How to adjust your treadmill belt

Disclaimer: Make sure the treadmill is unplugged and turned off. It is a safety hazard to perform maintenance tasks while the treadmill is turned on.

It’s time to dive in and get started on how to adjust your treadmill belt. Here we have another common problem that occurs in treadmills. Which is where the belt is not centered on the rollers. The rule of thumb on this is 90/10. If you have 90% of your gap on one side and 10% on the other, it’s time to make an adjustment. You’ll never get it perfectly centered, but the closer you can get to the center is generally better. Here you can see we have very little gap on this (left) side and a lot of gap on the other (right).

Generally these are mounted and tensioned with a allen bolt. Most of them are metric, so I have here a metric allen kit. I happen to know that this one (treadmill in the video) is 6mm. Many of them are, although sometimes you see 5(mm) and 8(mm). We’re going to tighten the side that the belt is travelling to (i.e. the side containing the 10% gap if using the 90/10 rule as an example). So, the side that has the small gap, we’ll find a small hole in the rear of your unit. We’re going to lock in (insert allen wrench into allen bolt head) and you’re going to want to start turning this (the allen wrench) clockwise. About one full revolution and then go ahead and start your unit (the unit will need to be plugged back in and turn on). I usually run it up to about two to three miles per hour and then you leave it run. You should see that the gap is starting to decrease. It’ll eventually come to a stop (i.e. the belt should find the center of the roller and not travel further toward the opposite side). If it’s in an acceptable position, then you are done. If it needs more, then I usually do quarter inch turns, clockwise, until we get it back into the position we want it to be. It looks like it’s going to take about one more quarter turn (for those who did not watch the video, the belt has been running for roughly one full minute during this adjustment).

Alright, and that looks pretty good. It’s not perfectly centered, but as I say they normally are not. Now you’ve centered up your walking belt. As you can see, it’s much improved. Your belt will never be perfectly centered, so don’t drive yourself crazy with a tape measure on either side. The 90/10 rule is there to keep you from grounding the treadmill (belt) to one side or putting too much stress on a right or left bearing on the rollers. You don’t need to have it perfect, you just need to have it generally centered.