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Slowtwitch Forums: Triathlon Forum:
spinning bike/watts/aero position kind of question

 

   


justgeorge

Jan 2, 10 18:47

Post #1 of 4 (3650 views)
spinning bike/watts/aero position kind of question Quote | Reply

OK so I'm in terrible cycling shape and marginal run shape, but getting back into it (M45-49). This morning I'm at spinning class at the Y on a Kaiser spinning bike that has a watts display. Now, I'm embarrassed about how low my watts are so I won't mention the actual number, but the question isn't really related to the actual number anyway.

So the workout focuses pretty much entirely on your wattage. Sets of intervals where you ride 1 minute at your starting wattage then you DOUBLE that wattage for 10 seconds. Working up to 2 minutes at a higher wattage then double that wattage for 20 seconds. The last set the instructor talked about "riding the rivet" to get a little extra power if you needed it. So I slid forward in the saddle, dropped down into an aero position, and behold, my base wattage increased by 20 watts at the same perceived exertion. Could have done without my thighs hitting my belly though....

Hopefully, the watts calculations on a Kaiser spinning bike are way off, otherwise I suck. The bike doesn't ask for your weight, don't know if your weight figures into the watts calculation though. So that's question 1. Question 2 is, by sliding forward in the saddle and dropping down as if I were on aerobars would that really increase my power output that much?

Thanks,
George
btw, the instructor was pulling 280 watts 2 minutes/560 watts for 20 seconds (times 5), and still talking pretty normally thruout the workout.


fawcettenator

Jan 2, 10 20:20

Post #2 of 4 (3615 views)
Re: spinning bike/watts/aero position kind of question [justgeorge] [In reply to] Quote | Reply

I know that weight doesn't go into watts calculation, so I can answer Question 1, but I don't know about #2.


Pantelones

Jan 2, 10 20:47

Post #3 of 4 (3600 views)
Re: spinning bike/watts/aero position kind of question [justgeorge] [In reply to] Quote | Reply

I looked at the product page and couldn't find out what the accuracy for their eddy current system is. But their system is based off of magnetic resistance (think electric motor) which is used in some stationary trainers and the computrainer (i believe). It is hard to say how accurate this system would be to a PT or SRM system which uses strain gauges. It is also not clear how the unit makes its power calculation... the unit could be measuring voltage*current of the stator. Who knows... my guess is that since they are not shouting power accuracy from the rafters it may not be "accurate".

Weight does not figure into watts... In a bike system watts are simply generated by (how hard you press the pedal) * (how fast you are pedaling).

Sliding forward in the saddle can make a huge difference in getting your knees over your pedals and allowing you to press "down" harder. You could have gone from a "bad" position to a more standard TT position which would increase your power. Now the caveat is that going into an aero position and having your "thighs hitting your belly" should decrease your wattage as this closes your hip angle and looses some muscle recruitment/leverage.

Congrats on getting back into the sport, good luck on your training this year.


Lejonhammar

Mar 7, 13 1:53

Post #4 of 4 (1241 views)
Re: spinning bike/watts/aero position kind of question [Pantelones] [In reply to] Quote | Reply

+ - 10% according their website and manual.