Why Is My Treadmill Belt Slipping? Causes and How to Fix It

Quick answer: Why is my treadmill belt slipping? In most cases the walking belt is too loose, so it hesitates each time your foot lands. Unplug the treadmill, remove the safety key, and tighten both rear roller bolts by the same small amount, then test. If it still slips, check for a dry deck, too much lubricant, a worn belt or a worn drive belt.

A slipping belt feels like a stumble. Your foot lands, the belt pauses for a split second, then lurches forward again.

That’s not just annoying. It’s a trip risk, so I’d stop running on it until it’s fixed.

When I compared Bowflex’s manual with WalkingPad’s repair guides, the diagnosis order matched almost exactly. Tension first, then lubrication, then worn parts.

Why Is My Treadmill Belt Slipping? The Usual Causes

Here are the causes, most likely first:

1. Loose walking belt. Bowflex’s Treadmill 7/18 manual lists belt tension as the fix for “hesitation or walking belt slips when in use.”
2. Dry deck. WalkingPad’s repair guide names a belt that’s too dry as a slipping cause. Bowflex also links a strained-sounding motor to the deck needing lubricant.
3. Too much lubricant. WalkingPad warns excess lubrication can reduce traction on the belt. Bowflex tells owners to clean up any excess after lubricating.
4. Worn walking belt. Frayed, cracked or stretched belts slip even after adjustment.
5. Worn or loose drive belt. This inner belt links the motor to the front roller. When it’s loose or worn, the walking belt may not move properly.

How to Fix It

Safety First

Before you touch a single bolt:

• Remove the safety key and put it somewhere children can’t reach.
• Turn the power switch off and unplug the cord. Bowflex says to wait 5 minutes before maintenance.
• Keep kids and pets away whenever the belt runs during testing.

Don’t skip that last point. Honestly, it matters more than it sounds. In a 2021 recall, the CPSC described adults, children, pets and objects being pulled underneath the rear of a treadmill, including a child’s death. The rear roller is exactly where you’ll be working.

Step 1: Tighten the Belt in Small, Equal Turns

The rear roller has two adjustment bolts, one on each side. Bowflex’s Treadmill 7/18 procedure:

1. Use a 6 mm hex wrench.
2. Turn the right and left bolts clockwise a 1/2 turn each, one then the other.
3. Lift the belt at its midpoint. A correctly tensioned belt has only about 1 inch of give.
4. If it lifts more than 1 inch, repeat.

Other brands use smaller steps, often a quarter turn, and lift-test numbers vary. Check your model’s manual. The rule that holds everywhere: turn both bolts the same amount. Bowflex warns that turning one side more than the other moves the belt off center.

Step 2: Don’t Overtighten

The trick is stopping the moment the slip stops. Not later. Bowflex says too much tension causes unnecessary friction and wears the belt, motor and electronics. WalkingPad says overtightening can damage the motor and rollers.

Step 3: Re-center the Belt

Run it at a slow speed and stand at the back to watch. On the Bowflex 7/18, if the belt moves left, you turn the left bolt 1/4 turn clockwise and the right bolt 1/4 turn counterclockwise, then watch for about 2 minutes. Reverse that if it drifts right.

Step 4: Check Lubrication

Lift the belt edge with the machine unplugged and feel the deck.

• Dry or rough? Lubricate. Bowflex says every 3 months or 25 hours of use, with 100% pure silicone lubricant, never a degreaser like WD-40. NordicTrack’s maker, iFIT, recommends annual lubrication even if you don’t use the treadmill daily. Your manual’s schedule wins.
• Oily or slick? Wipe up the excess. More oil won’t cure slipping; it can cause it.

Step 5: Inspect the Belt for Wear

Look for fraying, cracks or a glazed, stretched surface. WalkingPad says to replace the belt if it’s damaged or the slip returns after proper adjustment.

Why Is My Walking Pad Slipping?

Same causes, smaller machine. A walking pad belt slips because it’s loose, dry, worn or over-oiled.

The fixes match, too. WalkingPad’s guide says to tighten the rear roller bolts in small, equal quarter turns and test at low speed after each one. Its lubrication guide calls for just 1 to 2 drops of silicone oil, so over-oiling is an easy mistake on these compact belts.

If your walking pad squeals rather than slips, read why a walking pad squeaks. If it won’t power on at all, see our walking pad not turning on checklist.

When to Call a Technician

Stop and call the manufacturer or a technician if:

• the belt still slips after correct tension and lubrication,
• you suspect the drive belt (it sits under the motor cover),
• you smell burning or hear grinding,
• the motor keeps stopping mid-workout.

Don’t remove the motor control board cover. Bowflex warns that dangerous voltages and moving parts sit behind it, and only approved service staff should open it.

In practice, if the belt still slips after correct tension and fresh lubrication, WalkingPad points to replacing the belt. My take: don’t keep tightening.

For more machine fixes, see our cardio machines section.

Frequently Asked Questions

How do I know if my treadmill belt is too loose?

It hesitates or slips when your foot lands. On the Bowflex Treadmill 7/18, lifting the belt at its midpoint should give only about 1 inch.

Should I tighten a treadmill belt clockwise or counterclockwise?

On the Bowflex Treadmill 7/18, clockwise on both rear bolts by the same amount adds tension. Confirm the direction in your own manual before turning anything.

Can too much lubricant make a treadmill belt slip?

Yes. WalkingPad warns that excess lubrication can reduce traction on the belt. Wipe away any surplus after you lubricate.

Is a slipping treadmill belt dangerous?

It can be. A belt that suddenly hesitates can throw off your stride. Stop using it until it’s fixed, and keep children and pets away while you test.

Last updated: November 10, 2026. Sources: Bowflex Treadmill 7/18 owner’s manual (PDF), WalkingPad: how to fix a treadmill, iFIT: keep your NordicTrack treadmill in top shape and CPSC: Peloton Tread+ recall.