Planning a group ride.... in the same room!

Can anyone shed a little light on the following situation:

We are planning a 100-miles group ride with 10-20 Zwifters for charity. We will all be in the same room, but more importantly on the same internet connection! To distribute the load we will a least use 2 accesspoints, but my concern is mostly with the connection to the outside world. Zwift recommends a 3 Mbit connection and a ping under 50ms to work correctly, which of course is meant for 1 rider.
I think the bandwidth will increase if we show other riders in our group ride, so we will probably only show our own. Also all riders will show up with an up-to-date system, so last minute updates won’t be an issue.

Which leaves me with the following questions:

  1. Does anyone know if the math is simple as 10 players x 3 Mbit = 30 Mbit?
  2. Is this speed needed for both up- and download speeds?
  3. Are the recommendations accurate or will less (f.e. 2 Mbit) also work just fine?
  4. Will multiple users on the same connection have a negative effect on the ping?

Ramon

I cannot answer your concerns about the internet connection. But how close will your setups be? Because I know of others, who have done something similar and failed spectacularly, because of the amount of Bluetooth and Ant-connections in very close proximity. Nobody could get a stable connection (if any at all) between their equipment and their PC/Device.

Just a heads up, that you might need to consider that as well!

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Zwift can pull it off at their events, but only looks like 4 kickr bikes lined up next to each other, not 10 or more:

@shooj are you able to hook @RamonM77 with your events team in order to provide some advice?

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Agreed - my husband and I Zwift in the same room, and with even just two setups we’ve had connectivity frustrations! We’ve gotten to the point that if we’re not both riding at the same time, we make sure that the other person’s hardware is unplugged.

Definitely recommend OP and friends do at least one test ride using their planned setup for the big event, ahead of time.

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Hi @Ralph_Minkus welcome to Zwift forums.

Yours is a special-use case, and one that the Customer Support team doesn’t encounter very much.

I’ve forwarded your question internally, with the hope that someone may have some experienced advice.

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Well, Zwift can learn from the rowing community here. Mass events are no problem:

games_marathon

Big advantage of the rowing machines: They are connected via lan or USB which works rock solid. It´s a pity that smart trainers usually only broadcast wireless. If Zwift is planning to develop their own hardware they should consider something like this.

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I hadn’t thought of the BT and ANT-broadcasting yet, good thing you mentioned it! This could indeed mess the entire idea up :roll_eyes:

I can see the aluminium foil screens and Faraday cages emerge…

Thanks for this in advance. Hope to get some good advice

A couple of the staff that go to events around the world like the Super League Arena Games responded.

There are several areas of concern, as you’re aware. The major concern is to reduce radio frequency (RF) interference, to the degree that some things are out of your control.

Wireless link between trainer <> computer running Zwift
If the computers have a USB-A port, it’s strongly recommended you use ANT+ dongle on a USB extension cable. Place that dongle as close as possible to the trainer’s antenna.

Wireless link between computers <> WiFi access point
Will you have control over the WiFi router in that space? As in - will you be able to specify what channels the 2.4Ghz and 5 Ghz signals will broadcast over? Will your players have exclusive use of that WiFi access point, or is it publicly shared?

If you have control over what channel the router broadcasts on - you can optimize the router to reduce RF interference in that space. I use an app called WiFi Analyzer to choose the best channel to use at home. It would be important to use the analyzer after all the trainers and computer in the room are powered on and creating RF noise of their own.

If you are able to specify the computer / tablet’s WiFi connection to use only the 5Ghz band - it would keep the WiFi connection from being stepped on by all the 2.4Ghz noise in the room (Bluetooth and ANT+ operate in the 2.4Ghz spectrum).

On the router end of the WiFi connection: IF all the computers running the Zwift app have WiFi connections that you can manually set to transmit in the 5Ghz space only - make the WiFi router operate only in 5Ghz (i.e disable the router’s 2.4Ghz radio). This way, the router isn’t putting out
unused 2.4Ghz noise that interferes with the Bluetooth and ANT+ connections. Make sense?

This is an article from Teradek, a company that makes wireless transmission devices for the broadcast TV industry, and some of it is relevant to your situation.

If you have control of the router - you might consider hard wiring as many of the computers as possible using Ethernet cable and a series of switches spread around the room.

Broadband connection between WiFi router <> ISP
If the router is public and you share the broadband pipe, such as you’re in a hotel conference room - you might talk to the facility’s IT admins in advance and ask if you might be assigned a private subnet and have raised QoS on that subnet for the duration of your event. It’s a big ask, but you never know.

Alternately, you might consider bringing one or more of your own WiFi hotspots, and assign several players’ computers to each one. This approach is at the mercy of the quality of the 4G data signal in that room.

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Oooohhh I like this tip!

Please send my regards to the staff!

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As for the original question, the bandwidth used by Zwift while riding is nowhere near 3 Mbit/s. My recollection is that the data usage of a hour-long Zwift session is somewhere in the 10 MB range (of course varying depending on all kinds of things), meaning well under 10 kbit/s for a single client. I presume there is something of a peak when the game is started and a new world is loaded, so you would probably want to avoid everybody doing those at the same time.

Bandwidth will probably not be much of an issue per se, but rather how well your LAN handles a large number of simultaneous devices receiving and transmitting constantly. Use wired connections as much as possible, and if you have to use WLAN, use multiple channels and indeed avoid those conflicting with ANT+/BLE frequencies.

For a quick test, I guess you could try to see if you can get something like Youtube to play (at any resolution) simultaneously on the same number of devices on the same network setup without any hiccups. If that works okay, I think you should be fine with Zwift as well.

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@RamonM77
Received additional information that may serve you well.

The actual Zwift data usage is pretty low. Even when the server is loaded I don’t see the median data usage going much beyond 0.4 Mbps for download and 5x less than this for upload. There may be some temporary spike usages (like a big event start), but a constant 0.5 Mbps per user is a pretty solid expected value.

On your original questions:
(1+3): it does scale linearly (3 users require 3x more bandwidth), but the actual requirement is much less than 3 Mbps/user. Let’s say 1 Mbps/user to be conservative.

(2): the upstream requirement is 5-10x less than the downstream, which is how most ISP work, so upstream should be no problem if the downstream is ok.

(4): we don’t expect to see ping going up for multiple users in the same connection if they have enough bandwidth. Most users can play Zwift just fine with a 150ms latency. I’d say it’s lower quality starting from 500ms.

Will you be livestreaming this event? Livestreaming also adds to your bandwidth needs, so if possible - it’s best to put the stream on its own access point (or better yet, load-balanced across redundant access points)

Thanks for these insights!

We’re having a tryout with 5 riders tonight.

  • I’m using a dedicated accesspoint which is being monitored by LibreNMS to show the stats and/or hick-ups.
  • We’ll start out with everything in “full screaming mode”, so no limitations. Our AP will be broadcasting 4 SSIDs at both 2,4 and 5Ghz and 100% power. Wi-fi onsite is an unknown factor at this time, but I expect this will also broadcast at 2,4 and 5Ghz.
  • The riders will be using as much BT and ANT+ devices as possible, trainer, sensors, computer and a phone with the companion app active.
  • I’ll monitor the wi-fi activities with Netspot to see if any channels are interfering with each other.
  • The internet connection is a fiber connection, bandwidth is unknown at this point.

After a short ride I’ll switch off 2,4Ghz wi-fi and ride again, just to see the difference between both scenarios. Is anyone experiencing difficulties, we’ll analyse his connections and search for the best practice. I also want to see the difference between riders being very close to each other and spreading them further in the room. Let’s hope little troubleshooting is needed.

During the event (dec 19th) we’re planning on livestreaming it, depending on the available bandwidth. I don’t know which devices will be available, but I’d like them to have cables attached as much as possible :wink:

I’ll write up a little report after our test.

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