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fork rake?(6 posts)

fork rake?analog1
Apr 4, 2003 12:31 PM
What is fork rake? How do I know how much I want/need. I'm a heavy rider ~170lbs. Thanks.
try this site...C-40
Apr 4, 2003 1:18 PM
Rake is the horizontal distance between a line through the steering tube and a parallel line through the front axle.

See this site for more info:

http://www.spectrum-cycles.com/612.htm

The facts in this article are accurate, but not all builders agree with the idea of "neutral trail". All Colnagos have more trail than recommended by Spectrum.

Do a google search for rake and trail and you will get many more articles.

The formula for trail is (tire radius/tanH) - (rake/sinH), where H is the head tube angle.
Excellent! thanksanalog1
Apr 4, 2003 1:22 PM
correction...C-40
Apr 4, 2003 1:25 PM
Rake is the distance between a line through the steering tube and a parallel line through the front axle, measured perpendicular to the steering tube.
Please explain to me...Matno
Apr 5, 2003 3:20 PM
I understand the concepts behind rake and trail. What's throwing me off is what that site says about "neutral trail." He says "5.6mm of rake is neutral for a 700c wheel" but no bike even comes close to that. For example, my Cannondale has 45mm of rake. Did he really mean 5.6mm?! Considering that most forks are in the range of 40-45mm of rake, even if he meant centimeters, that still doesn't seem to fit with what I know. What's he talking about?
big mistake in the article...C-40
Apr 6, 2003 7:17 AM
Rake by itself means nothing. It must be combined with a particular wheel size and head tube angle to produce a trail value. Someone didn't proofread that article very well. It should say that 56mm or 5.6cm of trail (not rake) provides neutral steering. As I noted, this is strictly the opinion of one builder and should not necessarily be treated as gospel.

Colnago use a lot more trail on their frames, which are used by many pro teams. I would assme that their steering geometry was developed through many years of rider feedback. A bike intended for criteriums might steer more precisely with 56mm or trail, but more trail will make the bike hold a straight line better.

Trail is often changed to compensate for the effect of a change in wheelbase. It's common to see less trail for faster steering on large frames and more trail for slower steering on small frames.