Newb question. I just bought a Kickr Core, so I’m new to smart trainers. I notice in the description of this workout,“Obviously this work out is not suited for ERG mode.”
So I use slope mode? How exactly does slope mode work? Am to use gearing to hit the intervals as best as I can? I notice that some workouts automatically select between ERG mode in some sections, and Slope mode in other section. It seems that the only part that wouldn’t work in this workout in Erg mode is that last sprint.
Yes slope simulates riding up a hill (you can adjust the slope in the app) then you use gearing and cadence to hit power targets.
Some workouts are mixed mode, automatically switching between slope and ERG. Usually slope is used for the ‘all out’ efforts to failure (breakthrough) and also sprints.
You can actually leave it in ERG for that workout, but if your signature is accurate you won’t be able to even get to the sprint at the end. If you do, it is possible to sprint in ERG but you’ll want to have high cadence and probably be out of the saddle in advance… and if you can’t hit power targets the resistance will increase to offset the falling cadence which is never pleasant (usually best to stop to avoid injury). Hence slope is recommended.
Also, when you breakthrough in ERG mode your drop off in power is not ‘natural’ as it goes to zero quickly. Xert algorithms can have trouble interpreting that pattern and get the allocation between TP and HIE wrong. In my experience, ERG breakthroughs (which I don’t do anymore) overstate HIE and understate TP, but not sure if that’s a rule.
Main downsides to slope are that it takes concentration to hit power targets, and for shorter intervals it can be annoying changing gears all the time (mixed mode helps, as you can do the recoveries in ERG). Plus, like IRL, you can spin out and find power dropping off (until you hit a steady speed)… so if you are starting in the right gear for your steady state, you’ll be pushing a high torque / low cadence at the start of the interval if targeting power… or putting out too much power at the start and then seeing power drop off if aiming for steady cadence… not an issue for long intervals, but a bit annoying for 30/15s for example
What @wescaine said. 
Under Pressure in Slope mode is important because you may not reach the end of that long interval before you need to rise out of the saddle, spin up, and sprint as hard as you can for 5-7 seconds (until collapse). You may get to your break point sooner as shown below. In ERG mode you can’t make the decision when to go all out.
OTOH for BT workouts like A Pain that I’m Used To (Ronnestad classic) the goal is to complete all three sets as best as you can. Since you’re in Slope mode you might also be able to overshoot target watts at the end of sets (as below). I try to do that on the last set if I make it through the first two sets intact.YMMV
BTW there is a public BT group session tomorrow if the time is convenient.
I always go a little harder on a group session. Well, at least I try to. 
Xert - Breakthrough Sunday Ride - Ronnestad (xertonline.com)
I find it interesting you can view predicted MPA drawdown behavior based on your current signature in Workout Designer. Search the library for “breakthrough” and try them all over time. You’ll discover a favorite or two.
Thanks for pointing out the group session, but I’m having problems tuning my derailleur to the Kickr. Same cassette as the one on my wheel, but it still needs tuning each time. The problem I’m having is that I can’t seem to get the Kickr to let up on the resistance enough so that I can easily run through all the gears to check tuning while i’m off the bike, like one would do with a bike on a stand. And Wahoo support seems weak…no telephone support!
Unplug it?
No, still too difficult. What I did was use the Wahoo app to set a negative slope. I tuned the shifting adequately for Erg mode. Not so sure about slope mode. I need to try some workouts that use slope mode.
Slope mode does take some getting used to, but I think once you ‘get’ it, it really makes for a great workout experience, especially for HIIT workouts and Low-Intensity rides. I know it keeps me more engaged than having the trainer do all the work for me.
Can you recommend a good workout to “demo” slope mode? I’m not sure my shifting is smooth enough, but it’s hard to know without the right workout.
For an all-out style of SLOPE mode workouts, try a sprinting workout, like this: Xert - Login
Another variation is the micro-intervals, (30-30’s, 30-15’s) which also works well with slope mode. Check out this one: Xert - Login
Thanks. I think I’m going to design my own to mimic a real-life gravel segment that I have found is good for eliciting a breakthrough. It’s about 20 minutes, rolling hills, with one final hill covered in 3-4 of inches of gravel that I charge up. That last “hill” (interval) I’ll put in slope mode. I’ll add a good warmup too.
Works perfectly! And a perfect use case for MIXED MODE workouts
