Slope mode like ERG mode (completed)

Hey everyone. I was going to start a thread on this exact topic :medal_military:. Good to see.

I like Erg Mode for some structured workouts. The use case is: “I want a % FTP that translates to a particular amount of work over a given time interval”. Remembering that power = torque * rpm we end up with torque = rpm / power. If we agree that torque is the “resistance I feel at the pedals”, then resistance is constantly changing based on my pedalling speed. Faster pedalling = less torque and slower pedalling = more torque. Erg mode is great for many things - especially coaches who want to specify a power number and let the bike get the rider to do the correct amount of work.

Sprint Interval Training is a different goal: “Given a specific gear or resistance level, what’s the maximum power I can achieve and/or hold over a given time interval?” For any given gear, power = torque * rpm. If we agree that a gear translates to a measure of resistance applied to the pedals (optimally based om rider weight) then the power metric we are looking for is obtained by resistance * rpm. The higher the rpm, the happier I am :partying_face: .

I think Free-ride mode is the starting point. Instead of requiring me to manually select a virtual gear and watch the power reading, TrainerDay could set a virtual gear during each block based on %FTP or watts. I can increase or decrease resistance with the -/+ 100% control. I still watch the power readings but I don’t need to worry about resistance. I don’t do Zwift but I think this is a good description of their slope mode. I can’t find resistance training in any other smart bike software. My NordicTrack S22i spin bike had a programmable resistance mode that changed only resistance. I used it all the time.

Erg mode is good. Free-ride sprints are still the best for me, even if I have to manually set my resistance.

Very nice idea. You brought this forward in a way I had not considered. Zwift does automatic slope adjustments based on hills. We could do automated based on a workout structure. I had considered a similar idea which is allow you to upload a GPX and we will match the slopes but I figured it needed a new UI for this. Your idea means we could visually see slope adjustments just like ERG workouts and continue to use our same Training Tab.

Here is just the idea in our workout editor

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I did move this to a new thread even though it is related to the other one, just to allow people to vote on this idea. I like it, but I can’t exactly imagine it right now while riding.

You got it Alex! Slope is the right metaphor. The use case is: “Let me do a complete interval at a predetermined resistance level and see how I do in terms of power (watts)”. If I pedal faster, I do more work. Pedal slower and I do less work. When doing intervals in this mode, the smart bike can set a calculated resistance level and doesn’t need to hunt for a given wattage based on cadence like Erg mode has to.

Think of this way. In Erg mode, I want to the bike to create a calculated amount of work over a time interval regardless of cadence. This produces measurable results that can be used by coaches and riders to build and monitor a training plan. We get numbers like 400w for 1 minute. That’s fits nicely in spreadsheet and everyone is happy.

In slope mode (I have already adopted your term Alex - thanks :slight_smile: ), I want to do strength training. I want the bike to set an appropriate resistance that I use over a time interval. The overall (a.k.a., average) work performed during the interval is less interesting than the associated telemetry. What were the maximum watts I hit? How long did stay at a given power level? What’s my HR relative to resistance? What’s the function - based on something like linear-regression - that describes the work I did during the interval? I want it be a square wave. But often - especially in the beginning - the curve will resemble a reverse saw tooth. There are no convenient scalar values like 400w for 1 min. It’s more like resistance * sin(t). This not something every coach understands but could represent an opportunity for the next wave of training apps. Hint. Hint :slight_smile:

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User needs can be simplified - no math this time :slight_smile: :

Erg Mode
When you want to achieve a desired training volume, Erg mode is appropriate. You can target a HR zone or level of effort and let your smart bike keep you on track. Not too hard and not too easy. Just right. You provide a %FTP target and TrainerDay calculates the correct continuous power value using your smart bike’s Erg capability.

Slope Mode
When you want to train your muscles to endure high levels of effort including work in V02 max zones, Slope mode can help. Here you get an authentic, real-world simulation that creates progressively higher resistance as you pedal faster. You provide a %FTP target and TrainerDay calculates the correct resistance value using your smart bike’s resistance level /slope mode capability.

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This is nice clarification. I agree with you but had never really internalized this. You can do this now with our resistance mode but it would be interesting to see how this would work with automatic resistance/slope changes. I know slope mode on trainers is technically different than resistance mode but I don’t know how they actually feel different.

So wouldn’t this be similar in function to calculating normalized power for a specific interval? And from there you could calculation IF (intensity) of that interval.

We are going to start adding an interval break down in our web app based on completed activities using our app and this could make it into the mix but I need to understand a little bit better what you are suggesting and ultimately what would I do with that data? I guess generally you are saying to be able to compare one interval to the next and then one workout to interval to the next. If you bring time into the equation then maybe it would be the TSS of the interval not of the workout. This is an interesting idea but I guess the value would be to monitor progress across different workouts but the problem is TSS is not super accurate for comparing a VO2max vs threshold unless you factor in someones W’ … but still comparing two VO2max workouts it might be useful but again, W’Bal might be the right way to look at that for workouts over threshold.

Also as I mentioned slightly, I think now if you create an ERG workout (with approximate targets for a reminder) but switch into resistance mode you could do this yourself manually (less convientient) the Target Watts. I am just trying to make sure I fully understand as this is really a feature of convience to an athelete to specify the slope automatically rather than manual resistance like now.

@HighSpeed, I’m not sure why the thread has been split… seems to me we are suggesting the same thing :wink:

This thread is about setting slope targets like ERG targets. The other thread is about replacing resistance mode with slope mode… At least that is how I saw them. :slight_smile: Our current resistance mode should be very similar to resistance mode but rather than seeing that you are at 50% resistance you see you are at 18% grade, but technically trainers work differently in slope mode but I don’t know how that difference feels. I know TrainerRoad and Zwift use slope mode and we use resistance mode. Kickr Bike for example does not support resistance mode.

5 posts were merged into an existing topic: Please add sim mode so my trainer works and so we can specify slope %

Great questions all around. Let’s get our terminology aligned and I think we will be fine. I suspect it my terminology that needs to improved - I haven’t worked on these systems as long as you folks.

I am going to back off calling one feature. I think there are two: Smart Resistance and Slope Mode. I realize that Smarts Bikes (Wahoo Kickr Bike, Wattbike Atom, Tacx Neo Bike and Stages SB20) and Smart Trainers (Wahoo Kickr, Saris H3, etc) are different. Smarts Bikes can remotely set Resistance and Virtual Gear. They can benefit from a Smart Resistance and ** Slope Mode**. Smarts Trainers can remotely set only Resistance. The rider must select a Physical Gear on their bike. They can benefit only from Slope Mode.

How is a proposed Smart Resistance or Slope Mode different from the current Free- Ride mode?

Here’s how I think free-ride works today - If I am wrong please tell me - I will not be offended!!!

Free-Ride Mode

You create a workout in the TrainerDay editor to create Interval Blocks based on %FTP or Desired Watts. This result is: calculated Target Watts that will be used in each block when you do the workout in the TrainerDay App. If I select Free-Ride in the TrainerDay App, nothing is done with the smart bike resistance control (I am guessing here!!!). The goal of Free-Ride is to show the rider Target Watts for this Interval Block. The rider then selects a gear and cadence that lets them hit the Target Watts.

Proposed ** Smart Resistance** and ** Slope Mode**

You create a workout in the TrainerDay editor to create interval blocks based on %FTP or Desired Watts. This result: Target Watts that will be used in each block when you do the workout in the TrainerDay App. If I select *Smart Resistance in the TrainerDay App, the resistance level and virtual gear on the Smart Bike is set automatically so I can “just ride”. TrainerDay sets a Target Resistance and Target Gear for me. Slope mode is similar. TrainerDay sets only a Target Resistance. I set a Virtual or Physical Gear for myself. Either what I may or may not achieve Target Watts - it all depends on how hard I work. TrainerDay is helping by setting different Target Resistance in each block.

Target Resistance is simply a calculated amount of force relative to all the other Interval Blocks. It will take me time to find the correct amount of force needed, so TrainerDay will need to assist by giving me the ability to increase / decrease overall resistance so that eventually I automatically reach my Target Watts without doing anything “but ride”.

A Smart Bikes can support both Target Resistance and *Slope Mode. Smart Trainers can support only *Slope Modes. If I were looking for an MVP, Slope Mode would do the job.

BTW: I see some discussion about Sim mode. I don’t think this is a good term to show users. It is part of specs like Ant+ FE-C - so programmers will care. Bike riders will do better something like “slope” which is the constant resistance you feel going up hill. It’s not perfect. “Headwind” is another possibility. But it is not prefect either.

I also like slope mode and it comes from the old compu-trainers I believe. The problem that I have seen is that when setting a target in resistance mode (and I assume slope mode is the same) it can’t really be connected to watts. We could do it kind of like power match feature but that would be a bit of a mess and complicated. Meaning look at the target slope, read the current watts and then try to adjust the slope to get it to the watts. That would require some hunting around.

I think a user would almost need to create special workouts just for this slope mode because each trainer and gearing would produce different watt outputs for specific slopes. So you could create a workout with a warmup of 1% slope, followed by a threshold 8% slope and back to a 1% slope for a cool down. Now that 8% slope would not actually be 100% of FTP it would just increase the resistance and get it in the ball park but the user creating the workout and doing the ride would have to fine tune this. Sadly although I like the idea this is getting uglier… I am still not apposed to it as I think it might be interesting and once we do slope mode might be easy to implement. I do like the training effect. I might personally use this instead of ERG for harder efforts.

Alternatively maybe we could just imporve our slope mode with giant buttons to increase. Maybe two levels of buttons. + 5% or + 1%.

Just the idea I mean :slight_smile: Not real obviously

Maybe there is a way to estimate power. We have the formula to convert incline % + weight + power to speed. So we know how much power it takes to maintain a specific speed up a specific incline %. So a 30w increase in power would be approximately Y% for a new slope at the same speed. And if it is too much, you slow down… I think that might work…

Sounds good Alex.

Slope mode as you describe it is really all that’s needed. Give me slope resistance and I can do hard sprint intervals. That is what is missing with Erg mode.

Determination of slope from %FTP will only be an estimate of possible watts because you can’t be sure how fast I will pedal. The important part is to preserve the ratios for %FTP values in the workout. If 100% FTP maps to 10% slope, 50% FTP should map to 5% and 200% FTP should map to 20%. You can then use the -/+ controls to consistently scale the resistance level across the entire workout.


Yes now you are thinking like me. Meaning that is the simple approach (50=5%…). And have you tried our resistance mode (free-ride) and the problem is that the resistance mode is too flat and does not feel like slope mode? What trainer are you using now?

This might help. Here is a workout I created on my NordicTrack bike. You define only “incline%” for each interval block. The bike then responds with a different calculated resistance force for each interval during the workout. While pedalling, you can modify the overall resistance using the +/- control that changes the relative resistance level for each interval . + makes each interval harder. - makes them easier. This means you can share a workout with riders with different strength levels. Each rider sees the same changes during the workout. They select their personal level of resistance with the -/+ control.

My trainer is the Stages SB20 Smart Bike. It has Erg, Sim and Levels modes that you can control from one of 2 BT connections or any number of Ant+ FE-C connections. Not surprisingly, I chose this bike because I thought its software was good. The lack of resistance mode training option turns out to be due to limitations in workout apps and not the bike. So far no training app adequately exercises (pun intended) its sim and level modes (another hint :slight_smile: ).

Oh right now I remember… Ok yes :slight_smile: Slope mode is a good start for you and automated slope mode would be a super cool feature.

Super cool. I 100% get it (I think) and I really like it.