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Ducati ST4S's Suspension Settings, and any ST Tyre Setup

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VinceS:
Hi Randeep,


Whilst there is usually a way to thread it diagonally between the spokes it ain't easy. The usual solution is to get 90 deg tyre valve adapters fitted when changing the tyre. Cost about $15 ea and the problem goes away.


Also helpful in the event you spend any noticeable time high speed running, eg on the track. The plastic caps are dirt shields not air seals, and the centrifugal force will open a vertical valve and let the air leak out - took a std valve on a rear from 41 to 19psi on me in only 10 mins once, on a track in Central Oz somewhere, you know the one...? The 90 deg adapters are bullet proof in this regard, nothing leaks out of them!

Randeep Singh:
Hi Guys,


Can anyone let me know how to check tyre pressure at servos, as am unable to fit the servo nozzle on tyres. It just doesn't fit. Do I have to buy an adapter or my own compressor?


Sounds a dumb Q.


Thanks

TopDOG:
The only memory of buying tyres i have is fitting what I thought once were Pirelli's but are now Michelin PILOT POWER tyres & as can be seen in one of our trips somebody ended up needing to smoke what was left of my rear tyre near the tyre shop after being prompted to do so from memory by the tyre salesman who told me part of the tyres not down to the belts yet!! And I honestly cant remember what my bike was wearing while racing on her for the Ducati B.E.A.R.s race team or what it had on 11 years and 1 day ago when i become whats left of your old TOPDOG!!! :( :'(

VinceS:
Just thought I would log what I have learnt and use, in case that helps anyone and document tyre & suspension settings that work. I have "done the k's", been to the Stay Upright Suspension school, and fiddled, heaps. This is what I have found works best and gives me the most capacity to handle crap terrain / road situations arising while still loving riding the bike (I am 180cm and float 80-90kg, mostly I was around the 80 mark when establishing the following):

Tyres:
I have settled on Pirelli Angel GT's as the best all-rounder tyre for these bikes, but that is not what this post is about as tyres are a bit of a "forget about the facts, I've got this opinion, seee" topic. The GT's are great in the wet and in the dry, on a hot summers day with all 124 horses urging me on well cranked over, the tyre can just manage to leave darkies without spinning up / out. Beautiful, who needs more power and traction control when these high mileage performance tyres can just nicely reign it in! Previously I used to alternate between the Rosso's and Rosso 2's, depending on expected riding as the Rossos would break away too easily so needed the 2's for the safety aspect. Not any more, the GT's do the lot. I get about 8,000k's out of a rear and 12-15,000k's from a front. Previously Rosso 2 rears = 3,500; Rosso's = 6,000 and fronts were 6k for 2's and 9k for Rosso's. So GT's give performance and life, you beauty - and no, riding style has not backed off. I haven't managed to ditch a rear tyre from edge wear yet, it is always centre that gets it, but rarely have 20% left on the edges. These are all 80% two-up figures.

Tyre pressures: Front 33 / 38 / 37 psi and Rear 36 / 45 / 41 psi solo / pillion / track;

Re the track pressures, last Dec I went out in the green group with the slowest bike on circuit (oh yeah, they could all get past on the straight, and 80% of 'em had no road lighting, so dedicated racers), but I could keep the thing in the front 2/3 of the pack (just!). So I was riding the tits off it and had a two wheel slip in turn 4 at EC, without a fall (yay to those crispy old fart reflexes that keep the gas on a smidge and avoid the high-side!). I had a chat to the tyre guy and it turned out I had been overheating the Angel GT's with my exertions - he said to put 5psi more over std and should be all good. Chalk and cheese, I just loved the stability of that as I could get it titless again without anything "funny" happening - this may be contrary advice to what you (and I) may have heard before, but absolutely for me in this situation on this bike, it is the gospel truth!

Suspension:
Very helpful suspension advice comes from this link: https://www.sportrider.com/suspension-setup-guide#page-17. That is more important than the following, but here is what I have found for a 2003 ST4S:

Front suspension: Screw the top nuts fully in =25mm preload (factory setting is 16mm, in range of 10-25mm out to in); factory compression (bottom screws) is 12 clicks out but I use 8; factory rebound (top screws) is 11 but I use 15.

Rear suspension: solo / track use is with pre-load screwed to approx 80% in (yep, that's nearly all of it) and with pillion, screw it max in, which is not enough - really need to change the stock 95N/mm spring for 110N/mm, which I have just done, and find correct numbers again (learn about static sag). The stock spring is 57mm diam x 170mm uncompressed and 149.5mm with no pre-load added, according to the manual. I measured mine at 80% in to be 143mm. I note on the ST4S the end position is adjustable so maybe the Aussie models come with 147.5mm not 149.5mm, not sure and can no longer measure it!

Factory compression (reservoir under seat) is 14 clicks out but I use 4; factory rebound (spring bottom knob) is 14 but I use 17.

Ride Height: Amazing how much nicer the bike is with this maxed out, plus easier to get it on the centre stand! You set the length of that lovely shiny aluminuim rod that joins on to the rear shock rocker so, with new tyres on the bike on a flat surface with the bike on the centrestand, there is just enough clearance for the rear tyre for it to turn, say 3mm; factory is about 30mm. Bit of a cow of a job to do (note left and right hand threads, so look closely to see which one you are doing); you need two quality 19mm open ended spanners, don't try with any crappy spanner as you won't get it done, except if you take the whole thing out to replace the rose joints, which makes it easy.

Worn Components: Before you tackle the ride height job, check if there is much play in the suspension wear points - some wrestle over the back seat and lift the wheel up - very awkward; I prefer to just get my big 30mm ring spanner on the back axle nut and try to tighten it up - how much the wheel lifts is the give-away, and more than 1cm you need to fix it; should be less than 5mm. Most likely the issue is with the two rose joints on the ride height arm, but often the bolts themselves are also worn - just replacing the bolts may get you down to a small looseness, so easy to do. Note I haven't seen a shockie bolt wear yet, just the ride height adjuster arm ones. They are slightly different lengths so watch reassembly as otherwise interchangeable.

Shockie adjustment 101: is that the term "clicks out" is anti-clockwise looking from the end you are adjusting. The FIRST thing you do is carefully count the clicks IN as you screw it in, so you know where you were (write it down, you WON'T remember), nip tight to the end, don't force it! There is nothing "magic" about a click, that is just a ball bearing detent to help you know how much you have turned the thing. If you are 90% the way to a click but hit the end, count it as a click, or at least allow when comparing both sides on the front so they are as near to the same as you can manage.

Professional help: Best in the country is to be had in western Sydney at Shock Treatment. Book in for a same day full service jobbie and get yourself down there, well worth the effort.

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