My setup and erg v. gradient mode

(Jerry Perullo (B)) #1

I’m riding single speed. It’s not a steel-framed fixie and I do not have any tattoos, let me explain…
I use a nice but cracked old carbon frame on my trainer with minimal components I hand down from my road bike upon replacement. I have no front deraileur on and the back deraileur is “neutered”. I jammed a socket driver bit in it to lock it to the 17t and run just the big ring up front. There are no shifters; i found some cheap brake-only hoods on Amazon that work great. I do have a 60mm deep dish carbon aero wheel up front that is actually cracked. I mention that just for visualization purposes; it looks awesome :slight_smile:
Anyway, I chose the gear i use because
a) in erg mode it does not matter; I just ride by cadence and step through different power requirements
b) in gradient mode, this gear combo puts me right at about threshold power at 90rpm. This means I can FTP test with it and if I have a crap test I’ll only be able to ride 85rpm and if I get stronger (one day!) I’ll ride 92rpm and more watts. If I get REALLY stronger and one day test at 95 rpm, I’ll consider moving to a smaller nut-driver socket so i can go to the 16t.

This is interesting and relevant because my cadence and speed thus correlate pretty linearly for a fixed gradient, or you might say for a fixed power my cadence and the gradient vary inversely. This combo strangely worked fine through the entire Zwift Island loop. the 9-10% gradients brought me down to, I’d estimate, ~60rpm, but that is not at all what I would expect on the road. I’d expect this gear ratio to be completely impossible for me on a 10% grade on the road. My power was in the 260-300w range at these times so it wasn’t that I was killing it. This was weird. It makes it feel like we aren’t dealing with just simple gradient mode on the Kickr. Yeah?

(Greg Gibson-Haymarket) #2

I found on the 90-10% grades I could easily spin up those at about 210-220w which I would never be able to do in real life out on the road. This may have something to do with rider weight as currently the Zwift folks have indicated that all riders weights are fixed at 75kg for this phase of testing. I’m about 9kg heavier than that in real life, unfortunately!

(anon18154799) #3

I have noticed the same thing. When I ride on gradient mode via other apps, 10% means I have to either put out some serious power or shift to the small chain. I spun up pretty easily in the big chain. I am looking forward to inputting my weight, though. I’m only 63 kg, so lugging the extra 12 up the hill is killing me. At 350W (hitting it hard), I should be climbing like Quintana. :slight_smile: