Workouts on Rollers - incorrect (est) power figures

I do the occasional workout on rollers, if im warming up atthe track or race etc… but as with most rollers there is no resistance, and TR works out power (I assume) from speed and cadence I get higher power figures than Im realistically putting out, esp when Im spinning over 120.

Is there any way of getting a more accurate reading on the screen As in reality I could do TRs hardest workouts on rollers smash all the power targets and not even break a sweat?!

Unless you are using power meter, you are using VirtualPower. That requires a speed sensor and selecting your training device.

  • What do you have selected as your device?
    • If you don’t know, look in the Devices and make sure you are set to the exact set of rollers.
    • If yours are not there, you should be able to pick a generic set of rollers. But note that the power curve may or may not match up with the power curve of your rollers.

You can search here to see if your rollers are in the “supported trainer” section.

I am guessing that you are on a different device that is very different from the rollers you are using. That will apply the wrong power curve and give erroneous data as a result.

hi chad - Im using roodol rollers which have the same diameter rollers as the krietel ones so I select those.

Theres no power meter on my track bike, but its more the lack of resistance - because the power is est using speed and cadence and there is no resistance its a bit like suspending your back wheel and pedalling - the sensor will pick up youre doing 100rpm and the speed sensor will say you are doing for eg 20mph but the power and subsequent calorie figures will be no where near the reality of just spinning your wheels, it will assume there is resistance at the back wheel.

The power curve for any trainer or rollers was made at TrainerRoad while recording with multiple power meters, at a wide range of speeds.

That works well with a few caveats.

  1. It relies heavily on the type of tire used. There is a wide range of rolling resistance variations between tires. It is even more apparent on trainers and rollers since they deform the tire more. Easy money that they used some trainer tire or regular road tire.

  2. It also relies on tire pressure. Most often, you want to use the upper end towards the max rating for the tire and wheel. If my guess above is correct, then a pressure around 100-110 psi is likely.

  3. The above matters even more with rollers because many of them do not include a resistance unit. They rely on tire deformation around the drums for resistance.

All that is to say that any difference above can impact the feel and reported power. So those variations are very likely at play since I’m guessing that you are using high end tubular race tires at a very high pressure.

That alone could lead to a much different level of tire deformation. I suspect that is a big part of why the rollers spin faster, with less effort.

And the other clear variation is the difference in the rollers themselves. The diameters matter a great deal, but there may be other differences adding to the issue.

But my bet is that a track bike setup is the core issue here. What are you running for tires and pressure?

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Hi chad…

I use 23mm vittoria pista speeds at 210psi…

The rollers Roodol compact actually, (poss) due to their size, give more resistance then normal rollers, on for eg tacx rollers ill be spinning at 130 with a 52/14, and only reaching 120/130bpm after a sustained 5 minutes, but onthe roodols I can easily get to 165bpm same gearing same time.

Based on the conditions and bike setup, you really can’t trust the data from the VirtualPower with the “right” rollers selected.

This option is a royal pain, but I will mention it anyway.

  1. If you had access to power pedals and the same bike/rollers setup, you could try selecting different trainers and rollers from the VirtualPower menu. It is possible that something else might have a power curve that would give you a better guess on power compared to the “right” rollers.
  2. This is a hassle, because there is no telling which of the VP trainer options would be better. So it would take some testing with each one, and compare that VP setting to the real power from the pedals.

Other than that, you are experiencing one of the shortcomings that exists within VP.

Here’s the official power curve. It seems a bit high for a set without a resistance unit…but maybe??

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appreciate the replies guys.

Unfortunately power pedals arent for me, I use time pedals as they are more secure (without straps) than many ive tried, but Im trying to track down a Rotor Track Power crank, as and when one comes onto the market.

that chart is quite interesting, Roodol rollers are great but they do need to beef their frames up, anything over 25-30mph and the thing really starts flexing.
odd the Compacts have more resistancethan the track rollers, I found the track rollers literally like spinning on air - totally not what you want for warming up.

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