BIKE (UK)

Suspension sorted

Adam Smallman has been on a suspension set-up course. This is what he learnt…

- Adam Smallman contributo­r Been riding for: 33 years Annual mileage: 6000 Owns: Honda VTR1000 SP2 , BMW S1000RR track bike

GARETH EVANS cut his teeth as a race mechanic - Old Spice Ducati, Loctite Yamaha, Crescent Suzuki, Honda Britain - and now runs the Motorcycle Suspension School from his Reactive Suspension workshop near York. That senior people from Dunlop, BSB mechanics and an off-road KTM mechanic from Israel had showed up tells you about the man’s pedigree. These are my ten outstandin­g observatio­ns from the £110 day.

1 Tune the front for entry into a corner and the rear for exit. 2 Adding preload can, counter intuitivel­y, make a rear shock softer. It’s down to the linkage ratios and the equilibriu­m point between rider weight and spring force. A spring preloaded 13mm with a 75kg rider onboard would hit equilibriu­m at 35mm of wheel travel, Gareth explains. Set preload to zero and that point moves to 63mm, where the spring rate is higher. Try it. 3 Rider sag – the amount that fully-extended suspension (wheel off the ground) is compressed when a kitted rider is in position on the bike with feet on the pegs – should be around 35mm each end. Static sag – the difference between unweighted suspension and the bike-only sitting on its suspension – should be 25mm at the forks and 10 12mm at the back. Less than 10mm on the back and you’ll rip up your tyres, more than 12mm and you’ll feel a lot of movement on exit. If you can’t get these numbers the spring is wrong for your weight.

4 Big piston forks generate damping too quickly: ‘People go for a ride and come back knackered because they’re putting the effort in and the bike isn’t doing the work,’ Gareth says. 5 Lowering kits for short riders are a disaster. The seat’s lower but damping ratios have changed too. 6 Hammering in axles can knock fork legs out of alignment. 7 Identical tyre sizes from different brands can vary by as much as 10mm in ride height. Track riders should compare fully inflated tyre circumfere­nce. 8 Many trackday riders use too much rebound damping. ‘The less rebound the better,’ Gareth says. 9 Tight spots on chains screw up suspension performanc­e. Replace. 10 For many Doritos-fuelled riders, standard springs are too soft.

Alongside these set-up days, Gareth is launching a new specialist Race Engineerin­g Course, 10-11 August. For £720 the two days bring together suspension, tyre and chassis experts. e-mail info@reactivesu­spension.com or call 01347 811 529.

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