REAR RIDE HEIGHT GAUGES IN MotoSPEC

Ride Height Gauges are used as a reference for measuring the vertical position of the rear wheel relative to the frame.

A Ride Height Gauge is a better reference for vertical rear wheel position than a point on the seat cowl or rear subframe, which can be damaged or bent in a crash.

The MotoSPEC Ride Height Gauge function represents the physical gauge in the chassis program, calculating the gauge measurement as setup changes are investigated.

Ducati ride height gauge on Kyle Wyman's Ducati V4 R

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Ride Height Gauges are kept safely stored in the pitbox and installed on the bike when needed, to check if setup changes have altered the extension of the rear suspension.  If the position of the rear wheel at full-extension has been altered - either lowered or raised relative to the frame, intentionally or unintentionally - the geometry of the motorcycle is affected.

When a physical Ride Height Gauge is used, the gauge is installed on the bike and a measurement is taken down to the rear axle.  The gauge can be used to measure the ride height before and after a change, or a reference measurement may be provided by the manufacturer or suspension technician.

Ride Height Gauges are most often used on Ducatis and BMWs.  Gauges for each are available from Ducati and Alpha Racing, respectively.

For Ducatis and MVs with eccentric rear axles, gearing changes can significantly affect the height of the rear wheel relative to the frame, affecting the geometry of the bike.

Typical past practice for using a Ride Height Gauge has been:

1. make setup changes (gearing, linkage, pivot adjustments. etc)
2. install the gauge on the bike
3. adjust the shock length or linkage to achieve the desired gauge reading

This creates the potential for the compensating adjustments in step 3 to compromise the intent of the original changes, as the linkage ratio of the rear suspension may be altered.  Further modifications of the settings may be needed, wasting time and effort of mechanics and crew chief.

Using the MotoSPEC Ride Height Gauge function, the gauge measurement is calculated in MotoSPEC as gearing or setup changes are investigated.  The effect of the new settings on the gauge measurement are known before applying them the motorcycle.

MotoSPEC has two methods for specifying the Ride Height Gauge:

1. Mapped Gauge, specified from gauge readings at two swingarm lengths.
2. Measured Gauge, specified from measurements of the gauge installed on the bike, with a ruler and digital inclinometer.

Both these methods have proven to allow MotoSPEC to calculate the gauge reading to within 1 mm of the value measured with the physical gauge.