Custom Build Gallery, Zlatko’s Mental Manno

December 4, 2013

This months custom build is from Croatia, in Eastern Europe next to the beautiful Adriatic Sea. Zlatko Vidić is a mechanical engineer and when he decided to make an electric bike, he wanted something that would be distinctive, and also reminiscent of the race motorcycles from 1930-’36.

The full-suspension frame with the weight of the battery centrally located and mounted low,

With the full-suspension frame with the weight of the battery centrally located and mounted low, the Mental Manno handles very well.

By the time he had become interested in E-bikes around 2008, the best looking frames were only 3D concepts, and the existing E-bikes didn’t interest him. A close friend (ES member HAL9000v2.0) was the designer of the Greyborg E-bike, and he challenged Zlatko to design his own frame. Most of Zlatkos riding is in the city, and he spent months studying each part that he was designing, so the result would perform well in city riding, but still have as much of the eye-catching style that he visualized in his mind.


Zlatko, with his finished creation.

He knew he wanted a 2WD E-bike, and that was why he also had to design a strong front suspension, since he felt existing forks were not strong enough to safely handle the forces he anticipated using. He chose the girder style, which is what many classic motorcycles from the early days used. A girder fork does not have the extra long stroke you would want for an off-road E-bike, but for street use it performs perfectly. Since he made it himself, the Cromoly steel drop-outs are much stronger than he would ever need (in case a customer wants a more powerful motor on the front).

Although the classic girder style forks are an old design, you can see how strong it is from this close-up.

Although the classic steel girder style forks are an old design, you can see how strong it is from this close-up. Also notice the beefy gusset just behind the head-tube.

Since he was going to use two hub-motors, he did not need large hubs to have adequate power, and the mid-sized hubs he chose resembled the drum brakes of the classic motorcycles he loves. The throttle always operates the rear hub, and the front hub can be switched on for better acceleration, or to help spread out the motor-heat of hill-climbing. The motorcycles from that era did not have disc brakes, so he had two discs custom-made to look like they are part of the hubs.


The brakes are Gatorbrake 6-piston hydraulic units, with a 203mm disc on the front and 160mm on the rear.

Zlatko uses Computer-Aided-Design (CAD) software in his job, so he used that to work out the prototype versions of the frame. A friend of his has experience with Finite-Element-Analysis (FEA), and they used that to test the mechanical stresses on the initial design, to improve it while it was still just on a computer screen.

His cousin is a professional welder, and with the two of them working together, they tackled the next phase of the operation. They carefully cut and bent the Cromoly steel tubing to match the full-size drawings. But…with both of them being very busy at work and both having families…this part took six months to get it perfect, and work out the issues that arose.


The multiple front lights and leather-rimmed goggles add to the retro look of this E-bikes image, and the leather Brookes saddle is the perfect final touch. The red-white-blue “roundel” is an insignia from WWII RAF aircraft.

After he was finally satisfied with the form of the frame, he disassembled it and took the parts to the paint shop. Then…the emotional moment arrived when the paint was done and he was finally able to assemble all the parts. It ended up taking a year of passion and hard work to get it just the way he wanted it. He thought you would have to be a “crazy man” to spend that much time on something, so he named it the “Mental Manno“.

The long journey that took him from only a dream to a finished masterpiece…was an incredible learning experience. However, when Zlatko was proudly showing his achievement to his son Vito, the 5-year old said “Dad, the bike is nice, but there is no seat for me, so this is not good?!” Zlatko thought about this, and decided that…now he will have to design a 2-seat E-bike! 


The family dog takes a rest after a busy morning of chasing E-bikes.

So far he has sold one bare Mental Manno frame, and this original prototype shown here is also for sale. The price for the complete fully outfitted E-bike is 3500-Euro’s (roughly $4,760 at today’s rates). So, if you are interested, contact ES member “Dred”.  The design and production company Zelena Vozila (also from Croatia) is carrying the Mental Manno frame as a product. They are the producers of the extra high-power hubmotor called the Cromotor, and they are partners in the production of the Greyp E-bike frame, which is the most powerful E-bike for sale to the public.


You can see the screen of the CycleAnalyst, which is the best E-bike computer available. From this angle you can also see the sliding bushing built into the seat-tube, which keeps the rear suspension linkage aligned.

A 360W geared hubmotor may not seem very powerful, but since there are two of them, and they are run at 48V, it climbs hills very well! The system provides 25-MPH with the motors alone, and 27-MPH when the rider adds pedaling.

This well thought-out frame shape easily holds a very significant battery pack of high-quality LiFePO4 cells from A123. The 48V pack is also a very large 20-Ah, which equals a fantastic 960 Watt-Hours (WH). Zlatko has calculated that he can get as much as 37 miles on a single charge, and so far he has taken it 28 miles without pedaling.


Every journey begins with the first step...

Every journey begins with the first steps…



The rear drop-outs were drawn on a computer screen and then water-jetted from plate steel.



TIG-welding is the best type of welding, and provides a very professional result.



Using precise full-scale drawings helped the process at every step along the way.


The classic girder fork takes shape.

The classic girder fork takes shape.


The central housing will hold the battery, the charger, and the two controllers.

The central housing will hold the battery, the charger, and the two controllers. The hot ends of the controllers are exposed to the air for improved cooling, but I actually like the way it looks.



You can see the craftsmanship and care in Zlatkos methods. He test-fits all the parts at each step to ensure the shape and fit is perfect.



Notice the rear suspension pivot is concentric with the bottom-bracket, this simplifies chain-growth issues when the rear suspension moves. Also, the rear drop-outs are bolted on to allow a customer to shim the width to their particular rear wheel axle (or hub motor). Once properly sized, the customer can then have it welded permanently at a local shop, if wanted.


The parts are back from the paint shop, and the assembly can begin!

The parts are back from the paint shop, and the assembly begins! The bottom bracket crankset is a German Schlumpf internally-geared 2-speed drive.



Modern shock absorbers are much better than the ones from the 1930’s, so this E-bike is a fusion of classic style and modern performance.



Scwalbe “Fat Franks” are the balloon tires of choice for classic reproductions, and they can be ordered in several different colors.



Sometimes, a show bike is a “trailer princess”, but Zlatko actually rides his beautiful creation often.



He has embroidered shirts at his website…available in red, white, and the blue shown here.



When the weather is this nice, why go to work in a car?


Here is the build-thread for the Mental Manno.

And here is Zlatko’s website.

Here is the home website of Zelena Vozila (which means Green Vehicles in Croatian), which is home to the Greyborg Warp high-power DIY frame and the monster hub Cromotor.

Here is the Facebook page for Zelena Vozila if you want to keep up with any weekly updates.


Written by Ron/Spinningmagnets, December 2013

Grew up in Los Angeles California, US Navy submarine mechanic from 1977-81/SanDiego. Hydraulic mechanic in the 1980's/Los Angeles. Heavy equipment operator in the 1990's/traveled to various locations. Dump truck driver in the 2000's/SW Utah. Currently a water plant operator since 2010/NW Kansas


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