How Much Wind is Too Much for Coast Downs

[oldfartrunner]

I am trying to get a better calibration as my power fluctuates 30 to 50 watts on the flat at steady speed after my initial shot at calibrating. I had problems on my first calibration with the coast downs but eventually find enough of incline to slow reasonably quickly to below 8 mph. But since then I have tried two different days to recalibrate but cannot get anything but a bad coast. I started out today with a 3 to 6 mph wind but it actually ended up 10 to 11 mph by the time I got to trying to coast. I was concerned that the roads I was using were too rough and found a smooth road that stretches 2 miles long. I guess its orientation of NW to SE was not going to work for a 10 mph WSW wind. How much wind is too much?

[R Mc]

1. Such power fluctuations are not uncommon--in fact, they are probably typical. If you want to drive yourself nuts some time, ride a power tap set to display with no smoothing . . . constant power flux. (And . . . at the risk of being annoying . . . such power fluctuations COULD indicate uneven power production in the pedal stroke . . .)

2. I have gotten good coast-downs in winds as high as 20mph, so I'd check for some other culprit in the coast-down process, starting with tilt and moving on to wind offset. For that matter, I've gotten good cal rides in fairly high steady winds too. Gusts, however, mess things up.

[oldfartrunner]

1. Such power fluctuations are not uncommon--in fact, they are probably typical. If you want to drive yourself nuts some time, ride a power tap set to display with no smoothing . . . constant power flux. (And . . . at the risk of being annoying . . . such power fluctuations COULD indicate uneven power production in the pedal stroke . . .).

So how do you train using power? If you want to do tempo intervals for example, how can you ride at tempo range power when your power fluctuates more than your entire tempo range of pwer?

2. I have gotten good coast-downs in winds as high as 20mph, so I'd check for some other culprit in the coast-down process, starting with tilt and moving on to wind offset. For that matter, I've gotten good cal rides in fairly high steady winds too. Gusts, however, mess things up.

So is a change of a 3 mph wind with a 6 mph gust too much? I am a bit frustrated as the winds are blowing and the gusts can be 3 to 5 mph over the steady wind and have not been able to get a good coast. Wind offset and tilit are fine.

[R Mc]

As to the bad coast-down problem, I'd defer to the Velocomp guys--it might be necessary to diagnose the file to see what's going on.

All I know is that I've never had a bad coast-down display--and I've done a couple hundred over the last year what with new units, different bikes, and road tests of wheels.

As to training in ranges with power, well, there is a learning curve to getting used to riding evenly. One way to check whether it's you or a bad cal on the unit would be to do an interval set (or just a ride) on a trainer or rollers. (Assuming you've got the trainer mode unlocked on your ibike AND that you have a trainer). If you hop on, warm up, and are able to crank out a steady wattage--something's probably up with the calibration on the road. otoh, if you settle in on the trainer and your wattage still varies--there's a pedal stroke problem adding to other issues.

Remember, on the road, wind is never constant, grade is never constant, shoot, rolling resistance is rarely constant either--and as a result, power output is also highly variable. New users are often astounded to see how much power spikes at the beginning of small hills or into the wind.

What I do is ride for the average--i.e. accept that we don't produce power like a car on cruise control, and that sometimes the number will dip below the target, but shoot to keep it over the target wattage. I also try to do the bulk of my intervals into the wind. With practice, it does get easier to ride a steady wattage tempo (as opposed to a steady speed tempo--because they're not the same . . .)

[oldfartrunner]

As to training in ranges with power, well, there is a learning curve to getting used to riding evenly. One way to check whether it's you or a bad cal on the unit would be to do an interval set (or just a ride) on a trainer or rollers. (Assuming you've got the trainer mode unlocked on your ibike AND that you have a trainer). If you hop on, warm up, and are able to crank out a steady wattage--something's probably up with the calibration on the road. otoh, if you settle in on the trainer and your wattage still varies--there's a pedal stroke problem adding to other issues.

Thanks. Using the trainer is a really good idea to find out where the problem may be. I appreciate you getting back to me.