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what is "fork rake" when reading geometry #s?

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jacksonpt

jacksonpt

Turbo Monkey
Jul 22, 2002
6,791
59
Vestal, NY
Was looking at the geometry numbers on a frame and comparing them to the geometry on my 575. One of the measurements was "fork rake" - what is that?
 
binary visions

binary visions

The voice of reason
Jun 13, 2002
22,165
1,261
NC
If you don't wish to read the article, though, it's the amount that the axle is offset from the steering axis - that is, how far in front of the steerer tube that the axle is located.
 
jacksonpt

jacksonpt

Turbo Monkey
Jul 22, 2002
6,791
59
Vestal, NY
binary visions said:
If you don't wish to read the article, though, it's the amount that the axle is offset from the steering axis - that is, how far in front of the steerer tube that the axle is located.
Click to expand...
so that's dependent on the fork, correct? A taller fork will have "more" rake? and how is that different from HT angle, aside from the unit of measure? I assume a shorter rake means the axle is closer to the BB... thus steering is faster, correct?


ah, ok... nevermind... the velonews article finally loaded. Thanks.
 
binary visions

binary visions

The voice of reason
Jun 13, 2002
22,165
1,261
NC
jacksonpt said:
so that's dependent on the fork, correct? A taller fork will have "more" rake? and how is that different from HT angle, aside from the unit of measure? I assume a shorter rake means the axle is closer to the BB... thus steering is faster, correct?
Click to expand...
As I understand it, it's not dependant on the height of the fork, since whether your fork is at a 90 degree angle, or a 60 degree angle, the offset of the axle from the steerer tube is the same.

If you draw a line parallel to the steerer tube that passes through the middle of the axle, the distance between the steerer tube and that line is your rake. Again, as I understand it - I've been wrong before :D (just once or twice, though).
 
Wumpus

Wumpus

makes avatars better
Dec 25, 2003
8,161
153
Six Shooter Junction
binary visions said:
As I understand it, it's not dependant on the height of the fork, since whether your fork is at a 90 degree angle, or a 60 degree angle, the offset of the axle from the steerer tube is the same.

If you draw a line parallel to the steerer tube that passes through the middle of the axle, the distance between the steerer tube and that line is your rake. Again, as I understand it - I've been wrong before :D (just once or twice, though).
Click to expand...
The rake is a function of the fork, but the trail will change with a height increase. Trail is what affects handling.
 
binary visions

binary visions

The voice of reason
Jun 13, 2002
22,165
1,261
NC
Wumpus said:
The rake is a function of the fork, but the trail will change with a height increase. Trail is what affects handling.
Click to expand...
Right, but most bike manufacturers don't offer a measurement of trail - at least not the ones I've looked at (might be different for XC bikes - I don't look at those much). Rake is fairly common though.
 
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