Do I have a "regular height" or "low version" Sargent seat?

[pwillikers]

My Sargent seat doesn't fit me well.  It is tilted toward the rear of the bike and induces low back pain on extended rides.  

 

Do I have a "regular height" or "low version" Sargent seat? 

 

These are the most representative measurements I could come up with.  90mm from the bottom of the seat mounting tab to the seam at the top of the rear of the seat.

 

 

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[Dave_in_TX]

What model BMW do you have?

[pwillikers]

Camhead, specifically a 2011 R1200RT (Model: K26, 0440).

 

[don v]

I have that bike and a low Sargent seat. My guess is that is a low seat with the front bar adjuster set in the high position. Take a picture from the side of the bike with the seat mounted for a proper guestimate.

 

P.S. I just measured my Sargent seat as you did and my low seat measures 70 mm. Is your front seat adjuster bar set in the high position?

[pwillikers]

Yes, I have the front mount in the upper position.  Your supposition does make sense.

 

The perches for the rider seat (that receive the rubber bumpers which are attached to the bottom of the rear of the seat) have two positions with the lower ones slightly forward of the upper ones.  The rear of the seat is in the rearward/upper position of the perchs but the seat is still canted to the rear.

 

I'll do some fiddling and take some pictures.

[Dave_in_TX]

21 hours ago, pwillikers said:

2011 R1200RT (Model: K26, 0440).

 

That's the important information. The camhead GS, RS/R, and RT have different seats.

[pwillikers]

Here are some pics.  My phone's camera has a the capability to superimpose a level line so all the pics of the seats are properly aligned to  the horizontal.

 

Here's the seat in the low position.  You can see how the rider seat is tilted rearward.

 

Here's the seat in the high position. Again canted to the rear.

 

I fabricated a solution to level it out. Attached is a picture the rider seat perch and several additional pictures showing a 1/2" aluminum spacer I made which raises the perches and thereby raises the rear of the seat.

The frame section on which the perch mounts is itself canted forward so a uniform thickness spacer moves the perch up and, also undesirably, moves the perch closer to the seat mount at the tank.  This makes installing the seat a tight fit. The spacer really needs to be a wedge, i.e. thicker at the front.

I ended up shimming the front of the spacer up with some 1/8" aluminum stock. The seat now installs easily as it should.  It's a bit kludgy with the spacer but seems to work fine.

Most importantly, it is much more comfortable. :-)

 

 

 

 

 

And here are some more pics of the seat in both the low and high positions with the spacers installed.   You can see that the rider seat has been leveled out and is much more agreeable on my lower back.

 

Here it is in the low position with the perch spacer installed

 

and in the high position with the perch spacer installed.

 

I'm going to leave it in the high position with the spacer installed and ride it for a longer term evaluation.