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matthew matthew

ProForm VR980 EKG (PFEX3311.0) Pedals/Crank Slipping

I have a ProForm VR980 EKG Exercise Bike (Model PFEX3311.0) and it is having a problem where it slips while pedaling. At first I thought it was the belt slipping but I took the bike apart and found that the crank shaft is actually slipping inside the hub. I suspect that it has something to do with the freewheel mechanism but this is where we reach the limits of my knowledge on crank mechanics. Is it possible that something just needs to be lubricated better so the freewheel mechanism "grabs" properly when pedaling or am I going to need to find parts to repair this?

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Body Building and Toning
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Joseph Perez
I know how great it feels to get a good workout and an exercise bike can really come in handy. I am sorry for the inconvenience you are having with your bike and I did manage to find the owners manual for your exercise bike in where you can find some good information. I hope this helps while you wait for your expert response.
by Joseph Perez
April 3rd, 2012
Answered in 8 minutes
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matthew matthew
Thank you, although that's actually for a slightly different model (the PFEX34310). I was able to find the manual for mine (PFEX33110) here:

iconservice.com/CustomerService/pdfDownload.do?fileName=PFEX3311.0-177524.pdf&directory=%2Fpdf%2F
by matthew matthew
April 3rd, 2012
Answered in 19 minutes
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Sam A
Thank you for the question on the exercise type bike slipping.

This model has a dynamic braking and generating system and as you increase the resistance it will put more or less magnetism on the drive hub to create the work out resistance.

You can check the belt tension on both belts to see if an adjustment is required.

If both belts and tight and you can pedal but you getting little to no resistance on the drum then there may be a problem with the resistance electrical control.

The control has two double a batteries inside so make sure they are good.

As you pedal the bike it creates its own electrical magnetic field.

Beyond this it may require a technician to figure if the control board or the stator is the problem.

Please let me know what if changing the batteries helped.

Sam A.
by Sam A
April 5th, 2012
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matthew matthew
Thank you for responding.

I removed the crank and pulley from the bike and determined that the problem is not with the magnetic resistance system.

With the pulley removed from the bike, I reattached the crank arms to the crank shaft and tested it. When I turned the crank backwards while holding the pulley stationary, it spun freely as it is supposed to (just like it would if you pedal backwards on the bike). When I tried to turn the crank forward, I shouldn't have been able to move it without allowing the pulley to turn but it did turn. It didn't exactly spin freely like it does when pedaling backwards... there was some resistance but it shouldn't have been able to turn at all.

To be clear, I will reference the specific parts shown on the exploded diagram in the bike's manual. The Crank Shaft (part 33 in the diagram) turns inside of the Pulley (part 19 in the diagram). By design, the crank should spin freely within the pulley when turning it backwards but should "engage" the pulley when turning it forwards. As this is the first mechanical stage before the belt transfers the motion to the second stage wherein the magnetic resistance system comes into play, it's definitely not an electrical issue. It would appear that the freewheel mechanism inside of the pulley's hub has either worn out or has some kind of lubrication issue (maybe too much grease or not enough or...I don't know).
by matthew matthew
April 8th, 2012
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Sam A
Thank you for the update on the stationary bike drives system.

I think the problem may be with in the axle of the large drive wheel if it spins freely one direction and is suppose to grip the forward direction which means that the axle has a built in directional clutch that is slipping.

The problem is that many of these parts are no longer available for replacement on this model.

You may have to devise a way to lock the drive wheel and axle together so you can use the bike without the coaster feature.

Please let me know what you figure out.

Sam A.
by Sam A
April 9th, 2012
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