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I have noticed that on all the tandems I have seen the pedals are mounted in the same position. i.e. while the front right one is up, so is the rear right one, and not front right up and rear right down.

Is there a specific reason for this?

  • 2
    Not a tandem rider, but a guess is Cornering. – mattnz Aug 2 '17 at 8:21
  • @mattnz you could have a 90° offset and one person have horizontal cranks while the other has outside foot down. But cornering is part of it – Chris H Aug 2 '17 at 9:03
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    @Carel The reason would be more even application of power (especially with a 90° offset instead of 180°) and it's not clear to me why a tandem should look like a marching band. – David Richerby Aug 2 '17 at 13:38
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    @David Richerby: I've tried a 90° out on my tandem,once, when it was new, because I had read about it. I found that because the stoker moves differently balance was affected, making a straight line of travel difficult to keep at low speed. Also if the captain has one foot on the ground at a stop and the cranks level, the stoker sits uncomfortably with one knee high up and little pushing power at the start. – Carel Aug 3 '17 at 15:08
  • 3
    Because out of phase cranks leads to divorce. – whatsisname Aug 4 '17 at 5:42
35

Sheldon goes into some detail on this.

Having the pedals 180° out of sync would lead to a couple of problems:

  • Starting off, as most people have one foot on the pedal and lean towards the other foot on the ground, including both people on a tandem.
  • Foot overlap. There's often not enough room for the captain's foot to be at the back of the stroke and the stoker's to be at the front without them colliding.
  • You couldn't corner with the outside foot down, as the other person would have the inside foot down and strike the ground.

A phase difference of 90° is used sometimes. The power is more even through the stroke but handling is worse at low speeds among other downsides.

Another post dicusses 90° out of phase and also slightly out of phase

The second article suggests that most people ride exactly in phase because that's how tandems are set up by default. Changing takes some getting used to and a little fiddling so people need a good reason to mess with it.

  • Your first point is wrong - that's a really difficult way to start off a tandem. You do it by the captain holding the bike, the stoker fully mounting and rotating the pedals to the captain's preferred starting position, the the captain starts like it were a single bike while the stoker applies as much power as possible to bring the tandem up to maneuvering speed. – Marjan Apr 19 at 5:54
  • @Marjan: experienced tandem teams will often start together. – whatsisname Apr 20 at 1:22
4

My wife and I have ridden a tandem for 2 years. Shortly after buying it we wanted to ride High Pass Challenge, a ride up to an observation point on Mt. St. Helens. As newbies, we were not very good at stand-up pedaling together and I had to keep a death grip on the handlebars to keep the tandem going straight with the pedals in synch and my wife's weight shifting in synch with mine. We did that HPC ride with the pedals 90 degrees out of phase and it made my job much easier with a very smooth power input to the bike. However, we quickly found out after the ride we wanted to get back in synch for normal flat riding and here is the key. With pedals in synch, we push the pedals together and my wife immediately senses when I back off my power. When we are out of synch, her power strokes are always on her own and when I back off it takes a couple of crank revolutions for her to figure it out. It feels like a 4 cyclinder engine running on 2 and she really hates it.

So in short, I prefer out of phase but my wife prefers in-phase and to avoid divorce, we keep the tandem in phase for her. We are much better tandem riders now and do all our rides, even mountain climbs, in synch. To climb in synch the captain just needs to train the stoker to keep the weight centered at all times and warn of any unexpected weight shifts (water bottle, stand-up butt breaks, etc.).

As others have pointed out, you can't put the pedals 180 degrees out of phase without having the stoker's pedal hit the pavement when cornering. 90 degrees puts her level while the captain goes down on the outside, or the other way around if the captain is confident enough to keep track of which of the stoker's pedals will be down in a corner, but that seems like a recipe for a disaster that will likely end the tandem experience if the captain gets it wrong even one time.

  • +1 for "I like this, she likes that, so we settled on her way" Things we do for domestic harmony! – Criggie Apr 18 at 21:31

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