How to wreck your tyres, your bike and your fun

Next month, we’re doing an exclusive workshop with suspension expert Dave Moss, covering all the basics of getting your machine to handle the way you want. There’s already heaps of good advice on machine set-up at Dave Moss’s ‘Ask Dave’ section of the On the Throttle website.

But what if you’re not a track day fiend, and your everyday riding is laid-back, relaxed and gentle? Surely saggy suspension isn’t such a big deal?

Put it this way: it’s no big deal right up to the point when it’s the biggest deal of all.

The moment you have to emergency brake, swerve to avoid an accident or (most pronounced of all) do both is where you’ll find the downside of inadequate suspension is a complete lack of control.

Dramatic moments aside, duff suspension is also burning a hole in your pocket every kilometre you ride.

Get a grip

Suspension is what keeps your tyre in contact with the road and deals with the forces affecting the bike. Worn or incorrectly adjusted suspension puts these forces straight to the tyre without control. The sudden forces, and uncontrolled changes in geometry, mean the bike won't steer how you want it and can easily overwhelm tyre grip, resulting in a crash.

Even if you don't think theses things will happen to you, there’s a couple of other reasons why ensuring your suspension is fully functioning and properly set up makes sense.

Setting sag is the first, essential step in setting up your suspension.

Wasting money

The first is cold, hard cash. Knackered suspension, and even badly adjusted suspension, will wear your tyres out up to three times faster. How? Because your tyre is designed to roll along the road smoothly, not be constantly compressed and lifted off the surface as you ride. When your springs and dampers are not acting properly, the tyre effectively bounces off the road then presses back on it again. It will be doing this countless times per kilometre, and with every tiny bounce your tyre is being scuffed. This constant scuffing means your tyre will wear out prematurely, even riding gently along straights and through wide-radius curves.

Factor in some changes of speed and direction–braking, turning, accelerating–and the tyre wear will be even more pronounced. The effect will soon show on your tyres. One of the most common signs is feathering and chamfering at the leading and trailing edges of the tread pattern. These two edges should have a nice 90º angle on them (apart from Michelin Pilot Road 4s, which are designed to have a chamfer). If they look feathered or worn at an angle your suspension is trashing your tyres. Here’s an example of a suspension problem wearing the tyres, in this case lack of adequate rebound damping:

The feathering up is caused by the suspension rebounding too fast. If the feathering was on the front edge, it would most likely be too slow. This is at the track, but the same effect can be seen on road tyres.

Simple checks

Before getting too stuck into suspension issues, the one thing you’ll want to take out of the equation is tyre pressures. Wrong pressures are the number one cause of premature, uneven or strange tyre wear. So start by setting the tyres to the manufacturer’s recommended pressures. If you don’t have the handbook, you can search online. Here, for example is Dunlop’s advice for a fitment on a Honda CB 600F Hornet. With the tyres at correct pressures, you’ll be able to focus entirely on the suspension.

You might not be able to do an off-the-bike bounce test like a Pro, but you can easily feel for badly worn-out or underdamped suspension. The bike will want to bounce up and down like a yo-yo.

What to do?

You may be able to cure this with suspension adjustment. Again, there’s good advice online but if you don’t fancy tackling it yourself, book in at your local dealer. If they know what they’re doing about suspension adjustment, they’ll start by setting up sag with you on and off the bike, going on to adjust preload and damping for your weight and riding style.

This may not work. The manufacturer’s range of adjustment may be infufficient for your weight, if you’re very light or heavy. The springs may be too stiff or not strong enough.  If so, the next step will be replacement springs with different rates, and changes to valving or the oil weight.

But if your suspension has croaked it, the only course of action is a rebuild or replacement. Okay, it costs money. But so does wearing your tyres out in a couple of thousand kilometres. A rebuild to your shock or forks will soon start paying for itself.

Preload and, usually, rebound damping adjustment are located at the fork top; compression at the bottom.

And finally

Why do you ride a motorcycle? For most of us, fun is a big part of the equation. So is the satisfaction of riding well, with confidence. And few things contribute to riding enjoyment and confidence than a well set-up machine.

Human beings are incredibly adaptable. We can cope with and manage all sorts of inconveniences. But soldiering on with a badly set up bike or past-it suspension is simply not worth it. See your local dealer or mechanic, because the sooner you get it sorted the longer your tyres are going to last. And so might you.