ROTWILD R.G+ Ultra 36
ROTWILD R.G+ Ultra 36

ROTWILD R.G+ Ultra 36

7.999,00 €
Impuestos incluidos

Bici de DH perfecta para prescindir de los remontes. Ruedas de 27.5", cuadro con 200mm de recorrido y batería integrada de 500 Wh. Motor Brose Drive S. Amortiguador FOX X" Air. Cableado interno.

A downhill bike for everyone who likes to bike without shuttles and lifts. The R.G+ comes with 27.5" wheels and 200 mm chassis and a 500 Wh integrated power unit made from carbon with integrated shock absorber attachment on the drive. The 100% decoupled Brose drive system does not generate any additional resistance after cutting out and allows light pedalling. Individually adjustable levels of support as per your personal preferences - from very efficient to an extremely powerful mountain bike. The new XLS chassis is specially aligned to the FOX X2 Air shock absorber and the anti-squat is optimised to the higher chain hoist of an electric drive. The MSH I headset allows 3 adjustments to the steering tube angles so that the dynamic characteristics of the bike can be set according to individual requirements. The newly developed Multiple Dropout Inlay (MDI III) inserts allow the chain stay length to be changed so that adaptations specific to body size can be carried out and riding dynamics can be changed. The R.G+ also has integrated cable routing for the lowerable seat post and offers a tyre clearance up to 27.5 x 2.6.



  • Gravity tube shape with 27.5” wheel set and 200 mm travel
  • Carbon IPU 500 with integrated shock mount
  • Performance optimised, 100 % decoupled Brose Drive S
  • XLS chassis aligned to FOX X2 Air shock
  • MHS I headset
  • Special enlarged bearings for increased durability
  • Integrated cable routing
  • Tyre clearance up to 27.5 x 2.6
  • Integrated fork bumpers







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 2014 218 036.8.


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. In the first stage, a planetary gear with a transmission ratio of 1:9 is connected before the motor while transmission in the second stage takes place in a ratio of 1:3 via a belt drive. This transmission ratio is necessary so that the electric motor (driven by the rider’s relatively low pedalling frequency) always rotates within its optimum speed window in order to guarantee a high efficiency. 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.

Brose has continued to optimise the motor in the new Brose Drive S (available from MY 2018). The increased efficiency and the new thermal design increase the power output. The torque curve has been specially adapted for use in sport and the responsiveness has been improved for technical terrain so that uniform support is always provided and everywhere becomes accessible by bike.

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.  

Two different batteries are offered as of the 2018 model year:
The IPU.500.ALUMINIUM has a total capacity of 518 Wh. It is completely integrated into the aluminium bottom tube and is permanently installed in the frame. The battery consists of 40 lithium-ion cells (model INR18650 MH1), divided into 4 packs of 10 cells. Each cell provides 3,600 mAh. The IPU.500.ALUMINIUM will be used in all CORE models as standard. The IPU.R.660.CARBON has a total capacity of 648 Wh. The battery is integrated into a carbon bottom tube, is removable and can be charged both on and off the bike.

The IPU.R.660.CARBON has 50 premium lithium-ion cells (model 18650), where each cell provides a voltage of 3.6 volts (ranging from 4.2 to 3.6 volts) with a capacity of 3,600 mAh. What makes these lithium-ion cells special is their inner chemical make-up which was specifically designed for use in electric bikes and the automotive industry. The IPU.R.660.CARBON will be used in all Ultra and Pro models as standard. The IPU.R.660.CARBON is backwards compatible and can be integrated into all ROTWILD/Brose hybrid models. 

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.


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.


Modular Headset I (MHS)

The Modular Headset I (MHS I) has been developed entirely by ROTWILD and offers a variety of different configuration options to adapt the frame for individual use.

Semi-integrated design permits easy replacement

The MHS I headset has a semi-integrated design, i.e. the headset bearings are integrated in aluminium shells, which are pressed into the specially developed frame head tube at the factory. It is therefore possible to replace the headset parts or shells or change the configuration of the MHS I at any time. 

The ball bearings we use are completely sealed, stainless steel 45° angular contact ball bearings to absorb the axial and radial forces that act in the headset section. Unlike many headsets available on the market, our MHS I bearing shells including the ball bearings are fully protected against the ingress of dirt from the outside by means of three additional external seals.  

Adaptation of the head tube angle

The MHS I is part of the frameset and pressed into the head tube in what is known as a “zero configuration” as supplied from the factory. In the case of 34/140 mm suspension forks this is equivalent to a head tube angle of 67°. As an option the upper bearing housing can be replaced by a special 1.5° bearing housing, which reduces the effective head tube angle to a shallow 65.5° or increases it to a steep 68.5°.

Influences on riding dynamics

Changing the head tube angle has a strong impact on the dynamic riding properties and geometry of the frame, as the dimensions that change include height of bottom bracket, reach, seat post angle and wheelbase.

65.5° version of head tube angle: The shallow head tube angle biases the character of the bike towards descent. The wheelbase increases, the steering behaviour become less agile and, because the front wheel makes contact with obstacles earlier due to its forward-positioning, the flip-over sensation decreases when riding over or descending steep ledges or steps.

68.5° version of head tube angle In general a steeper steering angle equates with better manoeuvrability and lighter steering movements, which is expressed in more agile riding characteristics. 


Specific Geometry

A flat steering angle provides the necessary control in front, the low centre of gravity as well as the 450 mm short chain stay length the best compromise between running smoothness and agility.