Slope mode like ERG mode (completed)

Not sure if it’s just me, but resistance mode still doesn’t work with my wattbike atom. I increase the percentage in resistance mode and resistance doesn’t change at all. Maybe because it gets confused as it also has its own gear system. So for me, resistance mode is not filling the use case as it doesn’t work

Hi JPC, Yes the Watt bike does not support resistance mode. Once we do this slope mode it should solve this issue.

How high on the priority list is this at the moment?

Great question. Right now the big item app priority list is below

  1. Current build that is almost done (new training UI with cadence targets and other features) - next week
  2. Back and undo buttons - 1/2 weeks of dev
  3. Ant+ - 3/4 weeks of work of dev
  4. Virtual Power - 3/4 weeks of work of dev
  5. Switching to slope mode - 3/4 weeks of work of dev

So definitely by winter but hopefully Aug/Sept. It’s possible slope mode could move up in priority but this has been the core priorities for a while so I don’t imagine them changing that much.

1 Like

Craig, we are starting to work on this now. Can you tell me in your recorded data approximately where your FTP is? I would guess around 6%. Also looking at HR vs power does not make sense even for a pro rider 99bpm vs 537w

Hey Alex. I haven’t ridden indoors a lot since may but do have two good TrainerDay recordings in the last week:

I sent you the associated tcx files via email. I can’t seem to upload them here - tcx uploads are not supported.

The workouts I have built since March all have a 20% “over-shoot” at the start of each interval to simulate the real-world acceleration that is needed to reach a given steady-state resistance. As long as this “over-shoot” is 8 seconds or longer, erg mode on my Stages SB20 smart bike creates a very good 30 second interval with a proper resistance increase at the start of the interval. It works even better when I edit the workout do 600W+ intervals.

I have settled on using 240W as my FTP setting since May. I can easily generate 300w in an 8 minute FTP test and struggle to get about 200W in true 40km time trial. Such is the reality of being a 62 year old ex-athlete :slight_smile:.

I have thought about “Slope” mode for a few months. It is really “torque” mode. I want the bike to resist with a certain number of newton-meters for a specified period of timer. I can pedal harder or slower, and change gears if I wish. The bike resists with same force.

Given how few users really understand Erg Mode, introducing newton-meters or pound-feet would make things worse. I see the TrainerDay editor supports watts and cadence. I think this is a much better way for users to specify values that can be converted to torque.

At 55 I am not that far behind you and I have settled into thinking my FTP is around 208 even though ramp tests show 220-230. But I would struggle to do 200w for 20 minutes. Really I ride about 2 hours a week on average so it’s expected. I was excited when I was getting up to 4 hours a week and then shifted to more weight training. I have a friend and a guy I was coaching and he is 76 and won his US state championship. But he is exactly the opposite of you (and me) in that he can totally hit his TT / FTP numbers but can’t sprint at all.

I do agree with you there should be more of a focus on torque. I do low RPM (35-45) which can really do sustained high torque in Zone 2 power. The problem with torque is that it requires knowing the torque for each resistance or slope of each trainer. We have resistance mode now that works with constant torque but I realize for your trainer you need slope/sim mode which we are working on now.

But I think automatically switching to a specific slope will solve your issue although I believe the actual torque will be dependent on the gear you are in.

So we will be allowing people to upload GPX or TCX files and we will convert to slopes and erg targets. This will allow you to ride a route the same % of FTP as last time. But it also will alow you to ride slope mode so it is not the same power but does have the same slopes. You can control where it is ERG and where it is Slope mode or decide during the ride how you want to do it “Check or uncheck ERG mode.”

See screenshot of how it will look.

You also can download a GPX or TCX from ridewithGPS or other sites and follow a route in slope mode you have never done before. With a lack of power data in the GPX/TCX we will automatically estimate power but if you are in slope mode this will be for visual purposes as you will be able to ride how ever you want or in ERG mode it will be a typical ERG ride.


Gearing, Resistance and Slope

I agree that gearing will change pedal resistance - and the rider is free to choose. A 20% hill causes the bike to resist with a certain amount of force i.e., the force (torque in nm) required to turn the bike hub. The rider can change force at the pedals by changing gears and then pedalling at different speeds. If you record distance travelled over time (or rpm for the trainer’s freewheel), you can calculate “work” performed i.e., watts per second. It will be the same if you pedal a big gear slower, or a small gear faster.

The problem I have with the “slope” metaphor: the force created by a real-world incline is dependent on rider weight i.e., more force is needed to move heavier objects uphill. I’m not sure how many riders will understand this and I am not sure that exercise bikes can reflect “acceleration on a slope” anyway. Resistance that is like “steadily riding up an incline” is probably the best you can do.

Older Riders and FTP

Training plans have been harder from me to create after 60 years of age. Like the person you mention, my sprints have a fraction of the power they once had. FTP metrics are misleading too. For the first 6 months of 2021, routinely could deliver 250 watts in a short FTP test. My heart rate would be zone 5-6 at 150 bpm for the entire test. The same efforts today require zone 2-3 HR around 130-140 bpm which I can truly hold for a hour. That is an encouraging metric, suggesting better fitness. Here’s the odd part, increasing HR to 150 bpm does not change the watts produced by very much. I still get around 250 watts. This appears to be my old guy limitation: Power output is capped across all HR zones.

The other metric of note: changes take much longer. The fitness I saw reflected in lower HRs producing the same power, routinely took a few weeks by riding about 6 hours per week. This year, it took six months @ 8 hours week to see improvements.

This works.

Yes I am calling it slope mode because technically we would be sending the gradient or slope to the trainer and the trainer determines the resistance. Sim mode is what the manufactures seem to call it, outdoor simulation.

You can read a bit here

We still have not tested how this works but it seems pretty straight forward so yes we would send your weight and the slope and use constants for the rest. So as long as your gear, weight and slope are the same then the pedal resistance should stay the same and if you change only the gear the hub resistance stays the same but pedal changes. We are on the same page.

Interesting on your old riders. I think there are lots of “tricks” to breaking older riders out of being stuck, but you know your body. One of my best friends was a World Tour coach for many years (including one TDF winner). He has also coached amatures for many years as well. His belief is most riders need to consistently follow mini build patterns all the time to continue to grow so 5, 6, 7, 8, 4(rest week) hour a week for example 7hr avg. Not just a consistent 7,7,7,7… I do agree usually riding more is a key but most people are not good enough at recovery (you might be). With my friend Roger, when I started coaching him we focused more on recovery and that is when he started getting his personal bests and won his state championship. We were building recovery into every step of the way. Base period in the winter, recovery weeks every 3/4 weeks. Reducing intensity to 2 sessions a week… His FTP was 220 when he was 75 (2 years ago) and he is about 72kg but he really could do 210 in or close in a 40km TT.

I think this article describes the “slope mode” use case much better:

I would hope to be able to do handsfree HIIT sessions. The author above says you don’t need this feature - probably because it was not possible when the article was written in 2016. Smart Bikes (Wahoo Kickr Bike, Wattbike Atom bike plus one or two others) introduced since then, let you control both resistance (slope) and gears meaning hands free HIIT is quite viable. IMHO: The first app to properly automate HIIT will be the winner. When users try it, they will say “that’s what I wanted all along”.

Here’s why I don’t like slope that includes rider weight and other parameters. I am not playing a game like Zwift. I am doing structured training. I want reliable and reproducible HIIT resistance that I can set according to my training plan. I certainly don’t want the bike generating less resistance because I lost weight - or more resistance because I have some addition muscle. Bike resistance is based on my criteria including fitness, freshness and plan requirements which is then used to set bike resistance. Resistance should not be controlled by the simulation created (differently) by each bike/trainer vendor. Like a said, that’s for app playing games and running simulations. A structured training app needs to be able to control the bike and get the specific resistance needed.

The thing is most trainers support resistance mode as well as sim/slope mode and TrainerDay supports resistance mode now but your trainer as well as Wahoo bike and a few others do not support resistance mode. So in our current resistance mode we set the trainer to a % of max trainer resistance which is more in line with what you are describing.

This is the reason I don’t call it resistance because we really will be adding sim/slope mode and the only way to do this is to use slope and rider weight which in effect should be similar to resistance mode. Make sense?

Also we don’t currently support auto switching in and out of resistance mode which will be addressed at this time also.

Like the article you sent I don’t like ERG mode in Zwift and I also don’t like blindly following ERG workouts in our app either and so we made it easy to change but this request takes it to the next level which I really like.

I can say I also 100% agree with all of your thinking here. Especially in regards to learning to ride by feel rather than 100% ERG or ERG for Z2 or recovery and slope/resistance for hard efforts (hiit). Really TrainerRoad and Zwift technically support this now, meaning the 8 or 20 minute FTP tests goes from ERG to slope mode automatically but they don’t let you create your own workouts like this specifying the slope (resistance) as far as I know. I think bkool might and I know from a friend some older computrainer software did allow this as well. The guy that created ERGvideo built this software.

Also some users might want the slope to be accurate to their weight and some don’t. Really most that don’t should use our resistance mode but for bikes that don’t support resistance mode you will need to use slope mode. In your case just don’t change your weight in TrainerDay or your bike or gear and it won’t change your pedal resistance. :slight_smile:

You better be carefull with gpx or tcx from sites like RWGPS. Those files have elevation information from different sources. Could be from global elevation data where you will get a lot of noise due to GPS inaccuracies. Even elevetion data from a barometric pressure sensor is not perfect. If you use such a file, you will have a very nasty experience on your trainer because the resistance starts jumping allover the place. You would first need to smooth out those inperfections.
Look at how things are done for RLV videos.

We are doing serious smoothing on import, 30 second average or 1 minute on longer efforts so it shouldn’t be jumping all over the place but thanks for the warning. It also won’t be perfect for short sprint efforts. I have a feeling people will more likely use this to repeat an outdoor ride which will basically turn power into ERG efforts but if they want to manually change some of the segments to slope mode they can. Thanks for the RLV suggestion. I will review.

Basically, this is how I look at sim/slope mode :

The Power needed to overcome a certain gradient at a certain speed is dependent on the total weight carried up (rider + bike).

If you send « gradient » to a trainer, all it does is increase the offset of the « normal » power curve, so that you need a lot more power to keep the same speed. Thus if you reduce speed, you are working on the lower side of the curve, reducing power output.

You can’t rule out weight, because it influences the power needed to overcome that gradient at a specific speed.

Trainers simply add a power offsett according to the gradient they receive.

At 0% you need X watts to ride Y kph if your total weight is Q

At 5% you need (X + Z) watts to ride Y kph if your total weight is Q

Trainers can’t really « simulate » a hill because you will never have the downward pulling force that you have in the real world. It would need an adjustable flywheel weight to mimic the real world hill. Big heavy flywheel on the flats, that makes you ride fast with a smooth pedalling. And an almost zero weight flywheel on steep hills, so that the slightest hesitation in pedalling technique brings you to a halt.

Makes sense?

Here is a tool that is amongst the better smoothers for elevation data:

Downward pulling force for a rider just keeps the wheel spinning which the Neo does and I believe Craigs bike does too so I think it is a reasonable simulation. My interpretation of what Craig is describing is more like ERG meaning you specify torque and it is always that rear-wheel torque (ERG you specify power and you always get that power) but trainers don’t support this feature. Resistance mode like we have now is as close as you get to a torque setting but it seems like many riders would like slope mode which is as you describe varied on weight, wind, aerodynamics (outdoors), trainers try to simulate this and it gives Zwift and others a semi-realistic feel. It will be interesting to see how this automatic slope or resistance mode work. I still really like the idea. I am not sure if their is any feeling difference between slope and resistance but for some reason these bikes don’t support resistance.