Advertise on Bikeforums.net



User Tag List

Results 1 to 6 of 6
  1. #1
    モㄥ工匕モ 爪モ爪乃モ尺 evilcryalotmore's Avatar
    Join Date
    Feb 2010
    Location
    LA San Gabriel, California
    My Bikes
    Custom frame
    Posts
    2,135
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)

    How to measure the rake of a fork

    I have just received a free track fork, But i don't know what the rake is. I think it is a track fork because there is no brake hole, But i'm most likely going to drill it.

    So my question is how can i measure the rake, It doesnt need to be accurate, i just need it too be with in the 5mm range like 45mm - 35mm - 30mm

  2. #2
    Decrepit Member Scooper's Avatar
    Join Date
    Aug 2005
    Location
    San Francisco California
    My Bikes
    2007 Waterford 953 RS-22
    Posts
    8,720
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    The easiest way I know of is to mount the steerer tube in a fixture (could be a couple of "U" bolts in a 2" x 4") on top of a piece of butcher paper, and turn the fork 90° so that the dropouts are flat on the paper. Mark the paper halfway between the dropouts. This mark is the steering axis of the fork. Next, turn the fork 90° using a right angle "square" against the butcher paper surface and the rear of the fork blades near the crown to ensure it's at 90° and mark the center of the left dropout on the butcher paper. Draw a line from the steering axis and at a right angle to it, through the mark in the center of the dropout, and measure the distance from the steering axis to the center of the dropout. That is your rake or offset.

    Last edited by Scooper; 07-25-11 at 12:56 PM. Reason: Revised Illustration
    - Stan

  3. #3
    Senior Member
    Join Date
    Jul 2006
    Location
    beantown
    My Bikes
    '89 Specialized Hardrock Fixed Gear Commuter; 1984? Dawes Atlantis
    Posts
    702
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    Thanks Scooper! I've been wondering about that myself.

  4. #4
    Senior Member ftwelder's Avatar
    Join Date
    Apr 2010
    Location
    vermont
    My Bikes
    Many
    Posts
    3,093
    Mentioned
    7 Post(s)
    Tagged
    1 Thread(s)
    Nice demonstration!
    1886 Surrey machinists Invincible, 1900 Nashua, 1937 Raleigh Golden Arrow, 1938 Raleigh Silver Record, 1951 Armstrong tourmalet, 1970 Motobecane Grand Record, 1971 Raleigh Professional, 1971 Gitane TDF, 1972 Legnano Gran Primio, 1973, Peugeot PX-10, 1975 Roberts, 1984 Battaglin Giro, 1985 Grandis Speciale, 2012 FTW

    frankthewelder@comcast.net

    le prix s'oublie,la qualité reste ,(michel audiard)

  5. #5
    Senior Member
    Join Date
    Jun 2006
    Posts
    8,290
    Mentioned
    11 Post(s)
    Tagged
    0 Thread(s)
    Pretty good way to do it, I did it close to that but turned my 2x4 into a V block with a table saw. Then I got "fancy" and found a VAR fork alignment jig to help.

  6. #6
    Senior Member Road Fan's Avatar
    Join Date
    Apr 2005
    Location
    Ann Arbor, MI
    My Bikes
    Terraferma 650b, Mondonico SL and ELOS, Masi Gran Criterium, Trek 610, Breezer Liberty, Georgena Terry Classic
    Posts
    11,095
    Mentioned
    6 Post(s)
    Tagged
    0 Thread(s)
    I clamp a hub in the fork and lay the fork on a flat, level surface. Using a level on the steer tube, I prop up the steer tube (books, pads of paper, steel blocks, wood blocks, whatever is around) until it measures level. I then measure the height of the bottom and top of the steer tube above the surface. The average of those two is the height above the table of the steer axis. Then I measure the diameter of the hub flange and divide by two. The difference between the hub axis and the steer tube axis is the rake.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •