Workout Builder Features in Zwift & TrainerRoad

A workout builder is the tool inside apps like Zwift and TrainerRoad that lets you design a structured session as a sequence of timed blocks, each with its own power target, then hand the resistance over to your smart trainer to enforce. In plain terms: you decide the shape of the session once (warm-up, a set of intervals, recovery, cool-down), and the app makes your trainer do the work of holding each target. Combine that with ERG mode, which locks the trainer to a wattage regardless of your gear or cadence, and structured indoor training becomes almost effortless to follow.

The riders I coach almost all stall at the same point: they can follow a pre-built plan but freeze the moment they try to build their own. So I rebuilt a batch of my regular sessions in both Zwift and TrainerRoad to map exactly how each builder behaves and where the friction is. Here is how the features work and how to build a session yourself.

What a workout builder actually does

At its core a builder is a timeline. You drop blocks onto it, set how long each one lasts and what power it should demand, and the app plays them back in order. The clever part is the handover to your trainer. With a smart trainer connected over ANT+ FE-C or Bluetooth, the app sends a target wattage to the trainer for each block, and the trainer adjusts its own resistance to make you produce that number.

That single mechanism is why structured training works so well indoors. Outdoors, hitting 250 W for five minutes means constantly watching a head unit and feathering your effort against wind and gradient. Indoors, the builder removes all of that: you set 250 W once, the trainer holds it, and you just keep the pedals turning.

ERG mode: the feature that makes it all work

ERG mode is the one to understand first. When ERG is on, the trainer holds the target power no matter what gear you are in or how fast you spin. Drop your cadence and the resistance climbs to keep the watts up; spin faster and it eases off. You are no longer choosing your effort, the builder is, and you simply pedal.

In practice a decent direct-drive smart trainer holds ERG targets closely once it has warmed up for ten minutes or so, so the number you set in the builder is broadly the number you ride. That is the whole appeal: you stop managing your effort and let the block do it for you.

ERG does have quirks worth knowing before you build around it:

• The spiral of death. If your cadence drops too low at a high target, the resistance ramps up, which drops your cadence further, and you can grind to a halt. Keep a cadence above roughly 80 rpm during hard ERG blocks and it will not happen.
• A lag at block transitions. When a builder jumps from recovery to a hard interval, the trainer takes a second or two to load up. TrainerRoad lets you account for this; in practice just start pedalling firmly as the block changes.
• It is poor for very short, sharp efforts. For sprints and micro-bursts ERG cannot react fast enough. For those, build the block in resistance or slope mode instead. I cover the why in why short intervals matter on a turbo trainer and what micro-bursts are in turbo training.

The building blocks you will use

Whatever app you use, the same handful of block types make up almost every session. Understanding them is most of the battle.

Steady blocks

A flat power target for a fixed duration. The bread and butter of any session: a 200 W warm-up, a 280 W threshold effort, a 120 W recovery. Most builders let you set power as an absolute watt figure or as a percentage of your FTP, which is the better choice because the session scales correctly as your fitness changes.

Ramp blocks

Power that climbs or drops smoothly over the block rather than jumping. Brilliant for warm-ups, where you want to ease from 100 W up to 180 W over ten minutes rather than slamming straight into the work. Ramp tests, used to estimate your FTP, are a single long ramp that keeps rising until you cannot hold it.

Interval sets

Rather than placing twenty separate blocks for ten hard efforts and ten recoveries, you build one work block and one recovery block, then tell the builder to repeat the pair ten times. Change the number once and the whole set updates. This is where TrainerRoad’s builder in particular saves a lot of fiddling.

Text cues

Short messages pinned to a moment in the session: “two minutes to go, hold form”, or “drop to an easy spin now”. They sound trivial until you are deep in a hard set and a cue tells you exactly how much suffering is left. For long sessions they are genuinely the difference between following a plan and watching the clock.

Zwift versus TrainerRoad: which builder is better?

Both let you build custom workouts, but they are aimed at different riders.

Zwift’s builder lives in the Workouts menu and is visual and approachable. You add blocks from a simple list, drag to adjust, and you ride them inside the Zwift world with the scenery and group dynamics. It is more than enough for adding a bit of structure to your indoor riding, and the gamified setting keeps motivation up. The trade-off is precision: fine control over exact targets, ramp shapes and detailed text cues is more limited, and managing a large library of custom workouts is fiddly.

TrainerRoad’s Workout Creator is the better tool if you train to numbers. You get precise control over power for every block, proper ramp editing, repeat sets, and rich text cues you can place to the second. The environment is plain and data-led rather than scenic, which is exactly what some riders want. If your goal is a measured, repeatable plan, this is the one I reach for.

My honest take: if you ride indoors mainly to stay engaged and fit, Zwift’s builder is all you need and the world makes the time pass. If you are chasing specific adaptations and want every session exact, build in TrainerRoad. Plenty of riders do both: build precise workouts in TrainerRoad and, on days they want company, ride structured sessions in Zwift instead. Either way, see how training apps track your progress once your sessions are recorded.

How to build a custom workout, step by step

Here is the process I follow. It is broadly the same in either app.

1. Know your FTP first. Run a ramp test or 20-minute test so the builder can scale targets to you. Without a current FTP, percentage-based targets are guesswork.
2. Open the workout builder. In Zwift it is Workouts, then Custom Workouts, then the plus icon. In TrainerRoad it is the Workout Creator.
3. Add a warm-up. Drop in a ramp block, roughly 10 minutes rising from about 50 percent to 70 percent of FTP. Never skip this; cold legs hitting hard intervals is how you have a miserable session.
4. Build one work block. Set the duration and target for a single interval, for example 4 minutes at 105 percent of FTP for a VO2 effort.
5. Build one recovery block. Typically equal to or slightly shorter than the work block, at around 50 to 55 percent of FTP.
6. Turn the pair into a repeat set. Select both blocks and set the number of repeats. Five repeats of that 4-minute pair gives you a solid VO2 session.
7. Add text cues. Pin a cue at the start of each hard block (“smooth and strong, eyes up”) and a countdown near the end. These carry you through the worst of it.
8. Add a cool-down. A descending ramp from about 60 percent down to 45 percent over 5 to 10 minutes.
9. Save, name it clearly, and ride it. Use a name you will recognise later, such as “VO2 5x4 @105”. Turn ERG on for the steady and interval blocks, and switch to resistance mode for any sprint or micro-burst sections.

Do you need a smart trainer to use a workout builder?

To get the full benefit, yes. The builder’s superpower is handing target enforcement to the trainer through ERG mode, and only a smart trainer with controllable resistance can do that. If you are still on a basic magnetic or fluid trainer and you want to train to power properly, this is the single upgrade that changes everything. My best smart turbo trainers for Zwift roundup covers the trainers I would actually buy, and if budget is tight the best budget turbo trainers guide has the sensible entry points. If you are weighing trainer types before you spend, read direct drive versus wheel-on turbo trainers first.

The verdict

A workout builder turns your indoor setup from a way of pedalling on the spot into a proper training tool. Learn the block types, understand ERG mode and its limits, set targets as percentages of FTP, and lean on text cues to get through the hard bits. Use Zwift’s builder if you want simple structure inside an engaging world, and TrainerRoad’s Workout Creator if you want precise, repeatable sessions built to the watt. Whichever you pick, the moment you start following workouts you have shaped yourself, every session on the turbo starts pulling in the same direction.