What Rear Dynamo Light

I have one of these

https://www.bumm.de/en/products/dynamo-rucklichter/produkt/323-5altv.html?

I like the brake light and stand light.  a matching front light would also be good IMO - the one I have is no longer made but its a B&M one and the beam pattern is far superior being a proper shaped beam so you can light up the road without dazzling folk

had previously used:

https://www.bumm.de/en/products/dynamo-rucklichter/produkt/323alt.html?

but had three fail now.

now using:

https://nabendynamo.de/en/products/rear-lights/son-rear-light/

+ sep reflector

B&M internals still, but seem better sealed/built and been working for several years now.

Exposure red eye. Not had a failure in 6 years and all manner of weather. You’ll need to snip the exposure plug from the end to wire it into a non-exposure front lamp but you’d be wiring in any other lamp too. The new version has an m5 female thread in the back so just bolt on.

does a redeye actually work? given its not designed for dynamos I'd be surprised if it would accept the noisy electrical connection

i run the red eye off a dynamo via my revo works fine.

Biggest downside to the redeye is no standlight if your front light doesnt provide the standlight current. - Revo does provide the standby

Id like to add a red eye to a sinewave beacon but cant for the above reason.

I've been running a B&M View for a few years without issue, mounted using the saddle rail adapter. It has integral reflector and is pretty big so good visibility without lots of weight.

Thanks all, will take a look at those. I've also seen the Supernova one which might be a good option as with the front light I already have it'll have a standlight

Another vote for the exposure Redeye.

It's been on my commuter for 8 years and covered 17000 miles without being removed. Still works perfectly despite being so weathered the anodising has faded from red to pale pink.

It's paired with a Revo and Exposure branded SP dynamo.

i run the red eye off a dynamo via my revo works fine.

It’s paired with a Revo and Exposure branded SP dynamo.

doing a bit of googling, it seems the revo does something to the input voltage and reduces it so the back port is only pushing out 3-4V, compared with most dynamo lights which push out ~6 volts - I guess the conditioning its doing for its internal LEDs is passed out the rear port, whereas most lights just link the dynamo directly up. It might be ok, but its a bit of a gamble depending on how robust the redeye is with different voltages.

I've got a B+M Secula on my nice commuter, it's nice and bright with a built in reflector.  Mounted to the seatpost so it's protected from most of the spray by the mudguard, but sometimes makes it a faff to arrange bags out of it's way. I think it can be mounted to a sturdy enough mudguard though.

Cheap Chinese knockoff of a Topline on my cheap Chinese knock-off commuter. It's not as bright but does the job.

Another type of dynamo humm

doing a bit of googling, it seems the revo does something to the input voltage and reduces it so the back port is only pushing out 3-4V,

I've not looked at what is going on inside the light but I think it must be about 5v as I have occasionally used the Revo output port to charge my phone, gps and battery pack.

Exposure customer services are excellent. If you emailed them I'd be surprised if they didn't tell you whether it would work or not.

Edit - The Revo output is definitely DC though, not 6VAC that comes straight from the dynamo.

Just have a check that a supernova front will power a rear from a different manufacturer.  I know the rears only work properly with the front ones as the standlight capacitor is in the front. I think there may be an AC/DC compatibility issue.

Edit – The Revo output is definitely DC though, not 6VAC that comes straight from the dynamo.

Also bear in mind that if it's not regulated then the voltage from a dynamo is anything upto 72V, which is why Shimano still sell seperate regulators for use with older lamps. I'd check with the front lamp manufacturer as well to see whether the rear output is protected or not.

B&M D toplight here, it's big and has a large area, you can also get a replacement lens if it takes a knock so don't have to replace the whole unit.

https://www.sjscycles.co.uk/lighting/busch-muller-d-toplight-plus-50-mm-or-80-mm-bolt-centres-rear-dynamo-light-with-standlight-for-carrier/

@jonm81 What are you using between the Revo output and your devices?

now using:
> https://nabendynamo.de/en/products/rear-lights/son-rear-light/ < + sep reflector B&M internals still, but seem better sealed/built and been working for several years now.

+1. I have 2 bikes with this rear light on, fit and forget. It's bright but it's not too bright to ride behind in a group. Add some reflective tape to the cranks plus stays or guards and it's all you need.

Otherwise the B+M Secula is a great unit with a good seatstay mount. I think my Brompton has the dynamo-powered Toplight on it, that's also good - much larger than the SON plus a built-in reflector.

I'm using the SON that mounts to the rear of a rack (fitted to a custom made rack). It is beautifully made and fully sealed - tiny, bright and feels like it will last forever.

Previously used a B&M Secula on mudguard mount. It was poorly sealed and vibration broke the cable tabs off the internal board (had to do some lunchtime repairs with soldering iron and glue). Got it working again but wasn't very impressed with the internals.

..B&M Secula on mudguard mount. It was poorly sealed and vibration broke the cable tabs off the internal board

Oh : / I had one for a year or so, no issues. But it is a lot cheaper than the SON.

@shedbrewed To be honest it's been a few years since I charged anything with it.   I think I bought the cable from exposure years ago.  It's up in the loft packed away with my bikepacking kit.  If I remember at the weekend I might go up and find it.  It might be this one but I really can't remember https://www.amazon.co.uk/Exposure-Boost-cable-charging-devices/dp/B01CYM6QEU

I have to say it wasn't the best at charging as you only get the residual power after the front light has taken what it needs but if doing long rides it would keep a garmin ticking along.

Thanks. Appreciate that. 

there's some unboxed seculas on sjs at the moment

https://www.sjscycles.co.uk/lighting/busch-muller-secula-linetec-rear-dynamo-light-seat-post-seat-stay-fitting-unboxed/

I'm running a Secula and happy with it. Hard to beat at the price above 🙂