Go Back  Bike Forums > Bike Forums > Framebuilders
Reload this Page >

How to measure the rake of a fork

Notices
Framebuilders Thinking about a custom frame? Lugged vs Fillet Brazed. Different Frame materials? Newvex or Pacenti Lugs? why get a custom Road, Mountain, or Track Frame? Got a question about framebuilding? Lets discuss framebuilding at it's finest.

How to measure the rake of a fork

Old 07-23-11, 02:14 PM
  #1  
evilcryalotmore
モㄥ工匕モ 爪モ爪乃モ尺
Thread Starter
 
evilcryalotmore's Avatar
 
Join Date: Feb 2010
Location: LA San Gabriel, California
Posts: 2,136

Bikes: Custom frame

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
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
evilcryalotmore is offline  
Old 07-23-11, 09:20 PM
  #2  
Scooper
Decrepit Member
 
Scooper's Avatar
 
Join Date: Aug 2005
Location: Santa Rosa, California
Posts: 10,490

Bikes: Waterford 953 RS-22, several Paramounts

Mentioned: 64 Post(s)
Tagged: 0 Thread(s)
Quoted: 616 Post(s)
Likes: 0
Liked 2 Times in 2 Posts
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.

__________________
- Stan

my bikes

Science doesn't care what you believe.

Last edited by Scooper; 07-25-11 at 12:56 PM. Reason: Revised Illustration
Scooper is offline  
Old 07-25-11, 10:54 PM
  #3  
randomgear
Senior Member
 
Join Date: Jul 2006
Location: beantown
Posts: 922

Bikes: '89 Specialized Hardrock Fixed Gear Commuter; 1984? Dawes Atlantis

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 39 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Thanks Scooper! I've been wondering about that myself.
randomgear is offline  
Old 07-30-11, 03:57 AM
  #4  
ftwelder
Senior Member
 
ftwelder's Avatar
 
Join Date: Apr 2010
Location: vermont
Posts: 3,091

Bikes: Many

Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Likes: 0
Liked 2 Times in 2 Posts
Nice demonstration!
ftwelder is offline  
Old 07-30-11, 02:36 PM
  #5  
repechage
Senior Member
 
Join Date: Jun 2006
Posts: 13,416
Mentioned: 81 Post(s)
Tagged: 0 Thread(s)
Quoted: 970 Post(s)
Likes: 0
Liked 40 Times in 32 Posts
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.
repechage is offline  
Old 08-12-11, 05:57 PM
  #6  
Road Fan
Senior Member
 
Road Fan's Avatar
 
Join Date: Apr 2005
Location: Ann Arbor, MI
Posts: 14,307

Bikes: 1980 Masi, 1984 Mondonico, 1984 Trek 610, 1980 Woodrup Giro, 2005 Mondonico Futura Leggera ELOS, 1967 PX10E, 1971 Peugeot UO-8

Mentioned: 35 Post(s)
Tagged: 0 Thread(s)
Quoted: 846 Post(s)
Liked 30 Times in 27 Posts
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.
Road Fan is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
CrowSeph
Classic & Vintage
0
07-18-18 06:06 AM
PeregrineA1
Classic & Vintage
21
02-26-17 06:08 PM
greaterbrown
Northeast
0
04-12-13 05:28 PM
VA_Esquire
"The 33"-Road Bike Racing
9
07-02-09 12:35 PM
TandemGeek
Tandem Cycling
0
04-27-06 04:30 PM

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

Copyright 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.