15T vs 16T on the front sprocket - '16 /F800GS

Discussion in 'Parallel Universe' started by Scarfall, Feb 29, 2020.

  1. Scarfall

    Scarfall Adventurer

    Joined:
    Jan 22, 2020
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    17
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    UK
    Hi guys,

    I'm the poor soul who's been trying to remove his front sprocket and been posting here.

    I am taking the bike to a BMW mechanic who says he's dealt with a few seized sprockets. So very soon I'll be replacing the sprockets and chain.

    This bike stock comes with 16 teeth on the front. I was advised these bikes really benefit from a lower gearing for normal city riding. I was also told that this only applies to F800GS built before 2014, as in that year the fueling was fixed.

    Will I see any appreciable benefit from dropping a tooth in the front? Even though my bike is from 2016? My riding is 98% road around the city.

    Thanks
    #1
  2. Nunnga

    Nunnga n00b

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    Hi Scarfall I have a 2015 F800gs and I changed the front sprocket to a 15T. I did it because I felt that the 1st gearing was too tall for my use of the bike as I do a fair bit of off road. It has made it better to take off, haven’t really noticed much of an increase of fuel usage and probably only knocked off about 5 odd kms of the top speed. I would give it a go and if you don’t like it it’s very easy to change it back to 16T plus another front sprocket is only about 30 to 40 bucks.
    Mine was easy to change as it just slipped off after undoing the nut. If it has seized just use some penetrating oil and a two or three legged gear puller and they normally fall off.
    #2
  3. JimsBeemer

    JimsBeemer 2017 R1200GSA Supporter

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    Not apples to apples because I don’t know if gear box ratios and rear sprockets are the same, but I changed my wife’s F700GS from OEM 17 tooth to 16 tooth using f800 oem sprocket, for better low end in dirt. Was a definite improvement- she was happy with it. But it still needed “more” and I was considering a 15 tooth, but then came across the Rekluse auto-clutch. Kept the 17 tooth sprocket. That (Rekluse) made a HUGE difference. She constantly is thanking me for installing the Rekluse. Not an inexpensive upgrade though. It is a blast to ride with it!

    But bottom line is “just try it” (15 tooth). It is (should be, once your current issue with frozen sprocket are resolved) an easy and inexpensive thing to try out, and revert back if you are not happy. I got the sprocket from a dealer in Guadalajara Mexico and did the swap in the courtyard of our hotel using just the toolkit I had on the bike, in a hour or so.

    Note that one negative is that she looses gear indication in the instrument display with the non-stock sprocket, after reaching sixth gear, and it doesn’t come back until coming to a complete stop in first and restarting. This is a known issue (whole threads on the topic) on late model (I think 2017 and up) F700’s, I don’t know if similar occurs with the same model year F800’s.
    #3
  4. morfic

    morfic Been here awhile

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    Not all 2017 F700GS, some don’t mind the 16T or 15T at all.

    The verdict is out on what causes the gear indicator to work or not after a front sprocket change, so I’d suggest OP just gets the ~$30 15T and gives it a whirl to check for taste.

    I would suggest you do get the BMW MP3 paste or an equivalent (in Europe Castrol Optimol iirc is the same exact thing, not available in the US, many older equivalents weren’t available anymore so I bought the BMW paste), just so your sprocket keeps coming off easy next time, and your spline is protected from further damage.
    #4
  5. Scarfall

    Scarfall Adventurer

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    Will I see any difference in city riding? Will the vibrations be ok at 70mph?
    #5
  6. dpike

    dpike BeeKeeper Supporter

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    you will absolutely see a difference in city riding. i'm a fan of the 15 tooth sprocket.
    #6
  7. csw1742

    csw1742 Black Diamonds Supporter

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    Pensacola/Idaho
    Ditto, @dpike. Did my 2011 F800 before an extended (6350 mile) trip through the west and never felt the need for taller gearing. Much better off road and minimal change on road.
    Worth it to me !
    #7
  8. Grafspee

    Grafspee one bike is never enough

    Joined:
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    I believe you will see the vibrations move down to a slightly lower RPM - I considered moving to a 17 tooth sprocket to move the vibrations up in the RPM range as my F800gs is more a road bike now since I purchased a smaller dualsport bike. However I will likely stick with the 16 tooth sprocket as I rarely ride at interstate speeds for extended periods. I enjoy the F800gs the most on broken oil/chip and crooked backroads - lighter traffic. Years ago I learned when traveling on the bike to avoid large population areas and make my routes thru the contryside. It takes longer to get somewhere, but you know what - who cares I'm on a motorcycle ride. Smaller police presents also as I tend to ride well above the speed limit on my 800GS.
    #8
    morfic likes this.
  9. ADVwxyz

    ADVwxyz yep

    Joined:
    Aug 11, 2015
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    vancouver
    Stock 16/42.

    I have had it set at 15/42
    but the best travel set up imo is:
    17/43 for highway , then changing to 15/43 for dirt.

    The 17/43 is slightly better than stock gearing for highway, but at 15/43, you have low end dirt torque.

    17/43 from Vegas to Mex border, 15/43 in Baja.

    At 15/42 your top end is less, milage is less at highway speeds. Opposite at 17.

    fwiiw
    #9
  10. Tigershark48

    Tigershark48 My other BMW is a Roadster.

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    This is the spline grease readily available on Amazon that’s equivalent to what Morfic recommended. The tube is roughly 1” in diameter and 4” long, so smaller than expected making it pretty pricey. As you’ll find, high quality grease (that won’t dry up and freeze your sprocket again) is not cheap, but a little goes a long way. It’s doubtful that you’ll ever use it up.

    https://www.amazon.com/Kluber-Micro...ywords=Kluber+microlube&qid=1583328988&sr=8-3
    #10
  11. spencermarkd

    spencermarkd Been here awhile

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    15T is fun. It'll raise your RPM's for any given speed, so at 70mph in 6th gear your RPMs will be a few hundred higher. Not a huge difference though. I lost many MPG's cause I was tearing away from every stoplight and grinning the whole time. More smiles per gallon for sure.

    If I was going cross country I'd probably throw the 16T back on or go to a 17T but around town 15 is perfect.
    #11
    morfic likes this.
  12. Scarfall

    Scarfall Adventurer

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    Thanks guys.

    I just got the 15T fitted, and boy is it fun. Makes it much sportier around town and highway but past 70mph you feel like you're pushing the bike too hard.

    I also got a new 16T which I'll save for the summer long rides.
    #12
    dpike likes this.
  13. ROMAD

    ROMAD Been here awhile

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    I tried the 15 and loved it! I ended up going back to a 16t using a JT rubber mounted and a 45t rear (supersprox) and love the combo. I ended up using a 119 link DID X ring chain after checking things out on gear commander and looking at where the rear axle ends up with 118 or 119 links.

    I wasnt sure if the rubber mounted front sprocket would be noticeable but I felt it made a nice improvement.
    #13
  14. Tigershark48

    Tigershark48 My other BMW is a Roadster.

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    I’ve always done rubber mount sprockets in front. Just going neutral to first, they’re smoother and quieter.
    #14
  15. ROMAD

    ROMAD Been here awhile

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    I always used to take them off when I first got a bike that had them from factory like DRZ or DR650. I was surprised at the noticeable difference it made on the GS. Its a nice upgrade for sure.
    #15