Treadmill Belt Slow Down or Bogs Down? Reasons and Solutions

Affiliate Disclosure: As an Amazon affiliate, we earn from qualifying purchases.

The belt of a treadmill is extremely important for the optimal functioning of the machine. But there are certain times when the belt might slow down—when there is no one on the machine, but the treadmill keeps operating when slowing down just after someone steps on the belt, or when the treadmill operates optimally, initially belt slows down suddenly.

There are a couple of reasons why the treadmill belt slows down, and these include:

When the walking belt and deck get worn off, and this is the primary reason almost 85% of the time

The walking belt and motor belt are too tight, which is possible when we have made adjustments to them recently. This might be the problem almost 8% of the time

The motor has lost torque, is demagnetized, or needs brushes, and all of these are the cases almost 5% of the times

The controller is dropping output which happens 2% of the times

Let’s look at the issues one by one:

The Belt is Worn Out

The best way to check whether or not the walking belt is worn off is to take the DC amp draw when we have a DC treadmill and an AC draw when we have an AC treadmill.

Still, it is best to look at the belt to decide as the feel test can be unreliable most times.

See also  Top 7 Best Under Desk Treadmills for Heavy and Obese People Reviewed

Still, the coasting test or an incline test is better when we don’t have a DC ammeter (as most good-quality ones are expensive).

For getting the deck test done, it is better to visit the Troubleshooting section, download the belt and deck inspections instructions, and start working your way through the solution.

The coast test involves getting onto the treadmill and walking on it using the lowest incline at around 3 MPH.

Once the safety key is pulled, it doesn’t take more than 2-3 full steps for the treadmill to come to a complete halt. The fewer the number of steps, the higher is the friction on the machine.

Using the incline test, we put the treadmill at a maximum inclination and walked at a speed of 3MPH.

The best indication for replacing the belt includes when the treadmill operates smoothly at maximum inclination but bogs over at minimum inclination.

There is no need to bother about friction-related problems when gravity takes over the drive system.

But, remember that this test will not work out on belts that are heavily worn off.

The Walking or Motor Belt is Too Tight

Overtight walking or motor belt is a result of recent adjustments to them. I don’t have the misconception that tighter belts are better belts.

Most times, individuals crank down the belts when the treadmill belt starts slipping. But, tighter belts mean that the drive system must work more vigorously to keep the treadmill moving.

The right treadmill belt placement helps us lift the walking belt at the machine’s center for about 3 inches without straining. But do this only after unplugging the power supply from the machine.

See also  Can You Over Lubricate a Treadmill Belt?

If the belt is too tight, loosen it mildly but don’t overdo it such that the treadmill becomes a danger to the individual using it, resulting in slippages.

The motor belt must be flexible enough to turn the hand up to 90 degrees from its regular position in an unplugged state.

If the belt is too tight, loosen it mildly and test it for any slippages even when there is optimal tension. If yes, it is time to replace the motor belt.

Need for Brushes or Demagnetized Motors

In general, if a motor has lost torque, it is time to procure a new set of motor brushes.

If we don’t have it, it is always easy to make brushes for any motor.

Though motor demagnetization is not a common issue, there are chances of its occurrence but once again, diagnosing the problem is quite simple.

Once you are sure that the belt and the deck are not worn out, and the belts are optimally tight, we can conclude that it could be some problem related to motor torque.

Never use your hand or other parts of the body to stop the motor as there are higher chances of damaging the body parts if the motor is in good working condition.

Now, to test the motor, use a foreign object that’s kept on a long shaft. Observe for the direction in which the motor spins, making use of the motor tag that has the directions printed on them, and then apply pressure on the flywheel in the same direction in which the flywheel is turning, making use of any object with downward pressure.

See also  Why Can I Run Longer on a Treadmill Than Outside?

Please don’t impose any pressure on the opposite direction of the flywheel’s spinning motion, which could result in injury.

Using this pressure, if the motor speed slows down, it is time to replace the brush.

Test for demagnetization after disassembling the motor. Remove the bolts that retain the motor and take off the motor cover.

If you observe that the magnet pulls the core against the housing and that the motor is difficult to remove, the magnets are in optimal working condition.

In case the magnets don’t attract the core, the motor must be replaced.


Problems with the controller are one of the rare reasons why the treadmill belt slows down.

Replacing the controller is not the solution here, and you might even end up replacing both the control and the belt.

If there are problems with the control output, these occur irrespective of whether or not the individual is on the belt.

DC output dropping tests are normal, and most controls have a maximum limiter, which helps drop the output to avoid burning the board.

Conclude whether or not the controller is the underlying problem by eliminating other possibilities.

Once sure that the control is the reason behind the belt’s slow down, replace the control without any hesitation.