What's What

          This software is offered as free-ware. This means you don't have to "Pay Me My Money". But, nothing is free is it. This file was written using Visual Basic 6. The standalone "TrailSYM.exe" may run by itself on XP & Vista systems. It may also run on older systems with MS Office installed. If it does not it will have to be installed. This will add registry references to this program that "may or may not" be removed by un-install.

          This file will describe the application's form layout and the function of the objects that it contains.

1. Menu

2. Slider Control

3. Data Entry

4. Calculated Values

5. Known Errors


Menu

File

Exit - Duh! or use the "X" in the top-right corner.

Colors

Back Ground - this allows the background color to be selected for easier viewing.

Lines - this allows the foreground color to be selected for easier viewing.

Trail - this allows the trail color to be selected for easier viewing. Other lines are also drawn with this color depending on geometry selected.

Units

Inch - all values are entered and displayed in inches.

mm - all values are entered and displayed in millimeters.

Style

4-Link - The data and graphics are applied to a 4-Link geometry.

Springer - The data and graphics are applied to a Springer geometry.

Hydraulic - The data and graphics are applied to a Telescopic geometry.

Help

What's What - Displays this file using your default web browser.


Slider Control

          The Slider will allow you to cycle the suspension through it's travel. The range is limited to +/-45 degrees of rotation for the upper link arm.

          The "ReSet" Button will reset the slider to normal ride height and recalculate the values.

          The "Animate" Button? Push it! I dare you! If you right-click this button, an input box will allow you to change the animation speed.


Data Entry

          The startup data is only to allow the formulas to function. The data entry fields have reasonable limits to prevent excessive math errors. Some errors have been left in for many reasons, but mostly cause I don't want to take the time to do it right.

          Data entry boxes have a white background. Enter numbers only. If you enter text, the value may not be interpreted properly and be discarded.

          When entering data, the enter key will process the data entered. When you use the mouse to enter data into another text box, the data will also be processed. The last value that you enter will only be processed if you hit the enter key or click a different text box.

          When entering data, select the unit of measure from the menu "Units". Data sets using mixed units of measure can be entered this way. Switch to inches to enter some values. Switch to millimeter to enter the remaining values.

Yoke Hgt

          This the height from the ground to the intersection of the upper yoke and the steering axis.

Yoke Dist

          This is the distance along the steering axis from the centerline of the upper yoke to the lower yoke centerlines. With no offsets, it is the distance between the upper and lower link rear pivots.

Tire Dia

          This is the outside diameter of the tire. Tire squish is not used in any calculations. It would have been better to use axle height, but, WYSIWYG.

Neck Ang

          This is the angle of the steering axis. Zero degrees is measured from the neck perpendicular to the ground. Neck and fork angles use the same reference angle. All other angles measurements reference 0 deg. as horizontal to the ground.

U Link

          This is the length of the upper link arm from pivot to pivot.

UL Ang

          This is the angle that the upper link would be at normal ride height.

UL Off1

This value will offset the rear pivot of the upper link arm perpendicular to the neck angle.

UL Off2

          This is an offset perpendicular to the fork from the forward pivot of the upper link arm. For a typical girder this would be "0". A positive number will move the fork forward of the pivot, a negative number will move the fork behind the pivot.

L Link

          This is the length of the lower link arm from pivot to pivot.

LL Off1

          This value will offset the rear pivot of the lower link arm perpendicular to the neck angle.

LL Off2

          This is an offset perpendicular to the fork from the forward pivot of the lower link arm. For a typical girder this would be approx. 1.25". A positive number will move the fork forward of the pivot, a negative number will move the fork behind the pivot.


Calculated Values

          The calculated values are derived from the data entered. These values are not precise do to rounding errors. Please review the "Known Errors". The calculated values are in boxes with a light gray background.

UL Ang

          This is the calculated angle of the upper link arm according to the vertical travel of the wheel.

LL Ang

          This is the calculated angle of the upper link arm according to the vertical travel of the wheel. This number will be different from the upper link angle if the links are different lengths.

Fork Len

          This is the calculated distance between the wheel axle and the upper fork mount.

Fork Ang

          This is the calculated angle from the upper fork mount to the wheel axle fork. This angle is measured differently from all others. 0 degrees is referenced from the neck perpendicular to the ground.

Travel

          This is the current change in vertical distance from normal ride height.

Travel +

          This is the maximum positive wheel travel for an upper link angle of 67 degrees.

Travel -

          This is the minimum negative wheel travel for a lower link angle of -22 degrees.

Act Trail

          This is the trial calculated to represent a real number that acts as the length value when determining a torque at the steering axis. The force is generated in part by gravity and the mass of the bike. When cornering the centrifugal forces also apply. A longer trail or torque arm requires more opposing force on the handle bars to compensate thus making the bike feel heavier.

Ground Trail

          This is the distance more commonly used when trial is given in a motorcycle forum. It is easier to measure and varies proportional to actual trail.


Known Errors

Rounding errors

          This can be seen in situations were the link angle should be equal but are off by a small amount. Units conversion and rounding will also contribute to this problem. This error will also be present with all values, but will vary in degree and be less apparent.

Unable to View Help Files

          You are actually reading the help file right now. The "Help Menu" uses the default browser of your system. Open the file manually using your default browser or double clicking it in Explorer. This file is "WhatsWhat.htm"

Graphic Window isn't Drawn Properly

          This is a case of "Head Up Ass" syndrome. I didn't feel like taking the time to do it right. Click anywhere on the form and the window will be redrawn with current values.

Where's my Rear Tire?

          Who cares! This software does not compensate for rear suspension or changes in frame/neck angle do to dynamic weight distribution etc...

Why is the Terminology All Screwed Up?

          As mentioned earlier, this is a case of "Head Up Ass" syndrome. Yada! Yada! Yada...

It looks like it will actually work?

          There's allot I'm not telling you. For example, the clearance & length of the spring/shock is not considered at all in this simulation. It's an educational tool to help people visualize rake and trail.

Where's the instructions for Springer and Telescopic?

          Where's my money?