visually similar to the old Ever Read Night Rider.

I think so, if that is what I remember.

I still have stock of pre-LED large battery lights which I really must chuck out as they will never be used again.
The oldest have circular lenses and reflectors.

I suppose if you wanted extreme longevity you could replace the filament bulb with an LED which would probably run for months but they are very bulky and designed for fixings a few generations back!
Also the beam would probably be completely wrong anyway.

[Bmblbzzz]

I think it is possible to buy LEDs designed to slot or screw right in and replace filament bulbs of the most common styles. I've no idea how much they cost but unless you want to keep a period appearance, perhaps to match an old bike, I doubt it's really worthwhile for the reasons you state: the optics will be wrong and you've still got the weight and bulk of those enormous D cells (and in this case, those clunky and not particularly secure brackets).

Edit: It's probably not as simple as dropping an LED into a bulb holder. There might be voltage things you need to do. ???

[slowster]

However the start point was looking for an optional (not permanent) rear light to probably go on a rear pannier to give more width to my rear light profile.
...
It is looking as though nobody makes one specifically for bikes (as the proposed fitment is non-standard).

In that case, buy a battery powered Spanninga Elips and figure out a way of attaching it to your pannier. The back of the housing comes off (as shown here), and it should be possible to modify it and bolt or even glue a clip or other method of attachment that would suit your particular panniers.

The battery version would make much more sense than trying to power it from your dynamo, since that would entail remembering to disconnect it every time you took the pannier off (and apart from the 2-Pole Connection for Son's coaxial cable, most dynamo connectors are not designed or suited to frequent disconnection and re-connection) and having a loose hanging cable which would be likely to get caught on something and damaged.

[andrew_s]

For frequently disconnected dynamo lights, there are Dyna-snap magentic connectors (at a cost)

[gaz]

Edit: It's probably not as simple as dropping an LED into a bulb holder. There might be voltage things you need to do. ???

It would be that simple and you could run with AAs in D cell convertors but you'd still have all the other issues that both yourself and LGC gave mentioned.

In addition Reflectalite, the usual source for these things currently specs 1W rear LEDs, which IMO would be in the retina burning category.

[LittleGreyCat]

However the start point was looking for an optional (not permanent) rear light to probably go on a rear pannier to give more width to my rear light profile.
...
It is looking as though nobody makes one specifically for bikes (as the proposed fitment is non-standard).

In that case, buy a battery powered Spanninga Elips and figure out a way of attaching it to your pannier. The back of the housing comes off (as shown here), and it should be possible to modify it and bolt or even glue a clip or other method of attachment that would suit your particular panniers.

The battery version would make much more sense than trying to power it from your dynamo, since that would entail remembering to disconnect it every time you took the pannier off (and apart from the 2-Pole Connection for Son's coaxial cable, most dynamo connectors are not designed or suited to frequent disconnection and re-connection) and having a loose hanging cable which would be likely to get caught on something and damaged.

You are very tenacious in trying to change my design using methods I keep saying that I don't want.

Connectors for frequent make/break aren't an unusual thing, and there is no big problem in extending the spade connectors on the back of the rear light to an intermediate point where the multiple make/break actions can take place.
Such a flying lead would be a disposable item, easily replaced if it showed signs of wear.

[slowster]

Fair enough. Since you have a fairly precise idea of what you want, have a go at making it.