Author Topic: Brompton Dynamo Wiring  (Read 1069 times)

Torslanda

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  • Just a tart for retro kit . . .
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Brompton Dynamo Wiring
« on: December 27, 2017, 11:01:45 pm »
A very good customer has a sked me to fit a dynamo kit to a Brompton. 3-speed, bendy bars,no rack. She has provided an Evans kit which includes new wheel, front & rear lights and all bracketry, zip ties and most importantly, instructions.

So far I've read the instructions. Tomorrow I'm going to read them again. Then I'm going to follow them, step by step.

One thing I'm wondering though. Is it possible to run the last bit of the wiring from the rear axle up through rather than around the seat stay? To me it would be neater and less vulnerable. Any thoughts...?
VELOMANCER

Well that's the more blunt way of putting it but as usual he's dead right.

Kim

  • 2nd in the world
Re: Brompton Dynamo Wiring
« Reply #1 on: December 27, 2017, 11:33:52 pm »
The kit's probably got cable and I-can't-believe-it's-not-heatshrink tubing cut to an exact length, so it might not fit if you change the routing.

Without looking I can't remember what happens at the top end of a Brompton's seat stay - presumably it's open or you wouldn't be asking the question.  (Mine's got a rear rack, so the wiring goes up round one of the rack supports to the rack-mounted light.)  Consider that you might be trading less vulnerability when unfolded for more vulnerability when folded, and which mode a Brompton is more likely to be knocked about in.

To ride the Windcheetah, first, you must embrace the cantilever...

Torslanda

  • Professional Gobshite
  • Just a tart for retro kit . . .
    • John's Bikes
Re: Brompton Dynamo Wiring
« Reply #2 on: December 28, 2017, 09:23:48 am »
Excellent answer, thank you! I'll follow the destructions . . .
VELOMANCER

Well that's the more blunt way of putting it but as usual he's dead right.

Torslanda

  • Professional Gobshite
  • Just a tart for retro kit . . .
    • John's Bikes
Re: Brompton Dynamo Wiring
« Reply #3 on: December 28, 2017, 07:17:12 pm »
... and that's that one done.

The best reason for not running the wiring up the inside of the seatstay is there isn't enough of it. The kit BTW is comprehensive and includes a ready built front wheel, two flavours of skewer (one for the Ti fork), loom, bracketry etc. but, inexplicably, lacks the bolt to secure the front lamp to its bracket. Rectified with A4 stainless M6 hardware.

Anyone contemplating fitting one just buy it. For 150 quid there's no point trying to brew your own. Like most things Brompton, the bits are just sufficiently different that non-OE parts either won't fit or interfere with the fold. Once I read the destructions it took about an hour to fit - allowing for interruptions, customers etc.
VELOMANCER

Well that's the more blunt way of putting it but as usual he's dead right.

Kim

  • 2nd in the world
Re: Brompton Dynamo Wiring
« Reply #4 on: December 28, 2017, 07:36:15 pm »
Just to be different, when I replaced my Brompton-issue Lyt front light (which rubbishly lacks a standlight) with a Cyo, I replaced the run to the rear light with some of that lovely Schmidt coaxial cable, simply because it looks better (being thin and black, rather than dark grey and floppy).  In my defence, I was already committed to re-cabling the brakes and gears from scratch due to a non-standard handlebar configuration, as well as incorporating the cable for a wired computer, so it didn't add much to the required level of messing about to find the right lengths (which was exactly as tedious as it sounds).

So far it seems to be standing up to wear just fine, so it seems like a reasonable alternative.  I'm not sure that the standard figure-of-8 bell wire that B&M supply would last long, given the amount of flexing and rubbing it's subjected to in the bottom bracket area during the fold, so it's worth avoiding that.

On the gripping hand, you still need Brompton's version of the front light bracket - the regular one won't clear the brake and the luggage block.
To ride the Windcheetah, first, you must embrace the cantilever...

Re: Brompton Dynamo Wiring
« Reply #5 on: December 29, 2017, 12:40:52 pm »
.... I'm not sure that the standard figure-of-8 bell wire that B&M supply would last long, given the amount of flexing and rubbing it's subjected to in the bottom bracket area during the fold, so it's worth avoiding that....
I found flexible figure of eight cable OK: it lasted longer* than my mark 2's official wiring which broke at the its tight 180 bend /double back where attached to brake cable (Brompton and 180 degree cable bends: Grrr). Presumably the flexibility was more important than the standard stiff 'protective' sleeve..

*it lasted years until I removed the bottle dynamo (and a hub brake prevents a hub dynamo).

As I like none of the official  Brompton dynamo lamps, or their wiring, I would probably just buy the dyno wheel if I had  a standard braked brompton...

Re: Brompton Dynamo Wiring
« Reply #6 on: December 30, 2017, 09:04:22 pm »
Yeah I've used standard B&M type wiring. It works fine and lasted a two or three years, which seems comparable to the Brompton stuff.

The Brompton low level front light bracket is well known for snapping suddenly where it exits the fork washer. Have a spare on hand!

Re: Brompton Dynamo Wiring
« Reply #7 on: December 31, 2017, 09:39:08 am »
I found flexible figure of eight cable OK: it lasted longer* than my mark 2's official wiring which broke at the its tight 180 bend /double back where attached to brake cable (Brompton and 180 degree cable bends: Grrr). Presumably the flexibility was more important than the standard stiff 'protective' sleeve..

How did this happen? The 180º bend does look quite alarming, but it's securely zip-tied in that position so does not move after installation. The wires inside only tend to break when repeatedly flexed, which is unavoidable at the bottom bracket on folding, where both wire and brake cables routinely break.
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that's not science, it's semantics.

Re: Brompton Dynamo Wiring
« Reply #8 on: December 31, 2017, 12:42:07 pm »
.....How did this happen? The 180º bend does look quite alarming, but it's securely zip-tied in that position so does not move after installation. ...
Well it is a very  very tight bend (cable doubled back on self)!! And I suspect the hard outer cover makes it worse. Vibration on now work-hardended copper?  Ask Brucey?

I was careful to have a much more gentle bend in my plain zip wire routing which didn't fail there..