The Moveee team
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ERG mode is the feature that turned smart trainers from expensive resistance units into genuine training tools. The idea is simple: you tell the trainer what wattage you want, and it applies exactly the resistance needed to keep you there — regardless of what gear you're in or how fast you're pedalling. Shift up, shift down, speed up, slow down: the number on the screen stays put.
It's brilliant, and it isn't always the right tool. Here's how it works and when to switch it off.
How it actually works
Power is force multiplied by speed. Your trainer measures how fast the flywheel is spinning and adjusts its electromagnetic brake to make up the difference. Pedal faster and it eases off; pedal slower and it clamps down harder. The result is that your gearing becomes irrelevant — you can do an entire interval session in one gear without touching the shifters.
The trade-off is a slight lag. The trainer has to notice a change and respond, which usually takes a second or two. For a 12-minute sweet-spot block that's invisible. For a 10-second sprint it's the whole effort.
When to use it
Steady sweet spot and threshold blocks
Long, constant-power reps are exactly what ERG was designed for. It removes every excuse to drift.
Long endurance rides
Holding a genuine Z2 for 90 minutes is surprisingly hard by feel. ERG makes it effortless to get right.
Over-unders
The transitions happen instantly and precisely — far cleaner than trying to shift for them.
When you're tired or distracted
On a low-motivation evening, letting the trainer make the decisions is the difference between a session and a DNF.
When to turn it off
Sprints and neuromuscular efforts
ERG can't react fast enough. It fights you at the start and then dumps resistance. Use slope mode and a big gear.
Very short, hard reps (under ~45 s)
Half the interval is spent waiting for the trainer to catch up. Slope mode gives an honest effort.
Race simulations and free riding
You want the gradient to drive the resistance, not a fixed number — that's what slope/SIM mode is for.
Learning to pace
ERG does the pacing for you, so you never develop the feel. Ride some sessions manually on purpose.
The alternative is usually called slope mode (or SIM mode). There, the trainer simulates a gradient and your power is whatever you produce against it — exactly like the road. Gears matter again, and so does pacing.
The spiral of death
Every ERG user meets this eventually. You're deep into a hard interval, your cadence starts to fall, the trainer adds resistance to maintain the target, which makes your cadence fall further, which adds more resistance — and within about five seconds you're at 45 rpm, grinding, and about to come to a complete stop.
It isn't a fault. It's the logic of ERG taken to its conclusion. Here's how to avoid it:
Keep your cadence up
The single best defence. Let cadence drop below ~70 rpm and the trainer piles on resistance to hold the watts, which drops your cadence further.
Shift into an easier gear early
Counter-intuitive but correct: a smaller gear gives you a higher, more sustainable cadence at the same power.
Back off and reset
Most apps let you pause or drop the target. Spin easy for 20 seconds and restart the rep rather than grinding to a halt.
Use a middle gear from the start
Set up mid-cassette before the interval begins so you have room to shift in both directions.
Turn the target down
If you fail the same session twice, the target is wrong, not you. Lower it 5% and complete it.
A word on 'ERG makes you soft'
There's a persistent argument that ERG mode weakens you as a rider because it removes the need to self-regulate. There's a grain of truth in it: pacing is a skill, and skills atrophy when a machine does them for you. A rider who only ever trains in ERG can be genuinely poor at judging a 20-minute effort on a real climb.
But the answer isn't to abandon ERG — it's to ride some sessions without it on purpose. Do your long steady blocks in ERG, where consistency is the whole point. Then do your race simulations, your climbs and your sprints in slope mode, pacing them yourself. You get the precision and keep the skill. (Our guide to pacing a climb with power covers the skill side.)
Getting it set up
ERG needs a trainer with controllable resistance — which in practice means anything sold as a "smart trainer" in the last decade, speaking the FTMS standard over Bluetooth. If you're still shopping, our smart trainer buying guide covers what to look for.
After that, any modern app can drive it. In Moveee Indoor you pick a structured workout, pair the trainer over Bluetooth in your browser, and it holds each interval's target watts for you automatically — while you ride one of your own real routes rendered in 3D from map data. Outside a workout it switches to gradient-driven resistance instead, so when the road climbs, so does the effort. It's free while in alpha and there's nothing to install.
Use ERG for the work that needs precision. Turn it off for the work that needs feel. That's the whole rule.
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