So here’s an odd one. I was doing Luberon (On Location) today. This workout includes three MAP sessions in relatively quick succession and a fourth one towards the end that’s 4:30 long.
I was doing this workout in ERG mode and properly suffered through the third effort. About a minute in the fourth effort, I was about to crack and decided to quickly exit ERG and proceed with Level mode (just managed to hit the ‘4’ key on the keyboard) and see how far I’d get. I just put my head down, chew the stem and give it my best shot.
Oddly, from there on, the power output was actually a bit above the target value, bringing the whole effort - on average - back to where it should be. This baffles me, I’d expected a slow and steady decline towards the end.
It sounds to me that there could be a few factors here at play.
When you switched to Level Mode you did have a brief moment of relief from your effort, although it is likely not entirely responsible for your perceived recovery and subsequent ability to smash your way above and beyond the target, and perhaps just maybe that brief moment and a deep inhale did contribute to that Maximal Aerobic Power effort
When you switch from Erg Mode to Level Mode you likely changed your gearing, which changed the amount of torque required to hit your target. See the article, Indoor Cycling Tips For Training in ERG Mode for more on gearing during indoor workouts
This isn’t exactly the same question but after a MAP Block then the 2 A Week With I started a new Threshold Block yesterday with 5 x 6 mins and found it incredibly tough even though I felt I shouldn’t have struggled that badly with it. Will be interesting to see how tomorrow goes when I do Angels.
I’d be interested to see what your cadence was for that last section your power went up, my take would be your doing 90rpm and the trainer is holding your power back to the ERG level say 300w (for talking sake) once you moved to level mode that cadence might have increased slightly due to the change in effort giving you the increase you saw
Cadence went slowly down to about 85 when I was about to crash. Then in level mode it went from 85 back to 90 and slightly exceeding it towards the end.
Thinking about it, I would say “all of the above”.
I’ll be looking into doing a workout on Level mode on a regular basis and starting a Mental Training plan. It’s going to be interesting how much effect it has.
I’ve found before that I prefer doing some MAP based workouts in level mode. In addition to the reasons above, it also feeling different producing the power by being ‘pulled back’ (ie ERG mode) rather than ‘driving forward’ (ie level mode). I can’t think of any other way to explain how it feels anyway but I suspect muscle engagement is a little different.
In ERG mode the resistance increases when cadence drops, in Level mode the resistance decreases for a decreasing cadence. I’ve got no idea how quick that responds throughout the pedal stroke, but wouldn’t be surprised that it affects how it feels. Our bodies are weirdly sensitive to things sometimes.
I wonder if you give yourself mini-breaks in level mode, either intra-pedal-stroke or a second or two of slightly lower cadence, followed by mini-surges —over and over again.
I can’t believe that’s true. That would imply that, regardless of level, at 0 cadence (standing still) you’d have 0 resistance on the bike, which is definitely not my experience.
My understanding of Level (in the context of a Kickr in conjunction with SYSTM) is that it sets a (simulated) given incline. Thus, as in real life, when you get “on top” of the gear the resistance gets lighter (because you are gaining momentum up the incline).
I, too, have experienced an “easing” in level mode when compared to Erg for the same power and assumed it was due to this “getting on top”. I haven’t experimented but slowing your cadence in level should increase the resistance feel (because you are now going slower up the hill).
I know it sounds weird, but from a purely physics point the resistance is zero at zero speed. Once you start moving you first put effort to accelerate the flywheel. That will give you a torque to work with. However, if you pedal at constant speed of 0.1km/h, your resistance is indeed near zero.
To give you the absolute numbers: I was riding it in gear 50 x 17, target power 358W. The required Torque is calculated by dividing Power in W by Cadence in Rad/s.
(This is on the assumption that you can provide a constant Torque throughout the pedal stroke, which isn’t correct, but will do for the calculation)
ERG mode sticking to 358W constant:
At 86rpm, torque is 39.8N.m
At 87rpm, torque is 39.3N.m
In Level 4 mode:
At 86rpm, the power is 354W. The torque then is 39.3N.m
At 87rpm, the power is 362W. The required torque is 39.7N.m
My new Saris H3 smart trainer arrived yesterday, so last night I tested it on Ignitor and all seemed good. This morning I went with Joyride… and ERG mode broke me. I hit the Spiral of Death in the first three “proper” MAP blocks and I had to properly grovel to avoid it on the fourth block.
I’ve done Joyride 14 times on my old setup, which was a dumb Kinetic Road Machine and Assioma PM pedals. My ride notes from when I last did it in August said:
FW, 100%. Quick session after re-fitting PM pedals & circuits tonight. HR well into Z5 at times but hit targets well.
Tough but nothing like this morning.
Hopefully the link Coach supplied has given me a clue. I’d read ERG should be done in the little ring, so I’d stuck the bike in that last night and left if there. However, on my old setup the bike lived in the big ring. In fact, it’s spent so much time there that my front mech is really grumpy and it needs a kick to drop from big to little.
If you are a time trialist or sprinter who typically puts out most of your outdoor power in a big gear, then we would suggest replicating efforts indoors in ERG mode in a similar gear choice when performing sprint and time trial efforts.
Ah, hello! My rider profile is a TTer. Time to try again but back in the big ring.
In essence it is the same thing: the resistance in the flywheel determines how much power you can put into the system.
My earlier calculation shows a torque that you need to produce at the chainset. Translate that towards the rear (with a ration of 17/50 for the gearing) you get the required torque at the flywheel:
LEVEL
4
ERG
Cadence
86
87
86
87
Power
354
362
358
358
Torque (Chainset)
39.3
39.7
39.8
39.3
Torque (Flywheel)
13.36
13.51
13.52
13.36
This means that the brake in the trainer will be braking a bit less when reducing the cadence from 87 to 86 rpm when it Level 4. However, when doing that in ERG mode, you increase the braking power on the flywheel.
The variation is just over 1% at these cadences, which is super small, but could be noticeable.
Going to a higher cadence also requires accelerating the flywheel a tiny bit.
So when I’ve dropped a little in cadence whilst in ERG mode, I need generate more force on the pedals to remain at the target power. But now I also need to accelerate the flywheel, if I want to get back up to my preferred cadence, adding another power requirement. So I need to pay full price there and then.
Whereas, when I’m in level mode and falling a bit in cadence, the resistance drops a little and I only need to accelerate the flywheel to get back up to my preferred cadence. Whilst doing that, the resistance starts to increase. Like a “Pay in instalments”, if you will: first pay for acceleration, then start paying for increased speed.
I think you’ve hit the nail on the head there. ERG mode can be pretty unforgiving with many trainers, hence the term “ERG spiral of death” where if your cadence starts to drop, the resistance ramps up to maintain target power and then you tend to bog down even more and get into a vicious circle until failure.
Level mode avoids this situation. If your cadence drops, power drops proportionally and you get chance to make a recovery and go again.
