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 Xiu Serra    -     The     secret      engineer

If the clutch has a problem he can feel this and he knows where to modify this to make better. But sometimes he needs me to make something . I am not a competitor to Paxau. I make more simulation inside the computer. I can always make something.

I work with a CAD systems with his specifically geared around engineering . This CAD system is connected to a finished element analysis software system which allows me to check if the part is going to be broken or not. When I am testing I know the maximum load I can place on the component with this system. I make all of the components ready for the suppliers to place and decide all of the tolerances. I can give this drawing to the client and the client  go to a supplier and the supplier can make the components. Sometime I give the software as well.


Why did you design the reverse engine on the Osso ?.

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Xui Serra interview - www.retrotrials.com
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Xui Serra interview - www.retrotrials.com
It was made for a lot of  reasons not just to look. Because Ossa  give to me the freedom to make all that I want . Then I think why this position of the cylinder. Because a trial bike every time you need to reduce the weight and also put the centre of gravity position more in front below the position of the petrol tank. Why this position ? . I have a choice where I put every component. One reason is the centre of gravity. The weight must be under the body of the rider , like a pendulum. When the bike gets lighter it needs more weight on the front , like the Ossa .Another is the temperature because more in front less temperature. If I put the exhaust in the front all the heat from the exhaust is going to heat all of the other components. It makes no sense. 

For me the starting point is a lower centre of gravity , and a temperature. From this I arrive at the configuration to invert the engine with the intake at the front because this is less temperature so the entering air is cooler and this means more power from the engine and the engine will run better . I then place all the components on the front and the more hot components on the back. Finally I arrive at this configuration. I try some other configuration but finally for the reasons including the the flow of the engine I choose this. Sometimes I  start and put the cylinder here and the radiator the other side was not possible because you need the rear shock absorber in a certain place. Finally i find the compromise and this is the Ossa I make . It is made after much thought.
Are you now thinking about the net generation of trial bikes?


Yes of course


Nobody really knew of Xiu Serra before the Ossa bike


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Xui Serra interview - www.retrotrials.com
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Xui Serra interview - www.retrotrials.com
Yes this is true . Nobody hear about me before the Ossa but when they talk to me they now know I am the man who make the GasGas. Oh , i know this company

Did this bring you more business for you?


No . The same . Exactly the same because the owners of the companies already know me  . There are not a lot of client in the world for me. I work in other lines of design as well but on trials but more than 20 years ago.Paxau worked on so many bikes. Paxau , Pibernat , Beta i have not been directly in contact with them but I know inside the engine are some components from my engine. This is very good for me because this confirm to me that the decision i take 20 years ago with this type of clutch is still good today and relevant.


If you analise who might steer the direction of trial bike design then i would think of you. You have more time to think about it that the companies themselves. 


Yes  . Also my customers contribute. I have a lot of ideas . At the moment I concentrate on the industrialisation of the industry and I do this for 2 years . I always record my ideas for the next project which will be soon. I am placing these ideas in the box and when arrive I will lift up the white paper and open the box. This is my vision. Sometimes this is not good for the companies because when i make a new project the best truth for the company is that i no make anything for another company because I am trying to make better all of the time ha ha . This is my passion. The next project will always be a development of the one before. Its normal , no?. It is evolution.


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Xui Serra interview - www.retrotrials.com
Do the companies understand this?.

They understand this but sometimes they think these ideas are best to stay in the box ha ha sometimes. Sometimes it happens like this because companies think i have a very interesting model and I  want to have this same model for 5 years with no modifications.  
Why do manufacturers not develop a hub where they can inter change the sprockets and disc from one side to another?. This would save the time of a tyre change which often requires equipment and many people find difficult . Many people say “ Why don’t they do this?”


I know what you mean. The problem can arise from the different dimension. The disc is smaller than the sprocket. The sprocket is larger on a trial bike. The fixing points are different but possible in the future the sprocket will have to be still bigger .I have one idea which i make a patents for already.


Talon engineering in the UK did make this hub and wheel for this but the manufacturers didn’t follow.


I have other ideas in this area but never develop this. It’s a real easy thing to do in my opinion , what you propose. Then its possible , because of this. This makes it possible to make this thing that you propose. The wheel might not have the disc and the sprocket .....you know what i mean ?


The wheel doesnt have the disc and the sprocket ?


Its not on the wheel , then you can make all you want with the wheel.If you don’t place the sprocket  and the disc on the hub but on the swinging arm which is very easy to make this. I have made one prototype like this.


I think ATK made something like this


But there are a lot of things to do. It is only necessary that a customer want  to invest in this. Because what happens. Prototypes cost a lot of money. I spend a lot of money in prototypes and if this does not arrive in production , this is a lot of money not used . For this reason I give my customers these ideas and give them the choice . The benefits of these ideas are in the hands of my customers . A lot of people have a lot of ideas but sometimes the idea is no good for production and doesn’t come into production . You need these things. You need a good idea. It needs to be easy to produce . A lot of things are important for the success of the idea, including the money .

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