K2 Proflex 2000

Discussion in 'Photos & Bicycle Builds' started by Alaskavan, Jul 1, 2008.

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  1. Alaskavan

    Alaskavan Guest

    Well, I yanked the motor off my Trek and mounted it on this K2. Full suspension Rocks! I need to put some additional stabilizers on it before I get really wild off road with it. But the ride is smooth.




    Still a bit of work to do on the bike.

  2. stude13

    stude13 Active Member

    looks smooth as butter, great.
  3. ozzyu812

    ozzyu812 Member

    Is there some logic behind why the front dropouts are backwards?
  4. That is some crazy front suspension!
  5. SimpleSimon

    SimpleSimon Active Member

    Looks to me like the angle of the front dropouts brings the axle back in line with the axis of rotation of the headtube.
  6. Alaskavan

    Alaskavan Guest

    I'm clueless about why the forks are the way they are. But it looks like it was intended to be that way. The decals would be hidden if I turned them around, and I'm not sure I could anyway. My guess is that Simon is right. It is sure footed.
  7. srdavo

    srdavo Active Member

    prolly has to do with "rake & trail"
    somebody splained "that" to me once..... I dint get it:confused:

    Very tough looking bike....BTW!

    I like it!!
  8. Van. Did someone throw that away?
    Have I told you how much your job rules?
    That front fork looks to have some SERIOUS travel.
    I've never seen a fork like that.
  9. Alaskavan

    Alaskavan Guest

    LFL, a guy that I let pick through the Parts Pile gave the frame to me, so I guess it was job related. The suspension seems to smooth out the serious bumps while still giving me a good feel for the terrain. I'm likin' it.

    Dave. Yeah. "Rake and Trail", "Akerman geometry", it's all geek to me.
  10. SimpleSimon

    SimpleSimon Active Member

    It is exactly about rake and trail. Rake is the angle of the headtube back from the axis of forward motion along a horizontal surface - the greater the rake. the greater the vertical plane lean of the wheel when turning, and the greater the force required to control it and return the wheel to center. Think about a chopper - serious rake, and long "ape hanger" type bars. Without the lever arm those bars provide, controlled turning of a severely raked chopper fork and wheel is pretty problematic.

    Trail is about the difference between the wheel center axis of rotation "trailing" the head tubes axis of rotations projected point on the ground - if, with a raked fork there is no trail, the contact point of the tire trails the axis projected point by the reciprocal of the rake angle, in a 90 degree arc. The greater the trail angle in that arc, the greater the likelihood of scrub in cornering, and the more effort it takes to turn the wheel against its own inherent gyroscopic force from rotation.

    So, with springer type forks like those, unmodified straight dropouts on those straight tubes would put the contact patch with the groound AHEAD of the axis of rotation of the head tube - not good. In cases of that sort, steering "feel" is greatly decreased, steering effort is increased, and the likelihood of loss of control escalates rapidly. So, the back angled dropouts return the center of rotation of the wheel more nearly to the axis of rotation of the forks - mechanical forces are lessened, simplified, asnd more controllable.

    I'd bet it turns on a dime, and gives you $.09 change, while feeling easy as can be to control.
  11. azbill

    azbill Active Member

    very nice explanation...
    but now my head hurts (after reading it:lol:)
    very cool 'other' ride Van :D
  12. Alaskavan

    Alaskavan Guest

    I just took it for a ride. When you look down along the headset, the front axle does seem to be right in line with the headset.
  13. SirJakesus

    SirJakesus Guest

    That bike looks like a ton of fun van!
  14. Troph

    Troph New Member

    Amazing build, looks really really fun. Anyway you can post a pic of the rear suspension compressed?
  15. Alaskavan

    Alaskavan Guest

    Sorry, I can't think of how I'd do that. I have the suspension set as light as it goes, and I barely get the springs to flex.
  16. r5579

    r5579 Member

    How well does the friction drive work offroad? I figured that a bunch of dirt, etc. would make it slip? Or is water the main enemy of the friction drive? You like the Mitsubishi 2 stroke?
    Can I ask what sold you on that particular motor?
  17. Alaskavan

    Alaskavan Guest

    Dirt doesn't have any adverse effect on the drive. It might increase the wear on the roller. The Mitsu is a good motor. It's never let me down. I bought it because, at the time at least, it was the most powerful under 50cc that Staton was selling. At least that's my memory of my reasoning. I've got well over 1,000 miles on it, and I've had to change the spark plug once, and I cleaned the screen in the exhaust once. I have to pull the cord 4 or 5 times to start her when she's cold, not too bad. Very reliable.