Damping Technology

[Shaun]

PS Rob, Very good job on Craig Shirrifs bike it and he, looked very very good at Wanganui the other day

[DEATH_INC.]

Yes in a funny way the rotary damper thing on the TLs was very similiar in principle. But it is hard to define how much of the damping was created by friction!
I have now measured the od of the TTX valves, 26mm. Maximum of 12 shims able to be fitted.

The biggest problem I found when playing with a TL shock was the pitiful sized and shaped ports the oil had to flow through.....
Mr jd does have a point, surely it would be a lot to ask of even a 26mm valve to cope with that much oil flow.....have you found the point that you start to get resistance without the valving (shims) being the restrictor? Would it be low enough velocity to reach in the real world?

[JD Racing]

As for my habit of revalving at races I am guilty, guilty, guilty. Gareth Jones came to me first thing in the morning at Wanganui yesterday saying there was a little too much acceleration squat in the rear end of his Bernard Racing R6. It had a setting spec that worked well with Sam Smith ( similiar height and weight ) and his Dunlop tyres. But Bernard racing runs Pirellis which load the suspension rather differently. Following a trackside revalve and some ongoing optimisation of fork spring rate, preload and oil level the job was done. Guilty and charged.

Craig Shirriffs started his test season earlier than most of the top runners and we have relentlessly refined settings since with about 5, maybe 6 revalves. That he was able to walk away with all the wins at Boxing day races yesterday is testament to his undoubted ability and also finding a valving spec that so far is working pretty damn well. But we will continue on, THERE IS NO PERFECT SETTING and anyone who thinks so is in denial.

The fact that you would need to revalve your shock should you swap between Dunlop and Pirelli I find both surprising and quite alarming. Geometry changes yes but a revalve?
I'm also surprised that it would need 5 or 6 revalves before the season has even started, the picture is building up here of a shock that has an extremely limited adjustment range.

[cowpoos]

The fact that you would need to revalve your shock should you swap between Dunlop and Pirelli I find both surprising and quite alarming. Geometry changes yes but a revalve?
I'm also surprised that it would need 5 or 6 revalves before the season has even started, the picture is building up here of a shock that has an extremely limited adjustment range.

tyres are essentually part of suspension action...especially at lean angles where suspension is less effective...so when swaping brands with majorly different carcus make up [ie:very stiff sidewalls on dunlops with steep profile..pirelli's...softer side walls and more progressive profile...which I'm sure your aware of?] it would definatly alter how the hydralics on the shock need to act/re-act...much the same way if your ride ate 10kgs worth of pies for breakfast...it would alter how the suspension re-acts/act from the opposite side...so why would you not want to optimise it?? reguardless of the tool being used...Geometry changes won't always work...especially with 190hp trying to tie a rearend in knots hard on the power...

[JD Racing]

tyres are essentually part of suspension action...especially at lean angles where suspension is less effective...so when swaping brands with majorly different carcus make up [ie:very stiff sidewalls on dunlops with steep profile..pirelli's...softer side walls and more progressive profile...which I'm sure your aware of?] it would definatly alter how the hydralics on the shock need to act/re-act...much the same way if your ride ate 10kgs worth of pies for breakfast...it would alter how the suspension re-acts/act from the opposite side...so why would you not want to optimise it?? reguardless of the tool being used...Geometry changes won't always work...especially with 190hp trying to tie a rearend in knots hard on the power...

I understand all that, but then what purpose do the knobs at the top of the shock serve? Do I need an Ohlins technician with me at all times to revalve my shock for every time I raise or lower my tyre pressures, swap brands of tyre, go to a different track?

[cowpoos]

I understand all that, but then what purpose do the knobs at the top of the shock serve? Do I need an Ohlins technician with me at all times to revalve my shock for every time I raise or lower my tyre pressures, swap brands of tyre, go to a different track?

ummm...most adjustments are done with low speed damping after the fact...which the TTX has... out of interest...last weekend while I was doing my best to get in Roberts way while I was spannering for Mr Stroud...I did ask Robert if theres a reason why the TTX does not have highspeed compression adjustment on the shock...he did say you can have it...but he also explain why its not there...and I'll leave that for him to explain.

and maybe if robert feels like it...he could reiterate Andrews reaction to a straight shock change between brands...with a much lower spring rate.

[JD Racing]

ummm...most adjustments are done with low speed damping after the fact...which the TTX has... out of interest...last weekend while I was doing my best to get in Roberts way while I was spannering for Mr Stroud...I did ask Robert if theres a reason why the TTX does not have highspeed compression adjustment on the shock...he did say you can have it...but he also explain why its not there...and I'll leave that for him to explain.

and maybe if robert feels like it...he could reiterate Andrews reaction to a straight shock change between brands...with a much lower spring rate.

The difference in sidewall stiffness and it's impacts upon the shaft velocites attained by the shock can be adressed with a low speed adjuster, it has one of those.

[cowpoos]

The difference in sidewall stiffness and it's impacts upon the shaft velocites attained by the shock can be adressed with a low speed adjuster, it has one of those.

high speed shaft velocites aswell?

[TDC]

I understand all that, but then what purpose do the knobs at the top of the shock serve? Do I need an Ohlins technician with me at all times to revalve my shock for every time I raise or lower my tyre pressures, swap brands of tyre, go to a different track?

Its not brand specific (damper that is). As you are obviously aware the bleed is a bypass to direct fluid away from the shim stack, thus giving you a range of adjustability. What you are really doing is balancing the action of shim stack / piston combination against the bypass flow, assuming that the shim stack is close to perfect for a given set of conditions you would need little if any bleed / bypass and would have a good level of control at all flow rates.

Unfortunately the effect of the common bleed adjuster is most pronounced at low shaft speeds / flow rates, having less effect at the shaft speeds increase.

We really have no cost reasonable mechanism for adjusting the basic characteristics of the shim stack piston combination. We can adjust the low speed response by the bleed adjuster to a point, but we quickly end up in the undesirable place of having to compromise the damping response at one shoft speed to effect the target area, not ideal.

Hence we are forced regardless of brand of device to re-valve to suite the rider (including weight, height, what he she had for breakfast, style, and sometimes how they are feeling on the day), tyre, machine (including geometry, linkage ratios, weight distribution, etc) track, and conditions.....

It is only by getting the response profile of the stack / piston combination right in the first instance that we can approach ideal (or fastest for a given bike rider track combo). As progress is made the dampers like the Ohlins TTX40 and the Sachs equivalent as fitted to the MV Senna are beginning to allow us to have better high speed adjustability (when compared to the blow off valves of some) but the problem of balance between the low speed and mid speed response has not been adequately dealt with by anybody to date.

So until somebody produces a damper with adjustments that effect the various parts of the speed range with no adverse effects to other shaft speeds other than the target range, I guess we are stuck with with optimizing what we have by the only means available (read re-valve). But then again it would be entertaining watching the greater percentage of the population try to set up a shock with say 3 or 4 adjusters each for comp and bump, but at least we wouldn't have to re-valve very often......

Simply you can't tune in to a shock via the external adjusters performance that wasn't in there in the first place, regardless of brand, so you have to get your hands dirty.....

[cowpoos]

The difference in sidewall stiffness and it's impacts upon the shaft velocites attained by the shock can be adressed with a low speed adjuster, it has one of those.

I'm actully thinking...maybe you might need to have a play with one of these TTX36 shockies to try and find its virtues for your own interest???

[TDC]

The difference in sidewall stiffness and it's impacts upon the shaft velocites attained by the shock can be adressed with a low speed adjuster, it has one of those.

As you open up the adjuster you loose a measure of control at the wheel. The stopwatch would strongly suggest that better result can be had by keeping the bleed flows small and having a shim stack with the correct characteristics for the given conditions.

I was personally skeptical and largely held your view point for quite some time, but RT has demonstrated to me in convincing fashion that he was right all along.....

[JD Racing]

As you open up the adjuster you loose a measure of control at the wheel. The stopwatch would strongly suggest that better result can be had by keeping the bleed flows small and having a shim stack with the correct characteristics for the given conditions.

I was personally skeptical and largely held your view point for quite some time, but RT has demonstrated to me in convincing fashion that he was right all along.....

If it was squatting too much you would surely close up the adjuster.
MY point though is that one this shocks main selling points in all the promotional material fromOhlins is the performance of external adjustment, what your telling me is that if you use this adjuster you'll loose rear wheel control.

[TDC]

If it was squatting too much you would surely close up the adjuster.
MY point though is that one this shocks main selling points in all the promotional material fromOhlins is the performance of external adjustment, what your telling me is that if you use this adjuster you'll loose rear wheel control.

If the bike was squatting too much I would probably look at the rear geometry (read ride height) first, I don't believe that you can control squat especially on liter class bikes by hydraulic action alone.

However, the action of the compression adjuster is rather good, certainly a wider range of useful settings than a lot of other designs. But if you want the best out of it, it does respond rather well to a bit of tweaking / optimization.

Poos is right you really should try one, I would be very surprised if you were not very impressed!

[JD Racing]

What I'm looking for is someone to give me a proper technical explanation of why I should drop that amount of dollars on a new shock, not just spend the money and you'll arrive at the promised land.
Perhaps if you have one you can enlighten me a little.
I read in a magazine a quote from Ohlins press office about how when Rossi first tried the shock he didn't want it taken out of his bike... that was it, nothing else, we'll overlook the fact that it's a completely different shock, but to me my first question would be WHY???
What does it do that the previous shock didn't?
What can I expect to feel during the transitional phases of a turn?
How will it impact upon my tyre conservation during a race?

My questioning so far has led me to believe that it's a very sensitive to tyre choice with a poor range of adjustment, prove me wrong, give me a good reason to lever these dollars out of my pocket before the wife spends the money on shoes.

[cowpoos]

My questioning so far has led me to believe that it's a very sensitive to tyre choice with a poor range of adjustment, prove me wrong, give me a good reason to lever these dollars out of my pocket before the wife spends the money on shoes.

no that would be your selective comprehension...


I think maybe...your either taking the piss...or your trying to discredit people?