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Bülk: The Velomobile that can change your life

On this page you will find details about …

 

Introduction    Have you seen before?    Life changer    History    Philosophy

Introduction

Welcome to this place dedicated to Bülk Velomobile!

 

We are pleased that you are interested in our products. This applies to insiders as well as to newcomers to this subject area.

 

The Bülk MK1 velomobile is a muscle-powered vehicle for sports, leisure and mobility in general. Although it is technically a bicycle, it can do much more: it offers excellent weather protection, high riding comfort, high safety and requires considerably less power than a racing bike for the same speed.

We invite you to get an idea of ​​the many facets and history of this vehicle!

You have never seen anything like this before?

Many people have never seen a velomobile. It’s usually gone just as quickly as it appears: Oops, what was that? An electric car? Was that solar? Does this have a motor or why is it so fast?

 

If you have landed on this page anyway, we can tell you exactly what it is about.

 

The Bülk MK1 is a velomobile. Velomobiles have been around for more than 100 years. Originally, they were primarily intended as a means of transportation as very few people could afford a car. However, with the mass production of automobiles, velomobiles disappeared from the scene again.

 

A velomobile is a human-powered vehicle with an aerodynamic body. The driver drives in a comfortable lying position and is protected from the weather.

 

Modern velomobiles have evolved a lot. They have become lighter, safer and faster.

Today, climate change and the energy crisis have placed the velomobile in a new context and this is leading to a sharp increase in interest in these products.

Velomobile World is the world’s largest manufacturer of velomobiles. Our portfolio includes the world’s leading velomobiles such as Quest, Quattrovelo, Snoek, Df, Alpha7 and 9, Milan and Bülk.

 

The Bülk MK1 is a new development from 2021, is based on the Milan velomobile and is to be described in more detail on this homepage.

Why a Bülk velomobile can change your life

Should a product change my life? A daring thesis!

 

Give us some space here to justify this thesis.

 

In our experience, why did people buy the Bülk MK1?

 

As a rule, these are people who are in the “productive phase” of their lives. That means they are between 40 and 60 years old, work a lot, don’t have enough time for sports, think about spending their holidays in a sporty and active way instead of flying to distant countries and feel uneasy about driving a car.

 

People who are considering cycling to work instead of driving. But they can only imagine that when the weather is good. And therefore partially discard the idea.

 

People who want to replace car kilometers with bicycle kilometers. And people who want to get fit and vital again.

 

Some of this also applies to you?

People who have dared to take this step and become customers tell us again and again how their lives have changed.

 

They report how unbelievably fast they can drive under their own power and how much fun it is for them.

 

They report how comfortably and weather-protected they can now commute completely independently of the weather and how they look forward to the commute to work.

 

And how their fitness and health benefit from it, because you can now do sports all year round without a break from training.

 

Many take their velomobile directly on vacation trips and are amazed at how many people you get to know with such a vehicle.

 

All of these experiences create a life-affirming momentum that brings about change. In this way, this vehicle can become the focus of a new way of life in which awareness, health, joy and sustainability can be lived.

The history of the Bülk Development

The aerodynamic design of the Bülk MK1 is based on the work of the brilliant aerodynamicist Eggert Bülk.

 

The aerodynamic design of the velomobile is decisive for efficiency, driving stability and behavior at high speeds.

Eggert Bülk has made history in the racing and record-breaking velomobile scene with his developments over decades.

 

That’s why we want to pay tribute to him here with a biography. Enjoy the story of a pioneer who, with passion and obsession, pushed the boundaries of human-powered locomotion.

The Philosophy of Bülk MK1

What was the aim of this development?

 

The aim was to build a velomobile that made as few compromises as possible in terms of aerodynamic efficiency, driving pleasure and suitability for everyday use. At the same time, it should be extremely compact (length: 257 cm, height: 84 cm and width: 70 cm), but also allow shoulder widths of 60 cm and heights of up to 200 cm. With a 28 inch (622) rear wheel.

 

To reconcile these objectives, numerous competing objective functions had to be weighted and reconciled.

 

A coherent overall composition was created for this, which optimally implements all the essential requirements of a modern velomobile.

 

Tasks in the area of ​​the increasingly urgent mobility turnaround play a role, as do suitability for everyday use, driving pleasure, dynamic and aerodynamic efficiency, safety and sustainability.

What is meant by competing objective functions?

 

What is meant here are those properties of a velomobile that are expected by customers today, but which lead to collisions and contradictions when implemented in a vehicle concept:

 

For example, the demand for a lot of storage space collides with aerodynamic efficiency; as well as the space requirements of large and heavy drivers

Powerful thighs need space in the front wheel house; this in turn limits the steering angle

Demands for compactness of the vehicle contradict the desire to be able to accommodate the largest possible driver in the vehicle

In order to achieve aerodynamic efficiency, the vehicle’s air friction surface must be as small as possible. At the same time, the vehicle must not converge too bluntly at the rear in order to avoid wake turbulence

Low weight competes with demands for high stability and security

Velomobile riders want very good weather protection, but at the same time want to have as much contact with the environment as possible; experience the environment with the senses

Stability in crosswinds must not be at the expense of aerodynamic efficiency

There is a whole range of other antagonisms that need to be brought together in an overall composition when constructing a forward-looking velomobile. That’s why we saw it as a challenge to make the unproductive dead spaces between these antagonists usable or to productively overcome them, or to resolve the contradictions themselves in the process.

 

That is the philosophy of the Bülk MK1.

 

It is of course clear that there are no objective criteria for the respective weighting of claims and each consumer has their own individual preferences. Nevertheless, there are large intersections.

 

You can say that the Bülk is a velomobile that takes these intersections into account in a good way and thus concentrates on what really counts.

⬇️ Here are the main points of the philosophy in detail 

 The vehicle design is optimally tailored to the space requirements of the pedaling driver. A mix of teardrop and laminar design has proven to be suitable to accommodate the driver’s space requirements at shoulder and arm height. As a result, the vehicle can be very short.

 

 A very low head rest area, pulled up to the rear wheel arch, allows even very tall drivers a good view and sufficient space under the hood. This opens up a very wide adjustment range for small to large drivers … ⬇️

The Bülk MK1 can be adjusted to different driver sizes between 150-200 cm in just a few minutes:

 

With the adapter module for the head rest area, it can be easily adjusted to the driver using Velcro.

 

*Click on the image to enlarge/zoom

The leg length can be adjusted without tools using the seat-rest rail with 6 positions or, in extreme cases, by shifting the bottom bracket slide.

 

The space required for the knees and the head is determined by selecting the appropriate hood (3 sizes: flat, medium and high protuberances for the knees) and an optional module for the heel protuberances. Even the cross-sectional area of ​​the vehicle can easily be adapted to the driver.

 

With this modularity, an exact adjustment to very different driver sizes, leg or seat giants can be made within a very short time.

 

*Click on the image to enlarge/zoom

The different hoods also make it possible to drive with your head outside or to take the hood with you in the vehicle.

 

This means extreme flexibility in terms of usability in families, partnerships or communities.

 

In addition, this also increases the resale value, since the potential customer group is very large. Dealers have the advantage that they only need one demonstration vehicle.

 

*Click on the images to enlarge/zoom

The new and compact design of the Bülk MK1 is based on our many years of experience in velomobile construction and measurements in the wind tunnel. A semi-laminar design with a strongly flattened and short bow and overall great compactness has proven to be optimal. In this way, the Bülk MK1 redefines the optimal interaction of cross-sectional area, air friction surface and space requirement of the driver. This compactness also enables a new weight-stiffness ratio.

 

The space lines for heel and foot tips are adapted to a narrow bottom bracket size. This achieves a very efficient power transmission to the pedals with a small cross-sectional area at the same time.

 

With the new design, outstanding overall efficiency is possible.

 

Here is an example of driving efficiency in public road traffic with traffic lights, altitude difference, through-roads and the proportion of city traffic in Berlin: see the image on the right / next (on mobile)

EFFICIENCY OF THE DRIVE

 

The drive of the Bülk is extremely stiff. The bearing points of the carbon mono swing arm are stable due to the overall construction. The rear wheel house is connected to the head rest area of ​​the body and thus prevents movement of the swingarm bearing.

 

The front mast has a cross-section of 50 x 50 mm² and is arranged in a Y-design: it gets its rigidity from a vertical support between the transverse tunnel of the wheel house and the top of the body. This also prevents vertical movements of the deflection roller.

 

The rear idler is also anchored extremely stably and withstands the toughest sprint attacks without flexing.

The floor pan between the front and rear axles has been optimized for the driver’s center of gravity to be as low as possible. This is where space is usually wasted with velomobiles. The Bülk MK1 also pushes the limit in this respect. This increases driving stability and at the same time creates a higher interior and space for taller drivers.

 

The overall aerodynamic design is designed for high stability in cross winds. Due to the strongly rounded and flattened bow, the pressure point and center of gravity of the vehicle are so close together that the vehicle automatically stabilizes in cross winds. The buoyancy in cross winds is specifically prevented by the shape, and the floor pan causes suction towards the ground in cross winds. This defuses dangerous situations in strong winds and gusts.

So it can be said that the overall efficiency of the Bülk MK1 is outstanding. Also with regard to the fact that even tall drivers (with correspondingly more power) have space in this compact vehicle and can develop their power.

Suitability for everyday use is a decisive factor when assessing a velomobile. The personal weighting of everyday characteristics is individual for each user, but based on our decades of experience with velomobile customers, we can judge very well which are the decisive characteristics in everyday life.

 

Of course, this includes the overall efficiency (aerodynamics and drive rigidity as already described in the last chapter), because it determines the radius of action, the average speed and the driving pleasure.

 

The everyday characteristics also include the following characteristics:

 

Driving stability at high speeds, storms and cross-winds

Weight

Full suspension as standard

Convenient entry and exit

Comfortable seating position even on long journeys

Weather protection and ventilation

Luggage transport and shopping

Convertible mode with good contact with the environment and nature

Good visibility also in front of the vehicle to be able to read the road

Low maintenance and reliability of the entire technology

 Compactness of the vehicle

Flexible and tool-free adjustment to different rider sizes

And, existentially, of course, security, too, although we dedicate an extra chapter to this property.

✅ Driving stability at high speeds, storms and cross-winds

⬆️ Design optimized for driving stability

We have already discussed this point under the heading “Driving stability and driving dynamics”, but since it is of great importance, here is a brief repetition:

 

The floor pan between the front and rear axles has been optimized for the driver’s center of gravity to be as low as possible. This is where space is usually wasted with velomobiles. The Bülk MK1 also pushes the limit in this respect. This increases driving stability and at the same time creates a higher interior and space for taller drivers.

 

The overall aerodynamic design is designed for high stability in cross winds. Due to the strongly rounded and flattened bow, the pressure point and center of gravity of the vehicle are so close together that the vehicle automatically stabilizes in cross winds. The buoyancy in cross winds is specifically prevented by the shape, and the floor pan causes suction towards the ground in cross winds. This defuses dangerous situations in strong winds and gusts.

✅ Weight

 

With a weight of 24 kg, the Bülk MK1 is one of the absolute lightweight velomobiles. The body and all built-in parts including the mono swing arm are made of carbon (CFRP). The struts and shape create an extremely stiff but light chassis, high-quality drive components complement the lightweight construction.

 

This makes handling and driving on the mountain a pleasure.

⬆️ The complete vehicle in CFRP

✅ Full suspension as standard

 

The two front wheels are sprung via MacPherson struts and the rear wheel via an extremely stiff mono swing arm suspended on one side. You can choose between a soft and a hard sports suspension ex works.

This makes traveling a pleasure even on bad roads. Air suspension can be ordered as an option for the rear wheel.

All 3 wheels are hung on one side, which means that you can easily and quickly swap the tires without having to remove the wheels in case of a flat tire. 

This is a huge advantage over normal bicycles.

⬆️ Full suspension with wheels suspended on one side

✅ Convenient entry and exit

 

In everyday use of a velomobile, you want to be able to get in and out of the vehicle easily and quickly. This is also important as we get older, because it can decide how old we want to be to ride a velomobile.

 

That’s why the Bülk has a huge entry opening with a very low “loading sill”.

 

The low loading sill also allows you to maneuver backwards with your hands. This gives the Bülk an important unique selling point.

⬆️ Huge entry opening and low loading sill

✅ Comfortable seating position even on long journeys

 

The flat seating position and the wide, spacious seat allow for long and relaxed rides because the driver’s weight is distributed over a large area. The butt muscles are relieved and the head can rest on the softly padded headrest. This is how traveling is fun. The seat can be removed with a flick of the wrist and used to transport luggage into the house or to the workplace.

⬆️ Flat and comfortable seating position

✅ Weather protection & ventilation

 

Weather protection decides whether the vehicle can be used all year round.

 

All optional hoods of the Bülk MK1 have a circumferential overlapping water edge and effective water drainage in the hinge area. Rain, even downpours, are no longer a threat and make the vehicle a comfortable retreat from the cold and wet. This means that this velomobile can fully demonstrate its year-round suitability.

 

The highly effective ventilation over the front frame and the Naca air intake ensure sufficient air in the interior; both air inlets have an automatic water drain to the outside, which separates the incoming air from the rain.

In the hinge area of ​​the hood, a water tank catches the rain and directs it to the outside through the front mast.

⬆️ Race hood with overlapping rain edge and adjustable Naca air inlet

⬆️ Water tank with drain through the front mast

⬆️ Air-intake over the front boom

If you want, you can also choose an everyday hood with a scratch-resistant motorcycle visor, Pinlock technology and windscreen wipers.

⬆️ Everyday hood with Pinlock motorcycle visor and wipers

All of these features are the result of many years of experience with velomobiles in everyday life and enable mobility in the Bülk even in extreme weather events.

⬆️ There is no bad weather

✅ Luggage transport and shopping

 

The Bülk MK1 offers an enormous amount of storage space for luggage and shopping, a fundamental quality in terms of suitability for everyday use.

The interior has various luggage departments and compartments in which you can optimally organize your luggage.

Whether you are shopping for the week or on a camping holiday: the vehicle offers enough space and does not become unstable even when fully loaded.

 

There are luggage compartments on the left and right in the front, which, thanks to the huge entry opening, can be accessed without having to open the service flap at the front.

Most luggage fits in the back, next to and behind the seat.

⬆️ Camping holidays are no problem

⬆️ Luggage compartments also in the front of the vehicle

⬆️ Luggage compartment above the mono swing arm

✅ Convertible mode with good contact with the environment and nature

 

The hood can be dismantled in two easy steps. Then the driving pleasure in convertible mode beckons: this can only be experienced in this way in the Bülk MK1. Whether alone or in a group: in this mode, the Bülk MK1 enables an incredibly sensual and intoxicating perception of the environment while still retaining its high-speed properties. A challenge to all undisguised but slow tricycles!

In convertible mode you can experience the environment together with your companion and exchange ideas. The huge exit opening largely eliminates the separation from the environment without losing the security and protection of the velomobile body. Interesting encounters with people are pre-programmed in this mode…

The entry opening, which is pulled far forward, also allows access to the luggage compartments that are optionally mounted in the front. This is another unique selling point.

Due to the low-lying coaming, you can also drive in the so-called double manta position; sometimes a welcome change.

⬆️ Convertible mode: contact with the outside world

✅ Good view also in front of the vehicle to be able to read the road

 

The bow of the Bülk MK1 is kept as flat as possible. The protuberance lines for toes and knees create a central viewing channel, which enables a very good view of the road from the vehicle.

⬆️ Good visibility thanks to the flat bow

The hinged hoods allow you to raise the hood on steep climbs and still have a view to the front. This is made possible by the crescent-shaped hinge area. This way you can ventilate very flexibly and you can be seen better from behind.

⬆️ Even with the hood raised, you can still see ahead

✅ Low maintenance and reliability of the entire technology

 

When it comes to low maintenance and reliability, we can draw on more than 15 years of experience in velomobile construction. The entire drive train of the vehicle is encapsulated, saving not only maintenance but also wear. The drivetrain components last 5-10x as long as a regular bike.

 

Mud, snow, rain: the interior with the drive and components stays clean and dry.

 

Only components that have proven themselves over many years and have a long service life are installed in the Bülk.

 

For maintenance work, there are service flaps through which you can access the technology. With the Bülk, however, you can get very close to many areas of technology via the oversized entry opening. For example, you can adjust the bottom bracket and the gears at the front while you are sitting in the vehicle.

⬆️ Rear service opening open

⬆️ Front service opening open

✅ Compactness of the vehicle

 

With a length of only 257 cm, a height of 84 cm and a width of 70 cm, the vehicle is one of the most compact velomobiles. This makes it easier to transport by car or train and to park in general. The small width enables a high level of flexibility in narrow passages (e.g. doors, traffic gaps, barriers). Due to the compactness, the vehicle can be built light and very stiff.

✅ Flexible and tool-free adjustment to different driver sizes

 

Another important unique selling point of the Bülk MK1 is its modular concept.

 

This not only includes various optional features for everyday use, but essentially means the simple and tool-free adjustment to different rider sizes.

 

The advantage of a quick adjustment to extremely different rider sizes is obvious:

 You can use the vehicle in the family, partnership or in a club reciprocally

 In principle, there is the possibility of bike sharing or rental and rental projects

 The value of the vehicle is increased by these options

 Dealers only need one demonstration vehicle

 

⬇️ How to customize

⬆️ Stepless shiftability of the bottom bracket slide over a large area

⬆️ Seat adjustment via locking rail

⬆️ Seat backrest adjustment using hard foam spacers

These hard foam spacers can be stacked with Velcro and thus enable a very simple and tool-free adjustment of the seat back angle. For very big jumps there are 2 carbon adapters that are attached to the seat or the vehicle. The hard foam spacers are then only intended for fine adjustment.

⬇️ Adjusting the head storage area

The headrest surface can be adjusted so that small as well as very large people can sit optimally. For this purpose, various so-called carbon adapters are attached to the hood with Velcro so that the driver’s head can always rest comfortably on the padding. However, these adjustment steps are only necessary if there are large driver differences:

Persons from 145-165 cm choose the adapter small

Persons from 165-180 cm choose the adapter medium

People over 180 cm usually do not need an adapter at all.

⬆️ Very tall drivers do not need a headrest adapter

⬆️ Adjustment with headrest module for small drivers

⬆️ Different adapters

Finally, a modular adjustment to different driver sizes can be made using different hoods, each with different height protuberances for the knees.

⬆️ Here the combination foam lid with high knee protuberances

⬆️ Or flat knee protuberances, here with the race hood

Bülk MK 1 is a bike that offers safety

 

In principle, velomobiles offer a much higher strategic protection for the driver compared to conventional bicycles.

The Bülk MK1 attempts to technically exploit these strategic advantages in detail and adds further security features.

The entire design of the Bülk MK1 took place under the primacy of the greatest possible safety for the driver. 16 years of experience in velomobile construction and the systematic evaluation of accidents flowed into the design.

✅ See and be seen well: a standard high-performance lighting system with daytime running lights ensures good visibility. A so-called hotspot module can be ordered as an option, which ensures even better visibility and illumination of the road at the highest point of the vehicle. This module can accommodate a reversing camera and provides increased rollover protection.

⬆️ Hotspot-Safety Module

✅ The carbon body is secured with safety fabric between the carbon layers to prevent splitting and tearing in the event of a crash. This turns the passenger cell into a safety cabin that can absorb large amounts of energy without splintering or tearing open with sharp edges.

✅ Safety in the event of a frontal crash: the Y-design of the front frame means that it cannot shift towards the driver. This not only protects the rider, but dissipates a lot of energy by allowing the front part of the frame to be compressed without being pushed backwards. The flat seating position and the coaming with its hold-down devices effectively prevent the driver from sitting up and the upper body from accelerating forward. Compared to velomobiles with a steep seating position, the upper body is also prevented from being accelerated with its face onto a coaming in front of it. At the same time, due to the flat body angle, a large part of the energy can be absorbed by the legs.

⬆️ Y-design of the front-boom with up and down bracing

⬆️ Hold-down device adjustable to driver’s shoulder height

✅ Safety in the event of a rear impact

In the event of a rear-end collision, the driver’s head is effectively protected by the shape of the headrest surface and its foam padding. When using the head adapters, there is an additional buffer as the adapters contain foam blocks.

In the Bülk, the seat is not suspended at the top end, but is stored in the middle of a hard foam block. This prevents the thrust of a rear-end collision from going towards the driver’s neck.

In the back area, the stable seat with bars protects the driver’s spine. The shearing forces of a rear-end collision are distributed over the entire seat and passed on to the driver. The central seat support with hard foam panels forms another buffer in which energy is dissipated.

⬆️ Buffering in the seat support

✅ Lateral rollover

Thanks to the flat seating position and the hold-down devices integrated in the coaming, the driver remains safely in the vehicle if it rolls sideways. The high overhang of the hood effectively protects the driver’s head. The hold-down devices can be adjusted exactly to the driver’s shoulder height using Velcro and act as a very effective restraint system.

⬆️ Very good rollover protection thanks to the high hood

✅ Insensitivity to side winds

Every detail of the aerodynamic design is designed for maximum driving stability in cross winds. This is an essential safety feature, as the vehicle must be stable and controllable even in strong winds and turbulence.

 

✅ Safety-related components

With the safety-related components, lightweight construction aspects are subordinate in the Bülk MK1 in favor of high stability, long service life and tried-and-tested technology.

 

With all these features, the Bülk MK1 gets a top position in terms of safety.