Why Is My Treadmill Making A Knocking Noise?

Why Is My Treadmill Making A Knocking Noise?

Why Is My Treadmill Making A Knocking Noise?

While treadmills are meticulously designed and have been built with quality materials, they aren’t, unfortunately, immune to mechanical problems and breakdowns.

There are a number of things that can go wrong with treadmills including sudden stops, cracked decks, malfunctioning display screens and much more.

Today, though, we’re talking about one of the most common issues to plague treadmill users -- knocking noises.

Why Do Treadmills Make Knocking Sounds?

Treadmills can start making this incredibly irritating sound for a number of reasons. Knocking sounds can be described as “knocking” or “thumping” and can be quick in succession or only happen on occasion. In any case, they should be investigated and remedied to avoid additional problems with your machine.

Improper Belt Tracking

If you’ve just set up your new treadmill or have been making adjustments and you notice that your treadmill is now making a knocking noise, it’s a good idea to double check that your running belt is on correctly. When your belt is putting too much friction on either of the rollers because it isn’t aligned properly, the knocking noise can often be heard.

The running belt should be straight and centered between the two sides of the machine. This is something that’s easy to diagnose and shouldn’t require professional help.

When this is the case, it’s as simple as using your allen wrench to turn the belt adjustment screws ¼ of a turn at a time until the belt starts to track correctly when running at a low speed. As a helpful hint, if your belt is going to the left, turn the left screw and if it’s going to the right, turn the right screw.

Defective Roller

Treadmills have two rollers: one in the front and one in the back. Essentially, these rollers move like rolling pins, continuously rolling when the treadmill is in use. The belt stretches across the two rollers, which is what causes it to move when the machine is turned on.

Sometimes, however, the rollers can break down. This tends to happen after years of everyday or regular use and isn’t something that you should have to deal with too often. You’ll know to look into your rollers if you hear a knocking sound and have already ruled out an improper belt alignment.

Once you’ve diagnosed a bad front roller, the best option is replacement. To access the front roller, remove the screws of the motor hood and move it out of your way. To gain access to your treadmill’s rear roller, just remove the end caps at the back of the treadmill.

In both cases, you’ll need to loosen the walking belt using the adjustment bolts and the same ¼ turns as we mentioned above. When you’re finished loosening, the belt should have a bit of slack.


Keep in mind that not all rollers are the same! Before trying to replace your rollers, know which replacement rollers you need and be sure to order the correct ones for your specific make and model of treadmill. This information can often be found online at the website of your treadmill’s manufacturer, as well as in the included user’s manual.

Machine Unleveled

Another reason your treadmill may be making a knocking sound is if it’s not leveled on the ground. This is most often due to the construction of the flooring that your treadmill is on, which makes it simultaneously the easiest thing to fix and also the hardest. You can’t just readjust your floor, after all!

Luckily, the feet on most treadmills are adjustable and can be adjusted individually. This means that you can adjust one foot to be higher or lower than the other to correct any minor imbalance issues.

If the issue persists and you’re sure that it’s not your belt, or the rollers causing the knocking sound, you may need to move your machine to a different location. When you do, make sure that you adjust the feet again or your machine will be unleveled due to mismatched feet.


Whether you’re researching with the intent of purchasing your first treadmill or intending to replace one you already have, you might be wondering which treadmill is best for you. If so, you’re in luck!

There are a number of top rated treadmills under $1,000 that you can get your hands on today -- and then, when your treadmill starts to knock, you’ll be able to diagnose and correct the problem like a pro.