Sort your SPRINGS
Do you suspect you’re not getting the most from your suspension? Here’s a bite-sized gallop through the main issues
IN ITS SIMPLEST terms, for most road riding, a motorbike (and its rider) can be thought of as a lump of metal, flesh and leather with springy projections at the front and back. Each of these springy bits is attached to a wheel, and each wheel moves up and down over bumps so you don’t have to.
There’s more to it than that, of course: there are also linkages, damping systems, and even electronic control units on newer bikes to consider. But never mind that for the time being. The most important bit of your suspension is
the springs. If they are the right stiffness for your weight, bike and riding style, every ride will feel really nice. If your springs are too soft, the wheels move too far in response to bumps, as if you were riding a blancmange. If they’re too stiff, the suspension transmits the shocks directly to your wrists and arse.
Of course, a one-inch bump at 30mph produces a fraction of the force of the same thing at 100mph. Not only that, but bumps come in every size and profile. Nevertheless, there is an ideal spring rate for you - and it may or may not be the one your bike came with originally.
Being a nerd, I spent three years experimenting with springs on my 1998 Ducati 900SS. I ended up with 0.8kg/mm springs in the forks and an 8kg/mm spring on the shock. As the bike came from Bologna, the dual-rate fork springs were 0.62kg/mm for most of their travel, and the shock spring was 8.5kg/mm. The numbers are less important here than what they actually illustrate: your bike manufacturer’s spring choice might work for you or it could be improved on. You can find out by experiment, by looking at an online calculator (see www.racetech.com), or just by speaking to your nearest suspension specialist. Trust me, getting your springs right can be the best money you will ever spend on your bike.
The importance of springs
My friend Dave recently bought a Triumph Thruxton R. After his first ride on bumpy roads, he could not believe how uncomfortable it was. So he went on the forums and found lots of other people had noticed the same thing. The springs at both the front and rear are very firm. On a trackday (the first of which he did last week) they’re ideal. On