New Model D Seat Doesn't Auto-glide Down the Monorail

[Er1c]

Hi folks. Weird situation. I bought a used Model D that was manufactured in 2021. It's only got 150,000 lifetime meters and everything is in obvious pristine condition. An older couple owned it but never really used it. The only issue was the seat didn't glide down the monorail on its own when not in use, as every other rower I've seen, including my older model D made in 2006. However, the rail and rollers are all clean.

My understanding is that the seat should glide on its own if operating correctly. So I decided to conduct an experiment and switched out the rollers from my old one, and lo and behold, the seat now glides down the monorail by itself when not being used.

Just curious, does anyone have any idea about what would cause a near-new rower to have this issue? Obvious it's the rollers but they appear to be free of any problems.

[Carl Watts]

Wouldn't worry about is as long as the seat moves freely. Does it move after a very small nudge ? there may be a bit of initial stiction and once its in motion its fine. The grease in the bearings eventually redistributes itself and the bearings will free up slightly. Friction under load or no load can be two different things, a bearing will spin far easier with no grease or oil in at all if you hit it with compressed air, it will scream but that doesn't mean the friction will be lower with load, which obviously it isn't or standard metal bearings would be run dry.

[Nomath]

First thing to check : is the floor level?

If so, your seat doesn't glide down the monorail because of static friction. Do you have a set of wrenches and a kitchun scale? Carefully lie down each wrench on the seat, starting with the lightest/smallest. You wil find that beyond a certain weight the seat will glide down. You can calculate the static rolling resistance from the angle of the slide (a few millimeters over the length of the slide ?) and the weight of the seat plus wrench (my guess: seat = 1kg). Your body weight is surely in excess of the heaviest wrench in the set.

If the glide is not smooth, you may have damaged or sticking rollers.

[Carl Watts]

I assumed the floor didn't change because he tried new and used rollers.

There is quite a significant built in incline of the monorail towards the front of the rower to assist with the recovery.

Its essential the floor is level.

[Ombrax]

So I decided to conduct an experiment and switched out the rollers from my old one, and lo and behold, the seat now glides down the monorail by itself when not being used.

Just curious, does anyone have any idea about what would cause a near-new rower to have this issue? Obvious it's the rollers but they appear to be free of any problems.

Do the "new" rollers appear to be binding when you just spin them in your hands? In other words, do you have any evidence that it's a bearing issue, and not due to a different problem?

For example, something may have been a bit wonky in the alignment, and simply by replacing the original newer ones with the rollers from the older erg you might have fixed the problem (by installing them properly).

[Er1c]

So I decided to conduct an experiment and switched out the rollers from my old one, and lo and behold, the seat now glides down the monorail by itself when not being used.

Just curious, does anyone have any idea about what would cause a near-new rower to have this issue? Obvious it's the rollers but they appear to be free of any problems.

Do the "new" rollers appear to be binding when you just spin them in your hands? In other words, do you have any evidence that it's a bearing issue, and not due to a different problem?

For example, something may have been a bit wonky in the alignment, and simply by replacing the original newer ones with the rollers from the older erg you might have fixed the problem (by installing them properly).

I thought the same thing so I put the rollers on my old seat and it has the same issue when I place it on the monorail. There must be something with the bearings. Perhaps it's a breaking in period or something because I checked a few demo videos and a couple of them actually had seats that didn't glide towards the flywheel when not in use.

[gvcormac]

Probably thicker (or dirty) grease in the bearings. You could rinse & oil.

On an unrelated matter, how's your flywheel clutch?

[c2jonw]

The seat doesn't have to glide on it's own, so you shouldn't worry too much about it. New machines out of the box will exhibit a range of fit of the seat on the monorail and they often loosen up with use. Your machine is virtually new so just give it some time.

[jackarabit]

Ombrax writes:

For example, something may have been a bit wonky in the alignment, and simply by replacing the original newer ones with the rollers from the older erg you might have fixed the problem (by installing them properly).

My experience with binding or hesitation in the free travel of the seat carriage suggests that simply backing off the machine screws that fasten the two end brackets to the seat followed by retightening will sometimes return the bracket/axle angles to a degree of mechanical rectilinearity (90° included angles) sufficient to correct wrack in plan view.

I noticed this a few yrs. back when replacing the seat rollers. One might assume that sufficient rectilinearity of the bracket/axle unit (the truck) would be assured and maintained by the accuracy of jig-bored locations of the threaded inserts in the seat and minimum leeway in the diameter of mounting holes in bracket flanges. Better to assume that independent end brackets is a cheap and cheerful rendition of a carriage truck which can easily get out of whack and into wrack. If you think of the seat carriage as a unit with little rigidity beyond that provided by bolting to a rigid base (the seat bottom). you begin to understand the vulnerability to displacement and misalignment.

Extending this thinking from roller replacement to correcting occasional misalignment created by the repeated exertions of the rower and miscellaneous knocks and shocks, in either case leave one axle nut slightly loose on each axle. Then free up (just loose enuf to allow lateral movement of bracket) the bracket to seat screws at all 4 points of attachment, snug up the end play of the 2 loose axle nuts, and finally snug down the bracket flange to seat screws and test sensitivity to gravitational force.

There used to wuz a C.R.A.S.H.-Bs competitor/sculler/erg repairman posting here name of Norm Peterson who replaced seat brackets when he replaced rollers.

[Er1c]

On an unrelated matter, how's your flywheel clutch?

I totally didn't catch this question. But to answer, the flywheel clutch on the old rower worked flawlessly since cleaning out the old grease and adding a drop of motor oil, which was a suggestion I got on this forum. Not a single issue after that.

[mict450]

My experience with binding or hesitation in the free travel of the seat carriage suggests that simply backing off the machine screws that fasten the two end brackets to the seat followed by retightening will sometimes return the bracket/axle angles to a degree of mechanical rectilinearity (90° included angles) sufficient to correct wrack in plan view.

This has been my experience also. Jack expresses this with a precision I could never hope to achieve. Must be an engineer or at least an english major.

[Willy.VdW]

I bought my rower brand new some 5 months ago.
It sits in a spare, unheated bedroom, at temperatures of 10 - 15°C (50 - 59°F).
The seat doesn't return before a workout, but does so "hesitantly" after.
Now that temperatures are rizing, the seat returns better and better.
This suggests that the grease of the bearings in the rollers may be the cause
of the seat not returning, at least in my C2.

[Sandeman]

Wait, the seat is supposed to roll back forwards on it's own?
I don't think mine has ever done that (bought feb 2022)

I'm getting my level out in the weekend

[JaapvanE]

Cleaning the rollers and monorail helps a lot. My seat doesn't roll down when things are dirty, but it does when things are clean.