Road Cycling “It is by riding a bicycle that you learn the contours of a country best, since you have to sweat up the hills and coast down them. Thus you remember them as they actually are, while in a motor car only a high hill impresses you, and you have no such accurate remembrance of country you have driven through as you gain by riding a bicycle.” -- Ernest Hemingway

Fork Rake

Old 08-02-11, 11:05 PM
  #1  
s4one
Senior Member
Thread Starter
 
s4one's Avatar
 
Join Date: Aug 2007
Posts: 1,331
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Fork Rake

43 vs 45 rake, can someone explain the difference? As in how the two perform?

THanks
s4one is offline  
Old 08-02-11, 11:51 PM
  #2  
IcySmooth52
Senior Member
 
IcySmooth52's Avatar
 
Join Date: Nov 2006
Location: Portland, ME
Posts: 1,620
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 5 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
The rake is like a modification of the head-tube angle. The greater the rake, the less the HT angle. It won't act exactly like a HT of a degree measured to the front axle though, because it has more of a curve. This creates a smoother ride, but less 'connected' to the road, or quick in handling or perception.

To put it in a simple term; the greater the rake measurement, the plush the "plush" the bike is.
IcySmooth52 is offline  
Old 08-02-11, 11:55 PM
  #3  
s4one
Senior Member
Thread Starter
 
s4one's Avatar
 
Join Date: Aug 2007
Posts: 1,331
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Thanks, will I feel a diff between a 43 vs 45?
s4one is offline  
Old 08-02-11, 11:57 PM
  #4  
AlexZ
Senior Member
 
Join Date: Jun 2009
Location: Huntington Beach
Posts: 492
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Possible......but unlikely. The 43 will need a bit more care to keep you out of the ditch when you're not paying attention.
AlexZ is offline  
Old 08-03-11, 12:20 AM
  #5  
s4one
Senior Member
Thread Starter
 
s4one's Avatar
 
Join Date: Aug 2007
Posts: 1,331
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Thanks
s4one is offline  
Old 08-03-11, 04:40 AM
  #6  
Kimmo
bike whisperer
 
Kimmo's Avatar
 
Join Date: Dec 2009
Location: Melbourne, Oz
Posts: 7,954

Bikes: https://weightweenies.starbike.com/forum/viewtopic.php?f=10&t=152015&p=1404231

Mentioned: 9 Post(s)
Tagged: 0 Thread(s)
Quoted: 384 Post(s)
Liked 17 Times in 14 Posts
As I understand it, your head angle figures into it a fair bit...
Kimmo is offline  
Old 08-03-11, 04:59 AM
  #7  
scirocco
Senior Member
 
Join Date: Aug 2006
Location: Perth, W.A.
Posts: 935
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by Kimmo View Post
As I understand it, your head angle figures into it a fair bit...
I think the OP was assuming that the HT angle didn't change, just different forks on the same bike.

But if not, then, yes, HT angle and rake combine to create trail which is the real thing that affects the handling. This paper from Calfee explains it pretty well.

http://www.calfeedesign.com/tech-pap...bike-handling/
scirocco is offline  
Old 08-03-11, 05:17 AM
  #8  
Kimmo
bike whisperer
 
Kimmo's Avatar
 
Join Date: Dec 2009
Location: Melbourne, Oz
Posts: 7,954

Bikes: https://weightweenies.starbike.com/forum/viewtopic.php?f=10&t=152015&p=1404231

Mentioned: 9 Post(s)
Tagged: 0 Thread(s)
Quoted: 384 Post(s)
Liked 17 Times in 14 Posts
Swapping forks may actually alter the head angle by a poofteenth (like fitting a smaller tyre in front), but I was getting at the fact that a certain amount of rake may be right for one bike, but not for another, due to the head angle.
Kimmo is offline  
Old 08-03-11, 08:27 AM
  #9  
nhluhr
John Wayne Toilet Paper
 
nhluhr's Avatar
 
Join Date: Feb 2006
Location: Roanoke
Posts: 1,951

Bikes: BH carbon, Ritchey steel, Kona aluminum

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by IcySmooth52 View Post
The rake is like a modification of the head-tube angle. The greater the rake, the less the HT angle. It won't act exactly like a HT of a degree measured to the front axle though, because it has more of a curve. This creates a smoother ride, but less 'connected' to the road, or quick in handling or perception.
This is backwards. A greater rake decreases trail, the same effect as increasing/steepening the head angle. A lower amount of rake creates a larger trail and therefore more of a caster stabilizing effect. It's easier to ride a bike no hands that has more trail.

http://www.dclxvi.org/chunk/tech/trail/
nhluhr is offline  
Old 08-03-11, 08:49 AM
  #10  
Garfield Cat
Senior Member
 
Garfield Cat's Avatar
 
Join Date: Oct 2004
Location: Huntington Beach, CA
Posts: 6,838

Bikes: Cervelo Prodigy

Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 342 Post(s)
Likes: 0
Liked 5 Times in 4 Posts
Originally Posted by nhluhr View Post
This is backwards. A greater rake decreases trail, the same effect as increasing/steepening the head angle. A lower amount of rake creates a larger trail and therefore more of a caster stabilizing effect. It's easier to ride a bike no hands that has more trail.

http://www.dclxvi.org/chunk/tech/trail/
That's why its difficult to ride a unicycle. No trail, no rake.
Garfield Cat is offline  
Old 08-03-11, 08:51 AM
  #11  
nhluhr
John Wayne Toilet Paper
 
nhluhr's Avatar
 
Join Date: Feb 2006
Location: Roanoke
Posts: 1,951

Bikes: BH carbon, Ritchey steel, Kona aluminum

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by Garfield Cat View Post
That's why its difficult to ride a unicycle. No trail, no rake.
I tried to add some trail last time I rode a unicycle and fell backwards.
nhluhr is offline  
Old 08-03-11, 08:57 AM
  #12  
mmmdonuts
Gluteus Enormus
 
mmmdonuts's Avatar
 
Join Date: Dec 2007
Location: Raleigh, NC
Posts: 2,245

Bikes: Yes

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by s4one View Post
Thanks, will I feel a diff between a 43 vs 45?
If you notice any diff at all is that the bike could feel a tiny smidge more stable with the 43. All else being equal you probably won't notice a difference. Your fork tips move more than 2mm fore-aft just riding, hitting bumps, and braking.
mmmdonuts is offline  
Old 08-03-11, 09:00 AM
  #13  
Scooper
Decrepit Member
 
Scooper's Avatar
 
Join Date: Aug 2005
Location: Santa Rosa, California
Posts: 10,491

Bikes: Waterford 953 RS-22, several Paramounts

Mentioned: 64 Post(s)
Tagged: 0 Thread(s)
Quoted: 616 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
It is highly unlikely that other parameters being equal (head tube angle, fork length measured parallel to the steerer from from the bottom of the lower bearing race to the center of the front wheel axle), that you would notice any difference between a 43mm rake and a 45mm rake. On a bike with 700c rims, the 43mm rake fork will give you 2mm more of trail.

__________________
- Stan

my bikes

Science doesn't care what you believe.
Scooper is offline  
Old 08-03-11, 09:48 AM
  #14  
urbanknight
In beaurocratic limbo
 
urbanknight's Avatar
 
Join Date: Mar 2006
Location: Los Angeles, CA
Posts: 22,456

Bikes: Specialized Allez, K2 Razorback

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
__________________
"Well, I guess you can cut the arts as much as you want... Sooner or later, these kids aren't going to have anything to read or write about." (Richard Dreyfus as Glenn Holland)
urbanknight is offline  
Old 08-03-11, 10:54 AM
  #15  
Scooper
Decrepit Member
 
Scooper's Avatar
 
Join Date: Aug 2005
Location: Santa Rosa, California
Posts: 10,491

Bikes: Waterford 953 RS-22, several Paramounts

Mentioned: 64 Post(s)
Tagged: 0 Thread(s)
Quoted: 616 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
FWIW, retired framebuilder Dave Moulton has a couple of great blog articles you might find informative.

"As with any design aspect, more is not necessarily better; for a road bike with a 73 degree head angle the optimum trail seems to be around 2 to 2 ½ inches (50 to 63mm.)", so 56mm - 58mm of trail is pretty optimal.

Trail, fork rake, and a little bit of history

Head Angles and Steering
__________________
- Stan

my bikes

Science doesn't care what you believe.

Last edited by Scooper; 08-03-11 at 11:00 AM.
Scooper is offline  
Old 08-03-11, 01:44 PM
  #16  
AlexZ
Senior Member
 
Join Date: Jun 2009
Location: Huntington Beach
Posts: 492
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by Kimmo View Post
Swapping forks may actually alter the head angle by a poofteenth (like fitting a smaller tyre in front), but I was getting at the fact that a certain amount of rake may be right for one bike, but not for another, due to the head angle.
Swapping forks does not change the head angle, only rake! Unless the fork is shorter or longer in which case the whole geometry of the bike is in the crapper!
AlexZ is offline  
Old 08-03-11, 02:21 PM
  #17  
thump55
I got 99 problems....
 
thump55's Avatar
 
Join Date: Aug 2008
Location: Does anyone know where the love of God goes, when the waves turn the minutes to hours?
Posts: 2,087
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
This seems pretty simple to me.
Attached Images
File Type: jpg
fork.jpg (4.9 KB, 7 views)
File Type: jpg
rake.jpg (4.0 KB, 7 views)
thump55 is offline  
Old 08-04-11, 01:29 AM
  #18  
Kimmo
bike whisperer
 
Kimmo's Avatar
 
Join Date: Dec 2009
Location: Melbourne, Oz
Posts: 7,954

Bikes: https://weightweenies.starbike.com/forum/viewtopic.php?f=10&t=152015&p=1404231

Mentioned: 9 Post(s)
Tagged: 0 Thread(s)
Quoted: 384 Post(s)
Liked 17 Times in 14 Posts
Originally Posted by AlexZ View Post
Swapping forks does not change the head angle, only rake! Unless the fork is shorter or longer in which case the whole geometry of the bike is in the crapper!
There's nothing incredible about the possibility of different forks being slightly different lengths; in fact it's quite likely.

Do a little bit of trigonometry and you'll find that it'll take an awful lot of difference in fork length to make much difference to the head angle though. But, swapping forks may affect it slightly, as I said.
Kimmo is offline  
Old 08-04-11, 12:10 PM
  #19  
Scooper
Decrepit Member
 
Scooper's Avatar
 
Join Date: Aug 2005
Location: Santa Rosa, California
Posts: 10,491

Bikes: Waterford 953 RS-22, several Paramounts

Mentioned: 64 Post(s)
Tagged: 0 Thread(s)
Quoted: 616 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by Kimmo View Post
There's nothing incredible about the possibility of different forks being slightly different lengths; in fact it's quite likely.

Do a little bit of trigonometry and you'll find that it'll take an awful lot of difference in fork length to make much difference to the head angle though. But, swapping forks may affect it slightly, as I said.
Truth.

A picture may help. Remember that HTA and STA are the angles the head tube and seat tube make with a baseline through the dropout centers, so adding 18% to the length of the fork will move the front of the frame higher, making the HTA and the STA 2° less than they with with the original fork. Putting on a fork that is 118% of the original fork isn't something you'd ordinarily do, but the drawing is exaggerated to demonstrate the effect.

__________________
- Stan

my bikes

Science doesn't care what you believe.
Scooper is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
PeregrineA1
Classic & Vintage
21
02-26-17 06:08 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
spartacus88
Mountain Biking
0
11-17-04 09:18 AM

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.