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Old March 24th, 2014, 02:31 PM   #51
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Sorry, I left out details.

The original / standard kit from Andreani comes with .78kg/mm. These were a bit soft for my liking and the bike had too much sag so we ordered up and installed .88kg/mm. Those got the sag numbers I was looking for. But the kit called for that air chamber gap of 140mm.

I can't really measure where it is now without completely removing and dissembling the forks (which if you've done on your bike, you know how much fun it is….LOL). But I wouldn't think those small fluid changes brought it any higher than 130mm. Likewise, as you said, with completely different internals, the volume difference really can't be measured between mine and a stocker.

I've been told not to change what Andreani recommends, but I'm not riding around a damn bike that bottoms at the slight hint of a wheelie….especially on a bike designed to be somewhat like a motard. (sorry to vent…just frustrated with this thing)
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Old March 24th, 2014, 05:39 PM   #52
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Wow those numbers sound so close that I wonder what else could be wrong. This is not rocket science. Could something be loose that feels like bottoming? Honestly I have not been even close to full travel. But I have not done any serious offroading...
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Old March 25th, 2014, 05:54 AM   #53
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I have checked and double checked. I've also used the zip-tie method (as well as seeing the "oil ring") too see if the fork was actually bottoming. Plus...the nasty headshake that happens when it does bottom out is a dead giveaway. LOL

I'm going to run up to the shop this weekend I think and speak with them. The owner there has been racing/building race bikes for 20+ years. I think i may just speak with them or even give him the darn thing to ride. Either that, or I may just keep adding oil until the problem stops. I guess the worst that could happen is I would blow a seal.

It's just confusing. In all the "normal" riding conditions, the fork preforms flawlessy. But with a wheelie, it's like the fork just gives out.

We'll see.
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Old March 25th, 2014, 07:20 AM   #54
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I'll admit that I am no "stunta." My wheelies are limited to lifting the front wheel an inch or two when accelerating in first or maybe second, and not really on purpose. However I've hit some huge potholes, thought I'd bent a wheel a few times.

But if you saw the Cycle World video, those guys were wheelieing their brains out on standard Hypermotards. Their forks did not seem to bottom! Maybe it was the 20mm extra travel, but maybe not. Have you tried adding more compression?

FWIW, one more item in my fork setup - 5W oil. Stock was 7.5W.
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Old March 25th, 2014, 09:44 AM   #55
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Originally Posted by twozzie View Post
I asked Rob what was done and as the forks do different operations as you know, he put a 9mm/kg in one side and a 8. something in the other, (no idea which) overall he went to 8.75.
More than likely, it was a .9kg/mm and a .85kg/mm spring. Those rates are pretty common. They're soft, similar to a stock CBR600RR, but stiffer than something like a KLR.
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Old March 25th, 2014, 11:06 AM   #56
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Originally Posted by michdave View Post

It's just confusing. In all the "normal" riding conditions, the fork preforms flawlessy. But with a wheelie, it's like the fork just gives out.

We'll see.
Well, it's not a SM with 8" of fork travel and a twin-tube cartridge fork, nor is it a superbike fork with a 1kg/mm spring installed.

As you raise the oil level, the air gap shrinks. As a result, the fork’s effective spring rate will become progressive earlier in the stroke. Above a certain oil level, it will become effectively impossible to use the entire stroke of the fork.

To a point, this is good as it will protect you from mechanically bottoming over bumps or under emergency braking – you’ve created a hydraulic bottom rather than a mechanical one. Conversely, this can be bad as ride quality can suffer, available suspension travel becomes restricted to soak bumps, thus transferring too much into the tire and chassis, and rebound will not be linear throughout the stroke, as this is a function of the effective spring rate relative to hydraulic damping.

The important thing to know is what you are trying to achieve.

Do you want a plus ride with decent bottoming resistance? The solution might be a softer spring, modest compression damping and a higher oil level.

Do you want dive and bottoming resistance and consistent rebound through the stroke, at the expense of a plush ride? You might be better off with a heavier front spring, less preload and a lower oil level with good compression damping and initial stroke control by way of a mid-valve stack (typical of road-racing cartridge kits).

There’s no ideal solution for all scenarios (yet). BMW, Ducati and KTM are all bringing in semi-active suspension in an attempt to solve the riddle. I personally would prefer a slightly softer front-end to help me transfer weight on-demand while on the HS. My RSV4 is the opposite – heavy spring rates at both ends to control pitch and to keep ground clearance from being a problem when corner speed and lean angles are high on a track. It’s a compromise.

If you’re happy overall with the feel of the fork, but are bottoming doing wheelies, maybe the solution is to practice wheelies on a different bike, or at least try to roll into the gas a little as you set the front down.

The bottom line is, do what you’re doing… small incremental changes.
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Old March 25th, 2014, 11:40 AM   #57
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Originally Posted by ChrisMag View Post
More than likely, it was a .9kg/mm and a .85kg/mm spring. Those rates are pretty common. They're soft, similar to a stock CBR600RR, but stiffer than something like a KLR.
Yup, that seems about right.
Rode the bike at the weekend, was much improved over the stock shocks, potholes etc were now non existant and the bike seemed more planted in the corners which is great. However I seemed to feel more of the undulations in the road, I'll give it another few rides and then report back to Rob.
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Old March 25th, 2014, 12:19 PM   #58
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What did the stock springs measure in terms of rate?
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Old March 25th, 2014, 12:55 PM   #59
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What did the stock springs measure in terms of rate?
.65mm/kg
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Old March 25th, 2014, 02:12 PM   #60
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Originally Posted by ChrisMag View Post
Well, it's not a SM with 8" of fork travel and a twin-tube cartridge fork, nor is it a superbike fork with a 1kg/mm spring installed.

As you raise the oil level, the air gap shrinks. As a result, the fork’s effective spring rate will become progressive earlier in the stroke. Above a certain oil level, it will become effectively impossible to use the entire stroke of the fork.

To a point, this is good as it will protect you from mechanically bottoming over bumps or under emergency braking – you’ve created a hydraulic bottom rather than a mechanical one. Conversely, this can be bad as ride quality can suffer, available suspension travel becomes restricted to soak bumps, thus transferring too much into the tire and chassis, and rebound will not be linear throughout the stroke, as this is a function of the effective spring rate relative to hydraulic damping.

The important thing to know is what you are trying to achieve.

Do you want a plus ride with decent bottoming resistance? The solution might be a softer spring, modest compression damping and a higher oil level.

Do you want dive and bottoming resistance and consistent rebound through the stroke, at the expense of a plush ride? You might be better off with a heavier front spring, less preload and a lower oil level with good compression damping and initial stroke control by way of a mid-valve stack (typical of road-racing cartridge kits).

There’s no ideal solution for all scenarios (yet). BMW, Ducati and KTM are all bringing in semi-active suspension in an attempt to solve the riddle. I personally would prefer a slightly softer front-end to help me transfer weight on-demand while on the HS. My RSV4 is the opposite – heavy spring rates at both ends to control pitch and to keep ground clearance from being a problem when corner speed and lean angles are high on a track. It’s a compromise.

If you’re happy overall with the feel of the fork, but are bottoming doing wheelies, maybe the solution is to practice wheelies on a different bike, or at least try to roll into the gas a little as you set the front down.

The bottom line is, do what you’re doing… small incremental changes.



Chris,

Currently I'm running .88kg/mm springs which are significantly stiffer compared to the stockers. I also have the Andreani double cartridge kit installed; making the stock forks now fully adjustable (i.e. preload, rebound, compression).


The shop I purchased them from weren't instilling full confidence in the advice they were giving…so I had to jump ship. I called Ducati Winchester and spoke with the owner, who has been wrenching and racing for 20+ years, primarily on Duc's and a fully certified Ohlins (Andreani and Ohlins are in collaboration in Italy) dealer, …yada, yada….

He said that every other Hyper they're worked the suspension on, ran 100-120mm oil level. So…I'm pulling the forks as we speak and bumping them up to 100mm. We'll see what happens.
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