Wednesday, 24 July 2024

Exercise Bikes

Sunny SF-B901 Pro Indoor Cycling Bike Review

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Priced towards the middle of the range in terms of spinning bikes, the Sunny SF-B901 Pro Indoor Cycling Bike has hundreds of 5 star reviews and an impressive number of high-end design features.

This review takes a look at the bike’s design in more detail, as well as the workout options, ease of assembly, customer reviews, and the ‘Q Factor’.

Bestselling design

The solid steel frame and 40 lb flywheel improve stability and reduce any unwanted movement

If you’ve just started doing some research into studio style exercise bikes, a name that you’ll probably already be familiar with is Sunny Health and Fitness.

Over the past few years, Sunny have become the leading manufacturer of studio style spin bikes for use in home gyms, with the majority of their designs now ranked amongst the most popular in the world.

Without a doubt, one of the most attractive features is the price (most bikes in the range are available for less than $300).

But a low price doesn’t guarantee high review ratings from over 700 customer reviews.

With one of the highest average ratings of any exercise bike on Amazon, the Sunny SF-B901 has proven to be even more popular than their lower priced SF-B1001 model.

So what’s the difference between the two bikes?

Firstly, the SF-B901 has a much larger flywheel. Weighing in at 40 lbs, this represents a 30%+ increase in size over their earlier SF-B1001 bike, where the flywheel weighs just 30 lbs.

Having this extra 10lb of weight creates a much smoother cycling motion, and feels much more like riding on your outdoor road bike.

There’s also a difference in weight limit between the two models, with the SF-B901 supporting up to 275 lb of user weight, while the SF-B1001 supports just 220 lbs.

The extra 55 lb added to the weight capacity is due to subtle differences in the frame design, and makes the SF-B901 the strongest in Sunny’s range of spinning bikes.

Sunny SF-B901 Pro Indoor Cycling Bike

Sunny SF-B901 – Features Summary

  • Indoor cycling bike with 40-pound flywheel
  • Heavy-duty crank and smooth chain drive mechanism
  • Fully adjustable seat and handlebars for comfort
  • Adjustable resistance systems
  • Transport wheels

Adjustment options and resistance system

The resistance is applied via two friction pads rubbing against the flywheel. Replacements are available.

In terms of the adjustment options, the bikes in our comparison are almost exactly the same.

Each bike allows you to adjust the height of the seat and handlebars, as well as the distance between the two. This is thanks to the horizontal adjustment settings on the underside of the seat.

Having such a variety of height and distance settings is incredibly important, as it allows you to find a position that best suits your height and preferred cycling style. This is crucial for making sure your workouts are enjoyable and effective.

Moving onto the resistance system, this is another area where there’s a slight difference between the Sunny SF-B901 and B1001 bikes.

On the B1001 you have a single friction pad, which applies different amounts of pressure to the movement of the flywheel, controlled by the rotation of the resistance knob in front of you.

In contrast, the SF-B901 uses a dual friction pad system, with a pad on either side of the flywheel.

Essentially the resistance is controlled in the same way, but with the SF-B901 you also have the added feature of an emergency brake lever (similar to that found on some of the Keiser studio bikes). This has the effect of stopping the flywheel movement much more quickly, and helps reduce the risk of injury.

Workout options

Tabata Protocol, HIIT, and high resistance spinning are all effective workout options

If you’ve heard about the benefits that spinning can bring to your workouts, you might be wondering what the best studio style workout program is.

This is especially important with this particular bike, as the Sunny SF-B901 doesn’t offer any form of workout statistics tracking, or preset workout programs.

If you want to be able to track your improvements, you’ll need to keep track of the duration, distance, and changes in resistance / heart rate level after every workout.

This is made a lot easier if you want to plan your workout in advance.

But that doesn’t mean to say you have to be create it weeks or even days in advance. You just have to write down the time you’ll spend cycling at the different resistance levels, and perhaps include your target heart rate.

Having this as a guide makes it much easier to stick to a fitness plan, compared to simply stepping on the bike and starting to cycle.

In fact, if you haven’t tried HIIT training already, the Sunny SF-B901 is actually one of the best indoor exercise bikes that can be used for this advanced style of training.

Studio style bikes tend to be most effective due to the fact that you don’t have to wait for your bike to adjust to different speeds. This additional waiting time is exactly what you don’t want when interval training, which requires strict timing of varying intensity levels.

With a simple change of hand position and increase in resistance, you can quickly switch from lower intensity cycling to a much more challenging level. With HIIT workouts, this then carries on until you are ready to switch back to lower intensity again.

The wide range of resistance levels is another big benefit, making the SF-B901 the bike of choice for a variety of personal fitness levels.

Ease of assembly

The flywheel and frame arrive already pre-assembled, reducing the amount of instructions you need to follow

Something that often gets factored into the reviews left on ecommerce stores is how easy the equipment is to put together.

As with the other studio style spin bikes in the Sunny Health and Fitness range, the Sunny SF-B901 is surprisingly simple to put together.

The majority of work is actually already done before the bike even leaves the factory, with the flywheel and main bike frame arriving pre-assembled.

All that you need to do is attach the smaller and lighter parts, including the handlebars, seat, pedals, and base stabilizers.

With such little assembly required, there’s really no reason why it can’t be completed without the need for extra assistance.

Laying the frame on its side makes it much easier to get the base stabilizers attached, after which you can complete the assembly with the bike in its upright position.

In terms of the quality of assembly instructions, the user manual is quite comprehensive in covering what little setup is required. This includes a clear parts list and instructions on how to fit replacement brake pads.

You can actually find a copy of the user manual here, which can be useful if you would like a better idea of what to expect.

What about the ‘Q Factor’?

One of the terms you’re likely to come across when researching which exercise bike to buy is ‘Q Factor’. The basic definition is the distance between the pedal attachment points on the crank arms, when measured parallel to the bottom bracket axle.

Research has shown that having a narrower ‘Q Factor’ is best for cycling, as it helps to reduce the potential for too much sideways movement in your knees. This in turn reduces the risk of injury, and creates a more effective transfer of force from your legs to the pedals.

Out of all the spinning bikes in the Sunny Health and Fitness range, it’s the Sunny SF-B901 that has the narrowest Q Factor, measuring just 7 1/8 in. Other bikes in the range vary from 7 1/2 in to 8 1/2 in.

Customer reviews

Gel seat covers or a replacement saddle are options if you find the current saddle uncomfortable to sit on

Whether you’re looking to spend $200 or $2000 on a new exercise bike, it’s important to find out as much as possible about the various benefits of several bestselling models in your price range.

We’ve directly compared the Sunny SF-B901 to the slightly lower priced SF-B1001 throughout this review, but it’s important to vary your research sources to build up a better overall opinion of the pros and cons.

This is why we always recommend making a visit to online marketplaces, such as Amazon and Ebay, to read through the hundreds of reviews they currently have available.

While our own write-up tends to have more of an in-depth focus on the features, it’s often best to combine this with the opinions and experiences of a much larger audience.

But with over 1000 ratings and more than 700 reviews to read through, this is something that’s easier said than done.

For this reason we’ve been reading through many of these reviews ourselves, to provide you with a much clearer and more concise list of pros and cons.


  • Quick resistance changes make this bike ideal for HIIT and Tabata drills
  • Easy to assemble (10 to 20 minutes is all it takes)
  • 40 lb flywheel is the same weight you’ll find on bikes more than twice the price
  • Sturdy base frame design prevents any unwanted movement at higher resistance levels
  • Wide variety of handlebar and seat adjustment options
  • Ergonomic seat and handlebar design creates a more comfortable cycling position
  • Affordably priced
  • Fast response provided by customer service when contacted
  • Smooth cycling motion


  • Some people found the seat to be quite hard to sit on for extended periods. They recommended either replacing the seat with a cushioned version, or wearing cycling shorts with a gel insert
  • Lack of display console means you can’t track workout stats

It’s not just the high average review rating that makes this bike so impressive. You also have to take into account the distribution of ratings, with over 80% of reviewers rating the Sunny SF-B901 at 4 stars or more.

Warranty coverage

  • Frame: 1 year
  • Parts: 90 days
Sunny Health and Fitness Exercise Bike Guide

Review Overview

Overall Review Rating

4.5 / 5

If you've shortlisted several of the Sunny spinning bikes due to their high level of popularity and impressive average ratings, it's important to remember a few features that set the SF-B901 apart.

Although the flywheel isn't the heaviest in the range, weighing in at 40 lbs (the SF-B1002 flywheel weighs 49 lb), you do have the narrowest Q Factor, highest weight capacity, and full range of adjustment options.

The heavy-duty crank and smooth chain drive mechanism also make for a quieter and smoother cycling experience, allowing you to watch TV or listen to music while you workout.

Transport wheels are also a nice addition that makes it much easier to move the bike if required.

Overall, for less than $300, you're probably not going to find a design with a higher level of build quality, backed by such a large number of highly rated reviews from people who are using this bike in their workouts already.

Product dimensions: 20" (W) x 46.5" (H) x 48.5" (L) Product weight: 108 lbs Weight limit: 275 lbs

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