We've had our Thorn tandem for nearly a year now, and just returned from a great 3 weeks in Northern France – Brittany and Picardy.
We’ve nothing but praise for the bike, and also for the customer care and service from Thorn cycles. Their attention to detail at every stage was just great, and we rode away from Bridgewater on a machine that has not needed any adjustment to the ride positions as set up by Steve at Thorn when we collected the bike last year.
The only little niggle with the original setup was with how the wire to the SON rear light was routed. It was neatly clipped to the top tubes with black cable ties. I think that, in time, the inevitable rubbing of the ties would have scratched the high gloss powdercoat finish. Also, the standard SON lamp comes with with a cable insufficiently long for a tandem, so although Thorn had made a very neat splice, the combination of the wire, the splice and the cable ties detracted from the otherwise uncluttered lines of the bike.
So I've rerouted the cable so now it's less of an eyesore. Before doing so I ordered a replacement ‘special order’ SON rear lamp with a 2.5m cable. Thorn took care of placing the order for this with SON in Germany.
I planned to route the cable along the underside of the rear rack, then down the ‘spine’ of the back mudguard, under the rear bottom bracket and then clipped to the Rohloff cables under the base tube and up the underside of the front down tube, then into the Edelux headlamp.
The cable used by SON is a 2mm coaxial cable, and routing it along the underside of the bike exposes it to a greater risk of damage compared to the original route. Also, tightly clipping the cable with narrow cable-ties could damage the outer insulation. To better protect the cable I enclosed it in a protective rubber tube. I used a black tube with an outer diameter of 4mm and an inner diameter of 2mm. It's made by Hozelock
http://www.hozelock.com/our-products/watering/automatic-watering/classic-micro-irrigation/connection-components/4mm-hose/ as part of an automatic irrigation system – readily available online and in the big hardware superstores. It’s flexible, UV resistant and tough. I used baby oil to lube the cable and inside of the tube and then slid the cable through the tube. It took much patience – the knack is to keep the tube dead straight when feeding the cable through, and use plenty of baby oil!
Starting with the lamp fitted to the rear rack, I clipped the tube centrally under each of the rack cross-pieces. By having one cable tie around the rack crosspiece and then a second cable tie threaded through the first, I got a much neater look because the orientation of the second cable tie was in line with the cable route. Then I laid the tube along the top of the mudguard and down under the stoker’s bottom bracket, and, maintaining a little tension on the tube, clipped it to the pair of Rohloff cables at every cable guide along the base tube and up the underside of the front downtube. I didn't over-tighten the cable ties otherwise the feel of the gear change might suffer. Then I glued the tube to the ‘spine’ of the rear mudguard with Loctite ‘all plastics’ superglue. I used 6 spots of glue along the contact area with the mudguard in the hope that if I ever need to separate the joints, a scalpel will do the trick.
The termination of the lead with the correct connectors was, for me, straightforward, as I have the correct crimping tools and heat-shrink gun for the task. Without these, I'd say take great care, or seek out someone with expertise in soldering/crimping, or all your work making a tidy cable-run will be in vain.
The whole thing is, I think, an improvement on the top bar route.
