Training article
To ERG or not to ERG
An absolutely fantastic tool
As a coach, I do fear many have become too reliant on it.
ERG mode is a setting that certain smart trainers have, such as the Wahoo KICKR and Tacx NEO. It effectively allows you to hold a specific power output and therefore train in a very focused way, targeting a particular energy system.
It’s an absolutely fantastic tool that can simplify your training and really hone in on a specific area you are looking to develop. For instance, if you want to do 3 x 4 minutes at VO2max, you can hit that power output exactly and hold it, thereby inducing a consistent demand on your muscles and maximising the potential training effect. In essence, it strips out any surging in your power and allows you to hit a specific wattage and stay there for as long as you need to hold it.
This works often by magnets in the trainer controlling the velocity at which the super-efficient flywheel will spin. In fact, there will be a specific velocity the flywheel will want to spin at, and if you get it to that point it will in effect find a sweet spot. All you then have to do is keep pedalling hard enough to maintain that flywheel velocity. If you pedal too hard, the flywheel will go light and therefore prevent you from putting out significant power above the velocity it wants to spin at. So not only does it help you hit a specific wattage, but it can also prevent you from riding too hard and spoiling the session objective.
It’s an awesome development in indoor cycle training. However, as a coach, I do fear many have become too reliant on it as a tool. This is totally understandable, because it does enable you to really control your training and quantify the effect it will have. However, hitting a specific power at the exclusion of all other factors that contribute to improved performance shouldn’t be your only motive.
The advantages
There are many advantages to using ERG mode in your session. Here are a few.
A very specific wattage
There is no guesswork in whether you are putting in the requisite effort. ERG mode will run at a percentage of FTP and you can build an entire training session around how it will respond, and know you are doing exactly what is meant to be done. This enables you to quantify and progress training sessions in a precise way. So your 3 x 4 minutes at VO2max can become 3 x 5 minutes, and you can quantify the fitness improvement accurately, as one session will involve the exact same power output but has progressed to keep you there longer.
It simplifies the session
If you have a coach or a training plan, there is very little thinking to do. You just need to pedal to get the flywheel to the correct velocity and keep working to keep it there.
Terrain stops getting in the way
The training effect is not compromised by terrain or other variables such as rolling resistance. ERG mode creates a more scientific and controlled training scenario. There is no drop in power as you freewheel down a descent, or a struggle to hold a lower power going up an incline. You have all that uncertainty removed.
It can push cadence up
Depending on the software, you can set the flywheel velocity to respond not only to power but also to a specific cadence. For example, you can set its sweet spot to 100% of FTP at 90 rpm. The trainer will spin up most comfortably if the rider hits that power, usually within about 5 rpm of that cadence. Spin up too quickly and the flywheel goes light. Let leg speed drop too low and the flywheel becomes increasingly heavy. Think of it like a fixed gear, or a track bike.
You can just suffer
There are occasions when you just want to suffer and not have to think about anything else. In this respect it can be good for your mental well-being to do a session in ERG mode, because the trainer will adapt and all you need to do is pedal. Assuming you’re not working super hard, it means your mind can drift as you check out for a bit.
The sweet spot
90 rpm
For example, at 100% of FTP. Comfortable within about 5 rpm of the cadence you set.
Below that
80–100
The cadence range the flywheel wants. Drop out of it and the effort gets heavier and heavier.
The downsides
This is where things might get a bit controversial, as not everyone will agree with what I would consider cons, and some of them just plain contradict the advantages. Put simply, the cons are context driven. There are some key downsides to be aware of.
It can be horrendous on a bad day
ERG mode requires you to push a very specific power output and a specific cadence range, usually between 80 and 100 rpm, in order to keep the flywheel turning at velocity. If you are a touch fatigued, haven’t eaten enough before the session, or are simply on a bad day, the session can turn from a challenge into a massacre. If you are unable to keep within the required power and cadence ranges, the flywheel will slow down and become heavier and heavier. Think of a track bike again, and how hard sprinters have to work to get that single big gear up to speed. That is the scenario you are constantly battling if your leg speed slows down.
You can forget how to produce power smoothly
One of the positives of ERG mode is it allows you to sit at a specific power, and all you need to focus on is turning the pedals. However, if you rely on ERG mode too much and use it for all your turbo sessions, it can see you almost forget what it is like to produce power without it.
When I run sessions in the RIAK Fitness studio with ERG mode off, I can often tell who has a smart trainer and who does most of their riding outdoors. The owners of smart trainers tend to have far bigger peaks and troughs in their power output, as they’re not used to riding on a turbo without the crutch of ERG mode. This is a negative, because turbo training is meant to be about developing a level of conditioning that you can directly apply to the road. If your power is all over the place, you will not find a rhythm and will fatigue quicker out on the road than your actual fitness should dictate. It will also make you super annoying to ride with in a group, as you constantly speed up and slow down.
The mind can drift too much
ERG mode allows you to minimise the things you have to focus on, and you just drive those pedals round. In some scenarios that’s great for your mental well-being. If your session or interval is a relatively light one and you have nothing to hold your attention, your focus can drift.
This often means you start checking your phone, or other things, to occupy your mind, and that can have a negative impact both on your mental well-being and the quality of your session. If you are checking your phone all the time, you are still connected to the world, and all it takes is that message or email that gets inside your head. Then that is what you’re really thinking about, and not what’s coming up in your session. If your mind is elsewhere, it can really impact how you feel doing a session and make it so much harder than it needs to be.
It’s easy to do the session and not know why
ERG mode is great because you can create a session plan and it will adjust to replicate a percentage of your FTP, which means you can do some really cool dynamic sessions that you just wouldn’t be able to do out on the open roads. However, if all you need do is pedal harder or softer in order to satisfy the session plan, arguably you are less likely to engage and appreciate what that session is meant to be about.
For instance, say your session is about simulating a race finish, so you do repeated pickups off threshold. If you’re doing this in ERG mode, you just pedal harder when you need to. With it off, you have to focus on what you’re doing and be ready to drop that gear for the sprint or pickup. There’s a real technique to feeding in a gear at the right time without smashing your chain. Using ERG mode means you lose the opportunity to practise this.
If your FTP is off, so is the session
This is a key one, because your FTP is actually a dynamic metric and different on any given day. Your FTP is a rough measurement of your aerobic threshold and therefore a measure of a metabolic process which is not identical every day. There are a multitude of factors that will feed into the power at which this threshold is actually met. Having it set so specifically, day in day out, means that sometimes it will inevitably be too high and on others far too low.
This is why, typically, as athletes we work with power zones or training zones. We work within a range because an exact number isn’t always attainable. ERG mode, therefore, might see you on occasion missing your session objective, because when you think you’re in zone 3 (tempo), you might actually be in zone 4 (threshold), and your heart rate is not where it needs to be for the training effect you desire.
It can cap your peak powers
This last point is a big one I try to repeat in sessions regularly, when they involve sprints or very high powered efforts. FTP is one metric, but your 5-minute, 2-minute, 1-minute, 20-second and 5-second powers are also super important if you wish to be a well-balanced rider. If you’re sprinting, or doing VO2max type work, with ERG mode on, it is potentially going to limit your ability to improve on your short-duration peak powers. You therefore won’t have as good a gauge as to how your VO2max and anaerobic capacity are developing.
When not to use it
Whether I would suggest ERG mode or not is entirely context driven. It depends on what session you are doing. If your session is purely about conditioning and has no sprints, ERG mode is probably a good shout. A lot of sessions will fit this bill and, for the most part, ERG mode will probably feature in most of your turbo sessions. It’s perhaps a bit easier to suggest when using ERG mode might not be advisable.
Leave it on
Conditioning, and no sprints. Most turbo sessions will sit here.
Turn it off
Sprints, a benchmark, a bad day, a stressful day, or anything past VO2max.
Mix the two
So you still know how to produce the power yourself.
- Multiple sprint sets, so your peak power isn’t limited and you can see your repeatability: how close you can get to the same average power each time. That is your speed endurance.
- A benchmarking session, such as 3 x 10 minutes at FTP. That is a good indication of whether you are ready for an FTP test, and you will want to see how your power and cadence fluctuate.
- When you are not feeling great and the legs aren’t there. Out of ERG mode, your legs can find a point you can hold, and your power can surge and drop in line with what you can handle that day. You might still hit the average power for the interval. You have just taken a different route to get there.
- A stressful day, when you’re struggling to focus. Dropping out of ERG mode forces your mind onto what you are doing, so your power doesn’t peak and trough quite so much.
- Anaerobic work for racing. Any work beyond VO2max should be done out of ERG mode, so you can track your short-duration peak power and make the session realistic enough to replicate on the road.
The key message
Just make sure you mix it up.
- Conditioning, with no sprints: ERG mode is probably a good shout.
- Turn it off for sprints, benchmarking, a bad day, a stressful day, and work past VO2max.
- If the FTP in the trainer is off, ERG mode will train the wrong system.
- Use it for every turbo session and you can forget how to produce power smoothly.
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