BMW G310GS Thread

Discussion in 'Thumpers' started by Eddy Alvarez, Apr 22, 2016.

  1. JMo (& piglet)

    JMo (& piglet) Unicorn breeder

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    Thanks for the quick reply GNR' - for info (and for anyone else wondering), I know someone posted a link to a gearing calculator before, but I found this simple site here that helps to work out the difference in ratios (plus how many +/- links in the chain length are likely to be required too).

    Based on the stock gearing being 16/40 - that equals a 2.5 ratio...

    15/40 = 2.67 = -6.3% (GNRs bike currently)

    16/43 = 2.69 = -7.0% (My bike currently)

    15/41 = 2.73 = -8.5%

    15/43 = 2.87 = -12.8%

    ...the percentage change is the drop in speed for the same amount of RPM, or conversely the % increase in torque.

    So in summary, changing the front sprocket by -1 tooth (as GNR has just done) offers a little less % change than adding +3 teeth to the rear (as I currently have on my bike), while going to 15/41 offers more of a drop, and is, as I suspected, probably the best combo for more serious off-road use, while retaining reasonable on-road performance too. Any more than that (eg. 15/43) would be too much of a compromise on road I imagine.

    for info. the rear sprocket PCD on the G310GS is the same as the twin-cylinder F650GS, so technically you could grab an OEM rear sprocket from that bike (47T) and go crazy - however, 16/47 = 2.94 = 14.9% - so probably way too extreme for most owners.

    Hope that helps...

    Jenny x

    ps. I'm going to hang onto the 43T rear though to pair with a 15T front - just in case I decide to ride the Rubicon on this bike too ;o)
  2. ChappyADVR

    ChappyADVR Adventurer

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    That really does help - breaks it down nicely! Thanks @JMo (& piglet)!
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  3. rwiles

    rwiles Been here awhile

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    Losck some vice grips on a spring at the bottom of the hook, in line with the spring, good and tight. Lay down to get pull leverage. Pull the spring hook over the stud to the furthest groove first, and pop off the vice grips. If a weak old man like me can do that pretty easily, anyone can.
  4. Jeepster360

    Jeepster360 Been here awhile

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    Ok, so the 15 tooth front is in. Took about 30 min to install and adjust the chain. Took a 45 min ride around town and down river road. First off.........anyone who has this bike should consider this modification. We have a lot of 35mph roads in my town. With stock gearing, on the flat and level, 5th gear was ok at 35mph but just under 4000rpm. There wasn't much torque available at that speed. 4th gear was fine but if traffic moved up to 40mph it felt a little too low. 5th gear now fits the 33 to 40mph traffic perfectly for me. Pulling away from stop lights is much better. Feels much more "normal" to me. Out on the river road at 60mph the tach looks like 6100-6200rpm. I do have a 804 tire fitted to the front so keep that in mind if the Speed/rpm is off alittle. I can't believe highway travel will be diminished at all. The bike might even pull this gearing to a higher top speed overall in 6th gear.(slightly higher RPM of course). After this short ride I see no down side to this 15t front sprocket. Off road it should be a little better(could use more I'm thinking). In town it is better for sure. Highway is just as good up to 65mph atleast and maybe 70. I don't ride faster then that myself so YMMV. Best $35 I have spent on this bike for sure.

    This is the gearing BMW should have gone with from the factory. In fact, it's almost not noticable yet better in every way.

    John
  5. ovlaicu

    ovlaicu Noob

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    Where did you guys order the 15 tooth sprocket from?

    Sent from my SM-G950W using Tapatalk
  6. Citizen

    Citizen Been here awhile

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    Supplier in Illinois somewhere I believe.
    It's back a few pages.
  7. GreatNorthRider

    GreatNorthRider Adventurer

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    The 15t sprocket is ordered from KHS Bicycle Parts....http://www.khsbicycleparts.com/
    The Esjot part number for the 15t front is: 50-32184-15S
    The Esjot part number for the 41t rear is: 50-32050-41
    You’ll want to talk to Betty @ 618-393-2955. I have warned her that she may be getting a few more orders. :lol3
  8. ovlaicu

    ovlaicu Noob

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    Thanks a lot.

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  9. sonmaix

    sonmaix n00b

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    What about acceleration? Is 1-60 better with 15T sprocket?
  10. Jeepster360

    Jeepster360 Been here awhile

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    I don't really know if 0 to 60mph is faster or not. I'm not into that part of the game with this bike and what I use it for. I can tell you if you are cruising down a street at 35mph in 5th gear acceleration is better. 0 to 60 could be better, it depemds on the shift points or number of shifts vs the old gearing. If both take the same number of shifts then the 15 tooth is most likely faster.

    John
  11. HorakCM

    HorakCM Adventurer

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    Also put the 15t on, nothing really new to add the other members haven't already said, does exactly what you'd expect. Easier to lift or deweight the front wheel, less throttle input to chug along at low speed. Highly recommended if you ride tight trails.

    I wonder if a similar ratio was considered from the factory but changed to a higher option to lower revs/noise at speed? Will consider going larger on the rear after a few hundred miles. I try to avoid it but sometimes need 70+ to keep up with highway speed limits/traffic. Per gearing commander, a 15/41 will have a top speed of around 88mph, 15/43 will max out at around 84mph and may require a longer chain.
  12. stevetheb

    stevetheb mashed potatoes

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    It's extremely hard to go past 84 with the RR lvl 2 suspension and tall windscreen on. You can do it, after WOT for a long period of time and proper conditions (new top with RR kit of 88mph). Maybe I'll consider the 15t.
    HorakCM likes this.
  13. richard cabesa

    richard cabesa The Mayor Supporter

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    HEY !!! Look what followed me home :clap

    [​IMG]

    Just hit 200 miles so next ride out I get to twist the grip a little further :wings
  14. HorakCM

    HorakCM Adventurer

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    I'm waiting on a Level 1 from RR. Today it managed to hit 80 with the 15t on flat highway, although it felt like it was already maxed out so I wouldn't be surprised if the actual speed is 5-10mph lower than on paper.

    Then I found the baby GS's limit.

    20180808_212100.jpg

    ...hillclimbs. And now it gets to live in the woods through a thunderstorm, until it dries out.

    20180808_222205.jpg

    But at least it has a key and steering lock to deter any thieving deer? ‍
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  15. ChappyADVR

    ChappyADVR Adventurer

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    Do I recall that you were on Shinkos? Because that was my exact problem. Muddy hillclimbs. Except first thing in the morning, no storm, and fewer deer.
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  16. HorakCM

    HorakCM Adventurer

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    Yup! Shinko 804/805. I've been very impressed with how well they've been working and they've made that climb before, but that slick clay did them in. With both brakes locked up it still slid backwards downhill. :fpalm
  17. ChappyADVR

    ChappyADVR Adventurer

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    Haha, yes, that's *exactly* what happened to me. At least you managed to keep yours upright. I wasn't so skilled... :muutt
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  18. sonmaix

    sonmaix n00b

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    Maybe I'm in a wrong topic, but I have a few concerns with my GS.
    Sometimes throttle becomes jerky from idle. Like then closing throttle to decelerate and then opening it up just a tiny bit, it is jerky. Other times it's smooth again.
    I have this strange feeling with rear suspension. Then going over bigger whoops or holes, sometimes the rear is like diving and for a fracture of moment, it almost feels like I lose torque or wheel is stuck. I'm 67 kg without gear, have added 6 klicks of preload and it's better, but not completely eliminated. Also I get occasional very slight rear wheel wobbling.
    1 month and 600 km.
  19. ChappyADVR

    ChappyADVR Adventurer

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    Hmmmm, if I were you, I'd be seeing my dealer about that. Could be something loose or binding in the rear end? Someone else might have better insight though...
  20. mbikeboy

    mbikeboy Adventurer

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    I recall suggesting some TKC80's before you went ahead with the Shinko's mate! ;)