Category Archives: Bikes

Manufacture

Barely a month ago, I started working on the idea of a pedal-powered tractor for rice transplanting. This was for my Live-in-Lab project in India. I have just spent four days in the manufacturing workshop in a campus in Tamil Nadu, a 10h trip from my main campus. This post is tells how the manufacturing went on.

Manufacturing overview document and CAD drawings...
Project presentation and blueprints for manufacturing…

Day 1

After a short month of design work on my project, we are already starting manufacture! Aymeric, who is also doing a project in my lab, and who has already started manufacture announces in a stern voice: “one centimetre”. That is the precision with which our projects are being created. I’m not sure whether I should laugh or cry. As a microengineering student, I feel kind of sad.

In the manufacturing workshop, as well as the “Indian precision”, I also notice the Indian safety standards, or rather the lack of any. Here, the workers are bare feet or wearing sandals, and none of them is wearing safety gloves or glasses. The noise of the machines is deafening, and I often find myself plugging my ears while averting my gaze to avoid the bright flashes from the welding. I would be happy if I don’t become deaf and blind by the end of this project!

The Indians don’t have workbenches: they work directly on the ground. To discuss the design, we crouch besides the parts we’re talking about.

Discussions à propos d'une pièce. accroupis dans l'atelier de manufacture.
Discussing the design of a part, crouching on the floor.

My project is a rice planting machine. When I started doing my research about what already exists, I was disappointed to discover many machines already existed. From cheap machines to massive agricultural monsters, the subject seemed under control. Additionally, while checking out Youtube, I found so many student projects it seemed like all Indian MTech students have to build a rice planting machine. What is the purpose of my project then? I couldn’t see how my work could serve the subject. So I decided to take a radically different approach. Rather than building an average machine that farmers would push or pull across the paddies, I decided to create a pedal-powered machine. Based on a bicycle, with a transplanting trailer, I am convinced that my design could do the job. With countless hours of pedalling in mud as a mountain biking competitor, I knew it was possible to ride through a thick layer of mud. Now I had to prove them.

On rencontre l'artisan/ouvrier qui va construire la majeure partie de mon vélo...
First meeting with my project’s maufacturer…

Apparently, manufacture starts with a prayer. I join my palms in front of my chest, close my eyes, and listen to the prayer in Malayalam. I even recognise some sentences after a month and a half in the Ashram!

We start by building the back wheels. Soon enough, the long strips of steel get bent and welded together as tractor wheels. Yesterday, we went to get a second-hand bike. I like its “old school” looks, but it will soon be disassembled by a gang on young Indian workers.  Only the main parts are kept for my design.

Mon nouveau vélo... qui sera vite démonté !
My new bike… while it was still in one piece!
Voilà comment on fabrique des roues ! Des grandes bandes de métal sont courbées à la main, puis soudées aux rayons et au centre de la roue.
This is how wheels are made! By bending strips of steel then welding everything together..
Construction des roues. La précision : pas plus que la largeur du trait à la craie.
Building the wheels. Precision? Not more thant the width of a chalk mark.
Tout feu tout flammes : qui ne voudrait pas être ingénieur quand son équipe de manufacture fait cracher du feu à un simple bicyclette ?
Who wouldn’t like to be an engineer when your manufacturing team can turn your bike into a fire-spitting dragon?

Day 2

The manufacturing is going well, and my Ricycle is starting to take shape! When I arrived in the morning, I discovered with awe that my back wheels were almost finished, and they are impressive. But when I try to lift one up, suddenly, it isn’t as stylish: they are almost as heavy as my travel backpack. At 13kg each (ok, a bit less than y backpack), I start to lose faith in my project… How will my small farmers manage to pedal this prototype through the fields?! A sturdy mountain biking wheel weighs less than 2kg, I would never have imagined mine weighing more than double this figure! My supervisor tries to comfort me: “worst case, we give your system to an ox, it will be able to pull it!”. Cows are sacred in India, the ox gets all the work. I still haven’t understood the difference, but if they say so…

En arrivant les deuxièmejour, mes roues sont presque terminées ! A l'atelier, il n'y a guère d'équipement de sécurité, et mes yeux souffrent à chaque fois qu'ils s'arrêtent par mégarde sur un poste de soudure. Comme il y en a partout, c'est très dérangeant. Je ne suis là que pour quelques jours, je me demande comment les ouvriers font pour ne pas encore être aveugles !
When I arrived on the second morning, my wheels were almost finished! In the workshop, there is almost no safety equipment, and my eyes suffer every time they fall upon a welding station… As they are everywhere, it is very uncomfortable. I am only here for a few days, and I’m wondering whether the workers are turning blind!

The explanation for this general overweight is the materials used for prototyping. While mountain biking wheels are made out of lightweight aluminium, mine are in made out of heavy mild steel. I’ll have to write down the exact name of it. If we use less material, they would not be solid enough… So they’re heavy. Very heavy.

The other materials and parts used for my Ricycle are mostly second-hand and scrap parts from whatever lies around the workshop. For the gears, we swap the front chainrings and back sprockets. The bike will be easier to pedal with this configuration. For the transplanting system, we find some scrap sawing bands and cut them out. I was imagining having flexible blades, but that was in my ideal designer mind. When I see them hammering the strips to flatten them, I understand they won’t be flexible any more. We learnt in first year’s material class that if you work the metal it won’t be as flexible. Oh well…

Contrairement à l'atelier de mécanique où j'ai fait mon stage d'usinage en deuxième année, ici, tout semble être rouillé. Les matériaux sont les moins chers possibles, ce qui change la donne au niveau du poids, de la résistance, etc.
Unlike in the workshop where I did my metalwork course in second year, here, everything seems to be rusty. The materials are cheap, which changes everything regarding weight, strength, etc.
J'avais fièrement décidé d'introduire des lames flexibles dans mon mécanisme afin d'éviter l'utilisation de ressorts (spéciale dédicasse au Professeur Henein). Je trouvais ça très intelligent jusqu'à que je voie comment ils tapaient sur des bandes à scier le bois pour les rendre droites avant de les retordre et espèrer qu'elles soient toujours aussi flexibles...
I was proud to use flexible blades in my design to avoid using moving parts and springs (special thoughts to Professor Henein!). I thought it was very intelligent… until they started hammering the blades in shape, believing it wouldn’t change the material’s flexibility!

Day 3

My prototype is looking more and more like my computer designs, and I’m impressed. Until now, the biggest project I had made was my robot for the Robopoly contest, which had to fit into a cylinder of 30cm in diameter. The Ricycle isn’t anything alike! The bike is elevated by a dozen of centimetres and the back wheels are one metre apart.

Certaines pièces sont très semblables aux dessins que j'ai fournis, d'autres n'ont absolument rien à voir. Tous ont un point commun : un surpoids manifeste qu'en tant que microtechnicienne, je n'avais pas imaginé !
Some parts look very much like the ones I’ve drawn on my computer, other seem to be nothing alike. All have one thing in common: a considerable overweight that as a microengineer, I would never have imagined!

As the day goes on, the project is getting fine-tuned. At first, we set the parts in the right disposition, then we partly weld them (careful with the eyes!), and afterwards the position is adjusted according to additional parts. Everything is getting together thanks to the manufacturer’s work and it is an awesome thing to see. When I have a close look, I notice that it is far from being precision work, and when “fixed” parts are more that one centimetre lose, my microengineer soul dies a bit but then I take a step backwards and am still quite proud of my project.

Ca commence à ressembler à mes dessins 3D sur l'ordinateur !
It is beginning to look like my 3D drawings!
La mise en place des éléments est aussi soumise à la précision
The disposition of parts is also subjected to “Indian precision”! As one of my metalwork teachers would say: “there’s a shitload of sideshift!”.

I feel like a site supervisor, being a snob hidden behind my sunglasses. I have decided to cut myself out by wearing earplugs. My ears thank me for this but the already limited communication is further degraded. The workshop is so noisy that I hurt my ear. And the welding flashes are still as aggressive on the eyes. As I start coughing, I am thinking that with all these metal dust particles in the air I might replenish my iron deficiencies!

During the day, many Indians come to have a look at my tricycle. They try to spin a wheel, to understand how it works… They smile and nod in the typical Indian fashion, and my supervisor explains them what it is. In Tamil. I am almost never included in these conversations, or at the most with a slight nod towards me.

Les indiens sont curieux de mon projet et semblent heureux de le voir prendre forme.
The Indians are curious about my project, and seem to be happy to see it take shape.

Despite the language barrier, I feel some complicity with the other women in the workshop. They are five, two of them are working on machines. We curiously look at each other, and try a shy smile while nodding our heads. Yesterday, at the tea break, they asked me if I spoke Tamil. Unfortunately, I haven’t tried learning. At the chai break, they show me where to get my cup and make a sign to tell me to sit besides them. One of them speaks a bit of English and asks me some questions. Where I come from and for how long am I here. Even if we don’t speak I appreciate this outreach which makes me feel more accepted than in any of the technical conversations about my project in which I was barely addressed.

Day 4

The project is being brought into life! With pride, I get on my tricycle and start riding… before derailing after a few metres.

Une prière s'impose avant de tester le Ricycle pour la première fois.
Of course, we pray before testing the Ricycle for the first time.

The Ricycle has made its first steps! Or rather, its first wheel rotations. I can’t even imagine the efficiency of the machine, every part is lose. We spend the day assembling and disassembling the wheels and axle to align every part and tighten everything up. Little by little, the parts are welded and lined up with washers, and the wheels don’t have a path difference of 10cm when turned in in opposite directions.

My supervisor brought the axle to the lathe workshop to thread its extremities, and the wheels can now be tightened. This also allows the bike to turn, as one wheel slips while the other is rolling forward when the handlebar is turned. Now the bike is not limited to straight lines! Well this might not be a sufficient permanent solution, as when the bike encounters resistance both wheels slip and the bike gets stuck.

Une étudiante indienne a essayé le Ricycle, et ça a l'air de fonctionner aussi pour elle ! Dans ma conception, j'ai voulu prendre en compte la morphologie des fermières indiennes, qui font en moyenne 1m50, afin que le vélo soit adapté à leur taille.
An Indian student tried the Ricycle, and it seems to work for her too! In my design, I wanted to take account of the Indian female morphology, who are around 1m50 heigh.

Besides building the tractor-bike, we build the seedling tray. But with the change in dimensions of the back wheels and sprocket, we now have to adapt the length of the connecting parts between bike and transplanter. To solve this problem, I feel lost without my computer, I cannot manage to visualise the best bay to rearrange the parts so that they fit together. Luckily, we move on to another problem, which gives me more time for thinking about the former one.

Une fois boulonnées en place, ça tourne mieux, et en plus on peut faire des virages !
Once the wheels bolted on the axle, it moves more smoothly, and we can even take turns!

The bike moves, but is often derailing. Once all the parts have been fixed, it is better, but to guarantee parallel parts when no measurement is precise is a big challenge. We fix small pipes to the frame to align the chain with the sprockets, so it doesn’t derail from the back any more, but from the front! At least now we can pedal a bit further.

Avec l'artisan/ouvrier qui a fabriqué la majeure partie du Ricycle :)
Me with the manufacturer who built most of the Ricycle!

Work in progress…

Maintenant, il ne reste plus qu'à fixer le mécanisme de transplantation... et ça va pas être une mince affaire !
Now, we only have to attach the transplanting mechanism! Well, only… it will definitely be a difficult task!

In four days, we managed to build a mostly functional bicycle-tractor! Now that the biggest part of the job is done, the most challenging part stays ahead: linking the transplanting mechanism and make it work!

DR2: Cycling in Mud

Those who know I’m crazy about bikes might also know that before starting my engineering studies, all I did was cycling around and rolling myself in mud in mountain biking competitions. I have some very fond memories of a French Cup race where there was so much mud people would slide down the slopes on their backsides. Now that is what I call mountain biking!

Sliding down hills of your bike is one thing, but how do people actually ride through mud? With the right technical equipment and some driving skills it is possible to race through mud fields. Lets analyse how the champions do it!

Riding through mud

See, those who go furthest usually have high rpm, and go as straight as possible. The bike has narrow tyres with high spikes to avoid building up mud. They shift their weight to the back of the bike to have more traction.

For those who fail, they will most likely get their front wheel stuck of slide on their sides. Some unfortunate riders will get their bikes stopped by mud blocking the wheels in v-brakes or frame.

If this kid can ride his bike through that clay puddle, than certainly we could get a bike tractor through a rice field, couldn’t we?

The physics behind it

Estimation of cycling power

Power is the rate at which energy is used (energy over time) and is measured in watts. In cycling, energy is expressed in terms of work (such as how hard you have to work to ascend a climb). It’s a constant snapshot of your work rate at any given moment. […] A better measure, especially on climbs, is watts produced per kilogram of body weight.
How much better are Tour riders than the rest of us? A contender for the overall classification can produce just above 6 w/Kg on major climbs of the race. By comparison, a domestic pro could manage a best of 5-5.5w/Kg; a good, competitive amateur or masters’ racer can put out around 4w/Kg and an untrained person would struggle to produce 2.5w/Kg. Bicycling.com

Braquets

Torque