What the Heck is Rolling Resistance (RRC), and Why do we "Calibrate" at Cycling Center Dallas?

CompuTrainer Calibration Starts HERE.
One of the most important things that we can do at Cycling Ctr., Dallas is make sure that every rider properly calibrates their Compu trainer. If a is not properly calibrated, then the values on the dashboard are not accurate. We strive to give you information on screen that is both accurate and consistent, so that we can ensure that you are improving. Calibration is a critical part of that.
 
The first thing that you can do to properly set up and calibrate your CompuTrainer is to start back at the area where the tire contacts the load generator. Make sure that your wheel is mostly centered on that steel cylinder in the back. Then, as you twist the four star dial to bring the load generator closer to the tire, once it makes contact, try to achieve a contact patch that is roughly the size of a nickel, or perhaps the with of your thumbnail. It is always better to start light, then to& too far into the tire, and make the contact patch to large. Always check the air pressure in your tires, and keep them at around 100 psi. Two estimate proper press on force, grab the blue or silver flywheel, and grab a spoke from the wheel, and to see if the tire will slip when you apply pressure up and down on the spoke. If it slips rather easily, add half a twist. If it is completely immovable, back off about a quarter twist. This should put you roughly in the proper place for rolling resistance and calibration accuracy.
 
Secondly, go ahead and throw a leg over your bike and begin warming up. In a previous blog, I highlighted the importance of a good warm-up, both for the body and for the equipment. When instructed, or when you feel that you have performed an adequate warm-up of roughly 5 to 15 minutes, look at the handlebar controller which should be in front, at roughly handlebar height. It is either yellow or gray. If the controller has the word "PRO" or "PROe" on the screen, then we are plugged into either PerfPRO or ergvideo, and we can effectively calibrate. Here's the process for that:
  1. Make sure that you are in a gear that will allow you to speed up beyond 25 mph.
  2. Press "F3", or, the CENTER BUTTON on the BOTTOM ROW. You should see the screen on the handlebar controller change from the word "PRO" or "PROe" to a speed. Go ahead and speed up by pedaling faster until you see dashes appear on the controller screen.
  3. STOP PEDALING WHEN YOU SEE THE DASHES!!!! REPEAT - STOP PEDALING WHEN YOU SEE THE DASHES!!! Let the wheel coast down to a stop.
  4. Do not pedal! Instead, look at the handlebar controller screen. Ideally we want the top screen to read between a 1.8, and a 2.5. This is in pounds of pressure being placed against the tire. It is called press – on force. If the top number is above or below this range, call a coach over so that he or she may make adjustments to increase or decrease the force against the tire.
  5. If the top number is between the ranges of 1.8 to 2.5, press the bottom center button again, and look in the upper right-hand corner of your dashboard. The RRC value is interpreted as the rolling resistance calibration. If the value is green, and is between 1.8 and 2.5, then all is well. If there is a no reading, then you need to repeat the above process. If the top number is outside of that range, once again, get a coach to make the adjustments, do not hop off the bike and attempted your self, and repeat step three. Once you are in range, press that "F3" button in the bottom center row, and again, look at the dashboard in the upper right-hand corner.
CompuTrainer Handlebar Controller Press-On Force

Now, let's discuss the reason why RRC, or rolling resistance calibration is so important.
 
When you pedal a bike, you have to remember that rolling friction is always higher than sliding friction. This is what makes bicycles go forward. Without friction, we would all slip around as if we were on an ice-skating rink. When we ride outdoors, rolling resistance is much, much lower. That is because we have two contact patches of about 8 cm² each. The force required to move a bicycle wheel is somewhere along the line of I think 16 to 35 Watts combined.

When we are pedaling indoors, we are trying to get adequate friction against a small steel cylinder. That is why we have to set rolling resistance between 1.8 and 2.5 pounds of pressure. This actually sets your minimum rolling resistance, at anywhere between 60 and 100 W. Interestingly, if you notice during a workout that your minimum wattage when pedaling in a recovery, is higher than the minimum load being applied via the program, that is because of the rolling resistance calibration. It is nothing to worry about, and remember, we are there to burn energy and generate power. We are not there to coast.

Once you get comfortable with calibrating your you will begin to feel more confident in your ability to set up the bike and rear wheel properly. A proper rolling resistance calibration is critical to ensure good values, and a better workout. Sometimes we will ask you to calibrate twice, especially if you calibrate before warming up completely. And as a rule of thumb, you can assume that every .01 pound of pressure is worth one half of 1 Watt in terms of accuracy. Once Compu trainers have warmed up, they do not drift much at all, and their accuracy is within 1%. We have copy trainers in the studio's that are perpetually being rotated through to racer mate in Seattle for calibration with their machines. This is to ensure that your data remains accurate, consistent, and helps you improve your power output, your power to weight ratio, and measure your energy output.

Fore more in-depth information, I'm going to pull from the script itself, found in the CompuTrainer manual...

"An error during calibration of 0.01lb equates to a change in load of 1/2 W at a speed of 25 mph. You may wish to recalibrate more than once to confirm that your rolling resistance value is consistent to within .05 2.10 pounds. If the value continues to drop for two consecutive measurements, this indicates that the tire and load generator may not have yet reached a stabilized operating temperature. Continue to warm-up and repeat."

It is not necessary to have the same calibration numbers every time that you ride. Because rolling drag is always present, setting too much drag for a flat course can make your pedaling load feel like you are climbing a hill. Always set the press on force to a consistent range between 1.8 and 2.5. If you are dealing with a FTP that is lower, then you can get away with a lower RRC. The more fit you get, the higher we should probably set your RRC.

At Cycling Ctr., Dallas, when we use slope based intervals, we limit the grade 2 no more than 6%. If you are a fit cyclist, with a high FTP, then setting a press on force, or RRC, to about 3.00, is not inappropriate. Again, the lower your FTP, the lower you can set your RRC. Here's a table to help you out...

Fixed-Gear Workouts or Non-Slope Interval Workouts... Use an RRC of between 1.8 and 2.5lbs.
Slope Intervals up to 3% or Intervals with Sprints... Use an RRC that's higher, closer to 2.5lbs.
Slope Intervals up to 6%... You may set your RRC press-on force up to a 3.00...

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