| Unit | Size | Supported weight | Flywheel weight | Resistance | Fitness meter |
|---|---|---|---|---|---|
Circuit Fitness AMZ-948BK Check Discounted Price | L: 41" W: 20" H: 42" | 300 lbs | 30 lbs | Friction | N/A |
The Circuit Fitness AMZ-948BK indoor cycle is a smaller version of the AMZ-955BK that we’ve already covered here. It features a lighter flywheel, and a belt drive system rather than a chain drive. It’s a bike made for home use and does not include an exercise meter.
Key Features and Specifications
- Assembled dimensions: 41L x 20W x 42H inches (104L x 51W x 107H cm)
- Assembled weight: 84 lbs (38 kg)
- Flywheel weight: 30 lbs (13.6 kg)
- Supported weight: 300 lbs (136 kg)
- Handlebars: 2-way adjustable
- Seat: 4-way adjustable
- Pedals: With straps
- Drive: Belt
- Resistance: Friction, felt-pad
- Exercise meter: No
- Accessories: Bottle holder, phone holder
- Warranty: 2 years limited
Frame construction
The Circuit Fitness AMZ-948BK Revolution Cycle is an exercise bike designed for spin workouts. 
Even though it’s not a commercial-grade model, it still has a sturdy steel frame and offers a weight capacity of 300 lbs (136 kg). Most of the frame tubes are rectangular with the exception of the base bars which are cylindrical. All the steel tubes are coated with a corrosion-resistant paint finish. The color used is black, this being the only color available for the AMZ-948BK, at least for the moment. The only part that has a chrome finish is the flywheel.
The bike is not extremely heavy, but does weigh approx. 84 lbs (38 kg). Differently put, it is at least twice the weight of the average road bike. This weight adds stability. Plus, both base bars of the bike have adjustable levelers which considerably improve its overall stability.
Despite its weight, the bike is not too difficult to move once it is assembled. Its front base features a set of wheels which facilitate its relocation.
The Circuit Fitness AMZ-948BK cycle is a bit smaller than other spin bikes. It is only 41″ (104 cm) long, and 20″ (51 cm) wide. This means it can fit even into a small room but it is recommended to leave at least 24″ (61 cm) of clearance all around it, for ease of access.
Last but not least, the bike integrates several ABS parts as well. But these only have a protective role; they shouldn’t affect its overall sturdiness. The most notable ones are the belt cover and the brake pad cover.
Seat and handlebars
The Circuit Fitness AMZ-948BK Revolution Cycle includes a saddle designed for superior comfort. First of all, 
it is larger than the average race seat, so it provides extra contact surface. It integrates a generous layer of foam cushioning and its top is contoured for improved breathability. Its rear section features two springs which enable it to flex and adapt to your movement as you ride. Also, it’s cover is made of durable vinyl material which is also sweatproof and easy to maintain.
The bike’s seat is four-way adjustable (up, down, front, back). Its upright bar features several adjustment positions while its horizontal slider adds a few extra inches of fore/aft adjustability. But considering that the bike is slightly smaller than other models, it is only recommended for users between 5’0″ and 6’0″ (153 – 183 cm). Taller persons should still be able to use this exercise bike, but they may not benefit from a complete leg extension.
The bike is equipped with a multi-grip handlebar. It offers the possibility to adopt a standard grip, a race grip, and a climbing grip. It also has two short aero bars so an aero grip and a close parallel grip are also available.
The handlebar is fully covered by a layer of rubber foam material for a comfortable grip. However, it does not have pulse sensors. Also, the bike doesn’t include an exercise meter, so if you will want to monitor your distance traveled, calories burned, RPM, etc, you will have to use a separate device.
Resistance system
The Circuit Fitness AMZ-948BK indoor cycling bike features a friction resistance system with manual 
action. This means the bike doesn’t need an external power source or an adapter. But on the other hand, it doesn’t adjust the resistance automatically.
The bike’s resistance system consists of a felt pad brake attached to the tension knob on top of the bike’s main frame bar. By turning the knob clockwise, the brake pad applies more friction to the flywheel which increases the drag and the overall pedaling difficulty. The bike’s resistance system doesn’t have pre-determined tension levels like most magnetic bikes. So, you simply have to tighten the brake until you get the desired pedaling difficulty. As a general idea, the brake can be tightened up to the point you can barely pedal.
Since it’s a friction brake, and not a magnetic brake, the pad will almost always be in contact with the flywheel. Therefore, it will wear out over time, so after a while you will have to replace it. Also, since there is friction between the flywheel and the brake pad, the bike is not completely silent.
The tension knob also has the function of an emergency brake. You can press it down to immediately stop the flywheel from spinning. This may actually be required especially if you have been pedaling at a high speed as the pedals continue to spin for as long as the flywheel is spinning.
Drive system
First of all, the Circuit Fitness AMZ-948BK exercise bike is equipped with a 30-lb (13.6 kg) flywheel. 
It has a perimeter-weighted structure for improved inertia, which is great for spinning workouts. As we’ve mentioned above, the flywheel is chrome-coated, with black ABS side panels.
The bike’s flywheel is bi-directional. In other words, it gives you the possibility to pedal in reverse. However, coasting or free-wheeling is not possible on the bike. So, when pedaling in reverse, you will benefit from the same pedaling difficulty.
The bike is equipped with a durable 3-piece crankset with steel crank arms similar to a road bike crankset. This means it can withstand pedaling while standing up. The included pedals are also made of aluminum alloy featuring a non-slip surface, and adjustable toe cages. They don’t have SPD clips, but their threads are standard.
Last but not least, the Circuit Fitness AMZ-948BK Revolution Cycle is equipped with a belt drive system. It uses a heavy-duty poly-v belt which offers excellent traction. As opposed to a chain drive, the belt doesn’t need any lubrication. It also contributes to the overall smoothness of the ride as it generates slightly less vibration than a chain.
Assembly and Maintenance
The main body of the bike comes pre-assembled, with the flywheel, the crankset, the brake system, and the belt already in place. However, the rest of the parts still require user assembly. You will have to attach the two base bars, the seat post, the seat, the handlebar post, the handlebars, and the pedals. The whole task shouldn’t take more than 30-40 minutes, though. All the necessary instructions are provided by the manual, and a basic toolkit is also included.
Once the bike is assembled, maintenance doesn’t require much. All you have to do is keep the frame clean, wipe the sweat from the frame at the end of the workout, and periodically check for loose bolts and parts. The brake pad will eventually wear out and will require replacement. Also, in case it squeaks when in contact with the moving flywheel, a bit of silicone lubricant should solve the problem.
The Pros
- Sturdy steel frame – 300 lbs weight capacity;
- Durable paint finish;
- Transport wheels on the front base;
- Adjustable stabilizers on both bases;
- Durable steel crank and metallic pedals with toe cages;
- Multi-grip handlebar with aero bars;
- 4-way adjustable seat;
- Smooth belt drive system;
- Perimeter-weighted, 30-lb flywheel for enhanced inertia;
- Standard friction resistance;
- Bottle holder included;
- Phone holder included;
- Little maintenance required;
- Really easy to assemble;
- All the tools required for the assembly are included.
The Cons
- No exercise meter;
- No pulse reading function.
Summary
The Circuit Fitness AMZ-948BK Revolution Cycle is an indoor cycling bike designed for home use. It features a 30-lb inertia-enhanced flywheel and a friction resistance system. Its seat is 4-way adjustable and well-cushioned for extra comfort. It does not include an exercise meter but does have a phone holder. It’s a fairly decent exercise bike for spin workouts, interval training, intense cardio sessions, weight loss, and stamina development.