By Joe Michaud
[This Motorcycle Suspension Technology in Detail book review was originally published in the April 2007 issue of Rider magazine]
So says the intro by Werner “Mini” Koch and Benny Wilbers in their collaborative book, Motorcycle Suspension Technology in Detail.
Suspension tuning has always seemed a black art to me. Is my bike set up well? Can it be improved? Koch and Wilbers explain the basic set-up of modern motorcycle suspensions and work us through fine-tuning for our particular riding needs.
First, they advise ruling out any non-suspension handling variables like worn tires, inaccurate tire pressures or related mechanical problems. Check the chassis for correct spring rates by measuring three suspension value variables: full extension with the wheel off the ground, static length (or “sag”) of bike-weight alone, and compressed length with the rider aboard. All dimension ratios are specified in the text along with cures should your machine fall outside of the suggested specs.
Springs are the workhorses of suspension and Wilbers advises addressing them first. If preload cannot be properly adjusted, replacement is in order. The correct spring provides the optimum compression and rebound distances for the shock stroke. Too soft, the shock will bottom out; too stiff and the shock will rebound to the mechanical stop. Hydraulic damping—controlled by metering oil through adjustable valves—restrains and controls the energy stored by the spring, but valve tuning alone cannot compensate for incorrect spring rate.
To some degree, compression and rebound stroke length also affect rake, trail and braking forces, all of which contribute to our sense of “road feel.” Add “stiction” from inherent mechanical resistance into the mix and the whole plot can get complicated. But don’t worry. All is addressed, explained and demystified in this 95-page hardbound book (recently translated from German with some interesting typos).
Some tips for the home suspension tuner? The charts and graphs are in millimeters so acquire an accurate metric steel rule to avoid conversions. An additional person to measure and/or steady the bike is also a great aid. Some changes influence others, so proceed slowly and modify only one setting at a time. After each adjustment, ride the bike over the same course (and the same bumps, chattery pavement, etc.) to check for positive improvement. Keep notes of your original starting points in order to find your way back if you stray from the correct path. But remember… manufacturers provide adjustability features for a reason. Don’t be afraid to tune to your liking.
It will still take a certain seat-o’-the-pants sensitivity to achieve the “correct setting” for your own riding style, bike and weight. But Wilbers and Koch explain enough of the mechanical processes of modern suspensions to educate the average driveway mechanic. Beg the help of a riding buddy and see if your ride can’t become better attuned to the pavement. Mine did.
I found Motorcycle Suspension Tuning to be an interesting read; the text is fully illustrated with color photos and graphs and the instructions are clear. The book is available for $24.50.