Best lights for Brompton

[Kell]

As until now you did not mention which dynamo you used (and did not seem to know it): Which dynamo was it? And could you link those official figures please? I never saw official figures from Shimano regarding drag and efficiency and - until now - we were assuming that you were using the Shimano hub dynamo on your Brompton.

The bike I refer to was one of the bikes from a Brompton dock. It was around 4 years ago. Whatever factory fit dynamo was fitted to a Brompton at that time would have been the dynamo in question.

When I looked on the Brompton site at that time, those were the figures that were quoted for the dynamos. Whether or not that helps you to work out what it was, I don't know.

 

[Kell]

View attachment 464909

This picture illustrates the point perfectly to me. If the light was mounted on the factory mount under that bag, how visible is it really? Might be brilliantly located for lighting the road, but the bag blocks direct viewing of the light.

As mentioned above, it's all only opinions. Without conducting a test, I have no real evidence to provide you with, but from experience I know that people don't see cyclists at the best of times. Why make it harder?

And if you can find me a modern car with headlights mounted at 50cm, I'll be staggered. The ones on our Q5 are about 80cm. That's a guess based on the heights given below:

Ah, but that's a really tall car, so the lights are higher.

Well even our small car - a Mini, has the lights at about 75cm - again, a guess given on this diagram where the lights appear to be mounted slap bang in the middle of the car's height.

Besides, it's hardly a fair comparison. Car lights are brighter, fitted in pairs and spaced far wider apart.

 

[kais01]

i would hesitate to trust official figures. they have an agenda.

but tested figures are there for all to see. having a dynamo light on is a drag of 6-8 watts, according to cyclingabout eqivalent to on a flat road and steady speed have 20-30 kg of load on the bike. so no big deal

all giving a light output about a third of a good street legal usb light.

of course these figures are with 622 wheels. how the about 60 percent increased rpm of a brompton wheel influences this we can however only guess.

https://www.cyclingabout.com/dynamo-hub-drag-lab-testing/

 

[Kell]

PS. The irony of the fact that I think I’ve got a really good point, but no one else can see it is not lost on me.

 

[Ming the Merciless]

I was quoting the official figures for the dynamo fitted to the bike I used.

I googled them after I'd used them a few times as, despite what everyone else says, I definitely could tell the difference.

There won't be official figures as a percentage as they have no idea of your power output. Feel feel to provide a link to these official figures you think you have found.

 

[Kell]

There won't be official figures as a percentage as they have no idea of your power output. Feel feel to provide a link to these official figures you think you have found.

As I keep saying - this was FOUR years ago. And I've invited other experts to work out which factory fit dynamo would have been on a hire Brompton at that time.

 

[Ming the Merciless]

Anyway the point is you will really not notice any extra drag from a dynamo. It is not a valid reason for not having one. You may have other reasons but drag isn't one of them.

 

[Kell]

Anyway the point is you will really not notice any extra drag from a dynamo. It is not a valid reason for not having one. You may have other reasons but drag isn't one of them.

Well - it seems like it's up to a 2.7% reduction in speed - slightly less than the equivalent of carrying a 20-30kg load on a normal bike...

But the article quoted says that the gyroscopic forces generated by the wheels (assuming 700c or 26" wheels were used) makes the drag less noticeable - how much higher a figure would that 2.7% be for a Brompton wheel which doesn't generate anything like the same forces? For the sake of debate, imagine it doubles it to 5.4% and the article says that would be the equivalent of using Marathon Mondial tyres as opposed Almotion tyres.

People complain all the time about tyres having a noticeable effect...

As I said, I'm prepared to accept being wrong about the drag produced by more modern dynamos - hence my post about being willing to give a more modern bike a try.

I will still argue till I'm blue in the face about the factory positioning of them though.

 

[Kell]

A standard hub has some drag as a dynamo turned off. Unless your power output is extremely low it is nothing like 4% when turned on. You can get bigger differences in drag from tyres and wrong inflation pressures.

Light Switched ON While Cycling 10-30km/h
Schmidt SONdelux // 1.80w-6.10w drag
Schmidt SON28 // 2.15w-6.50w drag
Shimano DH-3N80 // 2.30w-7.25w drag

I highly doubt that you are able to notice the difference in power, especially given the fact that for 25 km/h on a Brompton you have to put in roughly 185 Watts (w/o) lights already.

7.25 as a percentage of 185?

3.91891891892

Or if you want to use the power figures that were featured in the article, then they estimate 150 watts.

So that makes the dynamo drag equivalent of 4.833333333333333%.

And that was on a bike with normal sized wheels with more rotational mass that generate greater flywheel effect. Would that figure be higher on a bike equipped with 16" wheels?

 

[Ming the Merciless]

Yep tyres cause a bigger difference as do a chain not lubricated.

 

[kais01]

yes tyres, worn jockey bearings and drivetrain can definitely be in the same league.

or a baggy jackets or a backpack protruding over your shoulders.

good reasons to not without thought use schwalbe marathons, marathon plus (ouch), and on your road and mtb bike 10t and 11t sprockets. with more than minimal use these wear themselves and the chain in short time.

taken together these factors can make a considerable difference. and the last watts are the hardest for your lungs and legs

 

[Britonabrompton]

Finding something to fit with the fold can be a little bit challenging, personally my issue with the standard lights (battery ones) is that the cateye 400 on the front is a little too bright, and I feel distracting for motorists as most of where I ride is cycle paths, especially on the flashing modes, which I like to use for visibility even in the summer, and the rear, I often forget to turn off, so often have flat batteries.

My solution (P-type bars ) is 2 smaller lights on the vertical part of the bars on the left side (traffic side for me, living in Sweden) as visibility lights. I have a Cateye wearable X (facing behind), and a smallish dual-purpose (does red and white, and flashing) light facing forward, but I guess any of the smaller lights from Knog (or countless others) would also work

 

[Kell]

Just bought one of these for the rear.

It's got motion sensors in so it gets brighter when you slow down.

Pretty reasonable at £16.99 but feels really well made. It's all metal rather than plastic. Zip-ties to the seat rails.

https://www.amazon.co.uk/gp/product/B07GYBBXC7/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1

 

[Britonabrompton]

just read through the whole thread, and noticed someone asking about the standard cateye light, and replacements for it. The current light is a cateye 400XC but with a different fitting, the same I assume as the old Volt400.

I bought a Volt150XC and an HL-EL135, both are compatible with the standard Bromptom fitting.

I don’t have an issue with the height of the front mudguard mounted light, as I also use a smaller flashing light on the handlebars, as mentioned above, and also a cateye duplex on my helmet

 

[PaulRoberts]

As I keep saying - this was FOUR years ago. And I've invited other experts to work out which factory fit dynamo would have been on a hire Brompton at that time.

My Brompton subscription bike has a Shimano DH-F703-SB front hub, I'd say they are all Shimano's in the docks.

(and yes I can feel the drag with the front light on)