Crank Phasing
 

Is there a preference? I've been reading all I can to learn about tandeming (just picked up a used Cannondale Road Tandem 2) and saw in Sheldon Brown's article that some prefer 45 degrees out of synch, some just a few degrees out of synch, some exact synch.

http://www.sheldonbrown.com/synchain.html

I'm not a tandemer... (??) but I think the majority of people who like out of phase (OOP) cranks do so at 90 degrees. The benefits being that one rider will be applying power when the other rider's cranks are vertical (and therefore not producing power.) However, one has to be very careful not to strike a pedal on a turn when in this configuration. (Because if one person's inside crank is up, the other person's cranks are horizontal.)

Some people say this reduces the "togetherness" of riding a tandem, which is part of the appeal. (I'm starting to sound like I'm just repeating Sheldon's page...) As for a few degrees OOP pedals, I'm not sure why you'd want that unless you have a specific reason for it which I can't think of.

I'd say that most riders default to in-phase. There are advantages to other phasing but in-phase is probably the simplest: when cornering, both cranks are in the same position. Also, the captain never has to think about where the stoker's cranks are. I think that teams could train themselves to adopt other phasing but it would be conscious effort.

The majority ride in-phase but their are advantages, as Sheldon states, to riding out-of-phase. We ride in-phase. If you start clicking on pictures here you will see how people are riding. Good luck with your new bike! I hope you have as great a time as we do riding together.

Rudy aka Zonatandem will have the best answer.. he has been riding many years and many many miles OOP.

I set our bike one tooth out of phase. some of that dead zone with the cranks in the dead zone at the top is gone and we don't have to think about what pedal angle we have to use to prevent a pedal strike since our tandem had a 75mm bb drop

I have only run in phase, however, intuitively, I would think that out of phase would require higher peak power from each rider during acceleration and climbing. Total power required would remain the same, but each rider would have to pedal harder during their power stroke to accelerate their combined mass than if both riders power stroke were in sync.

thats what I was thinking of doing. Just so I'm clear, the captain's crank is advanced/ahead of the stoker's crank?

You can set it either way.

Power output of each person should remain the same, so phase has no impact on power. It just feels more smooth for us, or I would probably be totally in phase. 90 degrees off or some other drastically different angle i haven't tried but it should reduce the pulsing of power especially on hills which would feel faster and it very well could be faster as well since you don't get a chance to surge in speed (though small surges) and have micro accelerations with the bursts of power to the wheel.


We don't use power meters but it would be interesting to hear of these tests. Powertap pm+two garmin power meter sets would be able to tell what's fastest.

Not mentioned so far is riding out of the saddle. I really enjoy it when we stand up and gently rock the bike side to side together. We can only do that when cranks are in phase.

I used to set the captains cranks a tooth ahead of the stoker, the idea being that the stoker would need less effort getting the pedals over top dead center. But recently I got a tip to put the stoker's cranks a tooth ahead of the captain so that she wouldn't feel like her pedals are being rushed over the top. This seems to work better for us as the stoker seems more comfortable with a higher cadence now.

We have ours around 10 degrees out of phase, We started changing it because when we were in sync, I pedaled so hard the stoker felt she wasn't contributing anything. This seems to help that a bit, though I probably need to work more on my technique.

After 28 years of 90 degrees OOP, we recently changed to three teeth out of phase (weaker rider leading). OOP was great for us. We lived in the Sacramento Valley, which meant that the opening and closing twenty miles of each ride were going to be on the flats. 90-OOP was simply faster and smoother for us on those flats, and with so much of each ride being flat it made sense to optimize that. Now that we're older and weaker and we live in a hillier location, we have switched over to nearly in-phase. In phase is a bit faster on the climbs for us. There's no meaningful change in our ability to stand; we could do that just fine OOP and I prefer to sit while climbing anyway (my smaller captain stands quite a bit).

We have always been in-phase, but that is primarily because my first tandem was set up that way rather than due to careful study on my part.

We ride in-phase with the captain's ring advanced a tooth or two, this has nothing to do with pedaling, but with standing/coasting. We've found that our "level" pedal positions aren't the same when we stand, I prefer the right foot slight lower than what the stoker prefers it.

If they pedaled with the same effort, cranks at 90 degrees would provide twice as many accelerations each with half the acceleration compared to in-phase or 180.
The net effect would be the same. Basically.

I would think there would be a possibility that in phase your deceleration in the dead zone would be more substantial than 90 degrees out of phase. with out of phase your smoother meaning you aren't accel/decelerating with power. just a thought though, we haven't ridden out of phase to try it.

Thanks everyone for the responses! I was looking for the technically correct answer, and it appears that while that may exist, it's probably more about what feels the best! So, this will give me something to do as we learn to ride tandem (experimenting that is).

Late to reply, we run 2 teeth captain advanced. We had ridden in phase, for a while, then took the time to use the monitors and computer to give meaning to how things felt. During a ride, we stopped and tested various settings after a baseline of in phase. For us, at the time, after several setting changes, we decided on the 2 teeth advanced. This gave the smoothest spin, easiest to spin 100 rpm constantly and lowest heart rates.

On the off-road tandem we ride in phase. Pedal strikes are a large concern and spinning off-road at 100 revs is a bit to bouncy for the suspension and tires.

The best answer, it just depends what you like and what works well for you.

^+1 exact same setup on our road tandem and in phase on full suspension mountain tandems and fat tire tandem. Works well for us

I second that last answer. It is workable to try various phases so that is the best answer. Even if all posters like one phase setting, why not test it yourself to see what your team likes? Have fun trying stuff out:D

if i may add another advantage of 90 OOP:
much lower (1/2 !) peak forces/torques in the drive train.
Increases lifetime of components.
Decreases chance of sudden failure like chain fracture and so on.
These arguments become more important as components become more sophisticated such as 10, 11 speed

We've always ridden OOP (captain leads stoker by 90 degrees) and it works well for us. We don't ride off-road (much) so we don't strike pedals. My stoker especially likes it because it feels smoother to her. And, I suspect we get longer life out of our drivetrain.

Next time I have to mess with the drive train I want to try in-phase to see if it helps climbing.

This thread is making me want to try having different size timing chainrings on the captain and stoker cranks, and see how weird it would be to have the pedal phase continuously changing. :P Depending on the bike, you could have captain and stoker hitting each other's legs at certain points.

I did have that situation when I converted our tandem to a 'kid-back' for taking our daughter school on my way to work and also for recreational rides. I put the necessary pieces together with parts from a LBS scrap parts bin including used cranks from a kid's bike which didn't quite match the number of teeth that I had on the left side of my cranks. Worked fine for that situation with greatly differing power inputs but looked a little funny to riders behind us on group rides.