Wireless is Good - and Complicated

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 My Smart Bike is Wireless!

Wireless connectivity is ubiquitous. Most of the time we can take it for granted. That changes when we see dropped connections and spotty Zwift performance.

If you are having wireless issues, it's good to ask: Is something causing interference? When looking my SB20 smart bike setup, I realized that a typical riding session is fairly intense in terms of wireless protocols, bandwidth and data transfer rates. Interference from just my devices is a possibility.

16 Wireless Connections and Counting

Here's the view from my smart bike saddle: two iPads, iPhone, Garmin bike computer, two Zwift play controllers, Heart Rate Monitor (HRM), power meter cranks plus wireless earbuds for an occasional Discord session. Collectively, these devices use 3 different protocol families: WiFi, Bluetooth and Ant+. Most share the same 2.4 GHz frequency spectrum. At last count: One indoor ride uses up to 16 wireless connections.  Add to that, family members in my house use WiFi on their cellphones, while accessing the Internet and streaming media. 

Zwift

Here's what my Zwift riding session looks like. 


Here's a summary of each wireless connection.

Connection

Type

Includes Data for

Direction

Description

Data Volume

5 GHz Capable

Usage / Update

Results

1

ANT+ 

Power

Right crank to left crank

Power and cadence data for the right crank

Low


Once a second.


2

ANT+ 

Power

Left crank to smart bike

Consolidated power and cadence data for both cranks

Low


3

ANT+ 

Power

Left crank to bike computer

Consolidated power and cadence data for both cranks

Low


4

ANT+ 

Bike Simulation

Smart bike to bike computer

Comprehensive data packet providing power, cadence, speed and distance data.

Low


5

ANT+ 

Heart Rate

HRM to bike computer

Heart rate

Low


6

Bluetooth

Bike Control

Zwift app to smart bike 

Set bike parameters for rolling resistance, slope (inclination), wind and surface type so the bike can set its internally calculated resistance. Can also set Erg mode for a given power target. 

Medium

⭐️


Sent by Zwift as needed.

Bike resistance changes.

Bike Simulation

Smart bike to Zwift app

Comprehensive data packet providing power, cadence, speed and distance data.

Medium

⭐️


Once a second.


7

Bluetooth

Bike Control

Smart bike app to smart bike

Set bike parameters for app simulations and erg workouts. Do crank calibration (zero reset). Enter listen only (external) mode where this app only receives data and another app, like Zwift, controls the smart bike.

Low


Sent by Zwift as needed.

Bike mode or resistance changes; Cranks are calibrated.

Bike Simulation

Smart bike to smart bike app

Comprehensive data packet providing power, cadence, speed and distance data. Can also include proprietary data like current virtual gear.

Medium


Once a second.


8

Bluetooth

Power

Left crank to Zwift app

Consolidated power and cadence data for both cranks

Low


Once a second.

9

Bluetooth

Zwift Play Control

Left control to Zwift app

Proprietary data for Zwift Play Controller button presses.

Very low


Controller button pressed.

Zwift app executes  action

10

Bluetooth

Right Control to Zwift app

11

Bluetooth

Heart Rate

HRM to Zwift app

Heart rate

Low


Once a second.


12

Bluetooth

Audio

Bi-directional link between Discord app and wireless ear bud/headphones

Audio data: talk and listen

High


Continuous 

13

WiFi

Zwift Data

Bi-directional link between Zwift app and Zwift web services

Zwift Avatar / simulation rendering, button press processing, bike data relay and everything else needed by Zwift to display app content is transferred over this WiFi connection to and from Zwift web services.

High

⭐️

Yes

Continuous 

Zwift app updates; bike is controlled as needed.

14

WiFi

Zwift Data

Bi-directional Zwift Companion app data and control

Synchronizes the companion and main app with Zwift web services. Handles button presses and other features implemented in the companion app.

Medium

Yes

Continuous 

15

WiFi

Bike Computer Data

Bi-directional link between bike computer and its web services (like Garmin connect)

Synchronizes the bike computer with its web services. Handles workout uploads and configuration changes.

Low to Medium


Continuous 

Bike computer and related services updated as needed.

16

WiFi

Discord Data

Bi-directional Audio link

Audio chat app: talk and listen

High

Yes

Continuous 



         Other Devices to Watch for


WiFi 🔌 

Apple TV

(can replace iPad)

Web connection

Content display and streaming

High

⭐️

Yes

Continuous 

Can replace #13 above

WiFi 🔌 

TV 

Web connection

Content display and streaming

Very High

Yes

Continuous 


WiFi 🔌 

PC/Mac Computer (instead of iPad)

Zwift Data

Zwift Avatar / simulation rendering

Same as #13 above

High

⭐️

Yes

Continuous 

Replaces #13 above

                                                                       🔌 = Supports wired Ethernet connection       ⭐️ = Critical data connection   



I have to admit, there are more wireless connections than I expected. Indoor riding is not as simple as the brochure says 🤣. 

Tips for Improving your Indoor Rides

  • Get a 5GHz router: Using the 5 GHz WiFi band, for devices that support it, will help alleviate congestion in the more common 2.4 GHz frequency band. Optimal placement: 5 GHz access points generally need line-of-sight positioning for best performance. 
  • Don't worry about ANT+ connections.  As the table shows, they are low band-width. ANT + usage of the 2.4 GHz band is on par with Bluetooth. Ant+ and Bluetooth usually suffer when then are too many high bandwidth WiFi devices nearby.    
  • Turn off unused devices. This includes set-top boxes, cellphones, cordless phones, microwave ovens, baby monitors, smart watches and wireless speakers.
  • Use 🔌 direct-wired Ethernet for devices where possible - especially for connections shown in the table above as High Data Volume and ⭐️ critical. Also look for nearby Smart TVs and streaming boxes.  Direct connections for these devices will make a difference.


Want to learn more?  See my post on Indoor Riding - ANT+ and Bluetooth. 

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