Got a wobbly flywheel on your RP?


Just received an email enquiry about a Rowperfect with a wobbly flywheel.

Hi, we have a rowperfect in our boathouse. The problem is on the recovery of the stroke when the chain is recoiling, the flywheel shakes violently. On the drive phase of the stroke the everything is ok. Its just on the recoil when the chain starts to rewind in. I have checked the chain and initial cogs, they are ok. Could you help me in being able to identify the fault?

This made us suspect a bent main shaft. The main symptom is

  • flywheel wobble on the recoil

Test for a Main shaft that may be bent

Pull the chain out and hold the flywheel section stationary.  Put your hand over the flywheel cage and touch your fingers onto the wheel itself and with a light finger pressure hold it still as you slowly recoil the chain.

If you can see movement and feel the flywheel moving in and out of contact with your finger the main shaft is bent.  There should be no side to side movement of the flywheel itself. If you can see movement and feel the flywheel moving in and out of contact with your finger the main shaft is bent.
Take a look at this main shaft replacement instructions The first bit is how to test to see if your main shaft is bent… I fear that’s what has happened to your RP.

This usually happens when an athlete hit the front leg hard with the fly wheel section during rowing.

Preventative measures

To prevent this happening, wind a bungee around the bar 50 cms from the back leg then the seat can’t go further forward than this point and unless the athlete has very long legs, will prevent the fly wheel section reaching the front leg.


A new main shaft can be purchased and fitted.  If you are confident following instructions you can fit this yourself.  If not, Rowperfect UK can do it for you – maybe within a maintenance service.  Read the service and maintenance sheet below for recommended daily, monthly and annual actions.

We find baby wipes are very good for cleaning the main bar after each workout!

Rowperfect bent main shaft replacement instructions

Rowperfect service and maintenance


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This Post Has One Comment

  1. peter

    Flywheel wobble is also caused by incorrectly balanced flywheels supplied by manufacture
    each flywheel needs to be individually balanced by testing and removing metal in more or less degrees, much like balancing a car wheel.
    If the machine has been doing this since installation then a new flywheel is the main culprit.

    another cause is over tightening the main nut securing the flywheel to the shaft too much tension [over tighten] will cause the flywheel to act in this matter, solution is to back off the nut till loose and just tighten so it is just secure and no more


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