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Prototype Öhlins demper?
Moderator:Beheerders
Gaat het nu eindelijk gebeuren de entree van Öhlins in de mountainbike wereld
http://www.vitalmtb.com/product/feature ... 50b-DH,171
http://www.vitalmtb.com/product/feature ... 50b-DH,171
Downhill is where it’s at – real proper scrambling on tracks rougher than Ryan Gigg’s home life
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de lachende derde
- Berichten:1319
- Lid geworden op:di jan 18, 2011 6:34 pm
- Contacteer:
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de lachende derde
- Berichten:1319
- Lid geworden op:di jan 18, 2011 6:34 pm
- Contacteer:
Dus? Op die CCDB's staat idd ook een Öhlins logo en het kan net zo goed zijn dat het een nieuwe verstevigde versie is want die shaft scheen zo nu en dan wel eens te verbuigen.Trekrules schreef:Het is een Öhlins demper onder de tape op de reservoir zie je het Öhlins logo,ook is de demper een stuk forser dan een ccdb
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Flip van Veen
- Berichten:2883
- Lid geworden op:zo jan 23, 2011 8:42 pm
- Locatie:Elburg
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illuminatastigmata
- Berichten:2836
- Lid geworden op:za jul 02, 2005 12:36 am
- Locatie:limburg
- Contacteer:
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Flip van Veen
- Berichten:2883
- Lid geworden op:zo jan 23, 2011 8:42 pm
- Locatie:Elburg
Öhlins TTX Shock Highlights
•Patented Twin Tube design
•High-speed compression adjustment (3-clicks)
•Low-speed compression adjustment (16-clicks)
•Low-speed rebound adjustment (7-clicks)
•Nitrogen-filled nitrile rubber reservoir bladder system
•Steel springs available in 23-pound (4 N/mm) increments
•Weight: ~460 grams without spring, 550-600 grams with spring
•Will fit 2012-2014 Specialized Demo 8 and 2013-2014 Enduro EVO bikes
•Upgrade program available through Specialized retailers
•MSRP: TBA
Inside The TTX
Ready for this? It's about to get techy up in here…
When the Öhlins TTX is actuated, the fluid inside is forced to flow through two types of orifices: bleed valves and shim valves. Bleed valves (Fig.1) are small orifices that create a flow restriction simply by being small. Shim valves (Fig.2) use fluid pressure to deflect thin steel washers (shims) to open up an orifice and allow fluid to flow through it. To control damping force, the bleed valves can be changed in size by the external compression and rebound adjusters
When the bike is compressed (Fig.3), the fluid above the piston is pressurized and has to move. It has three different escape routes:
1.Piston compression shim valve
2.Compression adjuster bleed valve
3.Compression adjuster shim valve
The fluid flows through all these routes during every compression, but at low damper velocities the percentage going through the bleed valve is higher and at higher velocities the shim valves take care of most of the flow. During compression movement, the piston rod volume enters the main body and the corresponding volume of damper fluid flows into the reservoir through the compression valve, the bladder compresses, and this results in an increased gas pressure.
When the spring forces the shock to rebound (Fig. 4), the fluid below the piston is pressurized and forced to move. Due to the one-way check valve design on the outer tube, all fluid is forced to flow through the piston where it takes two different routes:
1.Piston rebound shim valve
2.Rebound adjuster bleed valve
The fluid that was displaced into the reservoir during compression movement is now pushed back into the main body by the gas pressure.
During both compression and rebound, the gas pressure supports the low-pressure side of the piston to keep pressure at a controlled level. This is what makes the Öhlins design so special, as it ensures consistent damping performance and improves damping response. In a traditional absorber, without the Twin Tube design, all fluid has to go through the main piston and the volume displaced by the piston goes to the gas reservoir. When this occurs, there is a higher pressure on the compression side of the shim stack and lower pressure on the other. Öhlins plays with what oil goes where to eliminate that pressure difference. Adjusting the compression settings changes the percentage of fluid that goes through the piston versus what goes around the bypass tube.
Why is this beneficial? It all comes down to response time. In traditional shocks, oil is getting compressed to a greater extent, and when you switch from compression to rebound, the oil has to expand as well (that squishy noise you often hear). Because of the Twin Tube design, internal pressure changes are less dramatic, which enables the shock to reverse directions quickly while maintaining consistent damping, even on very short stroke movements. Öhlins says that creating damping force at lower pressures has a huge effect on the response of the shock. The difference between the two designs becomes more apparent If you raise the temperature and cycle frequency (think faster repeat hits on the trail). Öhlins claims the design eliminates the possibility of cavitation (bubbles forming in the oil on the low-pressure side) and the damping inconsistencies that can result, because there is no massive pressure drop when the piston changes directions. Lower pressures also allow them to use thinner walls - meaning less weight - without fear of them flexing much.
While the Twin Tube design is similar to the Cane Creek Double Barrel, how the oil is handled is what sets the TTX apart. Öhlins developed the Double Barrel with Cane Creek seven years ago and has learned a fair amount since that time.
One particularly interesting feature of the TTX is the use of an expandable nitrile rubber bladder in the reservoir, as opposed to the typical IFP (Internal Floating Piston) design found on most mountain bike shocks. The bladder system is said to be lighter and a little more sensitive than the traditional seal design. The biggest benefit has to do with cooling, though, and the bladder design allows more fluid to be in contact with outside wall, so cooling is more efficient. The nitrogen-filled bladder is set from the factory at 175psi (12 bar) and cannot be readily adjusted. Bladder pressure only needs to be checked when the shock is serviced (every 50 hours of riding is recommended).
Speaking of temperature, the TTX employs a clever way of maintaining stability and consistency when the oil temperature heats up. First, a flow restriction design in the bleed valves creates a turbulent flow at very low piston velocities, allowing the oil to cool faster. Also, an aluminum rod inside the steel shaft compensates for the viscosity change in the fluid due to temperature changes. Because the two materials have different thermal expansion rates, the aluminum rod grows relative to the steel shaft and helps close off some of the damping ports, almost negating the temperature's effect on damping.
Springs are offered in 23-pound increments (versus 50-pounds for most competitors). This allows the rider to really dial in their bike to the perfect spring weight, giving them the most amount of usable damping control from the shock.
Just like in years prior, the Demo 8's shock will be equipped with offset eyelets to accommodate +/- 5mm bottom bracket height adjustments. The shock is also easier to access that those on the Demo 8 in previous years, and all TTX-equipped frames will have slightly revised cable routing that follows the underside of the top tube.
Finally, the TTX uses a spherical bearing mount, which allows the shock to articulate freely. By doing this, the shock is no longer a structural component, which separates shock movement from chassis flex (not that the Demo 8 is a flexy rig to begin with, by any means) and allows it to move as freely as possible. This is also commonly done on motocross bikes.
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Downhill is where it’s at – real proper scrambling on tracks rougher than Ryan Gigg’s home life