The statement that tandems have twice the weight and twice the power is just wrong. Yes they have twice the weight approximately (2 x each rider + 2 x solo bike) and yes both riders can try to deliver the same amount of power as they would individually, but as has been stated previously in this forum, not all of this power reaches the rear wheel. I believe that the figures given by those who have researched this factor and know more about it than I, gave the value of around 16% loss in the drive train alone for an efficient set up.

So even if both riders are able to pedal perfectly in sync (something that I believe is almost impossible as mentioned in a previous thread), and ignoring drag (come back to that) a tandem yes has twice the weight, but only about 1.8 x the total power and hence will never climb as quickly as the faster climber on the tandem as an individual.

Back to drag... Again, I thiink the figures that others have given on the increase in frontal area for a tandem over a solo is around 30% greater. So in theory, in ideal conditions (a perfect head wind or no wind at all) a tandem has around 130% of the drag of a solo and about 1.8 times the power. I don't exactly know what the equations are relating to speed, drag and power, but I do know that for a given speed, you need to deliver proportionally much more power to overcome a small increase in drag. My gut feeling is that in perfect conditions, the proportionally greater increase in power over frontal area is probably just about big enough for tandems to be faster than solos on the flat, but it's marginal in my view.

The fact that the tandem also has higher inertia also means it is less likely to slow down as much as a solo when hit by gusts which may also help in windy conditions.

However, but for an in door track, we all know that the wind doesn't hit us on the nose. I'd be really interested to find out whether anyone has looked into the increase in drag when the wind hits you side on. Having spent around 14 miles in a TT at the weekend, 7 of which climbing 1200 ft at an average of 10%, with a gale force 7 side wind, I can tell you it hurt us a lot more in terms of time lost than the solos.

I believe this theory is supported by the fact that on reasonable courses, as far as I'm aware at least, virtually all the records for TTs from 10 miles upto 100 miles are all held by solo bikes, not tandems. I know tandems are necessary raced by the top riders these days so much but if they did have such an overwelming advantage you would expect them to hold more records. If any records are held by tandems, I suspect it was on a flat course and set in very still conditions.


Certainly my experience is that we are comparatively faster to solos in very still conditions than when it is windy.

And finally back to climbing...

While it is absolutely true that any advantage a tandem may have over a solo as described above, will become less significant at lower speeds, for example when you're climbing, this does not explain why a tandem should be slower than the fastest of 2 solo riders on any given climb when compared with them riding a tandem up the same climb.

It is as some body else pointed out, all about power and weight, and as described above, the tandem does not have twice the power and so will never climb as quickly.

When you also think that both riders will never pedal in perfect sync and on a hill, when they are not in sync, even for a fraction of a second, they will be trying to carry the entire weight of the bike and riders. On a climb this affect will therefore be far more fatiguing and hence both riders will ultimately become more tired - something I think we all understand.

I would also agree with others that the most difficult climbs are the long drags around 10%. When it's really steep and everyone is in a twiddly gear, we find we can stay with solos. This could be due to the fact that on these type of climbs both riders may pedal more smoothly in the smaller gears. But it's just not possible to sustain this for long drags on slightly bigger gears. Yes, you can hold the smaller gears but then you just don't go as fast. We've often thought that we'd climb better if we had a full range of sprokets from 25 to 34 so we could pick which one is just right for our pedaling.