21" wheel on a 2007 GSA

Discussion in 'GS Boxers' started by Zpider, Nov 1, 2009.

  1. Zpider

    Zpider Adventurer

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    Hi

    Anyone run a 21" front wheel on a 1200GS without servo (power) brakes?
    Some says the ABS will go nuts, some says it work without doing anything. Wunderlich used to market an adapter for their kit, but no longer carry that...
    #1
  2. signit98

    signit98 Nutcase... really!

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    You are adding 2" in diameter, which will throw the geometry seriously off... I doubt that the added off road ability will make up for that... if you ride offload that much, get a different bike!
    #2
  3. Zpider

    Zpider Adventurer

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    Well, the question was not really regarding the handling when fitting a 21" wheel, it was about the functionality on the ABS system. I know there are guys who have done this conversion, but did the ABS get a hickup or not?
    #3
  4. Boxerlove

    Boxerlove Been here awhile

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    There shouldn't be any issues. I have an 05 with a 21" front and servo with abs. The abs works as good as it did with the 19" and didn't throw any lights or codes. I'm not sure about a non servo bike but I don't think it will be a problem. The bike overall rides a lot better with the 21". It rides like the way it should of came from the factory. I'll never go back to a 19"
    #4
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  5. Russ

    Russ Let's ride Super Moderator

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    I have a 21 from woody's wheel works it has an abs ring fitted that allows the ABS to function correctly,
    The wheel has transformed the bikes off-rorad handling:thumb
    [​IMG]

    signit98 Your reply is ill informed.
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  6. Zpider

    Zpider Adventurer

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    From what i hear the problem comes with models without servobrakes, 2007 and up. Wunderlich used to sell an adapter to make their conversionkit fit on theese models, but now they dont carry that adapter anymore. I have no idea as to what the adapter did, but i think it "fooled" the electronics to think the wheel was the right diameter. I dont want to loose the ABS functionality by going with 21" wheel, so the question is, what would happend if i run without it. And yes, 21" does make a lot of difference.
    #6
  7. Russ

    Russ Let's ride Super Moderator

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    Contact Woodys wheel works ask for Woody or Zach they will be able to explain how their ABS ring works, so that the ABS works properly.

    woodyswheelworks@gmail.com
    #7
  8. signit98

    signit98 Nutcase... really!

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    No, it is based on facts and geometry... simple stuff engineers look at when designing a bike. If you don't change anything else but just add the 21" front wheel, the bike will turn in much less willingly and get's quirkier in high speed corners... you just lift the front end and change weight distribution.

    If you ride more off road than on road, the mod might be useful, but then again... the bike itself is limiting you, compared to even a big orange sail or better a thumper of almost any kind.

    If you don't believe me, throw a 17" front into the GS and try it again... you'll be amazed... you have almost a real (albeit heavy) sport bike!

    Keep in mind that I ride mostly road stuff and more twisties than anything else... I throw in the odd fire road and in AK was forced to do some stuff I would have questioned on a designated bike down here...

    The bike CAN do it... but it's not ideal... a 21" front wheel will not change that by much... adding an 18" rear might help that a tad, though...

    This, of course, just expresses my opinion/viewpoint/experience... as it were.
    #8
  9. Russ

    Russ Let's ride Super Moderator

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    Have you ever ridden a GS with a 21" front wheel on the dirt?
    If you have you should have noticed a big improvement in the handling particularly in sand or mud.

    I presume that this thread about the bigger wheel was because Zpider wanted to use the bigger wheel off road:dunno :dunno
    #9
  10. Boxerlove

    Boxerlove Been here awhile

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    +1 just contact woody. That's where I got my wheel from. He will know better then anyone else.

    signit98-
    Obviously if you mostly ride the twisties you wouldn't care for the huge benefit the 21" front adds off road but is still fun in the turns. I'm a dirt rider and would never consider a 17" front. The 18" rear is nice but then the gearing is too tall so I would prefer the 17" still out back unless there was a lower final drive ratio. I do agree though to get the full benefit of the 21" front you need to have after market suspension to adjust front to rear balance and to your personal settings so not to have the chopper effect. My GS is my do everything bike and it does everything very well.
    #10
  11. diabolik37

    diabolik37 Push Dumb C***

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    The ABS job is to prevent your wheels from loocking up. It doesn't really matter if the wheel are not rotating at the same speed. Now if you were asking about traction control, that is another matter and different wheel size would create trouble...
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  12. Zpider

    Zpider Adventurer

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    That actually makes a lot of sence when thinking of it. As i understand front and back dont really have anything to do with each other regadring the ABS. ASC on the other hand i would believe get confused.
    #12
  13. sab

    sab Been here awhile

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    But how would the computer know they are locking up? It would sense one wheel turning slower than the other. I wonder if the fix is a ring plate w/ a different number/spacing of holes to compensate for the increase in wheel diameter?

    Seems to me that would trick the computer into thinking all was well...
    #13
  14. Zpider

    Zpider Adventurer

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    I dont think the ABS work by checking that both wheels run at the same speed. It simply check if the wheel is about to stop turning ie locking up regardless on what the other wheel do. I may be wrong here but...
    #14
  15. Russ

    Russ Let's ride Super Moderator

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    The traction control is only affected for the first bit travelled if you pull off very fast it kicks in once moving it seems to calculate the wheel rotation and somehow does not activate unless the wheel does slip, I've tried this on dirt don't know how but works but it does.:dunno
    #15
  16. RudyBoy

    RudyBoy Been here awhile

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    Maybe I'm just enamored with the newness of my GSA, or maybe it was the more sophisticated suspension, but during a recent side-by-side comparison ride featuring my 650 Dakar (21") vs GSA, I/we found the GSA handled rough, rutted jeep roads way better than the Dakar! It would be interesting to do a similar comparison ride with two GSA's, one with OEM wheels and one with a 21".
    #16
  17. diabolik37

    diabolik37 Push Dumb C***

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    The ABS doesn't compare wheels, it just use a magnetic pick up (hall sensor) as a reader to see if the wheels are spinning (pretty much the same way an old mechanical computer mouse work but with infrared), but the principle is identical.

    So it doesn't matter how many hole the ring plate has or in the case of the back wheel, how many teeth the crown has, it will only check that there is a constant on/off from the hall sensor, so it knows the wheels are spinning. There is no need to trick the computer to think anything. As long the wheels are spinning his job is to check NOT to count.

    The traction control does the Counting and Comparing between wheels (the front using the ABS ring, the back using the speed sensor again).
    #17
  18. GalacticGS

    GalacticGS 1200 GS Rider

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    I've got a 21" wheel from Woody's on my 2006 GS with servo assist ABS. I just used the ABS ring from my original 19" wheel. The ABS works just fine - no problems at all either onroad or offroad.

    As far as handling, don't notice much of a difference at all on the road - a little slower in turning in twisties, but you get used to it pretty quick.

    Offroad, the handling is much improved - the 21" just runs over obstacles much easier, and easier to ride in sandy conditions. In my view, it was well worth the cost to swtich to a 21", but I ride an awful lot of offroad!
    #18
  19. Treadless

    Treadless Long timer

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    MY take is that the 21" TKC is much more squared off than smaller sizes and that adversely affects the tires' ability to lean/corner. So a question for those running a 21. What front tire are you using / have you used?
    #19
  20. Russ

    Russ Let's ride Super Moderator

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    Running the 21'' TKC 90/90 getting good wear out of them and the handle well on both tar and dirt, except if its wet on road you need to be a little careful.
    #20