• 03-07-2013
    DerBergschreck
    Karate Monkey with 120 mm fork = AM hardtail/trailbike?
    29" allmountain hardtails/trailbikes are very popular here in germany this time.

    So I compared the geometry of a few allmountain 29" Hardtails and took the calculator…

    Karate Monkeys geometry is suspension corrected for 80 mm forks.
    So what happens to the geo, if I take a 120 mm fork?

    Front is coming 40 mm higher -> good for descents

    Steering angle goes down from 72 deg to 70 deg -> more stable going downhill. OK, not the angle of a real AM/Trailbike (about 68-69 deg) but you should feel the difference.

    Seat angle goes down from 73 deg to 72 deg -> not so good for uphill, but if you use a setback seattube, you can compensate this with a non-setback one

    BB drop goes down from 68 mm to 59 mm -> some AM hardtails (e.g. Kona Honzo) have such values and so it should be OK.


    Has anyone tried a Karate Monkey with a 120mm fork and can write about it?
  • 03-12-2013
    Ilikemtb999
    Karate Monkey with 120 mm fork = AM hardtail/trailbike?
    I personally wouldn't run a larger then spec'd fork unless the manufacturer says you can. Call them up and ask?

    You run the risk of frame failure IMO and I've seen some pics of KM's failing
  • 03-12-2013
    vikb
    The Krampus is suspension corrected to 120mm and has a HT of 69.5. That might be a better Surly frame to start with for an AM 29er build.
  • 03-12-2013
    Wryknow
    I run a 120mm fork on my KM (REBA). Works great.
  • 03-12-2013
    LostBoyScout
    I agree with vikb, the Krampus would work better. Not that the KM would suck, but you're fighting an uphill battle - HTA is still too steep and STA is too slack.
  • 03-13-2013
    vikb
    BTW - I'm a Surly fan, but Kona just put out a low cost AM hardtail 29r called the Taro. I'd just buy something like that or the Kona Honzo or Canfield Nimble 9. Trying to make something it's not always ends in a compromise.

    If you own a KM that's another story, but if you are buying new go for something that was designed to be an AM 29er from the get go.
  • 03-15-2013
    nativeson
    i've been running my km w/an older 100mm reba and it's great. you might lose a little turning ability w/the bottom bracket jacked up just a bit, but who really knows. i've emailed surly about runnin a 100mm fork, they said it was fine. taken it on some long downhills in oregon and the local stuff here in santa cruz, and it's good enough for me. i had a 1st generation nimble 9 and once i took it to a steep climb w/a 100mm fork it felt way too floppy.