Not using power readings from Trainer in ERG mode


(Rob Wilkins) #1

I have seen a similar post on this but with no resolution and feedback so thought I would ask again to see if anyone can help…

I have my set up configured to use my Stages Power Meter for power and cadence, and a Kickr as the controllable trainer

When I follow a workout in ERG mode, it’s very difficult to keep in a specific power zone as the power seems to vary significantly meaning that I have to keep changing my cadence to compensate or vice versa. Sometimes also, on particularly short intervals it takes a time to get to the specific power for that zone (sometimes I miss altogether)… I’m sure some of this is down to the smoothness (or lack of in my case) my pedalling, but wondered if this is down to the fact I am not using the power feed from the Kickr and instead using another device? I kind of hoped it would be smoother in transitioning and smooth out some of the wrinkles but that doesn’t appear to be the case…

Anyone got any thoughts/help/advice? I might try using the Kickr but as I am mid program, wanted parity in readings when out on road, and done my pre-program testing using the Stages I am reluctant…


(Joe Daknis) #2

“power seems to vary significantly meaning that I have to keep changing my cadence to compensate or vice versa.”

The key is, actually, to *not* vary your cadence in ERG mode. That’s not to say it needs to be constant throughout your workout - but that you should try to settle into a steady cadence for each interval as quickly as you can and hold it while the trainer adjusts the resistance. 

If you’re pedaling faster or slower to try to hit the power target, the trainer is only going to keep adjusting the resistance down or up, respectively, trying to keep up with your changing cadence - and while that’s happening there will be wider swings in your measured power output. If you pedal at a consistent cadence, the trainer will adjust, get where it needs to be, and power will be steady (or steadier, at least). 

That said, it’s not unusual for power to occasionally drift a bit above or below the prescribed level in ERG mode on Zwift (again, usually because cadence goes up or down a few RPM).  Seems like the consensus is that if you’re concerned about being ‘locked’ tighter to the prescribed wattage, then there are better apps to use for that purpose (e.g. trainer road).

" Sometimes also, on particularly short intervals it takes a time to get to the specific power for that zone (sometimes I miss altogether)…"

Yeah, this happens a lot - especially on really short bursts (10 seconds) that repeat several times, or on big jumps in power for intervals <30 seconds.  The fix? Turn ERG off for workouts like that. 

 

 

 

    


(Rob Wilkins) #3

Thanks Joe, that’s good advice especially wrt to toggling off ERG…

I just wasn’t sure using Stages rather than the kickr for power was adding to the problem, particularly given the fact it’s reading off one crank… Probably me looking for problems as opposed to my poor pedalling technique! I obviously want to use the Stages as that is what I have out on the road and therefor wanted the consistency in output. I guess I have to work harder to keep the variations in my cadence down.