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Old 09-17-12, 06:55 AM   #1
bikingman
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Problems Measuring Power on Trainer?

Yesterday I did my first hard workout on my new trainer with my powertap wheels.

I have a SuperMagetoPro Trainer and G3 Powertap Wheelset by CycloOps.

On the road, pushing 320Watts is hard, but not that hard. On the trainer, pushing 320W seemed SO HARD!

I was on the Hill climb setting of the trainer. Has anyone else wondered if there is a difference the wheels capability to register power on and off the trainer. Does the trainer misread when on the road (I hope not) or on the trainer?

Just inquiring. Prob just going to have to suffer!

DP
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Old 09-17-12, 08:36 AM   #2
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It's not your power meter, it's you. Most people find that riding the trainer has a higher perceived exertion for the same power. Some of that is due to overheating. You need good fans to stay cool.
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Old 09-17-12, 09:00 AM   #3
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So by this understanding perceived exertion goes up but the actual work does not? It felt as though my legs were in more pain that they would be on the road. More LT buildup.

Noted - need good fan.
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Old 09-17-12, 10:48 AM   #4
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I've experienced your pain on the trainer as well. I agree the heating is an issue, but I also believe the resistance provided by the trainer is a factor as well. The inertial load presented by most trainers is significantly different than what you will experience riding outdoors. I think this takes some time to get used to. On the occasions when I've ridden on the trainer consistently over a 2 week period it does seem to get easier, or at least my legs get used to it and don't experience the same soreness I get when starting out.
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Old 09-17-12, 12:20 PM   #5
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I'm just wondering if there's a rolling resistance (created inside trainer) that the powertap wheels are unable to pickup. Probably not!
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Old 09-17-12, 01:46 PM   #6
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No, the powertap will detect any change in rolling resistance. The only possible effect the trainer could have would be from clamping the hub in the trainer. But I believe similar experiences to yours are reported by those with crank based powermeters.
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Old 09-17-12, 07:08 PM   #7
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Yes, it's the change in inertial loading. Every different sort of cycling or cycling simulation has a different inertial loading. Fixies, spin bikes, rollers, trainers, outdoor road, they're all different. Each requires a period of adaptation to the differing pedaling mechanics which are encouraged by the amount and location of inertia in the system. Many people also find outdoor riding easier because of the arousal produced by the kinetic sensations.
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Old 09-18-12, 12:33 PM   #8
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So there may be a difference in inertial loading which my body needs to adapt too... yes? Is it a difference in inertial loading that is harder to get moving and keep moving which I'm feeling - i.e. more power is needed to move.
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Old 09-18-12, 09:28 PM   #9
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So there may be a difference in inertial loading which my body needs to adapt too... yes? Is it a difference in inertial loading that is harder to get moving and keep moving which I'm feeling - i.e. more power is needed to move.
Well yes, but it's micro in the pedal stroke. The flywheel in the trainer isn't doing as much for you as the inertia in you and your bike going up the road. That's my theory, anyway. In that regard, another thing to think about is why do we pedal higher cadences on the flat than we use climbing?
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Old 09-19-12, 08:14 AM   #10
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It just dawned on me - I hope these questions have been studied by doctors and scientists.... I was told (by a doctor) recently that there are physiological differences between people and that some people actually perform better as higher cadences and others at lower. I'm guessing that it's how the body responses. I have noticed a more dramatic response at lower cadences than at higher while in my body while producing constant power. (i.e. my heart rate is higher). THis was a pretty cool discovery.
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