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ROTWILD R.C+FS 27.5 Pro

Las Rotwild RC+ ofrecen libertad, comodidad diversión y mucha acción. La batería está integrada perfectamente en el cuadro. El potente sistema Brose facilita el pedaleo en los momentos más complicados. 

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5 999,00 € IVA incluído

30 TAMBIEN PUEDE INTERESAR

The eMTB R.C1+ FS 27.5 offers freedom, comfort, fun and action. For more propulsion – the Integrated Power Unit (IPU) with 518 Wh. The battery is located as a structural part in the carbon bottom tube. The Brose drive system does not generate any additional resistance after cutting out above the legal speed limit because it disengages completely. This means the bike remains easy to pedal even at speeds in excess of 25 km/h.

One clear advantage of the IPU is that it can be integrated without any restrictions even in full-suspension bikes. The geometry of the R.C+ FS 27.5 is similar to the classic R.C1 FS 27.5. Kinematics are optimized for the additional forces from motor and crank, by adapting the virtual pivot point to them. This makes balanced biking possible without any influence from the drive system and the best possible traction. The XCS chassis with forward pivot point and Horst Link rear suspension is designed for higher torque values. It enables an acute configuration of the damper while maintaining a sensitive response and optimum acceleration. This gives high end progression and downhill reserves at all times.


 

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GEOMETRY:

 

ROTWILD Integrated Power Unit (IPU)

The ROTWILD IPU consists of a Brose drive motor and the battery unit developed by us. The aim in development was to integrate the two elements completely within the bike frame in order to retain the dynamic riding characteristics (geometry and kinematics) of classical mountain bikes. The system of the IPU has been registered as a patent with the European Patent Office under Reg. No. DE 10 2013 218 004.

 

BROSE motor unit forms a particularly suitable basis

The pedelec electric motor developed by the German automotive supplier BROSE forms the basis for our IPU. In electrical engineering terms, it involves a “brushless internal rotor”, which is characterized by an extremely compact design combined with high efficiency. The power from the electric motor is transmitted in two stages in a ratio of 1:27. This means that the electric motor always rotates within its optimum window of revs, guaranteeing high efficiency. Another unique design feature of the Brose motor is the use of two freewheel mechanism in the interior. This is very important in the case of pedelecs with a legally prescribed cut-off speed at 25 km/h. With the aid of the second freewheel mechanism, the electric motor disengages entirely once the 25 km/h limit has been exceeded so that the rider can continue to accelerate the bike with muscle power and without any loss in forward drive.

Battery designed in collaboration with a German battery producer

We designed the battery unit in collaboration with a German battery producer. Essentially, the battery consists of four basic elements: the 40 Li-ion cells, the battery management system (BMS) with cable harness and motor connector, the integrated charging socket and the housing that encloses and protects the entire battery unit.  

The 40 high-grade lithium-ion cells of type LG INR18650MJ1 are divided into 5 packs of 8 cells each (4P10S). One single cell delivers a potential difference of 3.6 volts (range 4.2-3.6 volts) with a capacity of 3,500 mAh. The special feature of this Li-ion cell is the chemical structure on the inside, which has been specially designed for pedelec and automotive applications.

IPU integration into various bicycle designs

Our IPU is designed in such a way that we can use it in all bike categories or ranges without any great restrictions in geometry, kínematics or compatibility, i.e. from ROTWILD MTB Cross Country via All Mountain to Enduro; yet at the same also in the multifunctional Tour or Trekking Bike sector. To this end, the motor housing becomes a permanent part of the frame, firmly bolted to the bottom tube battery and unit and the frame – the bottom tube battery unit becomes a supporting element within the frame structure. The compact design additionally enables us to achieve short chainstay lengths or appropriately position the pivot points which are important for the development of full-suspension frames.

Aluminium

The requirements placed on a high-quality aluminium bicycle frame are many and varied. The Al frame should be as light as possible while offering maximum rigidity, display a distinctive optical design and unique character of the tubes, possess certain damping properties and above all have a long service life.

ROTWILD aluminium frames made of Al 6066 T6

In our ROTWILD aluminium frames we use exclusively high-grade aluminium 6066 T6 alloy as the base material. This enables us to build very light, extremely durable aluminium bicycle frames. Al 6066 T6 contains a greater number of alloy constituents, namely silicon, copper, magnesium and chromium, which ostensibly results in a somewhat higher weight (density) compared with the standard Al 6061 T6 alloy. However, Al 6066 T6 offers significantly better properties in terms of the dynamic fatigue strength of the frame.  

If we consider the ratio of density to fatigue strength, the benefits of Al 6066 T6 become very apparent. The material yield strength, which is important for welded constructions, rises and therefore increases resistance to shock fractures. This is a particularly great advantage in full-suspension bikes where travel exceeds 140 mm because the stresses acting here have risen considerably in recent years due to improved spring/shock absorber systems and tyres as well as the higher speeds associated with these developments.

Hydroforming as a production process

Tubes for modern, high-quality aluminium bicycle frames are produced in a process known as hydroforming. It allows the tubes to be shaped individually and produced with a high level of process reliability.

In the actual hydroforming process, the preformed tube section is first placed into a die. This die comprises a lower and upper die, and represents the final contour of the component. The form is closed and the tube ends are sealed by hollow axial punches. The tube section is pressurized at up to 4,000 bar by filling it with a water/oil emulsion through the hollow punches. The high internal pressure is responsible for forming the tube section. The tube is pressed against the die and assumes the contour of the outer die in the process. Additional strain hardening of the material also takes place during the forming operation. In the final step the finished component is removed from the die.

The production technology of hydroforming enables complex tube geometries to be made from aluminium. This allows us to adapt the cross-sections, tube shapes and wall thickness optimally to the load conditions in the frame. The tube geometry and design can also be adjusted to other requirements such as position of water bottles, bearings, etc.

Forging

The advantage of forging is that the fine structure of the metal can be selectively altered. Controlled cooling enables additional material properties to be given to the component. As a result of the process, forged parts exhibit a higher strength than comparable parts milled by CNC and therefore offer a higher safety factor.

Aluminium blanks are used as semi-finished products for the forging process. Their alloy constituents must be identical to those of the tubes for the subsequent welding process. The blanks are generally produced using a casting process. This results either in profile rods or a separately preformed blank, which is already adapted to the final shape of the finished forged part. During forging the workpiece is formed into its desired final shape by hammering and compression.

 

Kinematics

Our aim is to develop the ideal suspension system for every application in order to offer maximum dynamics and riding enjoyment. Kinematic analysis of the entire system forms the basis for our chassis development. This includes determination of the virtual pivot point as well as the wheel trajectory curve, but also the pedal kickback and the transmission ratios between rear swing arm and shock absorber.

 

Virtual pivot point (instant centre)

The virtual pivot point describes a point that moves through the compression process, also known as the instant centre of rotation.

 

Wheel trajectory curve

In addition to the position of the virtual pivot point, the wheel trajectory curve also has a crucial influence on the mountain bike kinematics. The wheel trajectory curve is determined by a straight line for the instant centre, which passes through the virtual pivot point and the axis of the rear wheel.

 

Pedal kickback

The pedal kickback describes the change in length of the chainstay over the spring extension phase and is determined by the direct distance between bottom bracket and rear wheel axle.

 

Gear transmission ratio

The transmission ratio comes from the net result of the moments, which is calculated from the forces on the rear wheel and on the shock absorber.

 

Multiple Dropout Inlay (MDI)

With its Multiple Dropout Inlay generations I and II, ROTWILD introduced a system which allowed different axle standards and derailleurs (Shimano Direct Mount or SRAM Standard) to be installed simply by changing the inlays. The inlays additionally provide mechanical protection when mounting or removing the rear wheel and do not cause defects to the frame in the event of damage.  

The new third generation of the MDIs (MDI III as from frame model R.X1 and R.X+, model year 2016) additionally makes it possible to set a horizontal position for the chainstay length. Consequently, taking into account the wheel size, very short chainstay lengths of 422.5 mm and medium-length chainstays of 435 mm are possible.

 

Horizontal length adjustment and different wheel sizes at the focus of development

Length adjustment via MDI III takes place purely horizontally. This means that important dynamic geometrical dimensions such as height of bottom bracket, seat post and head tube angle are not affected.   

The different wheel sizes of 27.5” and 27+ can also be integrated without serious modifications to the geometry. For 27+ tyres with a breadth of 2.8” to 3.0”, the increased tyre deformation in comparison to standard tyres of 27.5” means that the statically effective radius of tyre to the ground remains practically identical, and consequently the effective height of the bottom bracket does so as well.  

You will find more on settings and configuration options for the MDI III in our knowledge database.

 

Dynamic influences on ride of different chainstay lengths

With the forward axle position, a very short chainstay length of 422.5 mm results, which leads to manoeuvrable, sporty riding characteristics at the same time as an agile and dynamic response when cornering. The rider is able to raise the front wheel more easily on trails in order to overcome obstacles. The chainstay length of 422.5 mm with 140 mm of travel and maximum possible tyre clearance with tyres of 2.4” in width represents the benchmark in the All Mountain sector. 

In the rear axle position, the chainstay length is 435 mm – a medium-length chainstay. This axle position leads to greater riding stability on fast descents and better uphill capabilities in steep terrain, as the front wheel stay in contract with the ground for longer. At the same time, tyres with a width of up to 3.0” (27+) can be mounted with this axle position.

 

Axle position adjusted to rider height

With the aid of the two inlay kits and the associated chainstay lengths, it is also possible to adjust the frame to a rider’s height. To optimize the theoretical distribution of the centre of gravity, we recommend a chainstay length of 435 mm for the frame sizes L and XL; however, the short configuration continues to be an option for the two large frames as well.