The Keiser M3i vs Bowflex’s C6 Bike – A Head To Head Comparison

Keiser’s M3i is one of the most popular and positively reviewed indoor cycles out there. This world renowned cycle is thought by many to be the pinnacle of what home exercise bikes can be.

Bowflex’s C6, on the other hand, is a little more down to earth; a little more blue collar if you will.

Comparing these bikes to David and Goliath might be a bit of an exaggeration, because let’s be real- it’s hard to consider Bowflex as an underdog in any situation.

But in this case, it’s probably as close as they’ll ever be.

What happens when we compare these 2 bikes head-to-head?

Well, keep reading and find out.

In this article, I’ll compare the specs and features these 2 elite home cycles have to offer.

After reading, you’ll know which bike is the better choice for your home.

Let’s get rollin’.

Keiser M3iBowflex C6
Resistance8 lb flywheel
24 levels of magnetic resistance
40 lb flywheel
100 levels of magnetic resistance
Frame92 lb assembled weight
350 lb weight limit
112 lb assembled weight
330 lb weight capacity
Warranty10 year frame
3 year parts
90 day wearable items
10 year frame
3 year parts/electronics
1 year labor
FeaturesSmall LCD console
Measures watt output
Heart rate monitor compatible
Bluetooth compatible
Fully adjustable seat
Fully adjustable handlebars
Dual-sided pedals
Small LCD console
Bluetooth heart rate monitor included
Fully adjustable seat
Fully adjustable handlebars
Dual-sided pedals
Pair of 3 lb dumbbells included
1 year of JRNY membership included

The Keiser M3i vs The Bowflex C6

  bowflex c6

Above image courtesy of Bowflex

Bowflex is one of the most famous home fitness brands in the world, so I don’t feel like they need much of an introduction here.

On the other hand, you might not be as familiar with Keiser.

If you made your way here, I have to assume you’re at least familiar with their M3i Indoor Cycle. This makes sense because this is their most famous product.

But Keiser’s been around for decades.

Their strength training and cardio machines can be found in elite gyms around the world, as well as in many professional athletic teams’ training rooms.

In other words, these guys are legit.

Keiser’s all about using science and engineering to design better fitness equipment and it seems to be working just fine for ’em.

The M3i and C6 are in 2 different price ranges (we’ll talk numbers later), so it may seem unfair to judge them on the same grounds…but I’m going to do it anyway.

In order to make this comparison as objective as possible, I’ll be comparing these 2 bikes on the key performance specs and features each has to offer.

Let’s start with their resistance systems, which just happens to be an area where they differ greatly.


If you’ve been researching indoor cycles for any time, you’re probably aware of the argument that heavier flywheels are better than lighter flywheels.

I myself make this argument on a regular basis on this website.

The idea being that heavier flywheels provide smoother operation because of the extra momentum they build and whatnot.

And to be fair, this school of thought is usually right.

I say “usually” because if we’re comparing 2 bikes that are designed to benefit from a heavier flywheel, it makes sense that the heavier the flywheel is the better.

But what if there was a bike designed to operate efficiently with a lighter flywheel on purpose?

Enter the Keiser M3i.

The M3i comes with an 8 lb flywheel – yeah I know, that’s tiny compared to the 40 – 50 lb wheels found on many spin bikes these days.

However, unlike 98% of the other spin bikes out there, the M3i is designed to get that light flywheel spinning really fast during your workouts.

The physics behind all of this is a bit outside the scope of this article, but basically you can create more momentum by spinning the flywheel faster than by simply increasing the weight of the flywheel (Groom & Style does a great job explaining it here).

To be more exact, the flywheel on the M3i rotates 11x for every time time you rotate the pedals.

This crazy speed of the flywheel allows it to provide a silky smooth feel even though it’s using such a light flywheel- the secret sauce is in the genius design that gets that flywheel spinning so rapidly.

The C6, on the other hand, is designed to take advantage of a heavy flywheel.

To be more specific, the C6 is packing a 40 lb flywheel, which is more on par with what we normally expect from home spin bikes.

Users agree both cycles provide very smooth pedaling motions.

When it comes to resistance, the M3i comes with 24 levels of magnetic resistance that are adjusted with the resistance lever near the handlebars.

The C6 comes with 100 levels of magnetic resistance that are adjusted by turning the resistance dial.

Flywheels aside, I like the idea of having 100 levels better than having 24 because it gives you more control by allowing you to fine tune the intensity you’re pedaling against.

Having 100 levels is also very convenient if you plan on using Peloton’s streaming app because that’s the same resistance scale they use.

Overall, the M3i and C6 both score highly in this department, but they do so from completely different schools of thought.

The M3i creates a smooth feel through the use of expert design and a really light flywheel, while the C6 uses the simpler method of utilizing a very heavy flywheel.

Oh, you’ll also notice that the M3i has the flywheel in the rear while the C6 has it located in the front.

In terms of performance, flywheel position makes no difference.

Having the flywheel in the rear does help keep it clear from sweat though (it also looks really elegant too).


Heavy vs light flywheels is a big one, but there’s more to look at with these 2 bikes- like the structural soundness of their frames.

It can be hard to tell how stable or “heavy-duty” a bike will feel without getting to ride it before purchasing, which, unfortunately isn’t always an option these days.

The next best thing is to look at the assembled weight and weight capacity.

Seeing higher numbers in both specs is a good indicator that the bike will feel secure during workouts.

The M3i comes with an assembled weight of 92 lb, which is pretty light for a bike in this price range, but keep in mind it doesn’t have all that extra flywheel weight.

By comparison, the C6 is heavy, with an assembled weight of 112 lb, but keep in mind 30 of those pounds are coming directly from the difference in flywheel weight.

When we look at the weight limits, we see that the M3i scores very highly with a limit of 350 lb.

The C6 also scores highly with a weight limit of 330 lb.

Something else worth noting is that the M3i’s unique V-shaped frame allows it to comfortably fit folks who are between 4’10” and 7′ tall.

This makes the M3i a great choice for the bigger and taller crowd.

Overall, both bikes score highly when it comes to the frame, but the M3i’s easily wins this category with its high weight capacity and ability to fit folks all the way up to 7′ tall.


Let’s see how each bike stacks up when it comes to the residential warranties.

Keiser backs their M3i with the following warranty:

  • 10 year frame
  • 3 year parts
  • 90 day wearable parts

And Bowflex backs their C6 with the following guarantee:

  • 10 year frame
  • 3 year parts
  • 1 year labor

Ok, so, very similar warranties here.

Both offer 10 years on the frame and 3 years on parts. Bowflex also offers a year for labor, while Keiser does not.

Overall, I would say both warranties are good, although when you consider the price difference, it makes Bowflex’s warranty even better.


Time to compare the different features these bikes have to offer.

Keiser’s M3i comes with a pretty simple looking LCD console that displays your cadence, time, distance, and resistance (gear). Unlike many though, it also measures your power output, or watts.

Keiser has even had their consoles certified for their accuracy in measuring power output- something that sounds impressive, but for most casual riders won’t make that much of a difference.

The console is also compatible with wireless heart rate monitors and can display your heart rate during workouts.

It’s also bluetooth compatible with several fitness apps, including all of Keiser’s free apps.

Otherwise, the M3i comes with a fully adjustable seat, fully adjustable handlebars, and dual-compatible pedals (toe cage and SPD).

Oh, it also comes with a tablet/media holder, but that’s it.

The C6 also comes with a pretty simple LCD console, but it tells you everything you need to know during workouts: cadence, speed, distance, time, calories, etc.

Unlike the M3i, it doesn’t calculate watt output though.

But it is compatible with bluetooth heart rate monitors and Bowflex even includes an armband with purchase.

The C6 also comes with a fully adjustable seat, fully adjustable handlebars, dual-sided pedals (toe cage and SPD), and a tablet holder.

Unlike the M3i, the C6 also comes with a pair of 3 lb dumbbells and a water bottle holder.

And since the C6 is designed to pair with fitness apps (I’m not sure if I mentioned that yet), Bowflex also includes a free year of their JRNY membership.

Overall, I would say the C6 definitely comes with more included features.


Alright, time to talk about one of the most important considerations- cost.

Numbers can change with time and deals and whatnot, but at the time of writing this, these bikes costed the following:

Keiser M3i: $2095

Bowflex C6: $999

So yea, the M3i is 2x the price of the C6.

At $2000, the M3i is a luxury cycle and the C6, at half that, is a more moderately priced option.

The question is, is the M3i really worth that much?

Keep reading.

Final Thoughts

This is a hard comparison to write because these bikes are so very different in almost every way.

The luxury M3i utilizes a light flywheel with really high flywheel speeds to provide a smooth workout, while the more budget friendly C6 uses a heavy flywheel to do the same.

Both bikes come with sturdy frames and great weight capacities and the warranties on these bikes are almost identical.

The C6 wins in terms of included features, but the M3i can measure power output, something not many consoles offer (and something elite cyclists will likely appreciate).

Overall, I can’t with good conscious conclude that the C6 is a nicer bike than the M3i because that’s kinda ludicrous- the design and engineering that goes into this bike demands respect.

Not to mention just the sleek, elegant look of this thing.

So yes, I would say that the M3i is a better bike than the C6.

I would also say that the M3i is fairly priced at around $2k, again, considering the sophistication it brings with it.

That said…

I think most home users will do better with the C6, especially those who like the idea of following streaming apps for workouts.

With its 100 resistance levels, included features, and affordable price, I actually think Bowflex’s C6 is one of the best deals in indoor cycles right now.

In the end, this was a tough comparison for me to do and you really can’t go wrong with either bike.

Elite cyclists or folks simply looking for the best should definitely consider the M3i because it really doesn’t get any better.

But if you’re simply looking for a great indoor cycle that won’t destroy your budget, the C6 is a great option.



Leave a Comment