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Zwift is the most popular virtual cycling app. Keiser produces the smoothest, most-durable spin bikes on the market. With spinning exploding in popularity and the trend of people ditching delayed Peloton orders in favor of the Keiser M3 and Keiser M3i, it’s not a surprise that folks are starting to gravitate toward immersive apps like Zwift. Setting things up can introduce a lot of complexity, so I’ve started to put together a series of guides on how to KeiZwift.

Gear Check

Here’s my gear setup. If you’re just trying to make sense of this for the first time, here’s everything that I KeiZwift with. Yes, I will take credit for coining that term.

Keiser M3: I purchased the “original” Keiser bike used at a deep discount. Notably, this bike does not transmit watts or RPM via Bluetooth, so I had to buy power pedals. In many cases, buying an old M3 and power pedals will be cheaper than buying an M3i.

FAVERO Assioma Duo Pedal-Based Power Meter: No matter what bike you have, these pedals are the best ticket to Zwift. Although the M3i can transmit wattage via Bluetooth with the converter, this is the cleanest option. By the time you’re reading this, I’ll probably have written a dedicated blog post. The less-expensive “Uno” Pedals get rave reviews as well.

2015 Macbook Pro: You need a decent computer to run the app. On the highest-quality setting, my MBP runs hot. With the Zwift process in the background, I can’t do anything else. It seems that many users prefer running on “inferior” devices while screencasting to a larger display, but the Macbook fits snugly into the M3 handlebars and I have no interest in adding more devices.

iPhone: My Bluetooth setup requires a phone running the Zwift Companion App.

Polar H10 Heart Rate Monitor: Provides a very useful metric without much hassle.

Entry-level Cycling Shoes: Not my favorite, but likely the cheapest way to clip into your Favero pedals.

Large Fan: You need a large fan. I’m not joking. This thing is a monster but it’s been going strong for three years.

Extended Introduction

Keiser bikes have been dominant on the spin scene for over a decade. Both the Keiser M3 and Keiser M3i are legendary pieces of equipment that are now overshadowed by Peloton and newer smart bikes. However, the secret that the new players in the market don’t want you to know is that the drivetrain and ride quality of Keiser bikes cannot be improved upon. They are as good as you can get, in fact, Keiser holds quite a few patents thanks to their innovation in the space.

If you already own a Keiser bike, it’s understandable that you might want to upgrade your equipment in order to use apps like Zwift. Likewise, if you’re looking to purchase your first indoor trainer, the cheapest path to get a high-quality setup is to buy a used Keiser bike and then link it up.

I’ll be covering both angles in this guide. If you’re just wondering if it’s possible with an M3i or an M3, the answer is yes, but you’ll need to buy some add-ons.

Zwift with a Keiser M3 Bike

A Keiser M3 is the older version of the M3i. The M3i has Bluetooth connectivity, which is crucial, but aside from that, the bikes are very similar.

There are still lots of Keiser M3 bikes out there because they are indestructible. They aren’t being sent to the scrap heap. The reason you don’t see even more of them changing hands is that they weigh 85 pounds and are difficult to move.  If you’re buying the bike used, it’s possible to get them for under $1000. Even less if the seller doesn’t realize how in-demand they still are.

I have a Keiser M3 bike that I use with Zwift. Unfortunately, you will need to make some upgrades in order to get KeiZwifting.

You need to be able to send your wattage via Bluetooth in order to do anything on Zwift. The Keiser M3 doesn’t transmit Bluetooth. You have a few options:

Option 1: Keiser M3 Conversion Kit

Quick take: Cheap, not applicable to most M3 models, flawed.

If you have a bike that was produced in the last batch of the Keiser M3 line, you’re in luck. There was a minor change made to the frame of the bike that allows a Bluetooth transmitter to be wedged in. If your bike qualifies (only 2015 models of the M3 do), just email Keiser, buy the conversion kit, then buy the M-series converter in order to use Zwift.

The M-series converter standardizes the Bluetooth transmission into a data type that is easily digested by popular apps.

Though this solution is fairly-reasonable in terms of price (< $300), it actually isn’t the most seamless setup with Zwift. The M-series converter ($100) gets pretty bad reviews and requires frequent battery changes. Also, the on-board computer’s wattage calculator has a flaw that can cause very annoying differences in accuracy as you get more serious about riding.

Option 2: A 3rd-party or DIY Converter

Quick take: Unsupported, at your own risk, but technically compatible with all bikes.

If you have an older-model M3 bike that isn’t eligible for the Keiser-sponsored conversion, you can still technically transmit Bluetooth through the M-series converter. You just need a circuit board that transmits the signal via Bluetooth. This is hacky and will burn up batteries, but you can do it yourself (if you have a hardware engineering background.).

There was one 3rd-party solution that is not widely available but occasionally pops up in message board discussions. This was the DPCycling Bluetooth adapter. It’s hard to find and has never been available in the United States. This is the “professional” solution to doing it yourself. Is it worth the hassle when you can buy pedal-based power meters that will be objectively superior? Not really.

Option 3: Power Meter Pedals

Quick take: The most expensive option which works flawlessly.

I purchased the Favero Duo pedals after reading the rave reviews online. They came packaged in one of the nicest boxes I’ve ever opened in my life, even putting Apple products to shame. With these pedals, I don’t need the Keiser M-series converter. I can transfer these pedals to any bike I own and then that bike can be used with Zwift.

Also, these pedals provide extremely-accurate wattage readings via several sensors in the pedal. There is a somewhat-complicated physics equation behind this and, trust me, you want Favero to provide this number, not the Keiser logic board. The pedals are chargeable and the charge lasts forever–literally weeks.

Option 4: Bolt-on Speed/Cadence Sensors

Quick take: Surprisingly cheap solution for all bikes, but the all-telling wattage calculation will be a mere estimation.

You can buy the Garmin Speed & Cadence sensor bundle. This price-point is accessible and the metrics can be useful. However, most stationary bikes, including the Keiser M3, already provide metrics like these. It feels redundant to have to add more sensors to track the same numbers. At the end of the day, speed + cadence can only provide an estimate of wattage.

On Zwift, your results will not have the “lightning bolt” icon if you do not transmit a real wattage reading. You won’t feel like a second-class citizen (most people don’t even know what the icon means), but it will cast some doubt onto the accuracy of your times and efforts. Nearly everyone I encounter on Zwift has a true power meter.

Zwift with a Keiser M3i Bike

For the newer M3i bike, Option 2 above is no longer relevant since the bike already transmits Bluetooth signal. You can follow any of the other methods to start using your bike with Zwift or Peloton. The other thing is you won’t need an M3-M3i conversion, since you’re already using an M3i. So, scratch that part from Option 1.

The sane option is to buy the M-series converter. The redundancy of bypassing the Keiser M3i computer if you buy power meter pedals or a speed sensor must be noted. However, the wattage calculation sent by the Keiser M3i has many flaws which I’ve explored in previous blog posts. I think it’s totally reasonable to buy the M-series converter and, if it works for you, keep using it! If you want significantly more accurate readings or the option to use another bike, treat yourself to the Favero pedals from Option 3.

First Time Setup

This section is intended to help first time users. Most of these steps only need to be completed once. The section below (“Putting It All Together”) contains the steps I take each time I KeiZwift. I will assume that you’re setting up the Favero pedals here.

1. Unscrew the pedals on your Keiser using a pedal wrench. Clean your grimy threads. Install the Favero pedals using the same wrench.
2. Pair and register the pedals using the Favero app (required–they provide thorough instructions).
3. Download the Zwift app on your main computer.
4. Download the Zwift Companion app on your phone.
5. Register for Zwift and create an account (credit card required). Optionally, sign up for Strava and Zwiftpower as well.
6. Install the cleats provided by Favero into your cycling shoes. You will need a hex key to tighten the screws. There is not a suitable hex key provided by Favero.
7. Start up Zwift, and, before you clip in, attempt to “wake up” the pedals by pedaling them using your hands. Once you start using clips, it’ll become more inconvenient to mount and dismount.
8. The batteries on the pedals last a long time, but ensure your bike is close enough to a spare outlet for charging. If it’s not, consider using an extension cord. You don’t want to have to remove your pedals just to charge them.

Putting It All Together

Okay, so I have the sleek pedals, the indestructible bike, a $2000 Designed-in-California blog-writing machine, and some other stuff that I haven’t even mentioned yet. How do I go from sitting on my ass to KeiZwifting?

1. I open my large window and set the thermostat to a cold temperature
2. I ensure all my gear is charged and has Bluetooth turned on
3. I pull my Keiser M3 forward and move my large fan in front of it
4. I open Zwift on my MBP and place the laptop on the Keiser handlebars
5. I remove my shirt (optional) and buckle up my heart rate monitor
6. I open the PolarBeat app on my phone to transmit my heart rate via Bluetooth
7. Using my hands, I spin the Favero pedals on my Keiser until they wake up. Note: I leave my cycling shoes clipped in at all times.
8. With the Zwift app loaded on my MBP, I pull up the Zwift Companion App on my phone. The Favero pedals and Polar heart rate signals are proxied through my phone. After 15 – 60 seconds, these devices will appear on the screen of my Macbook pro. Sometimes, they don’t, and I’ll restart the app on my phone.
9. I’m still not quite ready to mount my bike. On the closest piece of furniture, I’ll place my phone, two Airpods cases, and extra socks. I’ll place my bottle of water in the Keiser’s water bottle holder.
10. I mount the bike. I have very narrow feet, so I will often use extra socks to wrap around the boniest parts of my feet to provide some padding. Otherwise, the tightness of the cheap shoes will cause a lot of friction and pressure points. With the wraps in place, I lock my feet in place.
11. I set up the Zwift ride, which usually involves me picking my phone back up to check 1. What rides I haven’t completed yet (via pictures I have taken) and 2. Exactly how long these bike routes are (Zwift doesn’t provide lead-in distance)
12. At this point, I’m ready to Zwift. Usually, I’ll play music on my phone, so I’ll grab my Airpods and open Spotify as well.
13. I start Zwifting
14. After 2km, I’ll turn the fan on. If I turn it on any earlier, I’ll blast myself with cold air while I’m mostly inactive.
15. Hopefully, I complete my Zwift ride without any issues.

Conclusion

As you can see above, KeiZwifting requires more than just sitting on the bike and starting to pedal. Technology has come a long way, it’s opened up a lot of exciting possibilities in the exercise space. Zwift is a rewarding app and a fun experience, but to use it effectively you need to thoughtfully design a setup that works with your budget, available space, and even your schedule.

Let me know if you have any questions or would like to share more about your setup!

How to Use Zwift with a Keiser M3/M3i Bike (KeiZwift)