2020 here

2020 here

This new year is going to be full of initiatives, improvements and lots of work for us to do.
To start off our news: we have a new project named Handbike, born from the meeting of Policumbent and Eaton, one of the biggest global company in the engineering field and promoter of the Italian Handbike Run, a para cycling tournament opened in 2009.
As many of you already know, an handbike is a special kind of bicycle where the wheels are hand-actioned by the cyclist.
After a couple of meetings between our team and Eaton, it was soon obvious that both wanted to build a record-achieving Handbike.
The goal is the male world-record, held by Ken Talbot, member of the ULV team from the Liverpool’s University, who achieved 82,9 km/h (51.58 mph).

This new year is going to be full of initiatives, improvements and lots of work for us to do.
To start off our news: we have a new project named Handbike, born from the meeting of Policumbent and Eaton, one of the biggest global company in the engineering field and promoter of the Italian Handbike Run, a para cycling tournament opened in 2009.
As many of you already know, an handbike is a special kind of bicycle where the wheels are hand-actioned by the cyclist.
After a couple of meetings between our team and Eaton, it was soon obvious that both wanted to build a record-achieving Handbike.
The goal is the male world-record, held by Ken Talbot, member of the ULV team from the Liverpool’s University, who achieved 82,9 km/h (51.58 mph).

We are happy to announce you that our work is almost finished and is full of initiatives and innovations.

​Some of them concern the aerodynamic profile. CFD simulations are telling us that the changes we made should grant a power loss reduction of about 18-20%  compared with Taurus. 

We are also happy to announce that molds have already been made and the building of the shell is about to start. 
More news regard the new framework. Here we can only reveal that it won’t be made of composite sandwich panels as on TAURUS and TAURUS-X.
We will also have a new shifting gear cassette, smaller and lighter.
Our final important innovation will be done on the vision system.
Our goal was to higher our electronic system fault tolerance.
For those unwelcome with this term: the higher the fault tolerance is, the lower is the chance of having a complete breakdown of the vision system because of the malfunctioning of some components.
With that in mind, the vision system will be transformed in a full analogic one, based on fpv cameras, which will decrease the number of cables needed for the transmission and acquisition of the video and the possibility of detachment of microweldings. This aspect becomes fundamental if you think that, without the vision system, the athlete is completely blind and a malfunctioning may cause an accident.
Beyond having a more efficient system, we will try to better position our new cameras by closing them off in an external case, sealing them.
This changes will lower the image’s ping, which will help the athlete’s experience inside the vehicle and also will allow us to use less batteries for the functioning of the system, thanks to a lower need of calculus for the decoding of the signal.
With this method we also lower the vehicle’s load and we gain a faster start of the machine. This will lower the chance of having problems at the start of the run.

We are happy to announce you that our work is almost finished and is full of initiatives and innovations.

​Some of them concern the aerodynamic profile. CFD simulations are telling us that the changes we made should grant a power loss reduction of about 18-20%  compared with Taurus. 

We are also happy to announce that molds have already been made and the building of the shell is about to start. 
More news regard the new framework. Here we can only reveal that it won’t be made of composite sandwich panels as on TAURUS and TAURUS-X.
We will also have a new shifting gear cassette, smaller and lighter.
Our final important innovation will be done on the vision system.
Our goal was to higher our electronic system fault tolerance.
For those unwelcome with this term: the higher the fault tolerance is, the lower is the chance of having a complete breakdown of the vision system because of the malfunctioning of some components.
With that in mind, the vision system will be transformed in a full analogic one, based on fpv cameras, which will decrease the number of cables needed for the transmission and acquisition of the video and the possibility of detachment of microweldings. This aspect becomes fundamental if you think that, without the vision system, the athlete is completely blind and a malfunctioning may cause an accident.
Beyond having a more efficient system, we will try to better position our new cameras by closing them off in an external case, sealing them.
This changes will lower the image’s ping, which will help the athlete’s experience inside the vehicle and also will allow us to use less batteries for the functioning of the system, thanks to a lower need of calculus for the decoding of the signal.
With this method we also lower the vehicle’s load and we gain a faster start of the machine. This will lower the chance of having problems at the start of the run.

HERE IS VITTORIA AND SERENA

HERE IS VITTORIA AND SERENA

As we have already anticipated in previous articles, this year a girl will be running for our Team with a Taurus clone bike. We have two candidates to beat the record of 121.81 km/h of Barbara Buatois: Serena Corona and Vittoria Spada. In the last few months, with the first road tests, they started trying to ride on a recumbent bike. They have given excellent results, both in terms of technical performance and commitment they are putting into it. This is why the choice of the cyclist who will perform at Battle Mountain is getting more and more difficult.


​Serena, twenty-four, has been a member of the Team for several years. She knows all the secrets of our prototypes:  thanks to her passion for mechanics and her preparation as a student of the last year of master’s degree in automotive engineering, Sere has contributed to the design and construction of Taurus.

​Vittoria, 23 years old, is studying Economics at the University of Turin. She lives on sports: she is constantly moving, not only when she trains, but also when she studies, she walks around the house with books in hand!
​To let you know them a little bit better, we asked them for an interview.

● How and when was the passion for the bike born?
​SERE: I started mountain biking at the age of 11 because my brother was running. I tried and I loved it. I ran at a competitive level until the last year of high school.
VICKY: I don’t think there was an exact moment or, at least, I don’t remember. The bike has always been a part of my life since I was a child, with mountain bike courses in the mountains, with games under the house (obviously all by bike), with the challenges of “I don’t think you can skip that wall”. Then I started competing, and since my friends had my same passion, I had a thousand good reasons to ride.

● How have you decided to put yourself out at this competition?
SERE: I always liked being a member of the team, I love the teamwork and commitment to a common goal: the whpsc. Last year I went to the competition. It gives strong emotions and it’s hard to understand if you haven’t been there. I am very competitive and the idea of ​​such a big challenge attracts me a lot.
VICKY: I started competing when I was 6 and haven’t stopped yet. I am a very competitive person especially about what I like. The more I like it, the more competitive I get and  I love riding any kind of bike.
When I found out they were looking for an athlete I thought “nice”, I looked at the features and I said “that’s me”. I sent my CV and I passed the first selection. It was followed by other tests, meetings and interviews. The longer it went on, the more I learned about the project and the people who are working for it, the more I liked it.
I immediately got along with the team members, a little bit less with the bike. I’ve never tried a recumbent bike, I just heard about it. It’s completely different from a “normal” bike, the position changes all the balances and the way of seeing “beyond the handlebar”. I have to admit it took a few tries but I think something good is coming out of it.
Now, beyond the handlebars, I see through a screen, closed into a two-wheeled little egg-bullet it looks like a parallel world, I feel like I’m the protagonist of a video game (on the screen there are also the objectives to reach and how long until the race/test is over). But in this video game if you lose all those people who work on the project lose too. It’s a challenge … we’ll see how it ends!


●Engineering and cycling: two mainly man’s worlds. What do you think about it?
SERE: I honestly don’t think they are purely man’s worlds. When I competed there were many girls and in the last few years I think they have increased. Even at the engineering level we are not few and we have the same potential of men. Obviously males are in the majority but we stick up for ourselves.
VICKY: The number of men who practice cycling is certainly greater than that of women and we can discuss it in terms of a cultural or physical issue.

We could say that when people started cycling,
the social role of women was not the same of today and sport in general was more practiced by men.


​To make a purely physical speech, cycling is a sport based on strength and power, characteristics more developed in man. The “feminine sports” in which elegance, elasticity and above all feminine characteristics are still counted on the fingers of one hand.

​But luckily our society is changing and today more women than in the past are starting cycling and  the competition is more and more fierce.            


​● Is the fact of being a woman an added value for such an extreme, competitive and also very technical and technological sport?
SERE: I don’t know, men and women are always on the same level for me. Man has more power in this case. Perhaps women are more rational but in this case I don’t know whether to consider it an advantage.

● I don’t think it’s easy to reconcile Politecnico and Bike, what’s your trick?
SERE: No, in fact, the alarm rings very early.

● How do you feel about being the (possible) future Policumbent cyclist?
SERE: It would be an honor for me, I know what it means to design a bike like this one and all the responsibilities on both sides.

VICKY: I’m happy, happy, happy, yuhuuuuu !!! yeahh !!!!    
● Do your thoughts also spin at leg speed when you ride?
VICKY: I can say that it’s the exact opposite. The faster I go, the more blood goes to my legs and heart, removing it from my head and thoughts. When I pedal I don’t think of anything except to some “stupid” little songs like children’s cartoon theme songs, so I don’t think about the fatigue and the 200 things per second that could happen.

​● We know well that it is not a normal bike. Are you worried about the idea of ​​speed + claustrophobia?
​SERE: I like speed and the bike is not as claustrophobic as it seems. I like speed in general, and the idea of ​​being able to reach that kind of speed without an engine excites me.
VICKY: I’ve always liked speed, being closed inside a hull not so much. Then I realized that I can make faces to those who are outside without being seen and if I fall, even if I fall at speeds much higher than those of a normal bike, it hurt less (at least this is what they tell me, I hope not to try it) .

FIGHTING THE ROLLING RESISTANCE

FIGHTING THE ROLLING RESISTANCE

Analysing the factors that influence Taurus’ performance, we can’t forget to mention the contact points between the bike and the asphalt: the tires.
In order to maximize the bike speed, we studied the influence of the rolling resistance at the typical speeds reached during the Battle Mountain runs. This study was conducted throughout 2018.

To accomplish this task, our team has initially built a test bench in order to test the combinations of different tires and mounting configurations. How does it work? The test is based on a wheel-on-drum rolling configuration. The bench is composed of an electric motor that moves a 600 mm diameter MDF drum. A wheel is loaded with a weight that simulates half the mass of Andrea and Taurus and is then placed on the MDF drum.
As the drum rotates we measure the electrical power used by the motor at given RPMs. From the measured value we subtract the contributions due to the aerodynamic resistance of the drum and the wheel at that speed in order to obtain only the power dissipated by the rolling of the tires (plus a marginal contribution by the bearings, which is also present on the road).
This power is divided by the angular speed of the wheel in order to obtain the resistant torque. Dividing the torque by the wheel rolling radius we obtain the resistant force applied to the wheel hub. At this point the rolling coefficient is obtained by dividing the resistant force by the applied load.

​Finally, using the Clark formula, the effect of the drum curvature is corrected obtaining a more realistic estimate of the rolling coefficient on a flat road. Simple, isn’t it?
This procedure was repeated for the different mounting configurations and for the different tires we found on the market.

As we can see from the graphs, for each tested tire there is a significant difference between the assembly of the given tire in combination with a latex inner tube or with a butyl inner tube. On the other hand, the difference between a tubeless assembly (without an inner tube) and with a latex chamber is minimal. This is mainly due to the different thickness between the butyl inner tube and the latex inner tube, as well as the different interactions and rubbings that are created between the two different materials and the inside of the tire. Instead of testing them at a constant pressure we decided to test each tire at the maximum working pressure recommended by the manufacturer.
​In this way, we were able to have a comparison between the assembly compositions best performances. This decision allowed us to simulate at best the conditions of the Battle Mountain runs.

​What has changed for Taurus? With the new configuration we were able to save 27 W per wheel compared to the 2017 set up at record speed.
This measurement system brings with it the inconvenience of the electric motor non-linear efficiency. This behaviour of the motor makes it difficult to separate the effect of its non-linear efficiency from the measured input power to obtain the net power dissipated by the rolling alone. During this year the team has developed a completely new test bench, still based on a wheel-on-drum setup, that provides a different measuring method. In fact, two strain gauges positioned near the wheel hub are used to directly measure the resisting force applied on this point, from which we only need to separate the contribution of the wheel aerodynamics. Moreover, the contribution of the aerodynamics of the drum is irrelevant to this measurement method. Another aspect of the upgraded test bench allows for the testing of wheels larger than the 20” ones mounted on Taurus. This allows us to have an ever increasing understanding of the parameters that characterise the rolling of bicycle tires.

Predict the future with a Matlab algorithm

Predict the future with a Matlab algorithm

Since 2013, month by month, we have been blogging about all the small steps that allowed us to get where we are today. Many times we have focused about the bike’s aerodynamics, mechanics, electronics and so on.
However, we have never talked about one of the most “invisible” and most important department: the Data Analysis one.

It is responsible for elaborating all the data about the bike, its components and the rider in order to provide useful information about the performances achieved by the bicycle or by the rider himself. The Data Analysis work allows to answer to some fundamental questions during the activity planning stage of the team. One of these questions could be: if a rider develops this power on this vehicle, what speed can he achieve during the race? Or again: to reach this speed with this power, what characteristics should the vehicle have?
There are no tricks or magic to anticipate the future but, within certain limits, it is possible to predict some results even before getting on the saddle and pedaling. How? Through a good analysis algorithm.
The Matlab software package is used as computational support. The developed code works within a graphical user interface which makes it possible to use the simulator even for other members of the team without a full knowledge of the MatLab codes. It’s purpose is to:

  • estimate the tyre rolling resistance
  • estimate the drag coefficient,
  • estimate transmission efficiency
  • estimate the efficiency of the prototype
  • simulate the speed profile, frontal area and other parameters such as temperature, pressure and humidity given the power profile

Briefly, the code works as follows: the sum of kinetic energy and energy “lost” because of air drag and rolling resistance is set equal to the energy calculated by the data provided by the power meter (E = W x delta t). A typical run’s length in Battle Mountain is in the order of 5 minutes. That makes more than 8000 equations, one for every tenth of a second. The rolling resistance coefficient and air drag coefficient are the two unknown parameters. Using the least squares approximation, the code calculates the value of the parameters that minimize the quadratic error.
​The tool was successfully used during the race at the WHPSC 2018 in Battle Mountain (Nevada). Each run was evaluated and compared with the previous ones. This day by day analysis offered interesting hints on what could have been improved on the bike, whereas further post-processing elaboration were performed after coming back to Italy in order to have a clear overview of the most influencing factors for the performance. For instance, we found out that the tail prosthesis performed worse than the standard tail and that the final speed is heavily influenced by the atmospheric conditions. Also, exploiting the simulator, different technical solutions can be compared and the possibility of choosing the best one allows us to save precious time and money.

​Since a female rider will join our team, our department’s work concerns the adaption of the existing code for the testing activities. In fact, the original code package uses a length scale (in meters) whereas the adapted code package works with a time scale (in seconds). This is due to the fact that the only data that we can use to simulate a run of our new rider comes from the rollers and therefore the acquisition by means of a power-meter comes in time scale. Future work will be focused on improving the algorithm capability to estimate the drag and rolling resistance coefficients and understanding the geometry of the optimal power output profile, a factor which has been proven to have a great influence on the final speed during the run.

TAURUS’s transmission: features and upgrades

TAURUS’s transmission: features and upgrades

Talking about bicycles, especially those designed for extreme speeds, it comes natural to discuss about chains and pinions.
​The transmission has to be studied carefully in order to waste as little watts as possible because of friction losses. The saved power can be then used to push the bike faster! ​

“ First version of the transmission with moving cassette. Lateral view.“ 

The need to make a more efficient transmission took place in 2017 with the introduction of Taurus. The reduced dimensions of the prototype made it very difficult to have a rear drive wheel, like we had with Pulsar, our previous bike. We decided to work on the front wheel.

​This option usually leads to a limitation on the number of gears due to excessive misalignment of the chain caused by the short distance between the transmission axes. One way to solve this problem could have been using two chainrings combined to a 7-8 pinions cassette but, after discussing it, we opted for a moving cassette transmission.
The concept was not new, hence we were confident it would yield reliable and functional results. Therefore, we decided to focus on development of this design.
This type of transmission keeps the overall efficiency high forcing the chain to work on a plane parallel to the pinion’s one, this yields optimal power transfer conditions.

​Moreover, we can implement as many pinion as we need, limited only by the available space. No matter how many speeds we put on, the chain will never risk derailing to unwanted gears or working badly due to the excessive misalignment of the transmission pinions.

The transmission V1.0

​The system is made of two chains mounted on both sides of the bike frame connected by a transmission shaft. On the right side of the bike there is an impressive 108 teeth chainring. It is mounted on a power meter that can measure different values such as power and pedaling cadence. The chainring is connected to the 11v cassette by a chain that, as mentioned above, can move on the splined shaft (the cassette range goes between 13 and 40 teeth).
​The pinions move axially, while allowing the torque to be transferred. The splined shaft is made of steal while the sleeve sliding on the shaft is bronze thus reducing the force required to move it.

The transmission shaft is fixed to the frame by two hybrid ball bearings: one is mounted on the left panel of the frame while the other is backed by a welded aluminum structure that also backs the servos for the moving action.
At this point, the torque is passed to a fixed chainring on the left side of the bike that, thanks to a second chain, is transmitted to the freewheel mounted on the axle of the front wheel. Both chains have their own tensioner made of carbon fiber to reduce weight. The tensioners mount machined aluminum pulleys which have their dedicated hybrid ball bearings. The left tensioner has a curved shape which helps with the maintenance of the front wheel during its mounting or removal.

The servos of the V1.0

​The axial movement of the cassette is managed by two powerful electromechanical servos, based on “coreless” motors that are able to create almost 2Nm of torque each.
​With the connecting mechanism between the servos and the cassette, we can achieve about 20Kg of thrust. This enables the transmission to change gear very rapidly and precisely even if the cyclist is still applying power. The servos are powered by two lithium cells capable of generating 7.4V. The brain behind the shifting system is an Arduino Mega 2560, based on the Atmega2560. It interprets the signal coming from the two buttons on the steering handle and sends a command to the servos to correspondingly move the cassette.

The transmission V2.0

​In 2017, the competition in BM brought new ideas on how to improve the transmission system.
​The main points we focused on were:

​- Weight of the system: since Taurus was quite heavy, the new goal was to make it as light as possible. The transmission system definitely needed to be improved.

Aluminum and steel components were redesigned by removing material where it wasn’t needed and by using lighter materials, such as plastics and carbon fiber, where possible. We also managed to change many commercial components, for example the chain and the pinions, with more advanced and lighter ones. We decided to buy an ultra-light chain and to make a new carbon fiber chainring. Overall, we removed almost 1.6 Kg of weight. That means less inertial mass and less weight on the wheels, therefore less drag due to rolling resistance.
– Functionality: the old action used a crank-rod mechanism that imposes a nonlinear movement to the cassette,  making calibration harder.

​This problem was solved by using a different mechanism: rack and pinion system.

– Efficiency: even if the chosen transmission system is intrinsically efficient, we tried to maximize its efficiency even further with a deeper study of the chain and lubricant. 

Last version of the transmission. Lateral view

The improved system presents a splined shaft holder (the bridge like structure) which is more compact and lighter than its predecessor. In the picture you may notice the complete carbon fiber structure.
The new system has been tested during the competition in BM of 2018. It works precisely and rapidly and it doesn’t seem to require further modification. The only problem was that the chain could not perfectly engage the correct gear when working on the higher pinions. In that part of the cassette, the pinions have similar diameters: this caused the chain to jump over two gears. This problem was solved by changing the geometry of the right tensioner. The new shape brings the pulleys closer to the cassette when the chain is on the higher gears.

​The development of this technology brought three members of the team to register two patents, which in the future could even be implemented into the industrial production of high-end bikes characterised for high performances and efficiency.

Conclusions and ideas for the future

​Even though the actual transmission is very efficient, it has the disadvantage of having two chains because of the massive transmission ratio. The goal for the future is the development of a single chain transmission system. Though it would be quite a feat, it is not impossible. 

#TEAM10: 10 years of POLICUMBENT

#TEAM10: 10 years of POLICUMBENT

One of the most exciting things about being a member of my university’s Policumbent team is the recruitment of new members, or better, the participation of people who can help the team get closer and closer to achieving its goals. Team Policumbent’s goals are to beat records; Italian, European and international.

Since 2009 the team has been growing and improving every year by diving into their research, creating new prototypes, and working hard on improvements until they are satisfied with every aspect of their project.
This is a work that requires meticulous attention to detail, but which is no doubt worth it for the end result.

​During the 2017/2018 academic year we reached a very important milestone for the Team and for our rider Andrea Gallo who, on board our latest bicycle Taurus, reached a top speed of 133.26 km/h in the Nevada desert, winning the WHPSC first place and setting a new Italian speed record on two wheels.

​What better way to kick off the Team’s 10th year of competing?
Putting aside the impressive result, the Team didn’t waste time and immediately started to work on the new year's projects. Something is cooking and it's about a triple challenge!

The first goal is to exceed the 0,5 km/h that divides our rider Andrea Gallo from the European record. The data we collected show that in a favourable weather condition TAURUS should be able to extensively exceed the 133.78 km/h set by Sebastiaan Bowier in 2013. Therefore, TAURUS will be maintained as a flagship vehicle in the men’s category for another year.
We are working on some minor upgrades for the SR205, to improve the speed by at at least 0,5 km/h faster than last year.

The second objective follows the first. With the current wattages, the European men’s record is well within our reach but we can’t say the same of the 144.17 km / h world record achieved by Todd Reichert in 2016. A new, more efficient and totally revamped vehicle is needed. This is the reason the Team decided to devote an entire department to the design of a new prototype that will run in 2020. The aerodynamics team has rethought the entire structure of the vehicle and is already working to lay the foundations for a new hull and optimize it through use of software. Even the mechanics have rolled up their sleeves to participate in an equally important challenge: creating a frame that can make room for a larger front wheel in order to gain as much as possible from the breaking down of rolling friction.

In short, two years of intense planning and experimentation are expected.

Last but not least there is a third challenge: the female world record. As we have already revealed, the team decided to welcome a girl and take her towards and hopefully over 121.41 km/h at Barbara Buatois. To achieve this result, we must combine two fundamental aspects: a tested bike capable of reaching such speeds safely, and a cyclist capable of not only developing an appropriate wattage (about 200 W average over 5 minutes with a bike like Taurus) but that also manages to maintain stability and take control of a vehicle in the pursuit for a world record.

Given these goals, the Team decided to proceed by activating a department exclusively dedicated to the “cloning” of Taurus, a well-tested bike that we know is a high standard and in step with our competitors. The bicycle that will compete in the female world record could be called TAURUS-X, in honour of the Team’s tenth year of activity and it will be a revisited and improved copy of the current TAURUS, while maintaining the same dimensions and general structure.

About the cyclist, with the triathlon national trainer Andrea Gabba’s support, some candidates have already done the first threshold test sessions. At the moment we have a “first choice”, but there will be an initial period with a 2nd rider still to be selected and a final choice taking place in March after the first road tests.

The activities are not few, actually, they are many and some of them are urgent; once the recruitment was concluded, the teams were formed and within a few days each sub-group had already held a meeting to organize and plan every small detail that would have been necessary in for the new year’s projects.

Team 10 has 59 active members coming from the most varied faculties of the Polytechnic University of Turin, demonstrating once again that a seemingly simple project requires an interdisciplinary range that finds few rivals even within the Politecnico. In this framework, many works and activities that don’t directly concern the mechanics, aerodynamics or electronics of the vehicle often go unnoticed.
Almost never mentioned, but imperative to the team’s development are the Budget and Logistics Management’s and the Communication and Image’s teams.

Although the multimedia aspect is in fact the most lacking for engineering students, the care of the image and the diffusion through the most varied channels, social or otherwise, makes the Team known inside and inside and outside the Politecnico, which is why we decided to completely renew the communication department.
Innovation comes from the shape as well as, clearly, from the content.
Even more important than attention to multimedia content is the management of the budget and logistics of the team. In a year so rich in activities and challenges it will be necessary to take care of the best movements, tests on the track, event planning and management of the annual budget. They are all unseen things that are have a fundamental importance for the team.

​In this complex but always well-structured framework of activities, the Team is ready to
achieve its 2019 goals, be they Italian, European or international.

Hardworking until the last minute

Hardworking until the last minute

The 2018 has been a complex year for the team.
For a number of reasons we do not want to bore you, we have accumulated considerable delay in the implementation of the planned upgrades. Even the test sessions were few and often canceled at the last minute. But we never surrender. When you have a speed record in mind you can not forget it, it always comes back, while you do something else, while you’re even sleeping. It becomes an obsession and it push you to find time and energies even when it looks impossible.
​Exploiting intensely the month of August the delay has been recovered and the upgrade of Taurus is now completed.
The end result makes us very proud:

  • we removed almost 8 kg of total weight from components and front hull and we are still subtracting grams here and there;
  • we made our 20″ disc wheels with the support of Arol (which supplied the molds), of Faber Sum and of Renna Rowing Boats for the lamination: very robust, very precise and calibrated and just lighter (about 60 g) of the previous market wheels (although the weight was not a priority here given the structural relevance of the component);
  • we created a new and evolved version of the translating cassette electronic gearbox, still top secret as an object for the filing of a new patent application in the next days;
  • we created a new monoblade front fork with anchorage at the bottom of the fairing by assembling aluminum and carbon parts;
  • we implemented a telemetry system in order to monitor all data from the chase car that follows the bike;
  • … and much more that we leave out to detail to cut short and to not reveal everything 😉

Most of the updates listed above were implemented in the month of August and tested ONCE on Saturday 25/8 at the Orbassano FCA circuit. One take.
​There are still some vibrations to solve, the front wheel cover is 90% ready and we will work to complete it by the beginning of the competition.

Moreover, during the year, other important activities were carried out, including:

  • the set-up of a rolling resistance test-rig and the measurement of many tires in different configuration (butyl and latex inner tube,  tubeless) up to 150 km/h in order to select the best ones;
  • the development of a Matlab code for run analysis and simulation that is accurate and able to estimate non-constant coefficients (speed dependent Cd and Cr, as they are in the real word);

​In all this we neglected a bit of communication, so this blog was stopped and we posted few pictures and updates on social media.

We know well that the work could be not enough, because the WHPSC is a complex event and to break a record the bike is not enough, the cyclist is not enough, the team is not enough, the weather is not enough… you need all of these plus something else. The stopwatch on the SR305 will give the final verdict, but no one can steal us the satisfaction of completing the upgrade tasks despite difficulties and obstacles.

On August 30th, Taurus will be shipped towards US; on September 1st Andrea Gallo will follow to acclimatize and to recover from the jet-lag; on September 6th and 7th will be the turn of the rest of the representative.
Then, from 10 to 15 … GO! GO! GO!!!
Stay tuned for live updates on our social channels!

Some exciting news

We are glad to announce that Team Policumbent has officially decided to give space to a female cyclist, with the aim of going after the female world speed record on two wheels of 121,81 km/h, set by Barbara Bautois on Varna Tempest in 2010.


This decision comes at the same time of the beginning of a new specific physical preparation plan that our cyclist Andrea Gallo decided to undertake in order to increase and refine his performances for the upcoming WHPSC 2018. Considering the peculiarity of the competition, the team will be helped by the CUS (Academic Sport Center), the SUISM (Academic Facility of Hygienics and Sport Science) and two important personalities:

  • Andrea Gabba: FITRI (Triathlon Italian Federation) trainer. World champion coach of female relay and male acquathlon, silver medal of the academic world (2016). His capability is testified by the Olympic Games (Athens, Beijing, Rio De Janeiro) and European Championships (Baku 2015) partecipations. He had job experiences with endurance athletes in the best training centeres worldwide, and among all a four year experience as tecnical director of Triathlon in Turkey.
  • Felicina Biorci: biologist and nutritionist at the Medical Center for Sport in the Università degli Studi di Torino, Scuola Universitaria Interfacoltà in Scienze Motorie.

The path that will lead to the selection of a new cyclist will go through a first application phase, followed by some aptitude tests and meetings with the Team that will allow us to choose the ultimate profile among the applicants.
After the selection phase we will define a training plan with the support of the Olympic trainer Andrea Gabba and the nutritionist Felicina Borci. Our goal is to improve the feeling with recumbent bike through tests on previous Policumbent protoypes.

The debut will be at the World Human Powered Speed Challenge 2019, scheduled in September 2019 in Battle Mountain, Nevada. We hope that the debut will give us a lot of great results and a breath of fresh air in the female category of the fastest human powered vehicles in the world.

​Follow all the information for the application on the dedicated page: RIDE with US!

Diet for TAURUS

WHPSC 2017 gave us the chance to know our creature better. We picked out a lot of strong points, but even many critical aspects on which we are focusing our entire activity for 2017/2018, and one of them is the weight.

Indeed, Taurus weights 38.8 kg, it may not seem so heavy, but if we compare it with the 22 kg of other competitors’ prototypes it is a lot, infact a lighter vehicle allow us to reach high speeds quicker and with far less effort. Therefore this year we put Taurus on diet with a working plan that is affecting every aspect of the project, from the electronics to the aerodynamics and even the design of new components such as wheels and forks.

Therefore every member of the team has a new challenge: reaching the best performance possible reducing the weights.
We made various estimations about weight saving of the second version of the prototype so far: we estimated a 1 kg saving for what concerns electronics, thanks to a reduction of the powerbanks’ dimensions and to the development of an ultralight monitor. A great contribution will also come from the wheels, the fork and the gearbox, thanks to a new design that cares about the weight.

​2018 witnessed the birth of a new team’s sector: the FEM analisys division, that is the analisys of finite elements. It’s goal is to create models of finite elements of some components of the prototype in order to process them with optimization algorithms that give us a lighter version of the component, but with the same structural reliability.

​For those of you that aren’t familiar with structural mechanics or matrix calculation, you just have to know that finite elements method allows us to break down the object in smaller parts, the finite elements, and to solve few simple equations for each of them, rather than solving few complex equations for the entire component. Obviously, eventhough the equations are simple, they are thousands and we need a calculator with a software called solver. In our case we used Epilysis of BETA Systems.

During the first part of the academic year, the FEM division focused on the characterization of the materials, that is the research of the values of the mechanical characteristics of the materials, such as elastic modulus, shear modulus, density etc… that define the materials response to stress. The research of these values involved a lot of issues, in particular for what concerns the carbon fiber, because its values depend on the kind of fiber, the resin used, the kind of weaving and the process used for the lamination. All these elements contribute to the characteristics of the material through some empirical relations that have been implemented in a MATLAB code. In addiction, there’s the great uncertainty of the volume fraction that we are able to obtain with our manual lamination method. The volume fraction estimates the fiber percentage per unitary volume of composite material compared to the percentage of the matrix: the bigger the volume fraction, the better, because in this way we have a much stronger material, but with less weight. A tipical value of this quantity is 0,6, that is 60%. We think that we reached a value around 40%, but there’s the need of additional sperimental tests on samples of the same material to reach a more accurate estimate. 

Fairing mesh  [software ANSA,  BETA CAE Systems]

At the moment the FEM division is taking care of two main optimization projects: the fairing and the pedal cranks. For what concerns the fairing, the aim is to obtain a much lighter structure, reducing the amount of PVC and arranging it in way that keeps on giving the right stifness and minimizes vibrations.

​For the pedal cranks the goal is the same and consists in doing a topological optimization, that means that the software takes the finite element model of the pedal crank exposed to loads and tryes to figure out what part of them do not contribute to the component’s resistance and it deletes them with an iterative process. 

The images show the cronological order of the work on the pedal crank. It starts from the CAD of the original piece and then the finite element model is created. After this phase the optimization process starts generating a new distribution of the material from which we obtain the final shape of the new pedal crank.
For this work we estimate a 50% weight saving compared to the actual pedal cranks made of steel, but since we’re considering to use lighter materials such as titanium alloy, perhaps the lightening will be more significant.

Updates and more information will follow.
​Keep following us!

A blast of wind for TAURUS

A blast of wind for TAURUS

2017 has been an year full of innovations and development for Team Policumbent.
Goals like the second World place at WHPSC 2017 and a patent on the transmission are just two drops in a sea full of studies and researches that touches some of the most important fields of engineering.
One of them, maybe the most important in our case, is the aerodynamic one. 

​No matter how hard are you trying to perfectly develop something, there will always be some particulars that you missed and Team Policument made no exception.
So, despite the development of TAURUS’ fairing has seen more than 70 different shapes been designed, simulated and trashed, there still is something that can evolve.
Air drag is a silent but effective enemy and TAURUS knows how to deal with it.
​Just think that on a normal bike, to pedal at 40 km/h (24,8 mph) means that the 82% of the total power losses is gone in aerodynamic resistances (about 247 W on a total of 302 W) while on TAURUS, at 40 km/h the amount of aerodynamic power losses are just the 20% of the total ones, about 12 W on 61 W of total loss.
On TAURUS, in order to lose an equivalent of aerodynamic losses of 82% one should go far beyond 350 kmh! 

So the target is to minimize the aerodynamic losses, or rather to create a design that ensures laminarity and prevent any possible separation of the flux in the back part of the fairing.
Nowadays, prototypes that compete in WHPSC have reached an high level of efficiency and due to this, when a new bike is about to be designed it is required a deeper and more accurate planning. ​This is the reason why the Team decided to invest in a series of tests inside the Pininfarina wind tunnel. This kind of activity allow us to check visually if there is any turbulence on the fairing and to collect as many datas as possible about the vehicle’s behaviour.

During the first test, which has took place in December, TAURUS has been placed inside the tunnel at different speeds, from 30 to 140 km/h; this procedure allowed the Aerodynamic group to collect many information about pressures, drags and moments that will now be used to calibrate the CFD model. 

We also noticed some turbulences in the back part and a soft increase in vehicle’s Cd at about 120 kmh, feature to not underestimate if one thinks that the minimum speed required to break the male italian record is now set on 126,8 km/h.
At this point, a new planning phase has just made its begun and the aerodynamic group is now engaged in thinking any possible solution to apply on the yet made fairing or  to improve on a possible new one.​


One thing is for sure. 2018 is going to be an year full of work.