Rider backrest query
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Tourer
Joined: Jul 2019
Posts: 408
Likes: 103
From: Chesterfield, UK
Rider backrest query
I’ve just installed the rider backrest (52900-09A) for my 2019 road king and after using it today I wondered how much load it can take?
I’m a pretty big guy, 6’4” weighing approximately 270 pounds and all too aware that under acceleration and cruising at 70-75mph without the windshield on there’ll be a considerable amount of force going through the backrest, and that the backrest is only really two metal rods and I wonder just how strong these are. Also I have it set at its highest meaning that the support is probably at the weakest it can be. I can’t find any info on the Harley site as to the loads it can take, does anyone know? Am I being a bit over paranoid?
I’m a pretty big guy, 6’4” weighing approximately 270 pounds and all too aware that under acceleration and cruising at 70-75mph without the windshield on there’ll be a considerable amount of force going through the backrest, and that the backrest is only really two metal rods and I wonder just how strong these are. Also I have it set at its highest meaning that the support is probably at the weakest it can be. I can’t find any info on the Harley site as to the loads it can take, does anyone know? Am I being a bit over paranoid?
Tourer
Joined: Mar 2015
Posts: 469
Likes: 130
From: Portland, Oregon
I think it's unlikely you will have a problem. You would need to accelerate 0-60 in under 3 seconds to produce 1g force. And even at that acceleration, a good portion of your weight will be transferred to the ridge in the seat, and even more will get transferred to the handle bars. Short of sitting on the backrest while popping a wheelie, I doubt it's possible for you to transfer more than half your weight to the backrest.
I doubt the rods are hardened, so I suspect they are far more likely to bend rather than just break. I'm not sure how comforting that is, but it does mean you should feel it giving way more gradually than a sudden break.
But if you really want to know...you could test it under controlled circumstances by putting your hands on the handle bars and feet on the crash bars and pushing with both as hard as you can. That's likely going to generate more force than even the most extremer riding. And while it may break your backrest...it won't be at 70 mph on the highway. But if you do that...be sure to post pictures :-)
FYI...I'm about 270 as well and I've never worried about the backrest. But then...I have the adjustable style which has about a 3" wide and 1/4" thick bar.
I doubt the rods are hardened, so I suspect they are far more likely to bend rather than just break. I'm not sure how comforting that is, but it does mean you should feel it giving way more gradually than a sudden break.
But if you really want to know...you could test it under controlled circumstances by putting your hands on the handle bars and feet on the crash bars and pushing with both as hard as you can. That's likely going to generate more force than even the most extremer riding. And while it may break your backrest...it won't be at 70 mph on the highway. But if you do that...be sure to post pictures :-)
FYI...I'm about 270 as well and I've never worried about the backrest. But then...I have the adjustable style which has about a 3" wide and 1/4" thick bar.
Thread Starter
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Tourer
Joined: Jul 2019
Posts: 408
Likes: 103
From: Chesterfield, UK
I think it's unlikely you will have a problem. You would need to accelerate 0-60 in under 3 seconds to produce 1g force. And even at that acceleration, a good portion of your weight will be transferred to the ridge in the seat, and even more will get transferred to the handle bars. Short of sitting on the backrest while popping a wheelie, I doubt it's possible for you to transfer more than half your weight to the backrest.
I doubt the rods are hardened, so I suspect they are far more likely to bend rather than just break. I'm not sure how comforting that is, but it does mean you should feel it giving way more gradually than a sudden break.
But if you really want to know...you could test it under controlled circumstances by putting your hands on the handle bars and feet on the crash bars and pushing with both as hard as you can. That's likely going to generate more force than even the most extremer riding. And while it may break your backrest...it won't be at 70 mph on the highway. But if you do that...be sure to post pictures :-)
FYI...I'm about 270 as well and I've never worried about the backrest. But then...I have the adjustable style which has about a 3" wide and 1/4" thick bar.
I doubt the rods are hardened, so I suspect they are far more likely to bend rather than just break. I'm not sure how comforting that is, but it does mean you should feel it giving way more gradually than a sudden break.
But if you really want to know...you could test it under controlled circumstances by putting your hands on the handle bars and feet on the crash bars and pushing with both as hard as you can. That's likely going to generate more force than even the most extremer riding. And while it may break your backrest...it won't be at 70 mph on the highway. But if you do that...be sure to post pictures :-)
FYI...I'm about 270 as well and I've never worried about the backrest. But then...I have the adjustable style which has about a 3" wide and 1/4" thick bar.
Club Member
Joined: Jun 2007
Posts: 45,429
Likes: 2,898
From: Bedford UK
The part number of your backrest 52900-09A indicates it was introduced in 2009 and the extra 'A' that it has been revised since then. So as a product it's been around for over a decade! And I doubt if you are any bigger than some of the other owners of it!!!! 
Ride on in confidence.....
Ride on in confidence.....
Thread Starter
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Tourer
Joined: Jul 2019
Posts: 408
Likes: 103
From: Chesterfield, UK
The part number of your backrest 52900-09A indicates it was introduced in 2009 and the extra 'A' that it has been revised since then. So as a product it's been around for over a decade! And I doubt if you are any bigger than some of the other owners of it!!!!
Ride on in confidence.....
Ride on in confidence.....
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Road Master
Joined: Aug 2012
Posts: 1,008
Likes: 229
From: Saskatchewan
Even with a back rest I would think the handle bars are still taking most of the forces from acceleration.
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Thread Starter
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Tourer
Joined: Jul 2019
Posts: 408
Likes: 103
From: Chesterfield, UK
I was surprised how much was going through the backrest tbh.
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