Trailers are a good way to carry a Tandem, here are examples of ways to do it

Manufactuers

Pendle Family Bike Trailer

From the Tandem Club Forum:- You do need the tandem extension bit, though, which brings the front wheel quite close to the rear of the car, so opening the boot isn't possible on my Touran. It bolts onto the strut between the main body of the trailer and the coupling.  

There is the added bonus of being able to take another bike or two (or five at a push). 

Stating the obvious, I would check the dimensions carefully - I haven't tried using mine since upgrading from a Dawes Duet to a Moustache Samedi, so I don't know if it would fit. Pendle are (or at least have been when I've dealt with them) very helpful.

It's not cheap but it is a very sturdy beast. i see they have sold out at the moment, though but there are usually a few floating around second hand, admittedly less often with the tandem-specific add-on.

The issue we had when only transporting our tandem, was it became somewhat bouncy with the reduced weight. Our tandem was 2.5m long and fitted well, as there is room for adjustment on the rear wheel on the trailer (you load the front wheel next to the boot of the car). However, when going on longer journeys (Scotland to France), vibration could cause friction at the tying down points, so plenty of protection needed, especially sidewalls of tyres. The trailer went with us on Eurotunnel and back, so it won't limit your travelling. 

Make your own adaptions

I spent the afternoon making a bracket to hold the front and a slot to locate the rear wheel. I will add a strap to keep the rear upright and held down before actually using it. The bracket needs painting but my angle grinder burnt out and I couldn't quite finish. There is room for a solo bike each side.

Thoughts on this:- Good job, I would have made the bracket for the forks further back , nearer the front trailer board, and cut another slot in the rear for the rear wheel to slip through, that way you could still use the rear hatch of the car fully. Answer from the maker:- I did consider that but I prefer not to overhang at the rear because some drivers have difficulty seeing the back of a trailer at all! It also makes parking a bit easier. It only takes a few seconds to unhitch the trailer for access to the boot.

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