Differences riding outside vs turbo trainer
12-25-20, 08:44 PM
#26
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The main reason is for consistent figures. If you only use power on the trainer, you mostly want it to be precise and accuracy is more a nice to have. So when you also have a power meter to use outside you would also want consistency between outside and inside numbers.
I didn't investigate further if the smoother lines when using trainer only were real or from data smoothing as I was ok with using the power match feature anyway. On my trainer I am not getting as volatile ERG performance using power match as shown by gregf83:
On the third work interval, I switched to little ring for the first quarter, then the power wiggle is me moving up the gears again and spinning up the flywheel. So clearly ERG has a harder time with faster spinning flywheel but for me still works fairly well.
I didn't investigate further if the smoother lines when using trainer only were real or from data smoothing as I was ok with using the power match feature anyway. On my trainer I am not getting as volatile ERG performance using power match as shown by gregf83:
On the third work interval, I switched to little ring for the first quarter, then the power wiggle is me moving up the gears again and spinning up the flywheel. So clearly ERG has a harder time with faster spinning flywheel but for me still works fairly well.
12-25-20, 08:53 PM
#27
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What you are describing is the balancing of left right. What is happening as the pedals go round is that every foot has a phase when it is applying tangental force to the pedal in the right direction and a phase of no force or even negative force if you don't take the weight off when the pedal goes up. If we add up the torque provided by both legs, the resulting torque is never smooth. So when you go at a constant speed and cadence, the crank is always accelerating when torque is high and decelerating when torque is low, no matter how smooth it feels to you.
The ride feel of a trainer or roller and how much it resembles outside riding is dependent on these accelerations. Compared to riding outside on a flat, trainers will typically accelerate faster when you are pushing down on the pedals and decelerate faster as well when in the dead spots.
Are you familiar with the peanut plots? At best these become sausages if you become smoother, but never circles:
https://support.wattbike.com/hc/en-g...fect-Pedalling
And yes these calculations were fun to do, which was at least as big a driver as any practical importance that could come of it
The ride feel of a trainer or roller and how much it resembles outside riding is dependent on these accelerations. Compared to riding outside on a flat, trainers will typically accelerate faster when you are pushing down on the pedals and decelerate faster as well when in the dead spots.
Are you familiar with the peanut plots? At best these become sausages if you become smoother, but never circles:
https://support.wattbike.com/hc/en-g...fect-Pedalling
And yes these calculations were fun to do, which was at least as big a driver as any practical importance that could come of it
i forgot to mention peanut plot in my last post. that is similar to the analyzer i was on. like i said before, it was an eye opener and really taught me how to better peddle. certainly not an expert but i did manage to get a far better looking plot than the last, much more circular. it did not last for more than a few cycles though. it was really hard to maintain because i was trying to do it using my typical power output and rpm but with a different muscle group to get to the circle. but it surely did tell me what i needed to do. i no longer peddle only on the down stroke as a result. Carbonfiberboy is right though, it can be done but it is hard as hell to get there.
12-25-20, 10:14 PM
#28
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for what is it worth here is a shot of my application showing the power with 2 second moving average. the orange is 94% or 216w. flat green is 60% or 138w. i have found that at certain target power levels the controlled power is better tuned than at other powers. i used to think it was related to odd or even target powers but i don't think that is the case anymore. the power jumps by as much as 3w and is not noticeable, at least not by me. and for me cadence is not related as the data shows below (cadence in green). i noticed your target power is also not steady but seems to vary during the interval. what app are you using? i like the FTP line, i think i may add that to mine.
I am using Trainerroad, in this particular workout, the intervals are at sweet spot (88%-94% FTP), and target power moves a bit in that range.
if I remember correctly, when I did ERG mode with power data from trainer, I would also get those smooth lines.
12-26-20, 02:49 AM
#29
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Ah, but you see, what if the two added torques were always equal or so close to that as to be unnoticeable? In an alternate universe it's possible. It's absolutely possible in this universe and many people do it. Those plots show improvement with continued practice, Seems hopeful to me. Why wouldn't one be able to continue to perfect a skill over the next say 40 years?
Here are a couple of videos on the topic of pedal smoothness you might find interesting:
If you think about all the muscles used in driving the pedals round, the quads and the glutes are the big power houses, but you can't use them throughout the entire pedal stroke. Therefore IF you could achieve a PS of 100%, you would necessarily need to reduce the power from glutes and quads in order to balance it with the other muscles. That explains why perfect smoothness is not a goal of performance oriented athletes. Also in practice it is not achievable, in the first video above they note that a PS of 65% can be considered super smooth.
So most likely, it feels like 100% smooth to you, but measurements would still show a higher torque when pushing down on the pedals, vs horizontally pushing/pulling.
12-26-20, 01:45 PM
#30
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Pedal Smoothness (PS) is defined as the maximum torque as a percentage of the average torque over a full pedal stroke. A PS of 100% would give a perfect circular polar plot of torque instead of the peanut shapes we normally see.
Here are a couple of videos on the topic of pedal smoothness you might find interesting:
<snip>
If you think about all the muscles used in driving the pedals round, the quads and the glutes are the big power houses, but you can't use them throughout the entire pedal stroke. Therefore IF you could achieve a PS of 100%, you would necessarily need to reduce the power from glutes and quads in order to balance it with the other muscles. That explains why perfect smoothness is not a goal of performance oriented athletes. Also in practice it is not achievable, in the first video above they note that a PS of 65% can be considered super smooth.
So most likely, it feels like 100% smooth to you, but measurements would still show a higher torque when pushing down on the pedals, vs horizontally pushing/pulling.
Here are a couple of videos on the topic of pedal smoothness you might find interesting:
<snip>
If you think about all the muscles used in driving the pedals round, the quads and the glutes are the big power houses, but you can't use them throughout the entire pedal stroke. Therefore IF you could achieve a PS of 100%, you would necessarily need to reduce the power from glutes and quads in order to balance it with the other muscles. That explains why perfect smoothness is not a goal of performance oriented athletes. Also in practice it is not achievable, in the first video above they note that a PS of 65% can be considered super smooth.
So most likely, it feels like 100% smooth to you, but measurements would still show a higher torque when pushing down on the pedals, vs horizontally pushing/pulling.
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12-27-20, 11:53 AM
#31
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This materials under discussion in this thread are certainly complicated and fraught. I've been riding the same set of resistance rollers indoors for over 20 years. I don't notice any difference in the feel between riding them and riding outdoors on the flat. On hills there is a definite difference due to the crank inertial load issue discussed in a previous comment. I've always been puzzled when reading of riders' desire for a trainer which simulated road feel. My rollers perfectly simulate road feel because I've not adjusted or purchased the correct trainer, but rather have trained myself so that my legs feel the same resistance throughout the pedal stroke in either environment. I have tried trainers and found no difference there either.
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12-27-20, 12:38 PM
#32
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Bought them from Bike Nashbar a long time ago, for ~$120. ABS drums. Fluid resistance unit, so resistance increases with roller RPM. Bought them 20+ years ago, but IIRC the max resistance is 500 watts. Feels like maybe so, 35 mph is about all I can do seated. I get ~120 watts at 15.5-17 mph, depends on the fluid unit's temperature, which depends partly on how hard and long I've been riding, and to a large extent on the temperature of an unheated floor in the PNW. IOW, the thing has become an even better training tool now that I have a power meter. Between trying to keep my power where I want it and trying to move my legs in some appropriate pattern and attempting to keep pain at bay, all the while not falling on the floor, I don't see why people need to watch TV to keep from getting bored.
For a modern set, SportsCrafters is maybe the best out there. Magnetic resistance.
For a modern set, SportsCrafters is maybe the best out there. Magnetic resistance.
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