Quick Answer: SIM mode (simulation mode) makes your Peloton Bike+ feel like riding outdoors. Instead of holding a fixed power target like ERG mode, SIM mode simulates real terrain—resistance increases on climbs and decreases on descents. FitSwitch enables SIM mode on your Bike+ with 24 virtual gears you can shift from the on-screen overlay, turning your Peloton into a fully realistic smart trainer for Zwift, Rouvy, Kinomap, and more.
Table of Contents
- What is SIM Mode?
- SIM Mode vs ERG Mode
- How SIM Mode Works on Peloton Bike+
- 24 Virtual Gears
- Using SIM Mode with Training Apps
- SIM Mode Tips and Best Practices
- FAQ
What is SIM Mode?
SIM mode—short for simulation mode—is a smart trainer feature that replicates the feel of outdoor riding. When you ride a route in Zwift or Rouvy, the app sends terrain data (gradient, wind resistance) to your trainer, and the trainer adjusts resistance to match.
How SIM Mode Feels
- Climbing a 5% grade — Resistance increases, requiring more effort to maintain speed
- Descending a hill — Resistance drops, allowing you to spin freely or coast
- Flat road with headwind — Slight resistance increase simulating air resistance
- Drafting behind riders — Reduced resistance when tucked in a group
Unlike ERG mode where power stays constant regardless of what you do, SIM mode lets your power vary naturally based on your gear selection, cadence, and the virtual terrain. Just like riding a real bike outdoors.
Why SIM Mode Matters
For Virtual Cycling: - Feel the hills in Zwift's Alpe du Zwift or Rouvy's Alpe d'Huez - Race with realistic resistance that matches the course - Experience descents as actual recovery, not constant effort - Shift gears to manage effort just like outdoors
For Immersive Training: - Routes feel connected to your body, not just visual - Pacing becomes strategic—gear and cadence choices matter - Group rides and races feel competitive and tactical - Better preparation for outdoor riding
For Realistic Feel: - Indoor riding that translates to outdoor performance - Gear selection develops real cycling skills - Terrain management teaches pacing - The Peloton Bike+ finally feels like a real road bike on a trainer
SIM Mode vs ERG Mode
FitSwitch supports both ERG mode and SIM mode on the Peloton Bike+. They serve different purposes and you'll use both depending on the situation.
| Feature | ERG Mode | SIM Mode |
|---|---|---|
| What it controls | Maintains target power | Simulates terrain |
| Resistance behavior | Adjusts to hold constant watts | Adjusts based on gradient |
| Power output | Fixed (e.g., always 200W) | Varies with effort and gear |
| Gear shifting | Not applicable | 24 virtual gears available |
| Best for | Structured workouts, intervals | Free riding, racing, routes |
| Cadence effect | Power stays the same at any cadence | Higher cadence = more speed |
| User control | Set target and pedal | Shift gears and manage effort |
| Feels like | A controlled lab test | Riding outdoors |
When to Use Each
Use ERG Mode: - Structured workouts with power targets (TrainerRoad, Zwift workouts) - FTP tests and ramp tests - Recovery rides at a specific wattage - Any time you want the bike to maintain a fixed power
Use SIM Mode: - Free riding in Zwift, Rouvy, or Kinomap routes - Racing in Zwift or MyWhoosh - Exploring virtual worlds and feeling the terrain - When you want the outdoor riding experience indoors
Automatic Switching: Training apps handle the switching automatically. Start a Zwift workout and ERG mode engages. Switch to a free ride and SIM mode takes over. FitSwitch responds to whatever the app requests—you don't need to toggle anything manually.
How SIM Mode Works on Peloton Bike+
FitSwitch turns your Bike+ into a physics-based cycling simulator. Here's what happens under the hood.
The Physics Engine
When you ride a route in Zwift or Rouvy, FitSwitch runs a real-time physics simulation:
- The app sends terrain data — Gradient percentage, wind resistance
- FitSwitch reads your cadence — How fast you're pedaling
- Your virtual gear determines wheel speed — Higher gear = faster speed at the same cadence
- The physics engine calculates required power based on three forces:
- Gravity — Climbing resistance based on the gradient and your weight
- Rolling resistance — Friction between tires and road surface
- Aerodynamic drag — Air resistance that increases with speed
- FitSwitch adjusts the Bike+ resistance — The motorized knob moves to match the calculated power
- Your virtual speed is reported back — The app positions your avatar based on your actual effort
This loop runs continuously, creating a seamless connection between your pedaling and the virtual world.
What Makes It Feel Real
The physics model accounts for the same forces that affect outdoor cycling:
- Weight matters — Heavier riders work harder on climbs (set your weight in the app for accurate simulation)
- Speed matters — Aerodynamic drag increases with the cube of speed, so going fast gets progressively harder
- Gradient matters — A 10% grade requires roughly twice the power of a 5% grade at the same speed
- Gearing matters — Shifting to an easier gear reduces speed but makes climbing manageable
The resistance changes feel smooth and natural thanks to FitSwitch's PID control system—the same technology used for ERG mode, but tuned for the more dynamic demands of simulation.
Coasting and Descents
On real descents, you can stop pedaling and coast. FitSwitch handles this naturally:
- Stop pedaling — Resistance drops to minimum, simulating coasting
- Steep descent — You feel virtually no resistance
- Transition to flat — Resistance gradually returns as the road levels out
No more grinding through descents at full resistance like a dumb trainer. SIM mode makes descents actual rest.
24 Virtual Gears
Since the Peloton Bike+ doesn't have physical gears, FitSwitch provides 24 virtual gears that simulate a real road bike's gearing range.
How Virtual Gears Work
Each gear represents a different gear ratio—the relationship between how fast you pedal (cadence) and how fast you move (virtual speed):
- Gear 1 (easiest) — Low ratio, low speed per pedal stroke, minimal resistance on flats
- Gear 12 (default) — Middle of the range, good for general riding
- Gear 24 (hardest) — High ratio, maximum speed per pedal stroke, high resistance on flats
The 24 gears span a range equivalent to a real road bike's cassette, from a climbing-friendly easy gear to an aggressive high gear for flat-out sprinting.
Shifting on the Screen
FitSwitch displays a gear overlay on the Peloton screen:
- Current gear number shown clearly (1-24)
- Up button — Shift to a harder gear (higher number)
- Down button — Shift to an easier gear (lower number)
- Tap to shift instantly—gear changes take effect immediately
How Gears Affect Your Ride
Same cadence, different gears:
| Gear | Cadence | Virtual Speed | Effort |
|---|---|---|---|
| 6 (easy) | 90 RPM | ~20 km/h | Light |
| 12 (medium) | 90 RPM | ~30 km/h | Moderate |
| 18 (hard) | 90 RPM | ~40 km/h | Hard |
| 24 (hardest) | 90 RPM | ~50 km/h | Very hard |
Climbing strategy: - Hit a steep climb → shift down to an easier gear - Cadence stays comfortable, speed drops, but you keep moving - Just like downshifting on a real bike when the road tilts up
Sprinting strategy: - Hit a flat section or want to sprint → shift up to a harder gear - Higher virtual speed at the same cadence - More resistance, more power required
Gear Selection Strategy
For Climbing (5%+ gradient): - Shift to gears 1-8 - Maintain 75-90 RPM cadence - Let the easier gear keep you spinning
For Rolling Terrain (1-4%): - Use gears 8-16 - Shift up and down as the road undulates - Stay in a comfortable cadence range
For Flat Roads: - Use gears 12-20 - Choose based on desired speed and effort - Higher gear = faster but harder
For Descents: - Shift to gears 18-24 if you want to pedal - Or stop pedaling and coast - High gears let you maintain speed on the way down
For Sprinting: - Shift to gears 20-24 - Maximum speed per pedal revolution - Ideal for race finishes and KOM/QOM efforts
Using SIM Mode with Training Apps
SIM mode works with every training app that sends gradient or simulation data. The app controls the terrain—you control the gears.
Zwift
Zwift is where SIM mode shines. Every route in Zwift sends gradient data, and FitSwitch translates it into resistance.
Free Riding: 1. Select any route in Zwift (Watopia, France, Yorkshire, etc.) 2. Start riding—SIM mode activates automatically 3. Shift gears using the on-screen overlay as terrain changes 4. Feel the climbs, enjoy the descents 5. Your avatar speed matches your virtual effort
Racing: 1. Join a race event 2. SIM mode handles the course terrain 3. Shift strategically—easier gear for climbs, harder for sprints 4. Draft other riders for reduced resistance 5. Compete with realistic physics
Zwift's Virtual Shifting: Zwift introduced its own virtual shifting feature, and FitSwitch's 24 gears are designed to match. The gear ratios align with Zwift's native shifting system, so the experience feels integrated and natural.
For details on setting up Zwift, see our Zwift on Peloton Bike+ guide.
Rouvy
Rouvy's real-world video routes are a perfect match for SIM mode. As you watch actual footage of cycling roads, the resistance matches the real terrain.
Route Riding: 1. Select a route (Alpe d'Huez, Stelvio, Mont Ventoux, etc.) 2. SIM mode responds to the real-world elevation data 3. Shift gears to manage the climbs in the video 4. Descents in the video match descents in resistance 5. The video and your effort are perfectly synchronized
For setup instructions, see our Rouvy on Peloton guide.
Kinomap
Kinomap's community-filmed routes work similarly to Rouvy, with resistance matching the route's elevation profile.
For setup instructions, see our Kinomap on Peloton guide.
MyWhoosh
MyWhoosh supports SIM mode through FTMS and ANT+ FE-C. Since MyWhoosh runs on an external device (phone or tablet), it connects directly to FitSwitch's broadcast—no Bridge app needed.
For setup instructions, see our MyWhoosh on Peloton guide.
TrainerRoad
TrainerRoad primarily uses ERG mode for its structured workouts. However, if you select "Resistance" mode or do a free ride in TrainerRoad, SIM mode principles apply.
For structured workouts, ERG mode is the right choice. See our TrainerRoad on Peloton guide.
External Devices (Garmin, Wahoo)
SIM mode also works over ANT+ FE-C. If you're running a training app on a Garmin Edge, Wahoo, or other ANT+ device, it can send simulation parameters to FitSwitch and your Bike+ will respond.
For details on ANT+ connectivity, see our ANT+ on Peloton guide.
SIM Mode Tips and Best Practices
Finding Your Gear Range
When starting out: 1. Begin on a flat Zwift route 2. Start in gear 12 (the default) 3. Pedal at your natural cadence (85-95 RPM) 4. If the resistance feels too easy, shift up 5. If it feels too hard, shift down 6. Find 2-3 "home" gears for flat riding
Most riders settle into gears 10-14 for general flat riding.
Climbing Technique
For long climbs like Alpe du Zwift: 1. Shift down before the climb starts (anticipate the gradient) 2. Find a sustainable cadence (70-85 RPM for most) 3. Don't shift too early to easy gears—save them for the steepest sections 4. Shift gradually as the gradient increases 5. On switchbacks where gradient eases briefly, shift up 1-2 gears
Smooth Shifting
- Shift one gear at a time for gradual transitions
- Don't shift under maximum effort — ease off slightly, shift, then push again
- Anticipate terrain changes — Shift before you need to, not after
Race-Day Gearing
For Zwift races: - Start in a moderate gear (12-14) for the neutral start - Shift up for the start surge - Settle into your race pace gear - Have a plan for key climbs: which gear at which gradient - Save your hardest gears for the final sprint
Weight Settings
Your weight in the training app affects SIM mode physics: - Accurate weight = accurate simulation - Lighter riders feel climbs less intensely - Heavier riders feel climbs more - Set your weight honestly for the most realistic experience
Frequently Asked Questions
Does SIM mode work on the original Peloton Bike?
No. SIM mode requires the Bike+'s motorized resistance system. The original Bike has a manual resistance knob that can't be controlled by software. On the original Bike, you can see gradient data in the app and manually adjust resistance, but automatic terrain simulation isn't possible.
What's the difference between SIM mode and ERG mode?
ERG mode maintains a fixed power target—if you slow your cadence, resistance increases to keep power constant. SIM mode simulates terrain—resistance changes based on the virtual gradient, and your power varies with your effort and gear selection. ERG is for structured workouts; SIM is for realistic riding.
Do I need the FitSwitch Bridge app for SIM mode?
It depends on where the training app is running: - Apps on the Peloton screen (Zwift, Rouvy, Kinomap): Yes, the Bridge app handles FTMS communication - Apps on external devices (MyWhoosh, Zwift on computer): No, connect directly to FitSwitch via Bluetooth FTMS or ANT+ FE-C - Garmin devices: No, connect via ANT+ FE-C directly
How do I shift gears?
Tap the up or down buttons on the FitSwitch gear overlay displayed on the Peloton screen. The overlay shows your current gear (1-24) and shifting takes effect immediately.
Can I shift gears while in ERG mode?
No. ERG mode and SIM mode are mutually exclusive—only one can be active at a time. Gears only apply in SIM mode. In ERG mode, the bike targets a specific wattage regardless of any gear setting.
What happens if I stop pedaling in SIM mode?
Resistance drops to minimum, simulating coasting. When you start pedaling again, resistance returns based on the current gradient and your gear. This feels natural—just like coasting on a real bike.
Does SIM mode work in Zwift races?
Yes. Zwift races use SIM mode—resistance matches the race course terrain. Shift gears strategically for climbs and sprints. This is the default mode for Zwift racing.
Are the 24 gears the same as Zwift's virtual shifting?
FitSwitch's 24 virtual gears are designed to match Zwift's native virtual shifting ratios. The gear ranges align so the experience feels consistent and natural.
How accurate is the terrain simulation?
FitSwitch's physics engine models gravity, rolling resistance, and aerodynamic drag—the same forces you experience outdoors. The simulation is comparable to dedicated smart trainers like Wahoo KICKR and Tacx NEO.
Can I customize the gear ratios?
The 24 gears use a carefully calibrated range that covers everything from steep climbing to flat-out sprinting. The ratios are designed to match industry-standard virtual shifting and provide smooth, even spacing between gears.
Does SIM mode work with ANT+ FE-C?
Yes. FitSwitch supports SIM mode over both Bluetooth FTMS and ANT+ FE-C. Garmin Edge computers, Wahoo devices, and other ANT+ equipment can send simulation data and FitSwitch will respond with terrain-appropriate resistance on your Bike+.
Can I use SIM mode in the Peloton app?
SIM mode requires terrain data from a training app (Zwift, Rouvy, etc.). In the native Peloton app, you can use ERG mode to set a constant target power, or adjust resistance manually. There's no gradient simulation in Peloton's own content.
Can I track SIM mode rides on my Apple Watch or Garmin?
Yes. FitSwitch broadcasts your power, cadence, and heart rate to Apple Watch and Garmin devices regardless of whether you're in SIM mode or ERG mode.
Your Bike+ Is Now a Full Smart Trainer
With SIM mode, FitSwitch unlocks the last major smart trainer feature on your Peloton Bike+. Combined with ERG mode, your Bike+ now matches the capabilities of dedicated smart trainers costing $800-$1,200:
- SIM mode with 24 virtual gears for realistic terrain simulation
- ERG mode for structured workouts with automatic power targeting
- Bluetooth FTMS and ANT+ FE-C support for universal app compatibility
- On-screen gear shifting — Tap to shift, instant response
- Physics-based simulation — Gravity, drag, and rolling resistance modeled in real time
- Smartwatch connectivity — Apple Watch and Garmin support
Feel the hills. Shift the gears. Ride the world from your Bike+.
Get FitSwitch — SIM mode with 24 virtual gears on your Peloton Bike+.
Last updated: February 2026