Fork Threaded to Threadless

Discussion in 'Cycling Equipment' started by rplace13, Apr 6, 2010.

  1. rplace13

    rplace13 New Member

    Joined:
    Oct 30, 2007
    Messages:
    102
    Likes Received:
    1
    I have an older frame that I am bringing back to life. It currently has a 1 inch aluminum threaded fork/headset. If I wanted to pick up a 1 inch threadLESS replacement fork what do I want to look for to insure the handling of the bike is consistant? Are most road forks interchangable or do you need a fork specific to the geometry of your bike?

    Not sure if this helps or not, but the frame in question is a Kesterl 200sc from the early 90s. I believe the rake is 4.4 with a head angle of 73.5. The fork I am considering has the following info on its tag.

    [​IMG]

    Is it at all possible to fit a 1 1/8 fork to a 1 inch bike? I am guessing not...but thought I would check as there are a lot more forks available.

    Thanks!
     
    Tags:


  2. dabac

    dabac Well-Known Member

    Joined:
    Sep 16, 2003
    Messages:
    2,289
    Likes Received:
    139
    If the new fork puts the front hub in the same place wrt the rest of the frame as the old one did there should be no difference in handling characteristics.

    Offset/rake is the value that you want to match. Obviously you want your new stem to put the handlebar in its accustomed position too.

    That would depend on how finicky you are. Technically speaking a bike can be ridden with the fork reversed, so from a purely functional standpoint any fork that can be fitted can most likely be ridden. But some are very(or claim to be!)sensitive to even minor changes in geometry. I'm not, so from my personal perspective any fork that I can fit is one that I can ride.

    Usually not, but there's at least one workaround depending on what type of headset that you've got.
    I have a bike that originally came with an integrated 1" headset. It had enough room in the head tube for me to be able to fit a regular 1 1/8" headset instead. Of course having access to a lathe to cut a custom shim helped....
     
  3. rplace13

    rplace13 New Member

    Joined:
    Oct 30, 2007
    Messages:
    102
    Likes Received:
    1
    Thanks a lot Dabac!

    If I am understanding that rake/offset are the same and my current rake is 4.4 and the fork in question looks to be 40 offset...most likely 4.0 don't ya think, then they should be pretty close. Seems to me at the very least it will work and I just need to see if it is something I can live with. I ride several different bikes so I would not guess a minor change would matter much to me personally.

    I guess the only question to be answered is the change from 4.4 to 4.0 drastic or slight?

    Thanks again.
     
  4. alfeng

    alfeng Well-Known Member

    Joined:
    Jul 23, 2005
    Messages:
    6,723
    Likes Received:
    126
    You'll need to find a different fork for your Kestrel 200sc frame ...
     
  5. rplace13

    rplace13 New Member

    Joined:
    Oct 30, 2007
    Messages:
    102
    Likes Received:
    1
    Can you please elaborate as to why?
     
  6. alfeng

    alfeng Well-Known Member

    Joined:
    Jul 23, 2005
    Messages:
    6,723
    Likes Received:
    126
    Good question ...

    I could be reading the label incorrectly (which is CERTAINLY a possibility!), but it looks like the rake is 40mm ... and, you indicated that you wanted a fork with a ~44mm offset ...

    If you already have the fork (Hmmm, you took the picture, so I guess THAT must-or-may be the case) & if the notion of slightly quicker steering works for you, then I guess you could give it a go.

    I should probably have written:
    You'll probably need to find a different fork for your Kestrel 200sc frame (if you want the bike to handle exactly the same as it currently does) ...
    If you want the bike to handle exactly the same as it currently does, then you'll probably want a fork with a 43-to-45mm offset. Reynolds, LOOK, and Alpha Q are amongst forks which you can consider ... the older KESTREL forks with 1" steerers, too, of course!
     
  7. dhk2

    dhk2 Active Member

    Joined:
    Aug 8, 2006
    Messages:
    2,214
    Likes Received:
    39
    Fork offset moves the front axle forward which acts to reduce trail (the distance the tire contact point is behind an imaginary line on the ground projected through the steer tube axis). All else being equal, putting on a new fork with an offset of 40 vs 44 mm will increase the trail by 4mm and result in slightly slower steering. Since I'm a fan of stability for occasional hands-off and high-speed descents, the geometry wouldn't be an issue for me.
     
  8. rplace13

    rplace13 New Member

    Joined:
    Oct 30, 2007
    Messages:
    102
    Likes Received:
    1
    Thanks Alfeng, I get it. I am not 100% married to my current ride, it is a 2nd or 3rd bike that I am making a fixie out of so a slight difference would not be a deal breaker. Just trying to gauge if the 44 to a 40 is a big jump or just a bit. Thanks for the heads up on the Reynolds. I have seen them but they are in the 80-180 range and this no brand fork is currenlty 18 at auction. For 50 bucks or less I might want the threadless option and roll the dice. If I have to push $200 I think I am fine with AL and threaded.
     
  9. dabac

    dabac Well-Known Member

    Joined:
    Sep 16, 2003
    Messages:
    2,289
    Likes Received:
    139
    They are.

    That is pretty close.

    from a perspective of rake, it will work just fine.

    Exactly. The prognosis is good, but there will be a change. Whether you'll find it significant or not only a test ride can tell.

    You and me both then. I switch between bikes with fairly serious changes in setup on a regular basis, and the impact of rake/offset change pretty much drowns in the whole "other bike" feel.

    I'd consider it slight. Others might be more sensitive.
     
Loading...
Loading...