Riding a tandem has some things in common with a riding normal bike, and quite a few differences. Communication and co-ordination between captain and stoker are most important, of course. The captain is in charge of steering, balancing, braking and changing the gears, while the stoker plays an important role in starting off and supplying power generally. Because of the need to balance the weight of the bike plus stoker when stopped, the captain usually has both hands on the brakes and the foot – or feet – down. The stoker is already in the saddle with both feet on the pedals, so they are the bike’s main engine when starting off (apart from gravity down hill). For this reason it’s important that both understand that the pedals must be in position for the stoker to easily start a power stroke after coming to a stop, i.e. not straight up and down nor almost so. It’s the captain’s job to make sure that the gear selected is appropriate, which means thinking ahead if using derailleur gears, as with a solo bike.
The captain has the clear field of view so it is their responsibility to warn the stoker of any bumps, obstacles or sudden stops. It helps to keep the pedals horizontal over sharp bumps so that both can use their legs to help cushion the bump if required. Although the two sets of pedals rotate at the same speed it is possible for one person to do the majority of pedalling for a time while the other takes a rest. Taking turns according to how each is feeling can be quite helpful on longer rides. Accelerating or decelerating the pedals suddenly without warning can cause the other rider to lose their footing so it’s best to do this gradually or give warning e.g. “pedal” , “go” or “slowly” etc. I find when changing down derailleur gears it is sometimes necessary to put back pressure on the pedals if the stoker is pedalling hard, to take the pressure off the shift mech. for a smooth change. The gear cables are longer on a tandem so changes can be a little slower too. Stokers should of course give notice whenever they need to shift their weight in the saddle.
Because tandems have roughly the frontal area of a solo bike but with two people pedalling, they can be quite fast on the flat and exceptionally so downhill – one of the joys of riding two-up is catching (normally) faster cyclists downhill while not even pedalling, then pedalling in top gear to pull past them effortlessly ! Uphill the situation reverses, as the greater weight takes its toll. A good range of gears is essential as you really need to remain seated at all times and of course it’s more complicated for two to dismount and re-start than for solo biking. The granny gear on my wife’s 24 speed Raleigh is around 1:1 and very useful on steep hills. This is one case where more is better, within reason.
Riding solo on a tandem immediately after riding two-up is a really strange experience as one tends to wobble violently along the road, over-correcting the steering for the first few minutes, then after that it all feels normal, which makes me realise that one can get used to riding almost anything once acclimatised.
One final observation … women onlookers usually smile, kids mostly get excited, while some males, often older non-cyclists, sometimes have this urge to shout “she’s not pedalling, mate” which is pretty lame and unfunny after the first (let alone the 327th) time you’ve heard it …
Happy Cycling !