Differences BMW 2-Valve Paralever Monolever Twinshock
What are the advantages or disadvantages of the individual drive systems, and which model is better suited for building a Cafe Racer, Bobber, or Scrambler custom bike? Here, we try to shed some light on the subject and explain the individual systems, supported by a technical table. The table shows which fork width, shock absorber length, etc., are installed in the respective Boxer 2-valve bikes. BMW Boxers from 1970 to 1996 are a central focus in our motorcycle custom bike manufacturing, so we can perfectly advise you on which base vehicle is best suited for your motorcycle conversion. If you have any questions that are not answered here, please feel free to call us.
BMW Twinshock Models
Production period until 1984
TWIN for pair and SHOCK for shock absorber means it is a model with two shock absorbers, one on the right and one on the left, and a rigid two-arm swingarm.
Twinshock Models:
R45 78-85 -- R60/5 69-79 -- R60/6 73-76, R60/7 76-78 -- R65 78-85 -- R65LS 81-85 -- R75/5 69-73 -- R75/6 73-76 -- R75/7 76-77 -- R80/7 77-84 -- R80RT 82-84 -- R90/6 73-76 -- R90S 73-76 -- R100/7 76-78 -- R100S 76-80 -- R100RS 76-84 -- R100RT 78-84 -- R100CS 80-84 -- R100 80-84 -- R100T 78-80
Fork diameter 36mm Shock absorber length 330mm
The vehicles we use for our conversions are mostly BMW R65, BMW R80, or BMW R100 from initial registration 1980; the older /5/6/7 models are rarer.
All Twinshock models had a drum brake at the rear, except for the R100RS 76-84 and the R100S 76-80 (both, however, only from 1978 onwards). The final drives (cardan drives) were smooth on the outside until model year 1980; from 1980 onwards, they had circumferential cooling fins. (R80RT 82-84, R100 80-84, R65LS 81-85, R100CS 80-84).
The forks of all Twinshock models had a diameter of 36mm. The last TS models from 1980 already had the fixed caliper brakes of the later Monolever. All other Twinshocks, with the exception of the early /5/6 models which still had drum brakes at the front, had floating caliper brakes.
All R90, R75, R60, as well as the R100CS, R100/7 had spoke wheels; all other classic BMWs had cast wheels. The spokes of the Twinshock cast wheels were more filigree compared to the later aluminum wheels of the Monolever models. However, conversion is not possible. There is not much room at the rear for wide tires; a 120 is the limit. We generally use 120/90-18 or 120/80-18 at the rear and 110/80-19 or 110/90-19 at the front.
The /5 models had a short and slightly higher tank, but its shape already resembled the later Monolever. With the /6 came a flatter and smaller tank, which, however, did not prevail. From the /7 until the last TS model, it was then the identical shape of the Monolever series.
The TS models have a lot of electronics housed in the headlight. This makes converting to a small lamp more difficult. However, with the SE wiring harness and the corresponding handlebar switches, this problem can be solved.
For a Bobber conversion, however, it is complicated with a Twinshock. Since the shock absorbers are attached to the rear frame, these attachments are omitted in the case of a conversion to a single seat. However, we can weld new mounts to the main frame and have the conversion registered by individual approval.
The Twinshocks look more classic due to the two-arm swingarm. If one takes the production vehicles, the difference in terms of braking and handling is enormous. If the components are processed and modified accordingly, the difference is significantly smaller.
BMW Monolever Models
Production period from 1984 to 1996
A MONOLEVER is a single-sided swingarm with one shock absorber on the right side. The swingarm is made of steel and rigidly connected to the aluminum final drive. The shock absorber is attached directly to the main frame, independently of the rear frame, by a welded cast part.
Monolever Models:
Road: R65 85-93, R80 84-92, R80RT 84-94, R100RT 87-96, R100RS 86-92
Fork diameter 38.5mm Shock absorber length 409mm
Enduro: R80G/S 80-87, R80ST 82-84, R65GS 87-92
Fork diameter 36mm Shock absorber length GS 365mm, ST 350mm
The first BMW Monolever model was the R80 G/S, introduced in 1980, and thus also the first off-road sport motorcycle. In the road models, if you exclude the hybrid R80ST, the rigid single-sided swingarm was introduced into the BMW model range in 1984 with the R80RT. This drive concept was built until 1996; the R100RT was the last Monolever model.
The Monolever road models feature a fork with 38.5mm stanchion tube diameter and double disc brakes (except R65). The front brakes are equipped with two-piston fixed calipers. For the Enduro models, however, the 36mm fork width and a single disc brake system remained. All models have a drum brake at the rear.
The brake calipers are originally mounted in front of the fork. It is possible to swap the two fork tubes from right to left so that the brake calipers point backwards. Since the wheel axle is also slightly offset, this makes the bike even more agile and nimble.
The ML models are currently the most popular base vehicles for BMW conversions. Compared to the Twinshock models, they have wider rims, which allows for the use of wide tires. The forks and brakes are larger, but all road models have cast wheels. However, we offer complete spoke wheel sets (cross-spoke) for retrofitting.
The shock absorber is attached exclusively to the main frame. This makes the Monolever concept very suitable for Bobber conversions with a single seat.
BMW Paralever Models
Production period from 1991 to 1996
The PARALEVER drive system is a single-sided swingarm with a shock absorber on the right side. The swingarm is a solid cast aluminum body with a joint at the end towards the cardan drive. This can be recognized by the rubber gaiter located between the final drive and the swingarm. The shock absorber is attached directly to the main frame, independently of the rear frame, by a welded sheet metal profile.
Paralever Models:
Road: R80R 92-96, R100R 94-96, R100R Mystik 94-96
Fork diameter 41mm Shock absorber length 475mm
Enduro: R80/100GS 87-90, R100GS Paris Dakar 89-90, R80/100GS Paris Dakar 90-96
Fork diameter 40mm Shock absorber length 495mm
The Paralever first appeared in the GS models in 1987, and later in 1991 in the road models R80R and R100R. In addition to the new Paralever final drive, these models feature stronger forks (GS models 40mm, R models 41mm), stronger brakes (4-piston fixed calipers, GS single-sided, R double-sided) and spoked wheels.
If you don't like the new tank shape of the Paralever models, you can adapt the Monolever tank. The main frame was changed in the rear section, so the mounting points of the rear frame and the shock absorber differ from the Monolever models. The shock absorber is attached exclusively to the main frame. This also makes the Paralever concept very suitable for Bobber conversions with a single seat.