Sort your CBR Sport’s suspension

Published: 06 May 2002

Honda’s CBR600 Sport has a better engine than chassis – if you stick to the standard fork and shock adjustment settings. It isn’t until you spend a day dialling in your suspension that a good bike becomes a great one.

On standard settings, the CBR feels vague to most fast riders, but tweak it and, as well as finding your lap times will tumble, your enjoyment will increase massively, too.

The Showa forks and shock are of a reasonable quality. They’re fully adjustable and the range of adjustment is wide – but fine-tuning is vital to get the best from them.

We’ve used two riders at opposite ends of the weight scale – 10-stone racer James Doherty and 16-stone MCN road tester Keith Farr – to help you get the optimum set-up. Both spent a day at Bruntingthorpe Proving Ground getting the bike to handle like it should for fast road use and track days. Odds are your weight will fall between our testers, so use their settings as a guide:

What you’ll need: A tape measure, a 14mm open-end spanner, a flat-blade screwdriver, a rear shock C-spanner, pliers/cable snips, and one medium-sized cable tie. Plus a clear understanding of the following terms.

Pre-load: Forks and shocks settle into a natural position when a bike is static. When you brake, accelerate, or corner, they slide (travel) on their damper rods or stanchions.

Setting the pre-load means controlling how much of the suspension’s maximum travel you want to use. There is an optimum and it takes trial and error to find it. The spring has a pre-determined springing rate – how firm it is. Altering pre-load doesn’t affect this, but determines where the suspension begins to work and how it moves.

Rebound damping: Controls the rate at which the suspension returns once compressed. Too much and it returns too slowly. Hit a sequence of bumps like this and your suspension will " pump down " until it remains compressed. This makes the bike highly unstable. Dial in too little and you’ll get " chatter " – where the suspension returns too rapidly to the start of its stroke.

Compression damping: This controls the rate at which the suspension compresses. Too much and the bike " kicks " off bumps. Dial in too little and the bike dives unnecessarily easily. You also need to know the stock suspension settings, which are:

Front: Pre-load: Four rings out from hard (fully-in)

Rebound (top of fork): 1.75 turns from hard – lines up with dot

Compression (bottom of fork): 1.25 turns from hard – lines up with dot

Rear: Pre-load: setting two of seven

Rebound (right side of shock): 1.5 turns out from hard – lines up with dot

Compression (left side of shock): 1.5 turns out from hard – lines up with dot.

The more front and rear suspension a bike uses without bottoming out, the more efficiently it’s working. We want to set the handling so the forks and shock are doing all the work, instead of the tyres.

To work out how far the suspension is travelling, you’ll need to fit the cable tie around one fork inner leg, snipping the excess off once it’s secure. Ideally, you’d fit another around the rear shock’s damper rod to measure travel here, too, but the CBR’s shock is a sealed unit, which means the damper rod is hidden from view. That means we’ll need to rely on feel and feedback to decide the optimum setting.

Push the cable tie down the fork leg. As its travel is used, the tie will be pushed upward. As long as it’s firmly in place, it will remain in the position it’s pushed into, allowing accurate measurement.

Step One: Assess stock fork travel:

Farr: I only needed a warm-up lap to know the front was way too soft for me. As I braked at the end of the straight, the forks bottomed violently. On standard settings, they were using all their travel. The rear wallowed exiting corners, and mid-corner in some, too. I pulled in and measured the amount of travel being used. It came to exactly 120mm which I know from experience happens to be the full length of the forks’ stroke. There was nothing in reserve, so I needed to stiffen the forks a lot until I was only using about 115mm travel – leaving 5mm for big bumps. The rear needed a bit of adjustment, too. I noticed the bike pulling 118mph through Bruntingthorpe’s tricky left-hander. I’m sure I can improve on that.

Doherty: I stayed out for five laps and found I was getting exactly the same speed through the left hander as Farr. But the bike felt squirmy and I didn’t trust it much, even though it’s on mega-sticky Bridgestone BT010 tyres. When I stopped, we measured the amount of fork travel I was using at 109mm. As I need to use all but 5mm of the 120mm travel, the front needed softening. But the rear was too soft, wallowing out of two bends.

Step Two: Adjusting front and rear pre-load:

With both ends too soft for Farr and one too soft and the other too hard for Doherty, we needed to find the right settings for both riders. It’s pointless experimenting with a bike’s damping until you know the suspension is travelling the right distance. The greatest gains are made from getting the pre-load right. Damping adjustment is fine-tuning.

Farr: The stock setting of four rings out from hard felt like putty to me. On the track, if I were racing, I’d wind it in until only one ring was showing on both fork tops. But as I wanted a bike that would remain supple enough for fast road riding too, I adjusted the pre-load setting until three rings were showing. Going harder than that upsets the bike on the road – I know from past experience. Three rings is fine for most track days too, though a particularly smooth circuit might warrant a tweak until just two rings are exposed. As an all-rounder, though, I’m sticking with three rings showing which, at Bruntingthorpe, resulted in 116mm of total fork travel used, with 4mm spare if I happened to hit a big bump. Getting your bike to handle right isn’t all about making everything stiff. It’s about making it as soft and relaxed as it’s possible to get away with. That way the tyre does the work, not the shock oil. I wound the rear pre-load up from position two to number three, which felt OK for a while, but then I went to number four, which was better for me. The bike felt more planted. I’ve seen many 10-stone riders with their CBR600F-S rear shock set to number six or seven on the road. And they wonder why it handles like a bag of sh*t. Answer – it’s too bloody hard like that – unless you’ve got a fat missus on the back holding a lorry load of shopping. My new pre-load settings brought my left-hander corner speed up to 120mph.

Doherty: I wound the front pre-load off until five rings were showing. I race CBRs, so I know how to set them up. And soft pre-load for a man of my weight is the way to go. On this setting, the forks still had 9mm of unused travel – only 111mm was being used up. So, I wound another half-a-ring off until five-and-a-half were showing on both fork tops. That got me using 114mm of the total 120mm travel. The 6mm remaining is about right to help you soak up the extra travel needed if you hit a bump. Position three on the rear shock’s pre-load felt perfect. Suddenly, the pegs stopped dragging so readily. We were in the ballpark now and I was getting 120mph through Bruntingthorpe’s left hander.

Step Three: Adjusting front compression damping:

We wanted to get the front feeling roughly right before we turned our attention to the rear.

Farr: The compression and rebound adjusters on most bikes click when you turn them. The CBR’s just turn. So we measure the range of adjustment in turns. One complete turn is one complete revolution – 360°. Half a turn is 180° and so on. The CBR600 has four full turns of compression damping adjustment on the front. It is set at the factory to one-and-a-quarter turns out from fully in (fully hard). That means about two-thirds of the total adjustment is already gone before we start (the other two-and-three-quarter turns), and it’s still very soft. I know this because the front dives readily when I brake, ride a crest or even hit a bump. So, I wind the adjuster in until it’s half-a-turn from fully in. That will be too much for lighter riders, who’ll find Doherty’s setting better. My left-hander cornering speed climbs to 122mph.

Doherty: I made a more minor adjustment and dialled in a quarter turn. I’d make that half-a-turn if I was racing, but for fast road and track day use, adjusting it until it’s one full turn from fully in is better for a 10-stone rider. My left-hander speed rose to 122mph and I was able to brake later on the approach to each bend.

Step Four: Adjusting front rebound damping:

Farr: The stock 1.75 turns out from hard isn’t enough. The front still feels a bit like a jelly. So I went for 1.25 turns out instead and was rewarded with a 124mph run through the left-hander. Then, I went for another half-a-turn, until just three-quarters-of-a-turn from hard was dialled in. I got a 127mph run and the front felt totally planted. On the track, with my race head on, I’d go another quarter in until just half-a-turn from hard remained. That would be too much for me for the road, though.

Doherty: I went to one-and-a-quarter turns from hard, Farr’s original setting, and decided to stay there. The left-hander returned a 128mph pass and the front felt great. Another quarter of a turn could be wound in for a boiling hot track day, but I wouldn’t try it

on the road, or the rate of return once the forks were compressed would be slowed too dramatically, causing the forks to " pump down " over a succession of the kind of bumps you get on the road. Again, the minimum setting you can get away with is the best one.

Step Five: Adjusting rear rebounding:

Farr: The stock setting is 1.5 turns out from hard of a possible four, which suggests it might be quite " firm " , otherwise, what were the other 2.5 turns doing? Fact is, even turned more in than out as standard, the bike needs loads more rebound damping, so in came another full turn, leaving it just 0.5 turns out from fully in. The wallow disappeared and the bike was transformed, holding a much tighter line out of corners, picking itself up more quickly, and giving the tyre an easier time. My corner speed climbed to 128mph as a result of the increased confidence.

Doherty: I eventually settled on Farr’s setting, too. He piles into bends quicker than me and exits them slower, which makes his demand for rebound damping to control the rate of return comparatively less. But I come out quicker and need the rear to control itself better. If he rode like me, he’d have the rebound wound all the way in. My mid-corner left hander speed hit 129mph.

Step Six: Adjusting rear compression damping:

The rear still dived, or compressed, too readily for both riders, prompting them to go from the stock 1.5 turns out from hard to just three quarters of a turn from fully in.

Farr: This was almost perfect for me, but the few bumps I hit at Bruntingthorpe still nudged the bike a fraction. I eventually settled on half-a-turn from fully in and got a 129mph pass through the left-hander. In total, the pass speed through that one corner alone increased by 11mph. That’s a fraction off a 10 per cent increase just by tweaking the suspension. Amazing, really.

Doherty: I went to three quarters of a turn from fully in and left it there. I know when something feels spot-on and this was perfect. I got an indicated 130mph through the left-hander, the bike was unflappable and it was still supple and pliable enough to take anything public roads could throw at it. By that, I mean drains, overbanding, potholes, crests, bumps, dips and white lines.

Step Seven: The final settings:

The set-ups our two riders finally arrived at are poles apart. Chances are you’ll weigh something between their 16 and 10 stones, so use these as your starting point.

Farr’s perfect CBR set-up:

Forks: Pre-load; Three rings showing. Rebound; 3/4 turn from hard. Compression damping; Half-turn from hard

Rear shock: Pre-load; Position four. Rebound; Half-turn from hard. Compression damping: Half-turn from hard.

Doherty’s perfect CBR set-up

Forks: Pre-load; Five-and-a-half rings showing. Rebound: One-and-a-quarter turns from hard. Compression damping: One turn from hard.

Rear shock: Pre-load: Position three. Rebound: Half-a-turn from hard. Compression damping: 3/4 turn from hard.