JY Coaching Delta Company (Sue)

Hi Sue, welcome to Delta Company!

These intervals are KICKR-based interval training sessions for triathletes and TT cyclists.
Whilst ideally done on a Wahoo KICKR or other variable resistance trainer, these sessions can be done on a regular trainer in conjunction with a power meter.

KICKR Training Notes:
Often a discrepancy can be found between the power values of the KICKR and your power meter. This is attributed to the differences in inertia of a cyclist on the road, versus the inertia of the KICKR's flywheel. Cycling on the road is a high inertia environment, demonstrated by the degree to which the cyclist can coast when not pedalling, versus the rapid decline in speed of a fluid or magnetic wind trainer when pedalling stops. Due to the KICKR's heavy flywheel, it carries a lot more inertia, which allows it to have the 'road-like' feel that is appealing to cyclists. But, depending on the speed of the flywheel, it's inertia changes markedly.

Considering the ERG mode of the KICKR is generally the most used programme for a cyclist when undertaking strength work, use of the small chain ring will generate a lower level of inertia requiring the muscles to work more consistently throughout the entire pedal stroke, especially through the 10 o'clock to 2 o'clock position where muscle strength is lowest. Often an 8-10% difference in wattage can be seen between the KICKR's power output and that of the cyclist's power meter due to this difference in inertia, and also that the cyclist's power is being read at different points in the drive chain (i.e. crank arm vs. spider vs. rear hub/KICKR). Use of the large chain ring results in the KICKR flywheel having a higher rotational inertia, more in line with that of the cyclist riding on the road. In this situation we usually see the difference in power readings much smaller or the same.

What does this mean for KICKR training when in ERG mode?
My suggestion is this:

When doing strength intervals (i.e. >100% FTP),or when doing low cadence muscular endurance intervals, use the small chain ring, as this will help develop muscular strength/endurance around the entire pedal stroke. I select a gear on my cassette that results in the chain running in a straight line from front to back, as it increases chain life.

When doing race pace intervals (HIM/IM/OD) in ERG mode, use the large chain ring and select a gear on your cassette representative of what you would use out on the road.

NOTE: the above doesn't apply to intervals using KICKR power curves.