Just found this video, Shane. You have just explained a large physiological difference in muscle recruitment between climbing and flat riding that many have been pondering and guessing about for years. Awesome stuff.

Glad you brought this up because i felt a difference between the big ring and small ring and was told it was in my head because erg mode was the same. But i have been training for climbing so i usually use the small ring. Thanks for the advice!!!

I think it's also important to note that if you do a ramp test in a certain gear, all subsequent workouts should also be done in that gear.

A video like this for the Neo would be really useful

Thanks for the video! For 5-6 months a year, I use a CX bike on my Kickr2. Usually 1X. It's been interesting comparing the "feels" of different front rings (38, 40, 42, 44 and 48). For Zwift, the bigger rings feel better, but I usually have the 40 or 44 installed).

Fully agree. Did SST yesterday and today, 48x18 vs 39x24. The former felt like I was on flats and the latter felt like I was climbing a hill.

This is may be your best video, impressively "simple" but so useful!

Great video Shane. I would also love to se you do the same test with the neo. Maybe also a video of how to use the two new modes on the neo, what training sessions etc.

Thanks again for this great info. I'm new to my kickr 18 and zwift, a month in and learning about this ERG. Did the tour and now on to a build me up program, this will help me as I get used to the trainer. Cheers and happy days from California!!!

I've been waiting for this video. It shows exactly why I always train in big ring on my Vortex. I bet even training with high wheel speed on this trainer reminds more of climbing than riding on flats due to low inertia.

Totally makes a difference. On my old wheel on Tacx I was always between gears to get the right power output, not with the Kickr, I can move up and down the gears without issue and still hit power numbers without feeling like I'm between a gear. This means the legs respond better and I don't feel "cramped" trying to push a bigger gear while suffering. If the legs are tiring or I feel I need to flush them, up the gears to a nice high cadence, spin em out and then back onto a harder gear again. Seriously only a week in with the Kickr and it's the best investment hands down I've made for my training. Thanks for reviews and info making it an easy choice on which trainer to buy!

Shane does science, right. Great explanation for what I’ve experienced

The topic of kinetic energy always gets me going, but unless it's explained well, there's always the potential for improvement.

So glad I found this video. I just got my trainer and thought ERG mode was awful during my workout, but I was in a low gear. I’m glad I can fix the feel of the ride by changing to a higher gear, but this is also revealing that maybe I’m a poor climber if the low-gear ERG mode was a struggle for me. 😅

Great info! In addition I realized that when training on different cadence intervals, its better to pick a lower speed gear. If you have a big momentum and switch to a lower cadence interval, it will take a while for the kicker to let you get on top of the gear.

Great vid as usual! I’m on a kickr2 and I prefer to use the 52T in front for the lamest of reasons. There are 2 actually. Lol 1: Riding the bigger front 52T gives a higher distance covered reading on Strava. The smaller 36T always logged less distance covered. Btw I ride on trainerroad only. Eg, 1hr ride on big ring roughly equates to 40km on strava. The smaller ring usually equates to only 28km. 2: to keep the best chainline, I will ride 52T - 15T, the 5th sprocket on rear. This is more on trying to improve on wear and tear, thus reducing running cost in the long run. The fifth sprocket will normally be a single piece which can be replaced very cheaply vs a whole cassette. (No sram red 1 pc cassette for me!) I can run 36T - 17/18 to achieve the best chainline, 17/18 will be the 7th cog. However, the 7th n 8th cog will normally be a 1pc consisting of 2 cogs which also means they are a lot more expensive to replace. Yes, the front big chainring is normally much more expensive to replace compared to the inner ring. However they too last a lot longer. After watching this vid, esp understanding we are actually utilizing different muscle groups, I will definitely begin to alternate btw inner and outer rings in future.

Hello! You've just explained Q factor for bicycles. I don't mean the separation between pedals, but the quality factor in physics and engineering. That is the proportion of energy lost for each cycle of an oscillator.

I've tried this on my Kikr. Maybe it's personal but I find it easier to hold higher watts at higher flywheel speeds. So either higher cadence or higher gear or both. This has a damping effect on the load you feel at the pedal and is less demanding on where or how long your power stroke is. For me this also translates on the road. Higher rpm is less critical on where in the stroke you make the power. You don't get the spikes in the load on the muscular system.

Shane, great video. I've been noticing this on my KICKR SNAP as well. In fact, I previously owned a Cycleops Magnus and found I had to train in higher gears because the flywheel didn't have enough rotational intertia to not feel like slogging through mud. As a result, my climbing outdoors suffered dramatically. I've noticed my HR goes up faster and my legs fatigue more quickly in lower gears than "flying along" in a higher gears.

Great work! Any chance a piece on how the Neo works into your theory, as it has a simulated flywheel?

I just bought a smart trainer the other month. I always change up or down the gears depending on which zone I'm in. I figured it had more to do with the resistance the trainer can apply to the flywheel and the angular momentum of the flywheel.

Very useful - Thanks Shane!

Good video Shane and interesting take on this. I always like to duplicate what I use on the road so for a TT, I am riding in the big ring so that's what I will try to use indoor even with ERG mode turned on.

This is awesome stuff. I’ve learned so much already.

Shane, your experiment got me curious about the real power from the legs needed to keep the momentum with the low gear versus just "tapping" the high gear. You cover almost all aspects in your video, but you rely on the KICKR power as shown by the Wahoo app. I like my KICKR, but I don't have full confidence in the power numbers it generates. I did a quick test with my Powertap P1 pedals to validate my suspicion and it turns out that there is a gap and it's quite significant in some cases. I started with my lowest gear (39/28) and rode 30 seconds each at 100w/150w/200w/250w. I then did the same test with my highest gear (53/11). With the lowest gear, I got very consistent and stable power numbers from my P1s that were very close to the KICKR generated power numbers (within the +/- 2% advertised KICKR accuracy). With the highest gear, power numbers from my P1s were not even close to the KICKR's and they were jumping all over the place and were very unstable. At 100w (+/- 18%). At 150w (-35% to -3%). At 200w (-30% to -9%). Finally, at 250w (-22% to -10%). With this kind of discrepancies, I am glad Zwift and TrainerRoad implemented Power Match with the use of an external power meter. Sufferfest should implement this feature later this year.

Yes it makes a difference!! Doing a block at 280w on 50x13 is quite a bit easier then on 36x17. Had a Snap, now own a Kickr and it's the same feeling. Feel is something subjective but it would be interesting to see what happens if you do a 6 minute block around threshold, once at low gear and once at high gear. Heartrates will be lower on the high gear, i'm pretty sure. Maybe an idea for an other Lama video ;-)

Also have noticed that changing the height of the front wheel makes a difference. I have a kurk riser with three levels. I change to a different level each week to get a bit different muscle use.

Very interesting, something I never had thought of!

Very topical to me being new to ERG mode on Zwift. I suspected it was easier for me to maintain long efforts in a higher gear with the flywheel really flying due to it smoothing out my power spikes. That long-named software package and the muscle recruitment chart were very informative as well.

Awesome video. I'm still learning how to use my kickr there's a lot to it. Also I don't know if it's just the video but your kickr seems to sound really cool.

I've tested my wahoo in both high and low gears and it makes a HUGE difference on how fast my cadence is because the loading around the pedal stroke in low gear is much harder all the way around the crank. Sidenote: since the wahoo is so friggen noisy, I always train at a low gear to minimize the noise.

Great topic. I thought I was going crazy noticing this.

My wife has always wondered (and me too) why my ankle dorsiflexors were so prominent. I didn't really know (or even know what that muscle was called) until you showed the graphic in the last minute of the video. I guess this means I use the back side of the pedal stroke.

You had me at cruising at 300 watts... XD

With my Kickr in ERG mode I always put it in the small chainring just because it's a bit quieter...

Really interesting video Shane. I have tended to stick my old Kickr on the inner ring and around 5th at the back not just for noise, but also preventing cross-chaining. I have just bought a new Kickr with a Climb though so noise is no longer an issue. I'm training for an Everesting so I guess having a lower Inertia would help though!

Great video Shane!

Thanks! Well explained!

It would be interesting to see the same work with an oval ring like Rotor QXL

great video. your fly wheel looks like it is glowing orange hot like disk brakes.

How about with the Neo with the virtual fly wheel?

Another great video, Shane! I was with you until the very end. I am constantly hitting the death spiral after doing a hard interval when going into the recovery interval. I watched your other video on how to "stay on top" of the gear and will give that a try soon. But I was hoping this video would tell me exactly which gear ratio I should be in. What exactly is a "faster flywheel gear"?

The sound of the Kickr would drive me crazy after 20 minutes

Very interesting! I was looking into Elite Direto, but I think smart trainer loses bit of its appeal if you have to change gears.

this is intriguing

Yes it does create a different training experience. For reference i use Trainerroad and Kickr. The FTP test is done in normal mode so you perform that in say a 52-14. In ERG mode 52-14 is much easier to hold the watts than 36-14 even with a > 100 cadence. What I do is 1 set in the 52 and then 1 set in the 36 and then back to the 52. If I am failing an interval i'll micro adjust by changing the back ring to get through the interval. I thought that since it is harder, there must be a different training adaptation needed so I may as well do an alternate style of training and improve on that as well. Mix it up to become a more versatile rider. If you're interested, here's my un-scientific theory. The Kickr measures power by flywheel speed x brake force. Higher flywheel speed requires less brake force, so the giro affect of more flywheel speed and less brake force requires less pedal force to keep on top of it. With the smaller gear and less flywheel speed, it needs more brake force so you need more pedal force input to keep it going. There is only so much pedal force we have, so to get more, we utilise additional muscles earlier in the pedal stroke to perform the work.

What called that app for measuring torque with the chart?

So I guess the next step question... cadence is it harder holding a high cadence big gear vs small gear in erg same power?? should be similair...but if it feels more like a climb maybe not...Great video BTW :)

I do this all the time on my TACX Vortex in ERG mode. I no longer believe that ERG is a set 1 gear and forget it type of feature, I always have to adjust my gearing, depending on the workout that I have pulled up.

The taxc flux.. in erg mode, doesn't hit the bigger wattages numbers unless you start putting in the big ring and smaller cassette sprockets.. I.e say 370..upto 1000+(sprint efforts) can be frustrating if you select wrong gear on a sprint effort, also it take 3-5 seconds to hit the wattage too👎so on microburts efforts maybe factor that in on a workouts..

I’ve just gone to a Kickr Core from a Tacx Vortex and have noticed the Flywheel effect immediately. I’ve always trained with TrainerRoad and employed the 52 chainring theory as I like the feeling it gives me and suits my style on the road too. Great video as I’ve always wondered if I was feeling a difference or was it just my legs tricking me? 👍🏻

Thanks a lot, very interesting! I would love to know more about how to optimize my work on the trainer for my Ironman bike training.

stupid question: does anyone ever have a situation where you get too on top of the gear? on my kickr snap i essentially get to a point where the trainer can't keep up. I notice my cadence can jump up to 110-120 and it feels like im just spinning with no resistance. i stop and reset and it is all fine again.

Any chance with the Tacx neo. Just bought mine and starting northern hemisphere winter training, it would be v useful to see the same test on the Tacx neo

Real interesting.

How would this apply to a Tacx Vortex or similar wheel driven trainer?

I tend to just try and keep the chain line straight to minimise drive chain wear. Big ring on front / mid block rear.

Being on top of the gear is good for long intervals...but on shorter sprint/rest style workouts, being in the longer gears makes it almost impossible to hit your targets

Great Video. Any chance of the same on a Neo as sometimes a Neo feel like treacle!

Thanks Shane and it helps as I've just got my latest kickr for my training. One further question, will it provide better training for climbing if I use higher front wheel stand/kickr climb in order to simulate the slope?

funny enough wahoo is not allowing other power data source as a reference point for erg mode in their head units. I've been comparing various gear selections in ERG mode between trainer and a few power meters (e.g. various stages, vector dual) and the reading from smart trainer vs pedals/crank arm may be as much as 10% different. So if you're training on the road with let's say 330w target power - be sure it's not 330 on the trainer, and worst thing is that you never know what's the delta since gear ratio is massively impacting the reading.

Shane, great video and just confirmed the same myself. Scary how big the difference is. So I have a more pointed question for you.. For the last few years I've been riding small ring since a watt is a watt right, and it's just quieter.. After seeing this, I tried it out on 4x15 at 99% ftp and felt like a million bucks after and during with not a single heart rate spike..Frankly, it's just easier to sustain power. So the question is, despite a watt being a watt, is the large ring workout actually easier and less effective and by using the small ring are you actually getting a more complete workout? This preparing you for both climbing and flat roads, since I'd assume if you're able to sustain small ring erg mode then you're going to breeze through large ring at an equal ftp...

What do you use to measure powerstroke around the chainring

In the Wahoo app there is an option to turn ERG mode smoothing on/off. If I'm having the Kickr controlled by a 3rd party power meter and using some software (Sufferfest) to control the Kickr, would having ERG mode smoothing on or off make any changes to the resistance or how the unit "weights up" in response to changes in target power/intervals? I gather it's only reported power, but if that has an impact on the control it's getting from the power meter....may make a difference? Thanks! Great vid, too!

Interesting as I don't feel as much power coming from my glute (butt) muscles when climbing than my quads. But the muscle recruitment pic says otherwise. Learned working those muscles in the off season will improve my climbing prowess, an oft neglected theory!

I just keep it in the same place to approximate the average speed I would do outside on a flat road. I wonder if it would matter for this experiment if you raised the front block some or used the new fancy wahoo thing

had my elite intera/inertia (qubo variant) wheel on trainer for a couple of weeks now and have definetly noticed/feel you can "cheat" erg mode (since realising i try to avoid doing it) counterintuitively at fixed power and cadence it becomes harder when you change down and easier when you change up, i figured it was due to inertia maintaing/creating more of the power at high wheelspeed and me doing less work. surely this could be shown by comparing numbers from pedals to those from a trainer ? but what youre saying is that the increased inertia is simply changing the required pedal stroke to a more efficient/comfortable one and actual power is the same? on wheel on trainers i also wonder about the effects of wheel and tyre weight

Shane can you overlay the average torque curves somehow? Maybe on an X-Y graph as opposed to the radial graph that shows the "peanut". This might help illustrate some of the "feel". I stopped your vid at 5:47, when you explain the different resulting max power angles and zoomed in on the graphs. Notice that the radial graph scales "auto adjust", so they are not the same torque axis values. IF you pull out torque values off the "peanut", you see that the left, low flywheel speed values peak roughly at 55 and 45 Nm. The high flywheel speed values peak roughly at 45 and 40 Nm. I am not exactly sure what this means as obviously the "systems" (power meter, recording software, EGR mode software) involved are doing some sort of averaging to arrive at 330 Watts at 91 RPM. (Power = Torque x RPM, and Torque = Force x distance(crank length)) Perhaps the X-Y graph might show why there is a difference? My take is 1) your muscle use chart is key to that "getting on top of the gear" feeling and 2) that there is something else going on within the "systems". All that said, I am certain that yours is the best explanation I've heard so far. Cheers!

Awesome video! Is this similar on a wahoo kickr bike?

Where did you find the graphic of muscle recruitment for the pedal stroke around the 6:15 mark of this video? Thanks - and great job as always - I enjoy your work.

Could you explain what the shape of the graph represents at 4:00 ? Having trouble understanding the x and y axis and how the represent the pedal stroke. Thanks!

Running ERG mode on the Kickr with a set wattage at different flywheel speeds, I wonder what you would notice with... (a) Heart rate - by how much (if any) is it higher at a lower speed? Should that affect how we think of Power as a absolute training metric? (b) Does the Precision of the Kickr's power data change at different gears on ERG mode?

Can you pedal fast enough with no resistance using any weight flywheel and still reach maximum heart rate? With lighter wheels I am worried the workout will not be intense enough. The more resistance you add the more it becomes strength training and less of a cardio workout.

Interesting subject. I came here looking for insight into high resistance on my setup. With my Neo I find it's a HUGE hamstring workout compared with normal outdoor riding, there's no feeling of momentum or inertia to help through the pedal stroke. I've only ever used my QR axle road/crit bike, set up as 1x with 58t x 11-28. I'm going to try a smaller chainring, and maybe get a thruaxle adapter to use my other road bike with normal 2x gearing.

So if training for long climbs using erg mode, it's probably best to use the small ring and move that flywheel at a low speed then right? (And vice versa for training for TT efforts!) I never actually thought about the effect that the flywheel speed would have on pedal stroke and power delivery... this is a bit of a training game changer for sure!

I have just gone from a original kickr to a tacx flux 2 I assumed that it would be a bit of an upgrade but it seems that there is a lot more gear changing to be done. I use the little ring normally as I was told it was better, I cant get the watts up without changing onto the big ring or my recovery sections are over watts. is this purely a flux thing or is the kickr dealing with this better as it feels like a step back. who wants to change gear in the middle of a ramp test!!

This is a very enlightening video! But I am still confused. I have only had my kickr for about a month now, and I have noticed in ERG mode that if I chose a "high" gear (big ring up front, middle in back) the "speed" that is tracked on my Garmin is almost TWICE as fast as when I am in a "low" gear (small ring up front, middle in back) even though the WATTS are exactly the same!! It blows my mind. I am unsure after watching this video which is actually the best to train in... I want to get max benefits, but what I REALLY want is to see improvements outside. (If I want to go faster in Zwift with less effort, big gears it is!). My natural cadence is not really that high, but obviously tapping away seems to be healthier, but if I'm not strong enough out on the road I could see this slowing me down... I'm just confused :(

Hi Shane! I have a perhaps unusual issue. I have a Tacx NEO and also a Quarq DFour power meter on my S-Works Tarmac. When i do a TrainerRoad workout - except the FTP tests - i always put it in the small chain ring. I notice during my TrainerRoad workout, when the bike is in the small chain ring, the Tacx NEO is always showing about 5W higher than the Quarq power meter (paired to my Garmin Edge 520). If i shift to the big chain, both Tacx NEO and Quarq will display the same power. Can you think of a reason why this is happening?

Would this be similar results using the Kinetic with and without the large flywheel that is a purchase item? So, I could put it on and ride flat lap race, take it off and go up major kom climb?

Any idea if there is any software available to get a real time torque visualisation from the favero assioma pedals? Like the Rotor 360 in the video?

How are you watching your torque in real time?

Makes sense. Thanks. Why the block under the front wheel?

Had a new Kickr for a week, How do you set up sprint sessions with it on Zwift? Today I was going from 120w rest to 10 secs full effort x5 x 3, max wattage was 1075W. I found it best to kick it out of ERG mode 4 secs before the sprint, have sim resistance about half way and have 52 front, mid rear. I was power matching via Stages left arm (My ftp was set with it and Kickr is reading about 4% lower) . Not saying that's right, but how do you do them?

Is there snap the same way or does being in an easy gear cause the flywheel to spin to slow causing the accuracy of it's power reading to suffer?

EGR Mode. I like to ride EGR on High gear because if I have to adjust in the saddle it feels more "road like" However based on the graph below it seems riding in the low gear is more efficient on the wahoo kicker. I set ERG smoothing to "OFF and update to 1 Second www.screencast.com/t/KbNcP0BH

hello shane i have the tacx neo 2 and it feels the oposite to the kicker when i am in 52×17 its harder to keep a 90rpm and legs muscle feel beat up but the 36×17 feels better on my legs i can keep a higher cadence but my HR goes higher.

Great video Mr Miller, your techniqile content is awesome, this maybe a bit of a stupid question but I’ll ask it anyway, I realise that the kickr requires power so it’s able to operate and create the power output changes, but then why can’t it recapture, the power we are putting through the pedals which ultimately goes to the fly wheel and store it in a battery or go back into the grid like solar. I know these kind of machines exists as in 1 hour of cycling a day can generate enough power to run a house for a day, js there a way u could connect a belt to the fly wheel and drive a altanator to store the energy produced ???

Do you still sell the wahoo kickr stickers? Look like your checkout does not work.

Looking at your pedal power readouts have you ever considered using Osymetric style chainrings???

Cool video. I use this knowledge for my workouts using ERG mode. For low intensity and when I want to quickly notice changes on resistance, I use lighter gear and slow speed flywheel. The opposite for hammering VO2 workouts and sprinting. The problem sprinting with ERG mode and high gear is that we need to wait for the resistance to "engage", otherwise, the flywheel will speed up and the resistance will not rise accordingly. By the way, do you know a software similar to this which would work for Assioma Pedals powermeter?

Can you use the pedal analysis software with the kicker only? And what was the name of the software?

Shane, post the link to get the Kickr stickers. I would like to order the White ones. Thanks.

Will changing gears during a say a 5 minute workout interval mess things up? I have found that I get bogged down when I do, but there must be a solution.

I understand the idea behind, but still can’t answer myself where is the truth. Is the inertia something bad or good? Am I getting the most from the workout if I’m cycling using inertia or not? My understanding is that in the end, the important things are the watts and to complete the workout reaching the targets but I can do this easier using the inertia or trying to do the same without inertia and to give up in the middle…

Isn't it so, that the higher the wheel/flywheel speed is, the less resistance the trainer adds, to get the same wattage? On my Vortex, it certainly feels quite different doing 300 w in a low gear and a high gear. In the low gear, it feels much more "choppy" and nearly unrideable, so I always use the big ring. Have you guys had the same experience?

And, as you taught me for some trainers like drivo and direto by elite...erg mode simply doesn't work with big gear. Listenin' on what you explain in this video with this elite trainers some kind of workout cannot be perfomed.

Does this also apply to the virtual flywheel of the Tacx Neo ?

I don't roll with kinetics, I use synergy.

Does anyone have recommendations for an inexpensive spin bike good enough for interval training where you can reach maximum heart rate? Thank you.

When I'm in the low gears toward the 11t cog it seems like the is grinding in the drivetrain. When I'm in the 25t it is much smoother. Is this normal or is something wacko? Seems to happen on both my bikes.