Installing a dynamo hub & lights on the Charge Plug commuter

[JhnBssll]

I've been looking at dynamo powered lights for a while and yesterday I finally ordered some bits. I'm a pretty competent mechanic but having never fitted a dynamo before I thought I'd run through my plans to see if I'm about to do anything dim or make my life harder than it need be With that said I'm a bit of a perfectionist at times so the install will be as neat as I can make it Anyway, this is the gear I've bought:

- SP PD-8 6V 3W dynamo hub, 24 hole in black
- Busch + Muller IQ-X LED Headlight in black
- Busch + Muller Toplight Line Small back light
- Twin core cable to run from front to back
- 24 black spokes and nipples

The hub will be going in to this Mavic Aksium Disc wheel, replacing the standard one:

The headlight will be mounted on the fork crown but I'll need to tidy up the cable and hose runs to minimise shadowing...

I'm going to try and run the cables as neatly as I can so have decided on the following cable route, where pink lines show wires attached with tape (clear gorilla tape on the forks and black electrical tape on the rack) and yellow lines show the wires shrinkwrapped to the rear hydraulic brake hose with black heat shrink tubing...

The rear light is the rack mount type so will simply screw to the mounting point. I'll likely solder the joints rather than rely on the provided terminals, unless theres a reason why I should do so

So what haven't I thought of? The front light has a built in voltage regulator and outputs to power the rear light. Seems I just connect the hub to the front light and the front light to the rear light and it should just work...

 

[rogerzilla]

That's pretty much it. Think whether you really, really, want a dynamo rear light, though. Battery LEDs last the best part of a winter's commuting and save a heap of ugly wiring.

I just spiral the wire around a fork blade. It's easier to take it off in summer (and put a normal wheel back on) than if I'd attached it in any way.

 

[JhnBssll]

That's pretty much it. Think whether you really, really, want a dynamo rear light, though. Battery LEDs last the best part of a winter's commuting and save a heap of ugly wiring.

I just spiral the wire around a fork blade. It's easier to take it off in summer (and put a normal wheel back on) than if I'd attached it in any way.

Part of the attraction is the ease of having automatic lights in all conditions without having to remember to charge batteries, although I will retain the seat stay mounted rear light as well Once the wires are shrinkwrapped to the hydraulic hose they'll be hard to notice I'd think so not too fussed about that.

Regards swapping wheels in summer is that to reduce resistance? From what I've read I've been lead to believe you can barely notice the extra resistance, especially if it's daylight and the light is on low power mode. Is that not your experience?

 

[Ming the Merciless]

Presume the wire will run under the bottom bracket. Make sure you protect that well as could be a point of weakness.

 

[rogerzilla]

I do it for weight more than resistance. The touring bike keeps its dynamo lighting all year but the commuting bike gets all the lighting gear taken off.

 

[Ming the Merciless]

How about running the wire up the mudguard from the BB? The wire sitting outside the QR could lead to problems when you forget.

 

[DCBassman]

Regards swapping wheels in summer is that to reduce resistance? From what I've read I've been lead to believe you can barely notice the extra resistance, especially if it's daylight and the light is on low power mode. Is that not your experience?

I've no experience with modern dynamos, but with the relatively low current draw of LEDs, I'd have thought that even the most sensitive soul would be hard pressed to notice anything significant. [pedant]And old Dynohubs weren't dynamos anyhow, they were alternators![/pedant]. A dynamo is, by definition, a commutated DC device, so I'd imagine all modern generators to actually be dynamos if they're powering LEDs.
I'll shut up now...

 

[JhnBssll]

Presume the wire will run under the bottom bracket. Make sure you protect that well as could be a point of weakness.

Not under, no. It will still be heatshrunk to the brake hose at that point so will run over the top of the BB and along the top of the non drive side chainstay

How about running the wire up the mudguard from the BB? The wire sitting outside the QR could lead to problems when you forget.

Thats not a bad idea, I'll take a look at that option. If I go with my original route I'll tape the wire down under the QR to prevent any swearing later

I do it for weight more than resistance. The touring bike keeps its dynamo lighting all year but the commuting bike gets all the lighting gear taken off.

That's a fair point, although this Plug already weighs over 12kg so an extra few hundred grams of dynamo shouldn't make much difference I'm on a diet myself so will just have to lose a little bit more from the belly to counteract it Besides, any extra weight on the commuter makes me faster on the weekend bikes

 

[JhnBssll]

I've no experience with modern dynamos, but with the relatively low current draw of LEDs, I'd have thought that even the most sensitive soul would be hard pressed to notice anything significant. [pedant]And old Dynohubs weren't dynamos anyhow, they were alternators![/pedant]. A dynamo is, by definition, a commutated DC device, so I'd imagine all modern generators to actually be dynamos if they're powering LEDs.
I'll shut up now...

You'd think so, but they're not DC Just named badly They are actually still alternators, there's a voltage regulator in the light that converts it to DC

 

[DCBassman]

You'd think so, but they're not DC Just named badly They are actually still alternators, there's a voltage regulator in the light that converts it to DC

Better yet, alternators always have less mechanical resistance than dynamos.

 

[JhnBssll]

Better yet, alternators always have less mechanical resistance than dynamos.

Yeah, it's rated 3W max and I would estimate it to be ~70% efficient so can't see it adding much more than 4W of resistance ie sod all. Although I bet some would pay a lot of money to remove that 4W

 

[Ming the Merciless]

Yeah, it's rated 3W max and I would estimate it to be ~70% efficient so can't see it adding much more than 4W of resistance ie sod all. Although I bet some would pay a lot of money to remove that 4W

Turn light off and resistance drops close enough to a normal hub anyway. It is neither here nor there. You can get greater differences based on choice of tyre.

 

[mjr]

My wires are crimped into the connectors, not soldered as the rear light terminals are recessed so I'd probably melt the casing. It has also made it easier to repair when I snagged a wire soing something else and snapped it.

 

[rogerzilla]

They're technically magnetos, because they use permanent magnets. Obviously not the same as spark magnetos on lawnmowers!

 

[DCBassman]

They're technically magnetos, because they use permanent magnets. Obviously not the same as spark magnetos on lawnmowers!

Indeed, dynamo came to mean the self-excited () DC generator.