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Tandem Cycling A bicycle built for two. Want to find out more about this wonderful world of tandems? Check out this forum to talk with other tandem enthusiasts. Captains and stokers welcome!

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Old 08-25-06, 07:51 AM   #1
pjgonwa
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Wind resistance - Your thoughts

During our post ride discussions I mentioned to my stoker that it seemed that we were riding against the wind for most of the ride. It got me to thinking, when on singles and in a line, the guy second in line is riding in the slipstream and is not working as hard as the leader.

Does this same criteria apply to the stoker?

On one hand it does as the stoker is not feeling the brunt nor is pushing aside "the wind". On the otherhand, the stoker is propelling the same amount of "metal" as the captian and would therefor be exerting the same amount of work.

Thoughts anyone?
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Old 08-25-06, 07:56 AM   #2
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Regardless of the wind, How much work the stoker puts out is up to the stoker. They have to pedal at the same cadence, but they don't have to put force to the pedals.

As for the wind affecting how hard it is to propel the bike forward, its going to have the same affect on the captain and the stoker because you're linked together.

The bike as a whole will be less affected by a headwind than a single bike, because you have double the horsepower (giver or take) but you don't have double the aerodynamic drag.


Think about your single bike analogy. If the second rider in the draft had his chain linked to the lead bike so that he had to help push the lead bike through the wind, they'd both be affected by the headwind. Well that's what a tandem is.
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Old 08-25-06, 08:06 AM   #3
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If you streamline yourselves, the drag won't be double that of a single. I don't know the drag coefficients for those on tandems vs. singles but it shouldn't be double.
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Old 08-25-06, 08:59 AM   #4
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On a tandem, a side or quarter-side wind is more of a drag than a straight headwind. If you're heading straight into the wind, you've just got one profile causing drag since the stoker sits directly behind. If the wind catches you at any other angle, however, both riders catch it.

Unfortunately, it seems like the wind has a lot more angles to be against you than it does to help you. We try to keep a good attitude about it, by simply adjusting our expectations when the wind is blowing rather than trying to fight it.
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Old 08-25-06, 10:24 AM   #5
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From a similar question in the past....

Quote:
Originally Posted by operator
I thought tandems went faster than a non-tandem into a headwind because there are 2 people putting wattage vs 1 on a roadbike?
Yes and no. All things being equal except for the bike, (and despite myths to the contrary) a tandem road bike with two riders is between 30% to 50% less aerodynamic than a a solo rider on a road bike. Therefore, in order for a tandem to maintain a constant speed that is as fast (or faster) than a solo rider, the team must produce a net power output that is at least 30% to 50% greater than a solo rider.

Moreover, consider if you will that power production on a tandem is not necessarily linear since either one or both of the two riders on a given team may at any given time fall victim to poor form, individually or collectively. Put another way, even if you have two strong cyclists (1+1), they will lose some efficiency due to the nature of a tandem and, if they are not able to work well together, their efficiency will fall way off. So, in reality what you will often times find with a tandem is that you have two riders of different abilities who can produce variable levels of output which may or may not be as high as they are able to produce when riding alone. This is why some tandem teams who are weaker riders individually than a team comprised of two strong riders are often times as fast (or faster) than the stronger couple when both teams ride their tandems. The place where a team's combined efficiency level is most obvious is when they get to the hills where you have the same math problem with percent grade being substituted for headwind MPH and the added factor of team weight having more importance than aerodynamic drag. Less I digress...

So, to answer your question, if you have a team who can produce at least 30% to 50% more power as a team on a tandem they should be able to keep up with a solo rider. However, if a tandem team can produce a net power output above what is required to compensate for increased drag, the tandem pulls the train.
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Old 08-25-06, 10:40 AM   #6
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I think that it all balances out. The energy that the stoker saves by being in the captain's slipstream is balanced by the fact that she has two chains to pedal vs. the captain's one.
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Old 08-25-06, 03:24 PM   #7
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Quote:
Originally Posted by Retro Grouch
I think that it all balances out. The energy that the stoker saves by being in the captain's slipstream is balanced by the fact that she has two chains to pedal vs. the captain's one.
No. If the captain is contributing even the tiniest bit, then the top of the timing chain is taught and the captain is contributing to torquing the main drive rings.

If the stoker is pushing the captain's cranks, then the bottom of the timing chain is taught and the rear wheel is seeing the stoker's power minus the captain's resistance. Time to get a new captain -- one whoe pedals forwards, not backwards.

-Greg
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Old 08-25-06, 04:22 PM   #8
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Quote:
Originally Posted by gregm
No. If the captain is contributing even the tiniest bit, then the top of the timing chain is taught and the captain is contributing to torquing the main drive rings.

If the stoker is pushing the captain's cranks, then the bottom of the timing chain is taught and the rear wheel is seeing the stoker's power minus the captain's resistance. Time to get a new captain -- one whoe pedals forwards, not backwards.

-Greg
Man! You really should consider switching to decaf or something. You're taking this stuff way too seriously.
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Old 08-25-06, 04:49 PM   #9
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Thing I have found about headwinds is that you always have them on a Tandem.

10 MPH easterly headwind and you are ring into it at 18MPH. Headwind of 28MPH.

10 MPH easterly headwind and you are travelling west at 18 mph- Headwind of 8mph, except the easterly is pushing you a bit so your speed is up to 20mph and headwind of 10mph.

Sounds ridiculous but headwinds are not really a problem till they get up to 20MPH. Pilot can streamline on the bars and the stoker can tuck in tight. Then you only really have one riders worth of headwind. It is those side on or front quarter winds that get us.
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