Trail of confusion

Information on forks/springers/shocks
Post Reply
panster
Posts: 55
Joined: Fri Mar 19, 2004 2:07 am

Trail of confusion

#1

Post by panster » Tue Jan 20, 2004 9:29 pm

Hi all,
just trying to educate myself, am I correct in thinking that for a given rake angle,if you use offset, i.e. de-raked springers, you effectively increase
trail when compared to an inline springer? As I say, just trying to learn.
Thanks,
Jamie.



haggis
Posts: 158
Joined: Fri Mar 19, 2004 3:35 am
Location: Maine USA

Re: Trail of confusion

#2

Post by haggis » Thu Jan 22, 2004 3:00 am

Panster,
From where I look at it....any increase in trail is a good thing for straight line stability, but it will screw with your low speed maneuverability. ( 10'' over wide glide style) Negative trail is REALLY BAD , and will,have you spread all over some black tar.
The main thing I think, is to keep the two imaginary lines of.1 the head stock... and 2. the forks parallel.(stay away from raked triple trees)
You can then screw with the trail by rake, fork or wheel size.
Just don't make it smaller...........Haggis ;)

panster
Posts: 55
Joined: Fri Mar 19, 2004 2:07 am

Re: Trail of confusion

#3

Post by panster » Thu Jan 22, 2004 5:07 pm

Hi Haggis,
thanks for the input, what I'm really talking about here is stock length springers, and different combinations of the stock 30 degree frame and inline or offset fork with 16" 19" or 21" wheels.
I was just surprised when it seemed that the offset (de-raked) setup increased the trail figure, my instinct told me that a steeper fork angle must mean more skittish steering, but as you say the trail increase points toward better high speed stability compared to the inline fork.!!
still confused,
J.

DuoDave
Posts: 198
Joined: Tue Mar 16, 2004 10:45 pm

Re: Trail of confusion

#4

Post by DuoDave » Sat Jan 24, 2004 7:13 pm

No need for confusion....
Rake - a garden tool used to gather leaves.
Trail - what you are supposed to hit as the sun goes
down.
Easy, this technical stuff! ;)

Halc

Re: Trail of confusion

#5

Post by Halc » Thu Feb 26, 2004 5:44 pm

This has more detail:

http://www.american-v.co.uk/technical/h ... /geometry/" onclick="window.open(this.href);return false;

Also, try a google on motorcycle frame geometry, and you will find a couple of well written engineering papers by ME college students worth reading - if you're morbidly curious...
Hal

popspan
Posts: 25
Joined: Wed Sep 29, 2004 12:56 pm
Location: North Carolina
Contact:

Re: Trail of confusion

#6

Post by popspan » Tue Aug 10, 2004 11:17 am

"Life's journey is not to arrive at the grave safely in a well preserved body, but rather to skid in sideways, totally worn out, shouting "holy shit...what a ride!"

Billy
Posts: 719
Joined: Tue Mar 23, 2004 6:57 am

Re: Trail of confusion

#7

Post by Billy » Tue Aug 10, 2004 11:51 pm

Here's "Trail" & How to measure it;
You should have a nice length of Straight-edge & Put it Exactly in line with the center of the triple tree stem bolt, following that stem bolt angle to the ground. Put a Mark there.
Then off the front axle use a plumb-bob, or a level, from axle center, straight to the ground & make a mark. Then measure the space from mark to mark. That IS your trail.
As long as your axle mark Is behind the stem bolt mark, you have Positive Trail. How much depends on your bike's set-up. You can increase trail in many ways,
Low Profile rear tire, etc...
Once you do it you'll see it's easy to measure. When you feel pretty good at it, re-measure your bike & see if you still get the same reading. ;)
Trail can be reduced by adding modern tires to both rims, as they are not as tall as Full profile original tires.
Which are 26.5" & modern tires are around 25.6"
Which lowers both ends of the bike. The rake is the same but the trail has been lessened..

Post Reply

Return to “Forks/Shocks”