Our Moulton-based tandem


In June 2005 we took delivery of a custom-built Moulton APB-based tandem. As of October 2013 we have used the bike for 13 touring holidays of durations ranging from five days to three weeks and covering about 8500 km in total. The unique features of the bike have contributed substantially to our enjoyment. The extra comfort deriving from the excellent suspension and the low step-over height contributed to all of them and the separability was essential for some. (You can learn more about many of the tours by following the links in the experience table below).

We believe it to be the first separable-frame Moulton-based tandem constructed in the UK as well as the first to be based on an APB (but see the note from Bob Marshall in the Comments section of this page). We decided to undertake this project following 15 years in which we have used Moulton AMs and APBs for almost all our cycling but had to revert to a conventional tandem (a Dawes Galaxy) for extended touring holidays. After several years of holidaying on the Dawes Galaxy, we decided that we would like a more comfortable and transportable tandem, while retaining the durability and efficiency of the Dawes. Alex Moulton's space-frame design and suspension seemed to us to offer a very good basis for a comfortable and rigid tandem that could be separated for ease of transport, especially on the many UK train lines where conventional tandems are now banned.

We hoped the project would result in a tandem with performance, rigidity and durability comparable to a conventional tandem, but with the traditional benefits of Moultons including a more comfortable ride, easier mounting due to the lower step-over height and easier transportation due to separability. Other small-wheel and separable tandems such as the Bike Twosday didn't seem to offer all of those benefits.

In July 2005 we took our newly-built tandem on a three-week, 700 km touring holiday in France. It performed flawlessly and fully lived up to our expectations. We are delighted with the ride, performance and general usability of the tandem. As our sole means of transport for three weeks its reliability caused us no concern - until the frame failure in September 2011 mentioned above.

The project

We began the project in January 2005; the tandem was delivered in June 2005. After a couple of promising day rides we decided to take the plunge and use it on our planned touring holiday in southern France in early July.

We had read in The Moultoneer and the Yahoo Moulton group that a small number of successful tandem conversions existed in Australia based on the Moulton ATB (Alex Moulton's all-terrain version of his unique space-frame small-wheel design). But those tandems were built several years ago. None was for sale or even available to be viewed in the northern hemisphere. Only about 100 ATBs were built at Alex Moulton's Bradford-on-Avon factory before he licensed Pashley Ltd. to manufacture a lower-cost APB bicycle to a similar design. Apart from the use of cheaper components and tubing, there was one other significant difference - separable APBs have a fixed knuckle joint below the king-pin joint (picture) whereas the ATBs had a removable tube connecting the head tube to the bottom bracket (picture).

Despite the differences and their implications, we decided that the APB was the most practical basis for building a Moulton-based tandem today. When we announced our aim to the members of the Yahoo Moulton group we received a very mixed reception, ranging from valuable advice and in several cases material help ( mentioned below), to sometimes patronising criticism. The critics cited Alex Moulton's known opposition to such projects as their main point together with some points about the extra stresses to which tandems are subject. The latter is certainly a consideration to be taken seriously, but the construction of the APB and the experience of others with tandems based on the similar ATB convinced us that a safe APB-based tandem could be produced.

Fortunately one of those offering positive advice was Michael Kater, a knowledgeable Australian cycle dealer who is the owner of one of the ATB-based tandems mentioned above. He was able to confirm the long-term reliability of the Australian tandems and he gave us considerable support in the form of detailed photos of his tandem. Michael's photos showed the construction of the frame insert in much greater detail than this broken-down view.
(The photos of bikes other than our own linked from this page are on Mr. Yutaka's excellent Moulton photo gallery web site - click on the 'Bicycle' link there for a full listing of his Moulton photos).

The first step was to obtain an APB on which to base the tandem. A request to the Yahoo Moulton group led to the offer by Mark West of his very early but well-maintained and upgraded APB 12. This was offered by Mark at a very reasonable price and was purchased forthwith. Mark had upgraded wheels, chainset, handlebars, seatpin, etc. and many of these components were retained. However, a new Stronglight tandem chainset was fitted and a new rear wheel was built specifically for the tandem.

Roger England very generously offered to donate a portion of a damaged APB frame including the kingpin and head tube; this substantially simplified the task of fabricating the required additional kingpin joint.

After some fruitless initial attempts to discover a frame builder in the UK who might construct the insert and build up the tandem for us, John Bartlett (an experience Moulton owner and restorer) suggested Doug Pinkerton (aka Pinkerton Cycle Restorations). This was an excellent suggestion; Doug has much experience of working on Moultons. He designed and built the insert and put the whole bike together very professionally. Doug's contact details can be found in the specification section below (his workshop is in Redditch).

Let me also note here our gratitude to Moultoneers Michael Kater, Mark West, John Bartlett and Roger England; we owe them several pints each for their generous contributions to the success of the project.

For us, our Moulton APB-based tandem is the ultimate holiday transport. It is the third tandem that we have owned; we cannot imagine ever needing another!

This report continues in the form of an annotated set of photographs on a separate page.


Base/donor bicycle: Pashley Moulton APB 12 (Frame number 13). The early models were significantly heavier than Pashley's current products, perhaps stronger too.
Tandem insert: Designed and constructed by Doug Pinkerton based on photos of an Australian ATB-based example. The dimensions were based on those of our existing Dawes Galaxy. See drawing for details. The quality of Doug's work is excellent.
Chainset: Stronglight Escape tandem triple chainset with 30 42 54 chainrings A 120 mm bottom-bracket axle was fitted to the rear BB to give adequate clearance and the head of the rear triangle pivot bolt was ground down to make it clear the inner chainring. The front BB is mounted in an eccentric drum in the standard tandem fashion.
Rear cassette: 8-speed, 11-30 resulting in a range gear ratios from 19 to 94 inches These ratios are ideal for us.
Gear mechanisms: Front: Early APB's used a Shimano Deore band-on mech attached to a non-standard brazed-on fitting and this was retained.
Rear: Shimano Acera
Shifters: Shimano Alivio Rapidfire fitted to horizontal bars
A standard braze-on front mech would be preferable for ease of replacement.
Wheels and tyres: Front: Original 36 spoke APB wheel
Rear: New 36 spoke (13 g) wheel built on Shimano Deore hub with disk mounting
Brakes: A Shimano 515 cable-operated disk brake is fitted at the rear in addition to the existing V-brakes. Rear disk and front V-brake are operated by the captain. Rear V-brake is operated by the stoker. The disk brake gives powerful and progressive braking in all conditions, rendering the rear V-brake redundant except as a back-up in case of failure.
Suspension: No modifications have been made to the suspension. The front suspension height is set with the leading links roughly horizontal and it has not bottomed, even on unpaved paths. With riders + luggage totalling about 340 lbs, the suspension performs very well, with a similar feel to a heavily-loaded solo APB.
Weight: Approx. 50 lbs with pedals, saddles and mudguards but without racks. The use of a later-model APB as the base/donor would have reduced this. As it is, we are very happy with the bike's hill-climbing performance, which seems comparable to our former Dawes Galaxy Twin which was about 5 lbs lighter.
Cost: We spent just over £1000 on the construction of the frame insert and the parts required to complete the tandem. This does not include the cost of the APB on which it is based.
Builder: Doug Pinkerton 3 Well Meadow, Rednal, Birmingham B45 9NE.
Phone 07778 429313
Powdercoating: Redditch Shotblasting
Owners: George Coulouris and Jean Dollimore

Safety and durability

We endeavoured to design the tandem for safety, but we undertook the project with no firm engineering data on potential weaknesses or safety issues. Martyn Aldis and others have suggested that it would be helpful to include a safety analysis in this article so that others considering a similar project will be aware of the assumptions we have made. The table below is an attempt to do so.


Special issues

Discussion/ assumptions

Front stirrup (small fork)

Vertical forces arising from extra riders' weight.

The suspension spring does not bottom in our experience, suggesting that it and the stirrup can handle the stresses.

Little cause for concern.

Front main fork

Braking force from V-brakes. (ATB has caliper brakes mounted higher and hence better supported). Horizontal shocks due to hitting bumps. 

Use of a rear disk brake alleviates the problem.

The fork is massively constructed.

Little cause for concern.

Custom tandem frame insert

Must be constructed with tandem use in mind.

Designed to have similar strength to a conventional tandem; tubing is stronger than that used in the APB frame.
A joint failed catastrophically in September 2011, after about 6000 miles of use in a variety of terrain. Clearly, this due to an error of judgement. Retrospectively, we estimate that the stress (tension) on the relevant joint was about 2.5 times greater than on a similar solo APB.

Rear suspension monosphere

More stress and compression due to additional weight.

Needs to be monitored for damage, catastrophic failure unlikely, but lifetime might be shortened .

Rear suspension pivot

Additional stress.

Lifetime might be shortened.

Rear triangle

Additional stresses in all tubes

No information available other than positive experience with Australian ATB tandems.  A quantitative analysis would be useful.

Wheels & tyres

The wheels are not tandem-specific.

Tyre blowouts due to overheating of the rims under heavy braking have been reported on other 20-inch wheel tandems.

36-spoke 20-inch wheels should have similar strength to 48-spoke 700c’s. No cause for concern.

This concern is removed by the inclusion of a disk brake, which we consider an essential feature.


Total distance to date: about 9000 km. Follow the links for descriptions of some of the tours. The tandem is now seven years old and has seen nearly 6000 miles of touring use. Unfortunately, the frame failed catastrophically on a recent tour (see below).
Other minor issues with the original rear suspension monosphere and the three wheel failures are mentioned below, the bike has been reliable throughout the 11 holidays we have enjoyed on it to date. The rebuilt wheels now in use are built with stronger hubs and spokes than those from the original solo APB that we first used.
September 2013
380 km tour Carlisle to Glasgow via NCN 7 No problems.
September 2012
250 km tour South Holland No problems.
September 2011
450 km tour in Southwest France The frame failed catastrophically! Details of the frame failure and its subsequent repair can be seen here.
June 2011
450 km tour in Highlands of Scotland No problems, even though we covered a significant distance on off-road tracks.
September 2010
450 km tour in Northern Ireland Large number of broken spokes in rear wheel ('pulling' spokes, broken when climbing). Fortunately we were carrying spares and found a good bike shop in Ballymoney to fit them. We think the failure was due to a less than super rebuild while on the Cotswold tour in 2009. The wheel has now been superbly rebuilt with new 13g spokes by Graham Attwell.
September 2009
650 km tour of Burgundy Trouble-free, not even a puncture! The bike performed as we have come to expect, carrying us comfortably over terrain ranging from canal paths to farm tracks and hilly minor roads.
May 2009
170 km tour in the Cotswolds Stratford--on-Avon to Bradford-on-Avon (nearly). This tour was nearly ruined by a component failure. We discovered at the start that the freewheel body had detached itself from the Shimano Deore hub. The hub was irrepairable due to a stripped thread. Fortunately Broadribbs bike shop in Leamington Spa came to our rescue at short notice and rebuilt the rear wheel around a Halo SupaDrive hub. They were brilliant! Many thanks to Ashley at Broadribbs for foregoing his lunch hour on a Saturday afternoon to do the rebuild in only 1.5 hours, keeping us on the road! After that, the trip went well. Not sure what lessons to learn from this experience. Possibly the extra force of tandem pedalling had something to do with it, or maybe it was just 'one of those things'. The new Halo hub is designed for extreme mountainbiking, so it should be up to the job. Train transport to and from the Cotswolds was straightforward with no need to split the bike in either direction.
September 2008
630 km tour in Brittany First Great Western train to Plymouth, overnight ferry to Roscoff. The tandem survived the entire tour with no issues, not even a puncture. It's now shod with Shwalbe 35 x 406 Marathon Plus tyres. They seem to be bomb proof.
July 2008
260 km tour in the Welsh Borders Excellent hill country. The gearing was adequate but the riders weren't always! Trip was fine until the last day when we rode in pouring rain all morning and the front hub bearings eventually completely broke up. We had to arrange alternative transport (see trip blog for details). The hub was the original 1992(?) part from the solo APB and when we looked at the bearings we realised we'd be lucky it had lasted so long. The tandem now has a new wheel on a Shimano Deore hub, built for us by Graham Attwell.
September 2007
800 km tour of Flanders and the Netherlands We took the tandem to Lille on Eurostar. Tandems are banned had to be split and the parts strapped together to form a single parcel to qualify as a 'bicycle' and carried as separate baggage for £20. Packing/unpacking the tandem in this way took 15-20 minutes. No protection for the frame was used or needed. The tandem performed flawlessly throughout our two-week tour. We returned via the Hook-of-Holland to Harwich ferry service.
August 2007
270 km tour of Gower Peninsula and Carmarthenshire The Sustrans NCN routes in South Wales are outstanding - many miles of tarmacked tracks along disused rail lines and coastal paths. First Great Western express Paddington-Swansea to get there. Tandem fitted in the cycle racks provided with no problems.
November 2006
579 km tour in southern France Trouble-free. Returned from Hyeres by Ryanair. Tandem not separated. frame tubes protected with 4 m of foam pipe lagging bought from a local DIY shop. Pedals off, saddles lowered, handlebars turned, rear rack removed and taped to side of frame. Bike partially covered with polythene sheet. The packing operation took about 45 mins!
September 2006
522 km tour in northern France The tandem was trouble-free, though the riders came off, with some unpleasant consequences. Bike carried on trains in France. Fits door-to-door (with nothing to spare) across a standard SNCF train carriage.
April 2006
300 km tour in Normandy Trouble-free. Bike carried on trains in UK (London-Brighton).
September 2005
250 km various day rides At about 1300 kms the rear suspension rubber monosphere developed a slight split. This was the original sphere from the 13-year old donor APB and it really ought to have been replaced at the outset. A new harder monosphere from Shaun Moulton has been fitted and will be monitored. (No signs of wear to date).
August 2005
325 km tour in Scottish Highlands No problems. Some very steep hills (25%) successfully climbed and descended. Walked up only about two of them. Separated and re-assembled the tandem twice.
July 2005
700 km tour in Provence No problems. One puncture. On minor roads and some tracks. Separated and re-assembled the tandem twice.


George Coulouris 30/10/06