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Offline Nicolas

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TSAS in combination with progressive springs?
« on: July 20, 2018, 04:20:24 PM »
Anybody put progressive springs on a TSAS equipped tiger (like from hyperpro or wilbers for example)

I really like progressive springs, all my cars and bikes had them, or if not I backfitted it. But all TSAS like bikes (ktm, ducati, triumph, bmw) don’t have them. I guess as the shocks are the progressive part here.. Still I could see an advantage in combinig both.

Somebody tried? Somebody can explain why it wouldn’t work?

Many thanks
Nicolas

Offline Nicolas

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Re: TSAS in combination with progressive springs?
« Reply #1 on: July 21, 2018, 10:11:06 AM »
But don’t get me wrong, it’s a great system. Having roads in all kind of shapes, it dramatically increases the percentage of enjoyable roads. Eg when linked with other drivers on a dayride with a club or the NRR, you hear the other drivers complaining of poor road surface quality, while you tune the suspension for a bit more for comfort and happily zoom along.

Offline Dilbert

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Re: TSAS in combination with progressive springs?
« Reply #2 on: September 20, 2018, 01:05:06 PM »
Springs that get "stiffer" as the load increases would seem to be a good idea, as I understand it TSAS only increases the hydraulic damping under load, so if the spring isn't strong enough it still won't cope.


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Offline XCaTel

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Re: TSAS in combination with progressive springs?
« Reply #3 on: September 20, 2018, 02:47:57 PM »
*Originally Posted by Dilbert [+]
Springs that get "stiffer" as the load increases would seem to be a good idea, as I understand it TSAS only increases the hydraulic damping under load, so if the spring isn't strong enough it still won't cope.
I don't think that is what happens. The TSAS suspension is not as complex as most people think. TSAS is only adjusting the rear preload, adjusting itself to the load for ride height and no preload adjustment on the front (there is manual front preload adjustment on the XR non TSAS model). The damping part of TSAS is changed by pre-sets in your rider modes, which you can customise, or your joystick within that mode directly off the dash, but it is not dynamically changing in normal riding conditions (like some BMW models). I believe the only time the damping actively changes is when the bike thinks it has gone off-road for more than a certain amount of time (several seconds I think) and then reduces the damping effect, i.e. making it softer for greater off-road suspension travel. But still, it is not then dynamically changing the damping within the off-road setting either. In normal road use or even in off-road rider mode your damping and ride height adjustment will remain the same from one end of your 300-mile ride to the other. If you swap out your springs from non-standard your damping adjustment is going to be total guesswork by the TSAS system, it is calibrated for the Triumph OEM spring and not your new progressive spring. I would not change the springs on the TSAS equipped bikes at all unless you know the exact consequences of doing so.
« Last Edit: September 20, 2018, 02:49:41 PM by XCaTel »

Offline Zeebad

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Re: TSAS in combination with progressive springs?
« Reply #4 on: October 02, 2018, 04:42:17 PM »
Progressive rate springs make it impossible to properly set rebound or compression damping because of the varying spring rate. I can't imagine that combining them with an electronic automated system built for linear springs will work well.

Offline Zeebad

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Re: TSAS in combination with progressive springs?
« Reply #5 on: October 02, 2018, 04:48:33 PM »
Furthermore, Hamlin on the 1050 forum convinced me that progressive springs aren't all that anyway. I'll let him explain why...

Progressively wound springs work on the theory that they will be plush and compliant in the early part of the travel and then get firmer deeper in the stroke. Sounds good, right? What really happens is that the spring rate constantly changes through its travel, resulting in an unpredictable shock. You never really have the right spring rate for any given situation. Think snake oil here, sounds too good to be true because it is. If this was a really good idea to make bikes handle well you would see it on racebikes. You don't. If you ride a pace similar to a Vespa with the plug wire pulled off you would probably like it. If you are heavy, say over 150 lbs, you will squash down the softer part of the spring and ride in the harder part of it anyway (like Rhead and Indy), compromising shock travel. This will make the rear squat too much (think chopper) and cause your bike to steer poorly and run wide on corner exits as it transfers excessive weight to the rear, unloading the front. If the front doesn't have enough weight on it, it can't carve corners well. Most of you have this problem and don't know it. When you open the throttle on corner exit does the bike drift to the outside on its own? Do you have to close the throttle slightly to get it back on line? If you do your rear spring is too soft.

I only use straight rate springs because I need the shock (or fork) to behave the same in the first inch of travel as it does in the last. Consistency is what you are after here, as well as having the proper rate to keep the back high enough to rotate weight onto the front tire so the bike will steer properly.

Offline NiK

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Re: TSAS in combination with progressive springs?
« Reply #6 on: October 03, 2018, 09:01:08 AM »
*Originally Posted by XCaTel [+]
it is not dynamically changing in normal riding conditions (like some BMW models)
I can't provide any exhibit, but I read (probably from Triumph's website or user's manual) that the TSAS is active.
The auto preload allows for constant height (whatever the load), while the setting you change on the fly allows for more or less damping.
In addition, Triumph claims that the front constantly sends data to the rear to achieve consistency.
This could all be in my head, but I'd swear I can feel that last feature when hovering a pothole at speed.

As for progressive springs, I find Hamlin's analysis very wise!

Offline XCaTel

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Re: TSAS in combination with progressive springs?
« Reply #7 on: October 03, 2018, 11:51:21 AM »
*Originally Posted by NiK [+]
I can't provide any exhibit, but I read (probably from Triumph's website or user's manual) that the TSAS is active.
The auto preload allows for constant height (whatever the load).
If that is the case then I stand to be corrected, I am not sure about that though. The static load/SAG will not change once you are off because your static load is not changing (I'm not talking about forces on the bike). It is measured and set sure but why would it change once you are under way? OK if you change the load sure but that is not something you do mid ride. As the bikes rear suspension is constantly being compressed and extended how is TSAS to know if this is a load or just forces on the bike due to an undulating or potholed road and make a preload adjustment? I really do think this suspension is simpler than that. You see a few bike reviewers comment on the term semi-active TSAS and they highlight this same fact, it is not really active suspension, which I don't mind personally.

Offline Dilbert

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Re: TSAS in combination with progressive springs?
« Reply #8 on: October 03, 2018, 12:56:32 PM »
Hamlin is probs the only one I'd take advice from on the 1050 forum, definitely knows his stuff  :028:


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Offline Dilbert

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Re: TSAS in combination with progressive springs?
« Reply #9 on: October 03, 2018, 01:11:14 PM »
Interestingly when I went on the Factory Tour last Friday I got chatting to the guide, when I came out and checked his bike, a 2014-2015 Explorer like mine it was covered in Maxton's stickers, ok not the 2016 on with TSAS, but not exactly a shining endorsement fro Triumph suspension as a whole  :028:


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