Crowdfunding EN

Krowd Karl crowdfunding on Kickstarter


Our very first production frame is finished and you can be part of it!

After four years of prototyping and small batch manufacturing custom frames for B2B clients the time is now to start our own first new production model.

Alex Clauss, the founder of Portus Cycles, is a huge fan of Karl Drais. It was Karl Drais, who  made his first bike ride 200 years ago on his first and foremost invented balance bike for adults and can therefore be seen as the godfather and inventor of all bikes .

According to this original every model from us is a “Karl” because it’s a relative from Mr. Drais.

In this case it’s the “Krowd Karl!”


Krowd Karl - Enduro Version

Krowd Karl – enduro version – ED


Why Krowd Karl?

Krowd stands for “Kraut”, typical German roots, made in Germany, German engineering, fair payment and high ecological production standards, high quality and long durability.

Krowd stand also for “Crowd”, meaning you and all the supporting people on our first production model. It’s for all the Pinion and steel fans because it’s much more affordable in comparison to a custom frame.

Krowd Karl is very special because he’s made out of the best steel in the world with a heart out of gears. A heart that is made by gearbox company Pinion, who are on the market for ten years now with a full covered shifting system located around the the bottom bracket area.

pinion C1.12 Getriebe

Portus Cycles is specialized on manufacturing frames for the Pinion gearbox and the release of the affordable Pinion C-Line allows us to start our first production frame with a highly appealing price tag all still made in Germany.

offenes P1.18 Getriebe


Why pinion gear boxes?

We’re highly convinced of the Pinion gearbox since it offers a maintenance free high durability, especially in combination with a Gates Carbondrive. The low center of gravity in the center of the bicycle is another important reason that we build custom steel frames with Pinion gear boxes and our focus just changed naturally through rising customer demands.

Pinion C1.12 Getriebe - unmontiert

Next to all the great technical advantages there is another main aspect about the Pinion shifting system. The gearbox is almost 100% made in Germany and is assembled in the Headquarters near Stuttgart, where every gearbox is tested 100% before final release.

This is the best guarantee for high quality through a value added chain in Germany with fair payment of all labors involved.

According to pinion the usage of a C1.12 gearbox with 12 gears and a 600% overall ratio is just the best setup for Mountainbikes. Especially shifting with constant gear steps of 17,7% between every gear is much better in comparison to an usual drivetrain.

A SRAM Eagle shifting system has an overall ratio of 500% through a cassette with 50-10 ratio and much bigger steps between the gears.

For more detailed technical information about C-Line check here: C-Linie


Why Steel?

Steel is timeless, not only the fatigue stress endurance but also in an asthetic way with straight and round tubes.

Steel offers comfort!

In our opinion a lot of current bike desings on the market made out of carbon and aluminium are to stiff. A good balance between stiffness and comfort is possible by choosing the right tubing size and alloy.

Steel is modern!

Steel alloys and production processes evolved drastically in the last 2-3 decades. It is possible to create stronger and lighter tubing then 30 years ago which allows us to build light frames.

Steel is fixable

The myth of fixing your bike on a long biketrip at the blacksmith shop is true. Every skilled metal worker can fix a broken steel frame.

Steel saves our planet!

Steel is 100% recycable und consumes less energy in extraction and in the recycling process as well.


Why Crowdfunding?

Is there a better way for a small custom shop to check market chances for a new product?

Especially after a successful funding with the advantage of prepaid orders?

There is no better option!

In the past we supported projects on kickstarter and will keep on supporting.

But this time we need your support!

Right now there is no enduro based production steel frame for pinion gearbox available on the market and because of this one year ago the idea of Krowd Karl was born.


What we offer

We want to build to different versions of Krowd Karl

Krowd Karl ED

The Enduro-Version, made out of very reliable and the super strong Reynolds 853 tubeset for hard riding with an descent oriented geometry. The straight line between tob tube and seatstays doesn’t have only an astethic background. It’s providing plenty of standover height for technical downhills, if needed.

more pictures under the following links:

Krowd Karl ED im Walde

Krowd Karl ED im Studio


Krowd Karl CC

The Cross-Country version, made out of the lighter Columbus Zona tubeset with a modern geometry and higher top tube for two bottle cages and/or frame bags for bikepacking.

more pictures: Krowd Karl ED und CC im Studio


Geometry and specifiations for both versions


We use a headtube with 44mm consistent inner diameter, which allows a ZS44 (semi-integrated) on top and an EC44 (external cup) for assembling a tapered fork.

Every headtube will get our brazed on stainless double heart logo

Serial number:

Every frame that god made by us gets a brazed on stainless serial number. It includes the initials of the respective supporter in the end of the little plate. For example: Britney Bike – PC0090BB

Rahmennummer - Steuerrohr Herz


Thru-axle and rear end width

The frame has 142×12 rear spacing and will be delivered with a Shimano E-Thru axle. Boost is not planned because it’s not necessary due the use of a singlespeed hub with already perfect symmetrical spoke angles.

We use, the over the years approved, slider dropout system by US based company Paragon Machineworks, which also can be converted to usual quick release standard (135×10).


Shimano E-Thru Achse - 142x12

Tire clearance

Both versions are mode for a maximum tire clearance of 2,5“. The endure version takes 650b and 29er tires and according to this the geometry is fitting both.

The crosscountry version is a 29er only because it’s made for making pace and not super technical singletrails.


Cable routing:

By default the two cables for the gearbox are on the topside of the downtube.

An additional cable goes that way too by using a dropper post with internal routing and requires a triple cable stop.

In general the brake hose runs on the downside of the top tube and might get an additional cable when a dropper post with external routing is used.

Whichever setup you run: Cable stops for both setups will be included.




Seatpost and clamp

The inner dia of the enduro version is 31,6mm and allows the use of every a dropper post available on the market. You might need a reducing shim for 30,9mm but it will work either way.

A seat tube clamp for 35mm is required.

There is an inlet for internal routed dropper post at the seattube close to the gearbox bracket.

We currently plan to build the crosscountry version for 27,2mm seatpost but we are willing to build it with 31,6mm on demand.

For the 27,2mm seat tube a 31,8mm clamp is needed.


Bottle cages

Both version will be able to take a bottle cage on top of the downtube.

A second one on the seat tube is only possible when the 27,2mm seatpost is specified.

Belt drive option

To open the rear for a belt drive there is an M8 screw directly at the dropout. By disassembling the screw and bending the seatstay a little it’s possible to attach the belt into the frame.



It is obvious that a bicyle with gearbox can’t be on the same weight as usual chain-driven one. But if you agree to all the other advantages weight is not the main issue.

Regardless some weights for your own calculation:

The enduro version will approx. weight 2,7kg incl. powder coating without gearbox in size medium

The cross country version approx. 2,4kg in size medium without gearbox.

  • C1.12 gearbox weights 2,1kg
  • Crankset has 500g
  • shifter 100g



Basically we offer a modern, so long reach and slack headtube angle. Please checkout our geo-charts for more details.

* bei einer Übersetzung mit 32:32 und 113er Zahnriemen

* with ratio mit 32:32 and 113 teeth belt



Basically we offer two color schemes:

  • “Boom” – light blue with orange decals (RAL-5012-lightblue)
  • “Undercover” – grey with black decals (RAL-7031-bluegrey)

Custom colors and decals are available for an extra of 150€.

In contrast of the sample frames the decals will be covered under an additional layer of clear powder coat.

Custom geometry?

For sure we can offer the Krowd Karl with a custom geometry. Just write your questions via email and we will offer a quote for custom demands.

Will plus tires fit in the rear?

Basically not but we offer an option for an additional charge of 150€ after the funding.

Pinion Aufnahme

Beim ersten Musterrahmen der Enduro-Variante haben wir noch auf ein gegossenes Zukaufteil von pinion zurückgegriffen, das aus Fernost stammt.

Pinion bracket

On the ED-version (blue frame) we used a casted OE-bracket by pinion which is made in overseas.

It might looks good but it is a real struggle if you want to build frames with it and also doesn’t provide enough tire clearance

Coming back to asthetics, the design is too clean in our opinion and so we decided to use our self designed bracket, which we already use on our custom frames for years in different versions.

It consists of two lasered cutted base parts, three tube segments as tube connectors and three more turned and threaded round parts to mount the gearbox on it.

pinion-Aufnahme, geheftet

Aufnahme an CC-Musterrahmen


Manufacturing method

All frames will be TIG-welded by Alex Clauss himself, who is a mechanical design engineer. He learned his craft at the Bicylce Academy (fillet brazed), got startet in TIG-welding at Wiesmann Bikes three years ago and honed the process and skills over the years.

A longer story in German can be found here:

All stainless details, for example the headbadge or serial number, are brazed on with 55% of silver solder next to some special areas at the pinion bracket.


What is included?

  • Frame incl. Pinion C1.12 gearbox, crankset and shifter.
  • Inserts for slider dropouts and fitting
  • Shimano thru axle 142×12
  • cable guides for every possible setup

Not included are any parts of the drivetrain, because you can decide later if you want to use a beltdrive or a chain.


T-Shirt Krowd Karl

You can buy our Krowd Karl T-Shirt with graphics by Bernd Vonau as a supporter or get it for free by ordering a frameset.

Logos are screen printed in a local non profit printshop on fairtrade T-Shirts.


we love handmade - we love steel

we love handmade – we love steel

A statement and small detail which is always visible and good way to own a little part of us.


When do I have to decide sizing and other specs?

You can back our project immediately and later decide which size will fit you best. We will start a survey right after the funding to collect all needed information from you.

No credit card?

After the funding the goal is set we can offer additonal payment methods via paypal or wire transfer. We’ll add the frame set in mid of September to our online shop for direct order while the campaign is online.

Can I buy parts for assembling?

Indeed! We’ll offer great deals from the following brands after the funding is finished:

  • Gates Carbondrive (drivetrain)
  • Intend (forks, headsets and stems)
  • Magura (forks and brakes)
  • trickstuff (brakes and seatclamps)
  • tune (wheelsets, stems, handlebars and more)
  • Formula (forks and brakes)
  • Hope (wheelsets, brakes, stems and more)
  • SR Suntour (forks)
  • Acros (wheelsets, stems, headsets and more)
  • bikeyoke (dropper post)
  • Continental (tires and maybe drivetrain)

We’re very open to offer you a complete build according to your budget!

Project schedule

  • Beginning of Oktober 2017 – end of funding
  • Oktober 2017 – survey for specs and sizing
  • November 2017 – ordering materials
  • Dezember 2017 bis 2018 – production of the frames
  • Februar 2018 – powder coating
  • März 2018 – shipping frames and components

For sure we will release updates on kickstarter and our own social media channels.


Portus Cycles is small but not a one man show.

The following people are part of the team:

Alex, founder, visionary, welder and bicycle nerd


Maria – Alex‘ better half, temporary supporting by hand on the finish and digitally by graphics, fulltime with her heart.


Konrad – degreed industrial designer and Alex‘ right hand in the workshop.


Jonas – former intern, bike mechanic, prospective industrial engineer and always open for a testride.


Mitch – a very good friend of the family, testrider out of and on steel as well an encourager from the beginning of Portus Cycles.


Richi, he is able to let beautfiful things looking more beautiful through the lense of a camera. Very talented Self taught photographer and movie maker. Checkout shotbyliapin



mobile: (49) 0176 32054630