Rapid cadence changes in workouts on a Hammer

Some workouts require fast cadence changes. When you need to go from a fast to a slow cadence, it can take a long time for the flywheel to slow down on the Hammer because there’s so little freewheeling resistance. Although the usual is not to shift when in ERG mode, what I found is that by shifting 2-3 gears in the appropriate direction, I can quickly change cadence without needed to greatly change the flywheel speed.

ERG mode will take some time to adjust to a sudden large change in cadence or power. That is the nature of the beast. It is not instantaneous. I know with my previous Kickr and current Neo that it is about 3s for ERG to catch up to a large change in power at a given cadence (e.g., 30s on / 30s off type interval). Cadence change say from 65-100rpm at a given power is probably 3s, max 5s.

I have also found Zwift ERG mode to be a bit more forgiving or flexible than in some other training apps. It allows you a larger delta (+/-) around the target power. This is good in that it feels a bit better since the system is making fewer corrections or interfering less. On the other hand, it is a bit slower to respond.

Lastly, for really short intervals or sprints, you might consider exiting ERG mode since the system will not be able to keep up. You may or may not get to your target power depending on how short the interval is, but you will likely not make the intended avg power for the interval regardless of your cadence.

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Yes to all that. However, I am pointing out a method I use to mitigate the delay in trainer response when needing to make rapid large cadence changes in a training session. In this case, when in erg mode, shifting allows rapid cadence changes without the trainer flywheel speed needing to drastically change. .

I too have a similar experience in ERG mode with my Hammer, Louis. I will give your shifting tip a try. When not in ERG mode cadence and wattage seem to be all over the place.

In the past I also tried shifting gears while in ERG mode to help the ERG catch up. In the end, I decided it’s easier to do those kind of short efforts in sim/free ride mode. Otherwise, instead of enjoying (suffering?) through my workout, I would get upset w/the ERG mode. :laughing:

I’m not shifting to try to outsmart resistance changes. I’m shifting to quickly change cadence. For example; today’s workout had intervals going from 85 to 100 rpm while maintain the same power . Shifting 3 gears allowed me to rapidly change cadence while power and more important, the flywheel speed, remained relatively constant. I didn’t have to wait for the flywheel to slow down when dropping in cadence and didn’t have to put in a big effort to accelerate the flywheel. With low parasitic resistance direct drive trainers, it can take a long time for the flywheel to slow down. Shifting to a higher gear means I can slow cadence without the flywheel having to slow down.

This is kind of counterintuitive, but try riding in a much easier gear when you are in erg mode, especially if you have a wheel-off trainer. It definitely creates a smoother power curve, and I definitely feel like cadence changes are easier and cause less of a power jump or dip. Our Wahoo Kickr is also far quieter when you ride in an easy heat.

Yeah. I came to that same conclusion not long after I got the Hammer a couple of years ago. With a higher gear, you have a greater effective flywheel moment of inertia, which does’t help when the workout requires rapid power or cadence changes.

And yeah, the Hammer is a lot quieter in a lower gear too. It really starts to sing in a higher gear.