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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 05-07-08, 09:03 AM   #1
asu_gt
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Power output during single and tandem cycling

As some of you may know, we have a laboratory tandem that is capable of measuring the power output of the captain and stoker individually. We have used it for an exercise intervention for Parkinson's patients.

The recent thread regarding 'are tandems faster than singles' got me thinking that we can address this issue, at least from a power standpoint with our tandem. I am planning to make couple modifications to our lab tandem to make it road worthy and conduct some testing. What do you think of the following protocol:

8-10 experienced tandem teams (e.g. annual miles >1000)
two conditions on the same date (randomized); 20-30 minute rest between conditions.
1) three mile time trial on instrumented tandem (periscope so we should be able to accommodate most teams)...maximum effort
2) individual three mile TT on single bike with powertap or SRM

Primary outcomes: average and maximum watts for each rider under each test condition, total watts during tandem compared to summed individual efforts (e.g. test the social loafing hypothesis), average cadence, maximum cadence and time and speed measures. No heart rate monitoring as we have not found reliable methods to dissociate capt and stoker that interface with SRM units.

Maximum efforts are always difficult to get from subjects, we would likely use a financial incentive for the top times for individuals and teams.

thoughts, since this is a side project not directly related to my research.
j
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Old 05-07-08, 10:34 AM   #2
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Malkin and I would volunteer, except that we put our "maximum effort" into enjoying the ride, maximizing social loafing, and not necessarily producing watts. Might skew the results!

That being said, the research protocol is pretty simple and elegant, but I think the research question, "Are tandems faster than singles?" is hopelessly flawed. I'm pleased that your formal efforts are directed at helping Parkinson's patients, and encourage you to stay focused on that pursuit.

Cheers!
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Old 05-07-08, 01:45 PM   #3
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Wow, how fun is testing that going to be! I wish we were close so we could take a spin and contribute to the testing.
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Old 05-07-08, 08:13 PM   #4
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This study has the potential to start a lot of fights.

And what's the hypothesis?

My be is that if the subjects truely give a maximal effort. The tandem team's power will be very close to the sum of the 2 individual riders.

Of course that doesn't mean you get that sort of power output from the back under non test conditions..
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Old 05-07-08, 09:58 PM   #5
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Another test could be:
Capt. + Stoker do TT on tandem.
Then Capt. does TT on single
Then Stoker does TT on single
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Old 05-07-08, 11:03 PM   #6
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Another test could be:
I think that is what asu gt is suggesting.

I would expect power output on the tandem to be close to the sum of the two riders individually however something to consider...

I was working at a bicycle shop where someone had gotten a power meter installed. It was decided to have a contest as to who could reach the highest wattage, however nobody else there seemed to understand exactly what that meant. They all went out and as efficently as possible accelerated and tried to ride as fast as they could. When it was my turn, I shifted into the hardest gear possible before even starting my attempt and then just pushed the cranks as hard as I could for about a second, repeating a few times, never exceeding even 20MPH. I had the highest maximum wattage.

I accelerate differently on tandem than on a single. I'm not sure what the results of this would be, but I'd bet the acceleration cycle will not necessarily fit adding the wattage of the two individual riders. What might prove more interesting than the total results for the experiment would be how the teams performed during acceleration compared to the sustained part of the ride. I don't think the experiment would be complete without doing a test on hill climbing as well though.
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Old 05-08-08, 09:00 AM   #7
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i would hypothsize that the summed power on the tandem will be slightly lower than the sum of the two individual TT. Maybe a case of social loafing or drivetrain power loss is greater on the tandem. I would not characterize this as 'hypothesis driven' research.

the max effort is always tricky; we have a portable lactacte testing system, we could look at those data to asses consistency of effort to some degree.

I agree that maximum power alone is not that informative, assuming the times of single and tandem trials will be different, we could normalize based on time and overlay the data to assess acceleration issues.

i would like to do a hill trial, however, we are limited with the gearing (i.e. only the big chain ring is available) as the small ring serves as the timing chain.


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Originally Posted by merlinextraligh View Post
This study has the potential to start a lot of fights.

And what's the hypothesis?

My be is that if the subjects truely give a maximal effort. The tandem team's power will be very close to the sum of the 2 individual riders.

Of course that doesn't mean you get that sort of power output from the back under non test conditions..
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Old 05-08-08, 09:57 AM   #8
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I think it is a great idea to run the test. No matter what protocol you select, it will be imperfect but you will certainly learn a lot about power profiles on singles v tandems and how different teams perform.
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Old 05-08-08, 11:20 AM   #9
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count us in!

Hey,

we're an experienced tandem couple in COlumbus, Ohio who would like to participate in your research. Where do we sign up???
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