Can anyone tell me what baseline crank length is used as a baseline by the Zwift training programs? When it tells you to spin at - 100RPM - that number is based on a specific programmed crank arm length. I have long legs and long crank arms and want to calculate the equivalent RPMs I should be pedaling based on the ratio between them.
Does Zwift base this RPM on a crank length of 170mm, 172.5, 175, 180???
Or 165mm crank length, which is increasingly becoming the length of choice?
The Zwift training programs, as far as I understand, originate with myriad sources, including those that you might design yourself (custom workouts). As such, there would be no such “baseline”. Further, my gut is telling me that all the training programs are seeking a particular cardio/aerobic outcome by including cadence requirements coupled with power. 200 W and 70 cadence has quite a different outcome than 200 W paired with a 110 cadence, regardless of crank arm dimensions. In other words, crank length does not matter to the training effect being targeted by these programs - so NO, that “number is [NOT] based on a specific programmed crank arm length” IMHO. If your equipment permits, adjust your gearing such that you can meet both the power goal, and cadence target. All cyclists have particular cadence bands that they prefer (which may vary depending on slope and terrain), but nearly all riders know the difference between 60 RPM and 120 RPMs. These cadence zones are interesting to measure, individually, especially from the perspective of Heart Rate response.
On many of my training sessions, which I’m targeting at Velodrome events, I use a track bike with fixed gearing. These incessant cadence reminders drive me nuts, because in most instances I cannot meet the requirements of both power AND cadence. You should know, BTW, that Zwift workouts are governed (IOW: gold stars awarded) based on the power guidelines being met, and totally ignore the cadence targets. I just wish I could turn them off when I’m not on my multi-geared equipment…
Randy, I am not sure I understand your logic, how crank length is related to cadence? I mean, it is known that it is easier to maintain a higher cadence with shorter cranks. I noticed that when I moved from 175 mm to 170 mm cranks (moved pedals into other holes), my average cadence improved by estimated 3-4 rpms. This is a relatively small change, and I could vary cadence in a wide range with both longer and shorter cranks. I can do 100 with 170 and with 175 mm, and certainly can with 165 mm. Zwift does not enforce cadence, it is just a target, recommendation. You will not lose XPs or a star in a workout if you do not meet the cadence target. The meaning of it is to encourage you to spin faster. Are you sure you are not overthinking this? If Zwift tells you to spin at a 100, and you increase it to 95, it is still good! There is no hard core science behind it!