Why didn't BMW go with a 18/21" combo for the F800GS?

Discussion in 'Parallel Universe' started by bastimentos, Feb 17, 2013.

  1. bastimentos

    bastimentos Been here awhile

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    Please bear with me if it is a stupid question, but I tend to think of the F800GS as BMW's attempt to make a GS that is a lighter, and more capable machine offroad than its big brother - while still retaining civilised road manners and pillion comfort.

    Maybe that's not what they were going for and I've misinterpreted it, but say they were aiming for this - why did they go with the 17/21 wheel combo over an 18/21 that has seen action in offroad oriented bikes such as KTM's and the HP2E to good effect?
    #1
  2. shashankmittal

    shashankmittal Adventurer

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    I could be wrong, but I think the reason for 17" rim is that 17" is pretty much an industry standard these days for dirt, sport and ADV bikes. There are more tire choices for 17" rims and tire availability is not so much of an issue (specially in scenarios when there aren't too many bike shops around).
    #2
  3. seasider

    seasider Just a rider

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    HP 2 had 17 rear stock. But yes I agree having owned one a short time. The 18 rear would be a better separation from big brother which I went back to happily.
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  4. Pangia

    Pangia Been here awhile

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    Shashank: Why are you saying the 17" is a standard for dirt?
    As far as I know, all 250 and 450 dirt bikes have 18/21 as stock and I don't think that trend is changing. 18" is also stock on KTM690 and I believe the KTM 990 Adventure as well.

    I am interested in this question that was originally raised in this thread, Why didn't BMW go with a 18/21" combo for the F800GS... and how an 18" might change the F800GS dynamics. I have an 18" rear (Excel rim by Woody's) but I have not ridden either the 18" or the 17" enough to give a fair comparison as I have a new F800GS. I ride 70% off road / 30% on.

    Anyone else?
    #4
  5. ebrabaek

    ebrabaek Long timer

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    17 are widely agreed to be better on road.... 18 better in the dirt. Strange thing is.... after woody'ing my 8gs with a tubeless 18 inch, it is now better both on and off road. :D:D
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  6. JustBob

    JustBob Uh...who me?

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    When Woody did the rear on my 8GS I didn't know I had the option for an 18. Dang. Slightly off topic, but he wouldn't make the front 21 tubeless. Don't know why. Anyway, I'll have a new to me '10 KTM 690ER and it comes with the 18/21 combo.
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  7. TowPro

    TowPro Lets ride

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    Who knows?

    maybe 17" was to keep the seat height down to earth?
    maybe 17" because most 17" tires are DOT and lots of 18" are not DOT?

    I am just glad I got the 21" front wheel. Most ADV bikes are doing small front wheels as well.
    As soon as I test rode my F800, I knew this was the bike for me because of the way a 21" handles.
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  8. Loutre

    Loutre Cosmopolitan Adv

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    I didn't like how the 21" handled. come from a 17" then a 19 but though well that is a great bike to get on and like everything you need to get used to (ever had an emo GF? :lol3)

    well even though, lets stay on topic: I think they went 17 because of the street orientation of every GS. more tire options and it wouldn't satisfy most of the none 50/50 buyers out there. it's like everything BMW does: marketing!
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  9. picard

    picard engage!

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    21" rims in 1.6 - 2.15 sizes don't have enough of a bead groove for a TL tire to sit in. That's why Woody can't do a tubeless setup for you.
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  10. JustBob

    JustBob Uh...who me?

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    Thanks. I figured it was something like that. Now I know. The rear he did a year ago is flawless. Holds air better than a tubed rim.
    #10
  11. boomer bike-travel

    boomer bike-travel the F 800GS ADV twins

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    We are glad BMW chose the 17" because otherwise there would have been some places on our trip around the world where finding a new rear tire would have been a tough challenge :D
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  12. woody's wheel works

    woody's wheel works Built to Last

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    Here's the straight skinny,,,,

    Folks,we can seal most anything for tubeless,,,HOWEVER....knowing what I know,,cannot in good conscience seal certain rims...

    Here's why:

    1,,in the old days before tube-less one relied on the tube to push the tire in place and hold it there,,,the interface between rim bead and tire bead was close but not to exacting standards....slow leaks weren' too ibig. A problem ,,but tire punctures often had the same effect as pricking a balloon with a pin,,,BOOOM and instant pressure loss resulting in the tire slipping off the bead with disastorous consequences...

    2,,pneumatic tubes solved the problem during the transition time from wire wheels to steel rims and eventually cast wheels

    3,,with higher highway speeds came the awareness that tubed tires (TT) started failing and causing premature tire wear because of the excessive heat build-up caused from the friction between tire and tube.....

    4,? VOILA!!!! Why not get rid of the tube???,,less weight/cheaper/safer/better wear characteristics,,,,but what happens when ya get a nail or flat,,well same thing as TT,,,hence the safety bead was born and answer much tighter set of standards for rim/tire bead interfaces...so ,,,tubes-less(TL) tires are differentiated from their TT predecessors...'tips the safety bead or lack of one that is the main reason why I am willing to seal or not seal your wheel...

    5,, another reason I will or won't seal a wheel has to do with the type of riding you do and whether the rim choice is adequate for the job....there are certain 21" rims I will seal for a chopper/street-rod but won't for dual-sport use because of their tendency to bend easily with hard off-road use

    There ya have it:freaky

    Woody
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  13. _cy_

    _cy_ Long timer

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    original R80 G/S also came with 21/18 ..
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  14. bdx

    bdx Wheeeee!

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    I wondered the same thing about the 17" rear. When I was shopping 18" rears for my G650X, there was a myriad of DOT dirt tires and for the most part they were cheap. I ended up putting the MEFO Super Explorer on a couple thousand miles before I sold it and I LOVED THAT TIRE. So when I got my 8gs I went right back to MEFO and they don't make that tire in a 17". Ended up with the Heidenau which is OK, but the Super Explorer looked great on the bike, looked aggressive but had great road manner and would hook up in anything. It seems that DS tires in the 17" are mostly street tires with a few exceptions. Yes, I know the Conti looks great, but if I'm going to spend that much on a tire, I want it to last more than 4K.
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  15. Murf2

    Murf2 Been here awhile

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    What tubeless 18 inchers have you used? I didn't seem to see many when I was looking but a lot of them didn't say TT or TL on the interweb.
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  16. JustBob

    JustBob Uh...who me?

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    None. Never had many 18"ers.
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  17. woody's wheel works

    woody's wheel works Built to Last

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    FYI,,,you just swap em out!!!:wink: better off road manners to boot,,you'll need a different spoke kit and possibly a different rear sprocket,,will also raise rear end circa 3/4''

    just saying the off road crowd digs em the most
    woody
    #17