Yes. I put it down to a real flywheel (Kickr) vs a simulated flywheel (Neo). They're close on ride feel/inertia/momentum... just not the same.

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Shane Miller - GPLama
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You notice that it feels harder than the KICKR???

It's not as smooth on the Neo, so yes, harder than the Kickr.

My explanation might clear it up... and is purely my own observation from years of experience on egos.

ERG mode for anything >90% FTP sucks. It's horrible. The way most smart trainers hold wattage means it's not smooth like outside on the road or a LeMond Revolution (oh so buttery smooth!). They'll hit -+%2-5 in the ballpark wattage you set, some spiking and dipping more. If you're truly on the limit during the interval then 105% burns a lot of energy and the 95% "correction" of the resistance doesn't give you anywhere near the time needed to recover. Repeat, over, and over, and over.. and... you're cooked pretty quickly. I find time to fatigue is reduced greatly. I find the inertia on the Kickr/Drivo/Hammer a lot better than the Neo for keeping on top of things in ERG mode. This isn't to say the Neo isn't a good workout though, it's just different. I assume you're across this.. as it's even more obvious with the spikes/dips in resistance being the topic you raised.

A few weeks back I set ERG on the Neo. I only managed 339 for 15mins. Followed up a few days later with 356 for 20mins on the Lemond (wind trainer). Both sessions were good training but ERG on the Neo had me at less watts and pulling the pin 5 minutes earlier. I'd need to do the same on the Kickr to bring this paragraph back on topic... but this session isn't on the cards any time soon.

Over on a UK TT forum someone has suggested using the Tacx training app and putting the Neo in -0.5% slope mode, then selecting TT bike under the user profile. This seems to give the thing a little more road-feel... indicating that the Neo itself is capable of performing a little better. As to who's job it is to make it feel better, I don't know... TrainerRoad / Zwift / etc ?

Sorry for the rambling, the answer you were after was the first line.

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Shane Miller - GPLama
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Perfect response :)

Yes... >90% is brutal. No question.

Thanks for the thoughtful response. I'm glad it's not just me... :)

yes Neo is harder then kickr... and has little spikes in ERG mode... guess we all have that in common.

Interesting, I have Kickr my 3rd and was thinking about moving to NEO, due to noise. I use P1 pedals to control power.

What I noticed recently riding in small ring on kickr solves noise issues for me, but introduced spikes you are experiencing on NEO. Riding at 90% I go anywhere between 80% and 105%, average will be always the same at the end or very close +-2-3W

Are you riding in big or small ring at the front?

Have all of you experiencing large swings on the Neo updated to the newest firmware? They addressed this issue about a month or two ago. I saw large swings on TrainerRoad and Zwift workouts, but it has since gotten much better and the swings are only +/- 8-10W. As in, if my target is 330, it may go down to 320 and up to 340.

The spikes on the KICKR are different... at least in my experience. The KICKR (version 1)... had some crazy spikes up to 400+ watts. They really sucked!! The NEO doesn't do that... it just adds time above the the prescribed wattage by it's inherent variability.

I always ride in the small ring... as speed is no issue on the trainer.

Is there an advantage in controlling the Neo using the SRM (or any other PM)? Would it be smoother if it was controlled by its own power output? It's pretty accurate compared to other trainers.

The advantage is that you know it's accurate... assuming your PM is.

I would think that things would be a bit smoother without the intermediate step in between... but not sure 100%.

This is an interesting one... The flywheel speed on the Kickr (and other flywheel trainers) has an impact on the feel/inertia/etc of the pedal stroke. 300W in the 39/25 at 90rpm feels* a lot different to 300W in the 53/11 at 90rpm. So changing into the small ring may not be exactly what you're after training load wise.

I'm typically in the 53 11/14/15/whatever to get that flywheel cranking along and the pedal stroke / firing patterns matched as closely to real world riding as possible.... that typically being flat TTs for me. The LeMond Revolution is still my pick for most interval work.


*I dislike the world 'feels', so I am in the process of trying to quantify this with numbers. I've got a set of P1 pedals and possibility a set of Rotor 2INpower cranks that might be put to use for this.

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Shane Miller - GPLama
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Not sure what you want to quantify, but the lower inertia means your wheel slows down more in the "dead" parts of the stroke, requiring you to re-accelerate over and over. I have a KK which is better than most, but it still feels very different from riding on the road, and I can't come close to hitting the same power.

This is starting to become really interesting. So we've got 'ability to hold steady power in ERG mode' which varies amongst the various trainers (direct drive or tire based) in terms of how accurately and rapidly they adjust. Too quick and you feel like you've just ridden into sand. Tire based introduces slip and wear but this isn't the subject of this thread. Then you have the flywheel speed or inertia, which differentiates the 'feel' of these devices. Plus you have the funky features like bumpy road feel and positive spin to mimic downhill but neither are really that important unless you want the immersive experience. What are the benefits of low/high inertia? Dumb direct drive trainers come in various flavours, the Lemond is middle of the road whereas the BT ERG and RevBox are all about low inertia so they force "you to re-accelerate over and over". If that is a benefit then it would suggest gearing on ERG mode is relevant. Any consensus on this?

SteveMc

High inertia is the natural way to simulate riding outdoors. My understanding is that most flywheel based trainers have only have a fraction of the inertia of a bike+rider on the road. However, if you're riding erg mode, you've basically given up on simulating the feel of riding outdoors.

This thread has some really good information on the mechanics of how a Neo works to simulate intertia in slope mode: http://www.timetriallingforum.co.uk/...oo-kickr/&page=4

In slope mode -0.5% a neo.blow everything (except monster trainers like the lynx) out of the water on inertia and road feel.
In erg mode it feels garbage, like a kickr feels all the time.
Whenever people escape the need for erg mode and just hold their own power manually they'll find they can hold much more on a neo. Particularly close hip angled TT positions who need all the inertia they can get.

Great thread, thanks. Having had great success with ERG training (on a CT) I'm less inclined to get so excited by 'road feel' but I see what the argument is (i.e. able to produce same power inside as out). The ERG mode taught me that training a particular variable, with less realism, was effective and time efficient. Having weekly TTs helped convert the indoor training to the road. The arguments against low inertia are more in terms of ridiculing the manufactures claims, rather than the potential training effect. A week diet of long steady alpine climbs always translates into flat TT speed for me, and seeing respected national track coaches advocate low inertia means I'm less willing to dismiss it. Similarly rollers might fail the realism test but they do provide a host of other benefits which do translate to the road.

No doubt the debate rages on....

SteveMc
p.s. I'm looking forward to what Sportcrafters are doing with their hard-drive trainer. I understand that building it wasn't as easy as they initially expected but it might solve some of the tire based problems of conventional turbos but also bringing a distinct feel to the ride that might be very close to reality; much like the Lemond which gets ample praise on the aforementioned thread.

Great post. I always have this debate with my colleague who has a Kickr 2 and Stages. I have a Neo and Stages (also used to ride on a CT with Quarq) and have had to adjust my wattage due to the different readings. Basically Neo and Stages are a lot lower than CT, Quarq, and Wattbike (at work). Colleague says his Kickr 2 and Stages are pretty consistent with Wattbike (and higher).


For context:


Jan 29, 2017
Tri bike
20 min FTP -
Tacx Neo: 210-215w
Stages: 188w
HR threshold: 158

Jan 31, 2017
Wattbike (like a computrainer and road bike position)
20 min FTP - Wattbike: 246w
HR threshold: 167



I know there are a lot of factors that could effect the test, but it's pretty consistent in terms of PE as well the past 3-4 months. Like 240-250w on the Wattbike (same as CT/Quarq) feels like 220ish on the Neo...Stages just seems all over the place and about 20-30w lower than Neo (maybe leg imbalance, but can't believe it's that bad).

Very interesting you mentioned this. I use ERG mode for everything except climbing and sprints. 90% of my training.

I use P1 pedals to control Kickr, I have to admit ERG mode at eg 300W in 53-11 will "feel" smoother than 36-23 despite the fact average power is 300W in both cases, it feels easier in 53-11. I will record pedal phase in both cases. In both cases power is the same 300W but 53-11 "feels" smoother\different.

I think a lot may have to do with how the resistance is controlled in the two trainers. Totally electronic (simulated flywheel) in the Neo vs an actual flywheel.

Who is specifically advocating low inertia?

That was my experience with the Kickr as well. Bigger gear = more inertia from the flywheel and better "road feel" particularly when getting up to 95% of FTP and above. With a smaller/easier gear it seems that the power fluctuates more which in turn causes the resistance to fluctuate more.

I don't think it matters as much with the Neo, though. I've found there doesn't seem to be much inertia at all with the Neo in Erg mode - especially since the last update. While Erg mode is more "accurate" on the Neo after the update, I think it now micro-manages the resistance too aggressively which can make intervals really brutal, especially in that 2-5 minute VO2Max range. I'm actually thinking I may need to try slope mode on the Neo for my hard intervals, I just can't do them very well in Erg mode.

Using slope mode with the Neo works very well. There's no need to worry about the "erg death spiral" either when you're doing really hard intervals.

Hugh

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Genetics load the gun, lifestyle pulls the trigger.

RevBox go pretty hard on it on their website. Pulling in scientificy looking people to sell...er.. talk about it.

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Shane Miller - GPLama
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I'm so happy you guys agree :) This was today... 3x10 @ 95 97 and 99%... BRUTAL...

Don't believe the sales pitch. High inertia trainers are inherently heavier and more complicated (expensive), but they do a much better job of simulating reality. Though it is theoretically possible that low inertia provides a training benefit even though it's unrealistic, I doubt it very much. The story that it's helpful to apply even force throughout the pedal stroke has been disproven.

Oh don't worry. I don't, and didn't when I reviewed their unit a while back. I'm keen to hear Ray's take on it. He's had one for a while now in the collection.

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Shane Miller - GPLama
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Tom Don: https://www.youtube.com/watch?v=PAgflXV-cPM

question not specifically directed to you, but to anyone who can provide input on this topic:

I've read several people on different threads mentioned that Neo is harder in erg mode than the KickR, because in the KickR in erg mode if you are in bigger gears you can generate more inertia. Especially for above FTP intervals.

If I currently use a KickR in erg mode in small chainring only for my above FTP intervals, would I notice those same workouts to be harder if I do them on a Neo?
Are erg mode workouts in a Neo harder than doing those in a computrainer?

Questions above are assuming power is stable during intervals on a Neo and not having significant jumps, as I read one way to solve that is using the Neo in erg mode in small chainring.

I have a very good opportunity on a Neo, so curious to hear about that.

If by "harder" you mean that you expend more watts on a Neo than a KICKR, then no, they should be the same. Assume that they are both accurate or both are using an external PM for power match, the rotational inertial is irrelevant in steady state (you are not changing cadence within a fixed gear). The impact would be that the KICKR would need to apply more braking force to overcome the inertia, but it would match the same system input power needed or requested. Imagine it in the extreme. Picture that it has a two ton flywheel. It would take an enormous amount of power to get it moving from rest, but after that, the sucker would just want to spin. However, the brake just needs to apply enough power to overcome the inertia so that you need to apply your target watts to keep the system steady state.

The difference in feel between a system with no inertia versus huge inertia would be what happens during changes. It would take way more braking from the trainer to slow it down and way more power from you to speed it up-- cadence changes without changing gears.

In your example, when you do those intervals that go from recover to >FTP, if you do not change cadence, then both systems only need to apply the same braking force to equal your target watts. However, if you do a spin drill, you would likely spike power more to accelerate the flywheel.

Thanks, yes, my question was with the assumption both were accurate.

Based on your response, I see it shouldn't take me more effort to maintain the same watts in erg mode in a Neo vs a KickR.
Was curious as I saw comments from Tacx Neo users on threads saying it's a lot more taxing to do above FTP erg mode intervals on a Neo vs on a KickR because the Neo have no inertia in erg mode.

ERG in the small ring on the Kickr is different to ERG in the big ring.... same power, same rpm, different experience. Here's my take on this showing the differences: https://www.youtube.com/watch?v=uHUOhmG04M8

The Neo is less forgiving in ERG mode, especially when it comes to efforts at or over FTP. The inertia on the Kickr (especially with a higher flywheel speed) can be a real benefit in this case. As the Neo is effectively software controlled, there's no reason the 'feel' can't be optimised/customised/adjusted within whatever software is being used to control it. IIRC the optimal setting for flat TT work was to select the TT bike profile and set a -1/-2% slope in their training app.

*Disclaimers. High level overview by someone (me) with no expertise in the field of biomechanics. I just ride trainers. A lot.

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Shane Miller - GPLama
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The differences people discuss are probably more to do with the philosophy about the controls system and not as much about the flywheel. There is some serious magic going on and some high-end controls and feedback that requires some pretty high-level calculus. Here is a simplification of what is going on...

Imagine the trainer has a PM on its axle that it is using to measure the power coming in. When it gets a power setting, it is comparing the input power to the setting, and choosing to either decrease or increase the braking force. However, a rider's input power is not continuous, it is a pulse that occurs at 2x pedal cadence. So, the controls system has to have some latency to not immediately release the brake when you hit the bottom of the pedal stroke or jam it on when you are at 3:00. And, it needs to be overridden by the fact that you may choose to speed up or slow down your cadence, so it has to allow this without totally releasing or jamming the brake before you get to your new desired cadence.

So, the controls system is taking many samples and then deciding how quickly to respond and how hard to hit or release the brake. If it acts too abruptly with the brake, it could create sensations of jerkiness. If it lags too much as you are changing your inputs, it may allow greater deviations from set power. These decision in the controls system would have a significant impact on how it feels. And, this is happening largely independently of the freewheel.

based on your experience, how would you compare "erg mode workout with above ftp intervals with KickR in small ring" vs "erg mode workout with above ftp intervals in Tacx Neo in small ring (however it seems that gear in Neo erg mode workout is irrelevant?)

I currently do all of my KickR erg mode workouts in small ring.

Thanks, I see that size of the fly wheel in erg mode might not be that important considering how the brakes need to act on the training so the desired power is maintained.

One thing I haven't seen mentioned yet is that high inertia feels like riding on a flat while low inertia feels like climbing. So, if you're doing 300W @ 90rpm in the little ring and big cog then it will feel like you're going up a hill, but in 53x11 will feel like flat. And yes, they will feel different. Moreover that difference vary between individuals. Some people say a watt is a watt, but that's BS. It depends on your physiology. The muscle firing patterns are different for flat vs. climbing and people are usually better at one than the other.

Inertia plays a role, but there are two other huge factors...

One is that the system is moving a lot faster. So, the samples are happening faster and the feedback loop and ability to respond is different.

But the bigger factor is the braking force. At low speed, the braking force is 2x to 3x greater. So, slight variations in input power would feel very different against the higher resistance.

Combine the two, and you have a totally different feel.

H. Legs wrote:

One thing I haven't seen mentioned yet is that high inertia feels like riding on a flat while low inertia feels like climbing. So, if you're doing 300W @ 90rpm in the little ring and big cog then it will feel like you're going up a hill, but in 53x11 will feel like flat. And yes, they will feel different. Moreover that difference vary between individuals. Some people say a watt is a watt, but that's BS. It depends on your physiology. The muscle firing patterns are different for flat vs. climbing and people are usually better at one than the other.

This is exactly what I did in the video linked above... while mapping the pedal stroke with the 2INpower (50hz). It was interesting to finally put some visual data to it.

https://www.youtube.com/watch?v=uHUOhmG04M8

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Shane Miller - GPLama
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I apologize for dredging this thread back up but I am struggling and need some help - although I understand things better here.

Specifically this has to do with racing on Zwift. As explained here I can expend the same energy across the Neo 2T and the Kickr but really struggle with the Neo racing on Zwift.

Is there any way to change the feel of the Neo to mimic the Kickr on Zwift?

I also find that quite a few of the better racers on Zwift are using ... Kickrs.

I am a little disheartened because I have to admit I LOVE the design of the Tacx in general. Well thought out, clean, quiet and I enjoy using it cordless.

Thoughts?

- Make sure your weight is correctly configured within the Tacx Util app (when it's connected to the Neo). Rider weight does have an impact on gradient simulation/inertia/ride feel and iirc if you're connecting over BLE then Zwift won't send the rider weight to the trainer. I hope they've fixed/solved that one... but....

- If you're on an early firmware update the firmware to 0.0.36 (I think that's the latest). *Do so at your own risk, etc, etc....

- If those don't change anything, switch to a Kickr.

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Shane Miller - GPLama
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Sorry to clarify and THANKS for even responding - that's hugely appreciated. I should use bluetooth to connect - set weight. Do I need to keep the app open on my phone while I race on Zwift?

I wonder how it would feel if I set my weight heavier.

Again thank you very much as this at least gives me somewhere to start because I want to love the Neo.

Once the weight is set with the Tacx Util app and assuming the other software doesn't override it, you're good. Even if your software overrides it, it'll also be correct. The issue will be if you're a good distance either side of the default 75kg (or 70?) and it isn't being set.

Here's something I did back in 2018 testing different rider weight settings on the same virtual gradient and cadence: https://www.youtube.com/watch?v=edJI8A8SMso

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Shane Miller - GPLama
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68kg

Definitely interesting - ill have to play with the settings in the game to see if playing with my weights has a change in that inertia feeling to match closer to the kickr.

Your videos are as always super informative. Thank you again.

Why does this matter? The pros are sponsored.

Then there are people like DC who are not but prefer the Neo

Now a few years since this thread was started - by this point do you think that there is a smart trainer that rivals the Lemond Revolution for “feel”? If not, what do you reckon comes closest?

IMO there's still nothing like it. It's like riding with a tailwind on smooth road... with a new chain.... on a sunny day. There's something about it being 'non digital' that appeals to me.



The Stages Bike SB20 with the huge cheese-wheel flywheel is close... but still no LeMond. And it's bolted onto an immovable object (the SB20 is a TANK!).

At the end of the day most of the top end trainers are now much of a muchness. They're quiet, interactive, compatible, (mostly) accurate, and provide exactly what they're designed to do. People will debate Kickr vs Neo all day long trying to justify their choices. There's no correct answer on that one. The ride feel of the Kickr feels like it has a little more 'kick over' in a larger gear, but the NEO2T feels like it has closed the gap there with the updated magnet layout/brake strength.

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Shane Miller - GPLama
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Agreed to all of that – why I've been on my Revolution every winter for the last seven years, noise notwithstanding.* Losing out on these aspects still gives me an impediment to investing in a smart trainer...

*That and the fact that I can match (or sometimes even exceed) my power output on the road, so maintain a high training quality.