Jackyll the Tandem Part 4: Turning the night into day

As any regular reader of this blog would know, I'm a big advocate of dynamo lighting.  The ability to flick a switch and have regular, bright and dependable lighting at any time is important to me.  Having had to get by with battery lights on the tandem again reinforced this point.  The Taylor brothers normally built their bikes much like the classic French Constructeurs and typically allowed for decent sized tyres, mudguards, racks and integrated lighting.  Luckily our tandem was one of these, it features routing inside the frame for neat wiring installation as well as a braze on bracket for a bottle dynamo.  It's evident that the bike originally had dynamo lighting on it at one point as there were remnants of wiring left in parts of the bike and the frame.

We needed the dynamo lighting for the yearly Dunwich Dynamo ride which involves riding from 8pm in the night from London heading east until the coast, this requires reliable lighting for at least 8 hours continuously.  I'd done it last year on Phil which is also equipped with dynamo lighting which was fantastic to have.  Good lighting on unlit country lanes is essential for spotting potholes, hazards and generally lighting up the road.


Nordlicht MAX bottle dynamo 6v 3.0w
I generally have a preference for hub dynamos over bottle, however fitment of a hub dynamo would have been difficult on the tandem due to the 110mm front fork spacing.  There aren't really any hub dynamos which can be respaced to this nor did I want to respace the fork itself to a standard 100mm so I went with one of the best hub dynamos I could find.  The Nordlicht MAX comes in a chrome finish which looks appropriate on a vintage bike, I chose the rubber roller version which is not only quieter but due to the larger roller size over the metal roller version, is more suited to faster riding.

Phillips Saferide 60 front light
I chose this light as it is meant to be one of the best dynamo lights available, also it is quite well priced.  The beam pattern is very broad, with a consistent even pattern with no hot spots and it is very bright at a rated 60 lux.  The design is very simple being a minimal brushed aluminium finish.

Busch + Muller Secula rear light
I used the same light in the seatpost mount on Phil, so for this time around I chose the mudguard mounted version.  It's small, bright and is very visible from long distances.


I guessed the hardest part of the installation would be routing the wiring inside the frame.  Internal wiring or cabling is easier if there is already a wire or string inside which you can use to pull through the new wiring.  However there was none of the original wiring left in the frame which would mean we would have to do it from scratch...

There were a few different ways to wire the lighting.  As the dynamo is located at the rear of the bike, wiring in the modern style would have required a double cable run to the front light, then a return double cable back to the rear light, a total of four wires running through the middle section of the bike, this would have meant that I would need to run lots of messy wiring outside of the frame.  Instead I decided to wire it in the old style with a single wire running forwards of the dynamo to the front light and another wire running backwards to the rear light, both would run a ground along the frame back to the dynamo.  This would mean I could use the internal wiring of the frame which would keep it nice and neat.  Wiring in this style is only really possible with a bottle dynamo because the switch is in the bottle dynamo itself, whereas when you use a hub dynamo it is running all the time and the switch is located in the front light itself.  I've drawn a diagram overlaid to explain the wiring on the tandem above.

The string ran through fine...
We tried pulling the cable through by sewing some string to the end to no avail

I'd done a bit of googling on how to route wiring inside a frame, many people would use a very fine string inserted in one end with a vacuum cleaner on the other side.  Once it was sucked through you could use this to pull the wire through.  However we had a bit of trouble doing this, the fine string simply would not come through.    Also the other thing we weren't sure of was whether the internal tubing was simply a stub in the frame tube or if it was an entire length of thin conduit running the whole length inside.

The brake cable cleared a lot of dirt and muck left over from 40 years
We tried several fine strings from thin sewing string to fishing wire with the vacuum cleaner to no avail, we even tried   Eventually we just ran an old brake cable through it and voila!  It appeared that there was a conduit running the entire length of the tubing cavity, testament to the level of craftsmanship of the Taylor brothers, it would have been much easier to braze in stubs on either end of the frame tubes however they elected to run a conduit the entire length making installation significantly easier.  After cleaning the conduit with a brake cable several times we were able to run the electrical cable through both conduit runs.  I added a spade terminal on either end of the internal frame wiring which would allow me to disassemble the wiring more easily in the future.  

Finally we got the wiring through the back part
and through to the front
Spade connectors allow for a quick disconnect if needed
Internal wiring allows for a neater installation in an already cluttered downtube

Now we had to run the wiring through the mudguards and connect everything up.  The mudguard wiring was a fair bit easier, particularly as they had been made with wiring in mind.   The rear mudguard had an exit hole cut in it to allow the wires to reach the dynamo, also the front mudguard had a hole in it to allow cable to run from it into the frame tubing.  I only had a minor problem with a sharp edge of the mudguard biting into the wiring which caused it to short, however this was fixed by getting rid of the sharp edges and routing it again inside the mudguard.

Rear mudguard with loose wire showing the hole for wiring to get to the dynamo

Front mudguard showing the routing through the lip and out the eyeletted hole
The front lamp required only minor modification to the base of it to fit onto the bracket on the front rack.  The rear lamp only needed an additional hole to be drilled into the mudguard to fit it.   The bottle dynamo was installed simply on the bracket, taking care to align it so the roller ran at a tangent to the dynamo track on the wheel to minimise unnecessary drag.

The mudguards have a neat little eyeletted hole for the wiring, enough slack was left
in the wiring to allow for movement from steering
All wired up and ready to go
This took the better part of a day to get running.  I had recently purchased a proper crimping tool which I put to good use, as I had previously used pliers which can lead to spade connectors not making a proper connection and occasionally failing, which is the last thing you want on the Dunwich Dynamo.

First Impressions

We took it out for a short night ride to test it out, what was noticeably different from my other dynamo setups which use hub dynamos is the lack of flickering at low speed.  Near full brightness is achieved from a low speed of about 10km/h or so.  The drag is not really noticeable and due to the rubber roller on the bottle dynamo the noise was also barely noticeable.  However at a certain speed there was some harmonic thing going on in the dynamo and you could feel a very subtle vibration in the stoker's seat at around 15km/h however it goes away above and below this speed.

  The mounting of the front light far forward on the rack meant that there were no shadows cast by the front tyre or mudguard which gave a really nice clean beam.  Noticeably though the Phillips Saferide gave a very nice, broad and even beam.  The only negative I could find was that it's cutoff wasn't as sharp as the Busch + Muller lights typically are.  The side visibility of both the front and rear lights is very good which is reassuring in traffic.  The first big real test of the system will be the Dunwich Dynamo which I will write about next.  The lighting has to run for 8+ hours continuously which is much longer than most lighting systems would ever been run, what can cause it to fail is heat which the lights and the dynamo need to dissipate.

Overall I'm very happy with the dynamo setup, I was a bit skeptical of bottle dynamos in the past however having now installed a few, they can be quite good when properly installed.  Stay tuned for the ultimate test on the Dunwich Dynamo.  Thanks for reading.


  1. now you just need to install an espresso maker and coffee grinder, and it'll have everything the modern man needs for a journey through the english countryside.