Dynamo hub light bracket for disk frame

[simon.r]

Thanks for asking this question, @tallliman and for the replies.

I’ve been struggling with a similar issue and currently have numerous old brackets / spacers / odd bolts etc. on my workbench. I keep looking at them but haven’t come up with a neat solution yet! I think one of those mounts sold by SJS may be the answer for me.

 

[tallliman]

Which one do you think you'll go for?

 

[simon.r]

Which one do you think you'll go for?

My issue isn’t with discs, but with a long reach calliper and mudguard combination where fitting a conventional bracket means the brake blocks are moved slightly and can’t be adjusted to hit the rim, or the steering is restricted. It’s difficult to explain in writing, but believe me when I say I’ve tried everything.

I need to have a proper look at the bike and think about:

Possible obstructions (e.g. Handlebar mounted bag)
Wiring route to the light and from the front to the rear light
Aesthetics!

But probably the one that replaces a stem spacer.

 

[Ajax Bay]

Maybe the latters size is close enough to also fit the head tube.

I don't recommend a front light fitted to the head tube

 

[simon.r]

I don't recommend a front light fitted to the head tube

Why? That’s one of the options I’ve been looking at, mounted low down on the head tube (i.e. a few inches above the front wheel).

 

[rogerzilla]

It's terrifying in corners!

 

[simon.r]

It's terrifying in corners!

Ah, good point!

I suppose I’m coming from a ‘be seen’ rather than ‘seeing’ perspective as the vast majority of my night / poor visibility riding is in well lit urban areas.

 

[Yellow Saddle]

What is your fork made of? Mine is carbon and I drilled a hole where I needed it and fitted a threaded insert with carbon-fibre resin.

 

[Nigelnightmare]

You can fit a light to a mudguard eye too. Same principle as the low rider mount, just lower. Only strictly legal for 700c and larger, or the light isn't the minimum distance from the ground.

What is the minimum height "for a bicycle/HPV Front light"?
I only ask as according to the Road Vehicle Lighting Regulations the height limit is 1,500mm MAX not minimum.

Front light.
At least one lamp is required, showing a white light, positioned centrally or offside (the right-hand side of the bike), up to 1500mm from the ground, aligned towards and visible from the front. If capable of emitting a steady light, it must be marked as conforming to BS6102/3 or an equivalent EC standard.

If capable of emitting only a flashing light, it must emit at least 4 candelas.

Note: It might sound obvious, but the light needs to be fixed to the bicycle; there is a fashion for helmet lights which can be pointed in the direction you're looking which might be useful but is not legal. A single helmet mounted light doesn't conform - and if you're an adult, then the chances are that your helmet light will be more than the 1500mm height limit from the ground anyway.

The reference to '4 candelas' isn't very useful because most bike lights are given an output in 'lumens'; for a guide, 1 candela approximates to 12 lumens, so the tiny blinky flashing lights which usually put out around 25 lumens won't enough on their own; you'll need at least two of them.

HTH

 

[andrew_s]

12.6 (4π) lumens = 1 candela assumes that the light is evenly spread over a full sphere.

As soon as it's emitted over a smaller angle, or is unevenly distributed, the candelas go up. Most blinkies emit light backwards only, and have a very obvious hot spot in the middle, so it's quite easy to get 4 candelas from 1 lumen and still have a useful bike light.

The law says nothing about the angle over which your 4 lumens is measured, but I would imagine that a judge would decide that it was what was emitted towards a following driver that mattered.

 

[Ming the Merciless]

As above by @Yellow Saddle . Drill the hole through to the front of the fork assuming carbon.

 

[Nigelnightmare]

12.6 (4π) lumens = 1 candela assumes that the light is evenly spread over a full sphere.

(1),As soon as it's emitted over a smaller angle, or is unevenly distributed, the candelas go up. Most blinkies emit light backwards only, and have a very obvious hot spot in the middle, so it's quite easy to get 4 candelas from 1 lumen and still have a useful bike light.

(2),The law says nothing about the angle over which your 4 lumens is measured, but I would imagine that a judge would decide that it was what was emitted towards a following driver that mattered.

(1),
The Candelas/lumens don't increase but the LUXX does when you focus the light into a beam (*measured at a set distance from the emitter)

P.S. As you so rightly said the lumen/candela is the total output of the light which is easily measured.
So therefore the Minimum for a "blinking" front light is approx. 50 lumens or 4 candelas total output.
Plus the quoted output was for the FRONT light.
BUT that wasn't the point of it, what it was about is the Height of the front light which is a MAXimum of 1500mm above the ground not the MINimum.

(2),
Aimed forwards and visible from the front.

My previous thread quote was copied from the RVLR on the Govt site.

* Can't be bothered to look it up as it's not relevent to this discussion.

 

[avsd]

Use a light-weight steel bracket like these from Screwfix

Either get one with two 90 degree bends or add an extra bend yourself with vice/pliers

 

[simon.r]

I ended up using one of these:

https://www.veloduo.co.uk/products/vo-headset-spacer-bell-mount?variant=1037924389

It looks fairly neat I think:

Just need fit the rear light and to wire it up now!

 

[Yellow Saddle]

That's pretty elegant. Good plan.