In the past, Bertin utility and touring bicycles came with built in generator powered lighting systems fitted by the Bertin factory. Whether they were an everyday bike like the sixties Bertin C 10 shown to the right or the C 31 shown to the left below, they all carried seat stay mounted braze-on tabs for a 6 Volt, 3 Watt Soubitez generator as well as some form of taillight and a headlight as well. (Typically, also Soubitez.)
The tail light might be mounted directly to the generator braze-on tab as it was with plastic fendered Cyclotouristes such as the C 117 or the C 132. This was then complimented by a reflector on the plastic rear fender. In other cases, such as the C 116, the C 28, 29 and 31 the taillight and reflector were incorporated as an integrated, single unit on the rear fender.
One exception to these methods was the 1980s Bertin C 134 which used a Sanyo bottom bracket generator attached to a brazed-on plate on the bottom of the chainstays directly behind the bottom bracket shell.
The front lights of plastic fendered bikes would have the headlight hung from a TA rack or one of the in-house provided chromed wire racks supplied by Bertin. The stainless steel or alloy fendered bikes might have the front light on a TA rack or mounted to the upper lip of the front, metal fender. The two photos shown above give clear examples of each method of attachment for metal fendered bikes.
For those unfamiliar with the TA rack, various versions were made. There was a plain version without the dropped rod for mounting lights used just as a bag support, there was a dropped rod version with a threaded sleeve attached to allow screwing on a headlight and there was a third version with a dropped rod with no sleeve which permitted clamp-on light fittings to be attached to the rack’s dropped rod. All 3 TA racks were designed to mount to the pivot bolts and the mounting bolt of MAFAC center pull brakes.
I have used the version of the TA rack to the left attached to MAFAC 2000 center pulls brazed on to a Peugeot PF 40 and it was a very stable and effective light mount and bag support. No matter which of the two standard mount systems were used, the wiring was single strand of insulated 20 or 22 gauge copper wire (.75 or 1 mm). My current C 37 has 1.5 mm wire and I have no idea why, although everything works perfectly.
If you are an owner of one of the various Cyclotouriste models, as a recent correspondent is who has acquired a NOS frameset, you may be confused by the holes drilled in your bottom bracket and your lower head lug (See photo with wire to the left). Whether your Bertin is also NOS or a stripped down version oldie lacking its original equipment, the purpose is the same. These holes are there to permit the routing of the single wire which will carry current from the generator to the headlight. The Soubitez generator needs only one wire because the frame or fender acts as the return path for the current.
The generator itself has a spring tensioned connector/terminal at the bottom (see photo) where the wires to the headlight and the taillight finish their cable runs. The wires are inserted into a hole in the generator terminal and spring tension clamps them when the fitting is released. The wires (I twisted mine to reduce snagging) emerged from a hole I drilled in the fender (these are aluminium Honjos) where they were either taped to the inside of the fender or were tucked into the curled fender edge (mine are tucked in).
The left wire began at the head tube lug and was fed into and down the down tube then out of the hole in the bottom bracket, into the fender, taped near the edge or tucked into the curled edge, then out of the hole in the fender. The right hand wire began by being fed through the hole near the bottom end of the fender, tucked into the fender’s curled edge or taped to the fender until it passed through the fender hole adjacent to the generator braze-on. Both are then attached to the generator terminal as shown. On plastic fendered bikes such as the C 117 the separate taillight mounts directly to the brazed-on stay tab with a wire going directly to the generator terminal. The headlight wire can be attached with electrical tape inside the rear fender after it emerges from the hole in the bottom bracket and is then attached at the generator using the spring loaded brass terminal. The black cap on the generator is a soft rubber cover for the hard plastic generator wheel. It stops the generator wheel from damaging the soft, thin sidewall of skinwall tires.
Your bike’s headlight can be a period correct piece like my Soubitez or one of the new varieties of halogen or LED headlamps. The Soubitez headlight shown here was wired for another application hence the 2 wires but it is otherwise identical to the one fitted to my C 37. It is currently set up with a halogen bulb as is the headlight on my bicycle.
The original lights were supplied with standard incandescent bulbs (screw threaded base) and were retrofitted with halogens. In the left hand image the round bulb is OEM, the pointy one is halogen and the brake pad is for scale! The halogen gives a brighter but yellow-white light compared to the incandescents. LED conversion bulbs are available (I will be trying them in future) and are available through the Lake Pepin Tour site here (US) or through Reflectalite (UK) here.
Power is directed on the basis of 2.4 Watts to the headlight and .6 Watts to the taillight. With halogen bulbs, exact capacities must be observed but LEDs allow more latitude in application. With incandescent and halogen bulbs, the front bulb must be 2.4 Watts and the taillight must be .6 Watts to avoid burning out the bulbs by over voltaging them. To the right is a photo showing the headlight setup on my C 37 including the custom, tubular cro-mo light bracket for the Soubitez headlight. Further details of the bracket and the wire run are shown to the left.
The taillight set up on that bike includes an integrated light/reflector combination bracket. This entailed drilling three holes in the fender. Two allowed for the alignment tab and the attachment screw and the third allowed the passage of the light wire into the fixture. The .6 Watt bulb screwed into the socket and compressed the copper wire ends making contact and completing the circuit. If you have a C 117 or similar with plastic fenders then a reflector will be mounted here instead, especially if your are using Milremo or Bluemels fenders.
However, if you are fitting ESGE/SKS plastic fenders, these have a laminated construction with an aluminium core between a lower and upper plastic layer. With these fenders a combination fixture like the one shown can be fitted. I am uncertain as to whether it needs to be wired or can be powered through the alloy inner layer.
As an aside, you should be aware that fenders with mounting brackets inside the fender tend to channel water out and over the fender edges casting more spray than fenders with exterior brackets as shown on my black C 37.
As always, since you are the builder/restorer you must make the decision as to how accurate you wish to be in your work. Period correct with dim incandescent bulbs is no fun on the road at night but just fine for a bike that is a wall hanger. You may wish to compromise and keep the look of the bike period correct but sneak in halogen or LED bulbs which boost performance. Alternatively, you may decide on a whole new, LED based system altogether. For further details and elaboration, I would recommend Peter White’s excellent site as well as Compass Bicycles although they do tend to emphasize hub generators.