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 STAGES SB20 DRIVE BELT ADJUSTMENT (2025 Update) I adjust my SB20 drive belt once a year to keep things running smoothly.  I wish this process was easier. With practice, you can complete all adjustments in less than 30 minutes. UPDATED: December 2025 - New video and pictures. Simpler procedures. 📐 These instructions augment the Stages support documents:  Belt Tension Adjustment (SB20) Flywheel Making Noises . TWO GOALS Adjusting the drive belt accomplishes a couple of things: Gets belt tension right. Optimal tension means quieter running and no slipping during hard efforts. Aligns the belt to ride as much as possible in the centre of the flywheel cogs. This reduces friction and positions the front axle perpendicular to the drive belt.  🎬 VIDEO Here's a new four minute video showing how to adjust tension and align the drive belt. The Details Part Names Here are part names related to drive belt adjustment. BELT ADJUSTMENT SUMMARY “ It’s all about the tensioners ”....

The SB20 smart bike uses both Bluetooth Low Energy (BLE) and ANT+ to wirelessly communicate with apps like Zwift.  You can get communication dropouts and glitches.  Here's how to fix them. BUT FIRST, make sure your wireless environment is optimized: Better Wireless Communication  👈👈👈 Background ANT+ was the dominant fitness protocol prior to 2020. While there is nothing wrong with ANT+, most wireless development and testing in the past 5 years has focused on the Bluetooth Low Energy (BLE) protocol. Stages wrote the firmware for the SB20. It preforms 3 primary wireless functions: a) Controls bike resistance - usually as requested by an app like Zwift. ? b) Gets power and cadence readings from the power meter cranks. c) Sends updates to apps like Zwift. Includes power and / or cadence depending on how you configure the app. Stages did not write the firmware components for doing wireless BLE or ANT+ communication. It was written by Nordic Semiconductor who manufactu...

Breaking a Drive Belt Tensioner Adjusting SB20 drive belt tension is something your should consider performing every couple of years. Here's how: Stages SB20 - Drive Belt Adjustments The good news: A properly adjusted belt is quieter and extends the life of the drivetrain. The bad news:  The belt tensioners ( one on each axle ) can break if you over tighten them. The tensioner bolt will typically snap next to the washer assembly 😖.   DIY Fix Getting SB20 replacement parts is challenging these days. Here's how to fix a broken tensioner. 1. Drill out the broken bolt that is welded to the tensioner ring.  2. Find replacement bolts. I recommend M5 x 1 with thread length of 30 mm. Use stainless steel if possible. If you have a hex cap bolt, you can use it directly.  If you have a round head, you will need to file one edge.  You will also need matching lock nuts. You can also use SAE bolts.  A 10-24 or 10-32 bolt with 1-1/4" thread length works well. Here's a ...

Two bikes with Different Resistance Consider these common scenarios. You have: Bought a new indoor smart bike / trainer.   Two bikes / trainers of the same brand and model. Moved a trainer from one bike to another Something is wrong . The same physical or virtual gear does not feel the same as your other bike. If you take a single set of power meter pedals and measure the power produced by each bike at a given cadence for the same virtual gear, you can easily confirm different power readings. Why is Resistance Different? Imagine for a moment, all the indoor trainers and bikes available on the market. When doing a race or free ride, each bike/trainer is controlled by an app like Zwift in the same way. Zwift will say to the bike: "Produce the appropriate resistance to simulate a 70 kg rider going up a 5% incline on an asphalt road surface" where 70 kg is the rider weight set in Zwift, and incline and road conditions are determined by Zwift according to the riding conditions i...

Are my Power Meters Accurate? One of the most common complaints on cycling social media is: "My power meters are inaccurate." Reasons include: 1. Riders perform better in different environments. Whether it's outdoor or indoor, many cyclists see higher power in specific scenarios. 2. You’ve done a dual meter comparison using something like ZwiftPower ( Comparing Power Meters with ZwiftPower ). 3. The power meters are actually bad ( opinions vary so please keep reading )   Here's the problem:   Comparisons can be misleading. Indoor and outdoor riding environments differ significantly . The resistance and acceleration vary greatly, causing many power meters to struggle with accuracy in one environment versus the other. Riding style is also a factor; smooth riders often see different average power measurements compared to those who vary their cadence and acceleration. With dual power meter comparisons  it is impossible to know which power meter is correct when only two a...

SB20 owners occasionally report that their bike is producing resistance  that is too high or low. Here's how to verify that your bike's resistance is correct. What is resistance and what causes it to change? Resistance is the pedal tension that you push against to generate power. The faster you pedal against a given amount of resistance, the more power you produce.  Note:  Erg mode  behaviour is different. Here's a description if you are interested:  What is Erg Mode?    This discussion focuses on  free ride/race/sim mode  resistance. What about Power Meters? Power meters  measure  how hard you are pushing against the bike's resistance. Pedalling faster against this resistance, increases power (watts).  Pedalling slower, decreases power. Power meters do NOT affect resistance. They only reflect increased resistance if you choose to pedal harder against it 💪. Example: Zwift Resistance Here's how resistance is set in a ...

The Stages Cycling app is normally used to set the Stages SB20 crank length .  It is a quirky process. Many people complain: The crank length changes after they set it.  They aren't necessarily seeing things... Here's how to set crank length correctly every time Start by opening the Stages Cycling app and going to the  Stages Bike > Devices > Power Meter  tab. 1. Before attempting any crank configuration, make sure the cranks are awake . Things get messy when they go to sleep or get disconnected . 2. Take Note: The Stages Cycling app sends the last setup configuration changes made in the app to the SB20 bike each time you restart the app . Examples are: gear settings ( Custom or Dream Drive ) and shifter button layout ( Campagnolo, Shimano or Custom ).  Summary: The Stages Cycling app saves bike configuration settings and updates the SB20 bike each time you start the app. If you have more than one copy of the app on different devices, the SB20 bike ...

When your Stages SB20 smart bike is working normally, the built-in power meter cranks provide power and cadence data to apps like Zwift . Behind the scenes, they also provide the data that lets the SB20 regulate resistance when running in Erg mode. Some riders also add 3rd party power meter pedals .  They can work very well.   It surprises many people that Erg mode requires the built-in Stages power meters even when 3rd party power meters are in use.   For more information on SB20 erg mode , see: Erg Mode with a Stages SB20 Smart Bike . Question of the Day 📣 Question:  If my Stages crank power meters fail a nd I have another set of 3rd party power meter pedals , can I still use my SB20 bike?  The Short Answer: You can still do free rides and races in Zwift and other apps. You will not be able to use Erg mode.  ------------------- Urban legend: Erg mode still works with 3rd Party Cranks   Some people report that Erg mode still works when they use ...

Free Riding is Easy Let's start with the relationship between resistance , cadence and power (watts) when doing an indoor free ride (sometimes called sim mode ). Free riding follows a simple formula:  Power in watts  =   How hard you push   ⨉   How fast you pedal   Your indoor bike offers constant resistance when you stay in the same physical or virtual gear. Pedal at a constant RPM and you get a consistent number of watts. If you then pedal 10% faster, you produce 10% more watts.  Pedal 10% slower, you produce 10% fewer watts. 📣 Free Riding Summary: When simulated riding conditions stay the same, pedalling faster produces more watts. Pedalling slower produces fewer watts. And don't forget: There is one way to go faster in Zwift.  Produce more watts 💪.    If only indoor riding was always this simple... Erg Mode When doing structured workouts, Erg mode is popular. It allows you to produce a desired number of watts whether y...