My S1wl has showa x1 forks and an AST shock. These were fitted at the end of 2010 and have done about 8-9k miles and are on original oil. The forks are better than the rear but aren't great.
Despite the sag and dive under breaking being about right they are rock hard particularly the rear it just kicks you in the arse so hard you get thrown out the seat constantly. The only time it works well is when its set up harder for two up riding.
Yes I've tried various settings but they seem to make very little difference, I have about 25mm of preload. I have never touched the high speed rebound.
My Fireblade floats effortlessly but firmly over the same roads even on its track settings.
If I'm brutally honest the AST has always underwhelmed me despite it being initially very adjustable.
Tyres are right and the suspension has no leaks.....I'm at a loss
Any Ideas most welcome as this is taking the fun out of riding my special old bike.

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Buelling is exhillarating
But downhill bike racing is so terrifying it makes your arse grow teeth

AST high speed damping is back to front... As are the Ohlins and Penske...

You need a WillyPro...

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08 Specialized Langster

Could you elaborate on the high speed damping, pash.
As I understand it the slow speed rebound is how quickly the shock returns to normal after compression what does the high speed do and will it stop the rock hard feeling as you go over a bump if altered.
i.e does it soften the ride?

_________________
Buelling is exhillarating
But downhill bike racing is so terrifying it makes your arse grow teeth

Sounds like the rear shock is over sprung

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Mithered ta death.
92 MB
96 S2T
98 S1W
00 M2
01 X1
03 P3
10 CR

I would agree there Maz ......but initially the shock was too soft and would wallow out of bends so I gave it 8mm more preload and 2 clicks more comp damping, and it was much better. (its currently 3 clicks lower and still v hard)
Would dropping the preload soften it, or does that just lower the ride height.
Could the shock oil be clagging up the comp valves? Can it be serviced.

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Buelling is exhillarating
But downhill bike racing is so terrifying it makes your arse grow teeth

High speed damping takes the shock out of rapid loadings at high speed, like ripples on the road surface. It does this by the use of shims that bend as you force fluid through them. Less shims, less damping. Normally this is an additional circuit on compression but as the damper is a conventional one back to front, this is now on the rebound circuit and about as much use as a chocolate teapot.

Do a google

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08 Specialized Langster

Changing the preload will only affect sag/ride height. Reducing the Spring Rate (n/mm or kg/mm) i.e. changing the spring will be the only way to sort out over springing.

Do you know what spring was fitted with the shock from AST....is it marked on the spring?

Ignore the spring rate. It only affects the ride height and range you operate in. Strangely it can be that the harder the spring rate the softer the ride is. Too soft a spring allows the shock to compress too much and you ride outside the working range.

When my ast blew it's oil seal on a ride, the first thing I noticed was how smooth the road had become. It was only bouncing round the next corner that alerted me to what had really happened.

Are we back to the high speed damping circuit being reversed?

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08 Specialized Langster

That was the same problem that I had with mine , I fitted a softer spring , the original spring was only good for two up riding.

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2001 X1 2009 1125CR 2006 Uly X3 2010 Uly a fully Maz'd S1 and a 1991 RS1200 Westwind.

when i had my ast , they asked for my weight so this wouldnt be a problem and no im not telling what it is

When I chatted to Ronnie whilst in Belgium about mine he said that the earlier ones were oversprung because he didn't have a tuber to use when he first started making them , he then realised they needed to be sprung a bit softer than he'd originally worked out.

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2001 X1 2009 1125CR 2006 Uly X3 2010 Uly a fully Maz'd S1 and a 1991 RS1200 Westwind.

I've had my AST for a long time, and the spring rate is spot on As the others have said, altering pre load on a constant rate spring won't affect it's stiffness, you'll just alter the sag.
This is why manufacturers lie when they claim their bikes have 'Fully Adjustable Suspension' - unless they supply a big box of springs with the bike. Appropriate springing is the most important of all.

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If your dreams don't scare you, they are not big enough.

Anyway, the main problem with motorbike suspension is, the use of stupid telescopic forks. Millions of Honda 50 riders can't be wrong

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If your dreams don't scare you, they are not big enough.

I had the shock sprung for 92kg and mentioned that I would be occasionally doing two up with additional 62kg (I know she's a bit of a lump ) all weighed while suited and booted.

The shock was initially too soft.........over time it has got progressively harder
(must be the blue pills )

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Buelling is exhillarating
But downhill bike racing is so terrifying it makes your arse grow teeth