These bikes have become very popular in the home cycling community. Compared to the Keiser M3/M3+/M3i that retail for $1800-2000, or the Peloton bikes which retail for $1800-2500, the IC4/IC8/C6 retails for $900. The IC4/IC8/C6 (all the same bike, incidentally, sold under different names) has magnetic resistance and a screen which displays resistance and cadence, putting it a step above the sub-$500 options, and making it a great solution for people looking for a Peloton mimic with a lower price tag.

The problem

The challenge with these bikes is that there is a wide range of calibrations that the manufacturer considers correct. This means that if you line up five correctly calibrated bikes, they may not all produce the same wattage at the same resistance level.

The Original Conversion

The conversion numbers used in our original IC4/IC8/C6 conversion plate came from an IC4 owner who used power pedals. Power pedals are the most accurate way to get the real-time wattage output of the bike, because they contain very accurate power meters.

Calibration Matters

The IC4 owner who gave us these numbers has since ridden a number of other correctly calibrated bikes and noted that some seemed to be much harder than the bike from which the original numbers were obtained.

Other IC4 and C6 owners have recalibrated their bikes multiple times and noted that while their bike may pass the Schwinn calibration tests, indicating correct calibration, the difficulty level of the bike can change significantly (and somewhat unpredictably) with re-calibration.

New Solutions

So, if your bike may not be calibrated exactly like another bike, but will still be considered “correct” by the manufacturer, what’s a cyclist to do? The most common solution has been to use the Kinetic app (on the app store here). Although the IC4/IC8/C6 do NOT show wattage on the screen, they DO transmit this information via Bluetooth. The Kinetic app can be paired with the bike, and will then display output in watts in real time during your ride. You can use this to develop your own custom conversion chart.

To do this, you ride at a constant 80 rpm. Start at the lowest resistance level that your bike allows. Then slowly increase the resistance and note what your bike’s resistance is set to when your wattage output hits the following benchmarks:

46-52 watts

58-62 watts

83-85 watts

111-115 watts

143-146 watts

186-190 watts

The first number will be your bike’s equivalent to a resistance of 25 on the Peloton, the second will be equivalent to 30, the third will be 35, and so on, up to 50.

What’s the catch?

Well, the catch is that the data the bike sends to Kinetic may not be entirely accurate. The general consensus seems to be that the outputs sent to kinetic run a little high. This means that if you get your numbers from Kinetic, you may end up with a conversion chart that is ultimately too easy, cheating yourself of the challenging workout you may want as you improve your fitness level.

It’s easy starting out to assume your conversion is “too hard,” but the fact is that indoor cycling is hard work! Remember that not too long ago, people were ending up in the hospital because they were working out so hard in spin classes. Depending on your starting fitness level and the kind of exercise you have been doing, it can take months to reach a fitness level that allows you to complete the classes as cued by the instructor.

This doesn’t mean your conversion chart is wrong (believe me, I triple-checked mine!), it just means that these are intense workouts and it’s normal to have to work up to them. So don’t be frustrated if, even with a conversion chart, your workouts seem really hard.

Why does the chart only go up to 50?

The chart only goes up to 50 because resistances above 50 are usually a heavy climb, and how far above 50 you go is really up to you and your fitness level. It’s a lot more important to match the lower resistance levels (rest vs active recovery vs gentle climb) than for your all-out tough climb to be the same as the instructor’s all-out tough climb.

That being said, the plate has room for six pairs of numbers of your choice. So if you want your plate to start higher and end higher (30-55, for example, instead of 25-50), or if you want to go higher but in increments of 10 instead of 5 (20, 30, 40, 50, 60, 70), just send us the numbers that you want.

Why use a 3D printed plate?

We made the first 3D printed plates after getting tired of papers blowing away in the breeze from the fan or getting spoiled by drips of sweat and splashes of water. Since Ian already owned a 3D printing business, Megan asked him to 3D print a waterproof version of her conversion chart. The main advantage to the plate is durability — the plates are sweatproof, waterproof, and can easily be wiped down with whatever cleaner you use to clean your bike.

So how do I get a plate for my bike?

To get a custom plate for your bike, go to the item in the store (here) and enter the numbers that you want on your plate.