In the case of a beginning team, the captain will need to use a bit more upper-body strength than is needed for a solo. As the team learns to work together, this will become less important.
The captain has two main responsibilities:

• To control the tandem, including balancing it whether stopped or in motion, as well as steering, shifting and braking.
• To keep the stoker happy!

A tandem isn't a tandem without a stoker. The captain must earn the stoker's confidence, must stop when the stoker wants to stop and must slow down when the stoker wants to slow down.
Since the stoker cannot see the road ahead, the captain has a special responsibility for warning of bumps.
When a couple fails to make it on a tandem, it is almost always due to either the stoker being scared or saddle soreness.

The captain should also warn the stoker of gearshifts, especially gearshifts to a lower gear which could cause the stoker to lose balance if they come without warning. Experienced “teams” get past the need for this fairly quickly.

The Stoker
The rear rider is commonly known as the "stoker." Other names for the rear rider include "navigator", "rear gunner" and "rear admiral".

The rear rider is not a "passenger", but is an equal participant. The stoker has two main responsibilities:

• The stoker serves mainly as an additional motor. Since the stoker is not needed to control the tandem, this rider should be able to generate more power than the same rider would on a solo. Depending on the strength and endurance of the stoker, this may take the form of a steady output or may be held in reserve.

If the stoker is acting as a "reserve," it is OK to take it easy for general cruising, so long as the stoker helps out with a burst of power for the climbs.

Since starting up on a tandem is a bit trickier than on a solo, the stoker should apply as much smooth power as possible when starting up, to get the tandem up to maneuvering speed quickly.

• The stoker's other major responsibility is a negative one: The stoker must not attempt to steer!

Unpredictable weight shifts on the part of the stoker can make the captain's job harder and can lead to crashes in extreme cases. The stoker should keep in line with the centreline of the tandem, and lean with it as it leans through corners.

When the stoker needs to shift position, or adjust clothing, or take a drink; it is vital that they do so without disturbing the equilibrium of the tandem. These activities should not be attempted while the captain is dealing with tricky traffic or narrow spaces.

The Team
An experienced tandem team develops a very special level of non-verbal communication, via subtle weight shifts, variations in pedal force, and general empathy.

After a few hundred miles together, you will find yourself coasting at the same time, shifting without the need for discussion, and maneuvering smoothly even at slow speeds.

This is not just a matter of each rider acquiring captaining/stoking skills; when two equally experienced teams switch stokers, something is lost, this special communication doesn't happen...it really is unique to each couple.

Tandem Fitting
In general, it is preferable for the larger rider to be on the front, particularly for an inexperienced team, however this is by no means cast in granite.

Because a tandem frame needs to fit two riders, the chances of finding one that will fit both perfectly are low, unless you have a custom frame built.

Where there needs to be a compromise in fitting, it is better to make sure that the tandem fits the captain. In particular, the front of the frame must not be too large for the captain to be able to straddle with good crotch clearance because the captain will need to spread their feet further apart than normal to balance the extra weight of the stoker.

On the other hand, if the front of the frame is too small, a longer handlebar stem can usually make up for it.

In the case of the stoker, it is not actually necessary to be able to straddle the frame as it is on a solo. Thus a frame size that would normally be considered "too large" on a solo may be perfectly reasonable for a stoker, assuming that an appropriate handlebar stem is used.

In general, a somewhat higher handlebar position is advisable for tandemists who are not primarily into it for the speed. In the case of the captain, a higher bar helps reduce the upper-body fatigue associated with handling the longer and heavier tandem. In the case of the stoker, a somewhat more upright position provides a better view. Plus there is less of an aerodynamic penalty for the stoker's more upright position on a tandem.