roller bearings uneven on monorail

[Tartuk]

Hi everyone, I have a Model D and have started noticing that my legs are not well-aligned to the monorail, ie when seated, my left leg seems to travel in an angle from my toes up to my hip towards the monorail, while my right leg is more or less parallel to the monorail. I image the original cause may be bad technique, with my right side doing more work than my left. In any event, this seems to have affected the mechanics, and I can't straighten things up by deliberately pulling harder with my left hand side. An inspection of the under-carriage of the seat today may provide a clue to the cause and a solution: the bearing on the front, ride hand side, is not in contact with the monorail. I assume the ideal is to have the bearings meeting the monorail overall? Any thoughts on this problem? Any advice gratefully received - thank you!

[mict450]

Hi everyone, I have a Model D and have started noticing that my legs are not well-aligned to the monorail, ie when seated, my left leg seems to travel in an angle from my toes up to my hip towards the monorail, while my right leg is more or less parallel to the monorail. I image the original cause may be bad technique, with my right side doing more work than my left. In any event, this seems to have affected the mechanics, and I can't straighten things up by deliberately pulling harder with my left hand side. An inspection of the under-carriage of the seat today may provide a clue to the cause and a solution: the bearing on the front, ride hand side, is not in contact with the monorail. I assume the ideal is to have the bearings meeting the monorail overall? Any thoughts on this problem? Any advice gratefully received - thank you!

Welcome to the forum. So, if I understand you correctly, the front top seat roller is not in complete contact with the rail? Did you buy this new or is it used?

[Citroen]

Since you can get a new pair of seat rollers for USD$20 it wouldn't hurt to just replace the pair and see how you go from there.

https://shop.concept2.com/parts/105-sea ... r-top.html (you need two)

[jackarabit]

How about twisting deformation of the seat carriage end brackets. The torquing force created by your leg drive could be a contributor. What do you weigh?

There used to be a fellow on here name of Peterson, did C2 erg repair/refurb in the Philadelphia/Camden NJ area, who routinely replaced the brackets along with the rollers on high use machines.

[mict450]

How about twisting deformation of the seat carriage end brackets. The torquing force created by your leg drive could be a contributor. What do you weigh?

I was thinking that the brackets could be racked, but more so from some daft repair/modification job on a used erg. They're pretty sturdy....I can't imagine poor technique causing them to be bunged out of alignment.

[ampire]

Hi everyone, I have a Model D and have started noticing that my legs are not well-aligned to the monorail, ie when seated, my left leg seems to travel in an angle from my toes up to my hip towards the monorail, while my right leg is more or less parallel to the monorail. I image the original cause may be bad technique, with my right side doing more work than my left. In any event, this seems to have affected the mechanics, and I can't straighten things up by deliberately pulling harder with my left hand side. An inspection of the under-carriage of the seat today may provide a clue to the cause and a solution: the bearing on the front, ride hand side, is not in contact with the monorail. I assume the ideal is to have the bearings meeting the monorail overall? Any thoughts on this problem? Any advice gratefully received - thank you!

Another thought is it might come from a leg length discrepancy. If that is the case, you could see a PT and have a lift orthotic added to the shoe of the short leg.

[Tartuk]

@ampire, @mict450, @jackrabbit, @citroen...

Thank you for the welcome! Please bear with me as I figure out the protocols for posting. If it's better to reply individually, just let me know.

Answers to the collective questions:

Yes, you have understood my description of the problem correctly - the front top seat roller is not in complete contact with the rail. I bought the rower brand new. It's done 1.3mill metres and I'm the only person who uses it.

I weight 145 lbs, 5ft10in or 66kgs, 179cm. I do a little weight-lifting, but doubt have I have strength to twist the materials out of shape. There's been no modification or repair work done on the erg, daft or otherwise! Other than routine maintenance, it's as it came out of the box. Unfortunately I'm not in the United States, so it would be good to find an equivalent person in my own country (NZ) who could have a look.

Different leg lengths had not occurred to me; interesting. I'm 55 years old, though, so think it would have manifested itself sooner in other ways? But I will check, anyway.

The problem causes the seat to wobble quite a bit - less so, obviously, when I'm sitting on it and rowing, but still. I wonder if this is exacerbating the whole problem. The rollers themselves look ok, but at least replacements are in stock here, so I'll give that a go.

Thanks again!

[c2jonw]

I'd try this- loosen the two nuts and bolts that hold the two top rollers in place- just loose enough so they can be turned by hand in the frame. Now have someone sit on the seat as you retighten the fasteners. Worth a try.

[Tartuk]

Thank you, I'll give that a try!

[jackarabit]

. . . Unfortunately I'm not in the United States, so it would be good to find an equivalent person in my own country (NZ) who could have a look.

Might contact Carl Watts, Kiwi and member here, does C2 repairs, mostly PM electronics refurb but also experience troubleshooting/correcting mechanical issues. Don’t know which island (think maybe he has a repair service in Auckland) but as near as a private message or he may see the thread.

(Googled him. Currently located Tauranga.)

[ampire]

Different leg lengths had not occurred to me; interesting. I'm 55 years old, though, so think it would have manifested itself sooner in other ways? But I will check, anyway.

I have a slight leg length difference that isn't visually noticeable to an untrained eye. I only learned about it due to suffering some repetitive strain leg issues when I was running track and cross country in high school. I am not certain which of my legs is the shorter one as it has been 20 years, but I have notice my own rowing stroke isn't entirely symmetric between legs and my feet splay slightly to accommodate it. I sometimes feel like I am mis-aligned with the rower seat.

When I was in high school, a physical (physio) therapist carefully measured my legs and I was issued an orthotic, which I found to be too firm and unpleasant to actually run on. I no longer have it, unfortunately, or I would try adding a slight bit of foam to the shoe of the shorter leg, alas I don't know which leg is the shorter one anymore, just the lingering suspicion that it influences my leg drive asymmetry.

My roller bearings all ride evenly, for what its worth.

[jackarabit]

Different leg lengths had not occurred to me; interesting. I'm 55 years old, though, so think it would have manifested itself sooner in other ways? But I will check, anyway.

I have a slight leg length difference that isn't visually noticeable to an untrained eye. I only learned about it due to suffering some repetitive strain leg issues when I was running track and cross country in high school. I am not certain which of my legs is the shorter one as it has been 20 years, but I have notice my own rowing stroke isn't entirely symmetric between legs and my feet splay slightly to accommodate it. I sometimes feel like I am mis-aligned with the rower seat.

When I was in high school, a physical (physio) therapist carefully measured my legs and I was issued an orthotic, which I found to be too firm and unpleasant to actually run on. I no longer have it, unfortunately, or I would try adding a slight bit of foam to the shoe of the shorter leg, alas I don't know which leg is the shorter one anymore, just the lingering suspicion that it influences my leg drive asymmetry.

My roller bearings all ride evenly, for what its worth.

. . . and the osteopath cried Wee Wee Wee all the way to the bank! Differential muscular development and function leg to leg is very possible. The bone-measurers are quacks. Much of the current literature concludes that discrepancies as large as 20mm in the collective length of bone and collective tissue armature side to side are routinely compensated by functional adaptation. Could be Tartuc’s seat carriage mech has also adapted to repetitive wracking forces. Or could be the seat bottom is in winding? If the seat carriage was a 5 lb. braced weldment, the probability of maintaining axle alignment against wracking loads would be much higher than for two independent axle-mounting brackets.

[ampire]

Different leg lengths had not occurred to me; interesting. I'm 55 years old, though, so think it would have manifested itself sooner in other ways? But I will check, anyway.

I have a slight leg length difference that isn't visually noticeable to an untrained eye. I only learned about it due to suffering some repetitive strain leg issues when I was running track and cross country in high school. I am not certain which of my legs is the shorter one as it has been 20 years, but I have notice my own rowing stroke isn't entirely symmetric between legs and my feet splay slightly to accommodate it. I sometimes feel like I am mis-aligned with the rower seat.

When I was in high school, a physical (physio) therapist carefully measured my legs and I was issued an orthotic, which I found to be too firm and unpleasant to actually run on. I no longer have it, unfortunately, or I would try adding a slight bit of foam to the shoe of the shorter leg, alas I don't know which leg is the shorter one anymore, just the lingering suspicion that it influences my leg drive asymmetry.

My roller bearings all ride evenly, for what its worth.

. . . and the osteopath cried Wee Wee Wee all the way to the bank! Differential muscular development and function leg to leg is very possible. The bone-measurers are quacks. Much of the current literature concludes that discrepancies as large as 20mm in the collective length of bone and collective tissue armature side to side are routinely compensated by functional adaptation. Could be Tartuc’s seat carriage mech has also adapted to repetitive wracking forces. Or could be the seat bottom is in winding? If the seat carriage was a 5 lb. braced weldment, the probability of maintaining axle alignment against wracking loads would be much higher than for two independent axle-mounting brackets.

I agree about the frequent quackery relating to posture, bone length discrepancy, etc. It is overblown, and I have experienced it enough personally from PTs before I had a diagnosis. Anecdotally, Usain Bolt, fastest man in the world, has scoliosis and a leg length discrepancy associated with it and he has presumably adapted to it as evidenced with his amazing olympic sprinting career. I have slight scoliosis (which likely the cause of the leg length discrepancy) relating to the T4-T5 spinal cord tumor I had and since having that out courtesy of a world class neurosurgeon, coupled with a lot of my own self directed walking, rowing, and weight lifting, a lot of my spine has noticeably straightened out, not sure if I had started using orthopedic devices early on following the surgery whether my body would continue to straighten as much as it has, I'd rather not have that straightening and healing process halted, that is one reason I haven't experimented with orthotics for rowing... yet. On the other hand, I have considered it as an experiment to see if it would make my seat position less cockeyed and more comfortable.
As an aside, I am pursuing a career change to become a physical (physio) therapist due to my interest in rehabilitation, I'd like to do a better job for future patients than the PTs I encountered when I was ill.

Apology if I derailed the thread. Just figured it might be a cause for uneven roller bearing wear and OP's description of leg form asymmetry.

[jackarabit]

Don’t think the thread is derailed. As experienced gamba cortas we followed up on Tartuk’s speculation about causation. He can’t possibly derail his own thread, can he? Fixing or replacing the seat is pretty simple and painless cf. to fixing and maintaining the only body we’re ever gonna have. I usually assume that those who set the stage will stay to see the play.

[Tartuk]

I don't think the discussion has been derailed; rather, some very interesting points have been made! Grateful for all the input. I'll follow up on the suggestions when able (I'll need to bring in an extra pair of hands to try the loosening/tightening suggestion a few posts back) and report back on progress, in case it helps anyone else.