How do tandem bikes work



Do the front and back bikers have to pedal at the same speed? If the front biker is pedaling faster than the back biker, how can 2 gears rotating at different speeds work together? As a kid I used to just assume the back pedals were fake and not connected to anything.

In: Engineering

It’s part of the same drive train. So they will be doing it simultaneously. You just have to synchronize.

But there are multiple variations. Even with separate drive trains.

The two cranks are linked by a chain, so they have to turn together.
The two riders are necessarily pedaling at the same pace, but not necessarily with the same effort.
The front guy gets to choose what gear the bike is in.

> As a kid I used to just assume the back pedals were fake and not connected to anything.

There *are* bikes like this, *for* kids.

The standard format for tandem bikes is to have both sets of pedals directly connected together with a chain – this means both riders will have to pedal at the same speed. At the back of the bike, the rear riders pedals are also connected to the rear wheel to power the bike.

Both riders will not necessarily have to put in the same effort however – if one rider is pedaling hard, the other can just let their legs move on the legals without putting in any effort, or take their feet off the petals entirely and leave them spinning around based on the other rider pedaling.
The only real problem occurs if one rider is pedalling hard, and the other rider purposely tried to stop the pedals going round, at which point they will be fighting against each other which isn’t ideal.

The trick is that when you are riding a tandem, the riders have to work together – the rider on the rear had to trust the control of the one in front (who had the ability to steer and brake), and if the riders don’t ride in sync they can throw off the balance of the bike and cause problems.
It is also worth noting that tandems are typically used for recreation under pretty calm conditions – so if one rider is riding a bit faster or slower than they would ideally like, they still won’t be cycling hard enough for this to be a problem. This is very different from riding flat out where your cycling efficiency will make a big difference, riding slowly it is not a particularly big concern.

There will of course be other taken designed that are more technical and involved, but directly connected pedals is the normal solution for a standard tandem.