[Technique] Réalisations de Maarten JANSSENS

fpayart a écrit:

Just as Polux rsv, I too am puzzled about the transverse and longitudinal rigidity of the swingarm fixings.

+1. Your craftsmanship is superb, but the ribs around the swing arm fixing look rather fragile. The chain will try to pull the engine backward and the force exerted by the suspension triangle will try to twist the lower transverse tube.
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Au minimum une "vraie poutre" entre les deux fixations moteur.....mais il faudrait un petit coup de CAO (en maillant en conséquence) pour valider.

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biger a écrit:

Au minimum une "vraie poutre" entre les deux fixations moteur.....mais il faudrait un petit coup de CAO (en maillant en conséquence) pour valider.

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Maarten has put a huge amount of time and effort into this but I fear that this is weak in several area's.
On a basic level it will 100% not survive a crash. The footrest mountings are not remotely strong enough.
Sometimes it's better to keep a low profile until something is proven.

J'espère que je n'ai faché personne.........parce que la langue anglaise et moi c'est difficile.

It seems that Martin has experimented a few FEA models.

Le problème de toutes les simulations c'est de savoir quantifier les efforts, où les appliquer et dans quelle direction.

Hey guys,

I understand the worries but I don't share them.

The ribs might look fragile but that's because of the big chamfer on them (and that was the point, to make them visualy thin).
For the chain forces we took 200 HP + a too tight chain + suspension 100% pushed in for maximum force + maximum chain effect--> this purely for strenght and not for stiffness calculations offcourse.

What I read here about it not surviving a crash is bullshit. First of all you have to look at it in real life (or at technical drawings) and not at pictures before making those kind of remarks!

Secondly, "a crash" is not a standard kind of thing. I've seen original R6 frames that were completely ripped to pieces at the welds and others that didn't have a scratch because it all depends of the type of crash.
The footpeg mountings are strong enough, again you should look at it in the flesh before making that kind of remark.

All calculations were done so that it would be stressed to maximum of 73% of the yield strenght.

I agree with what Dave said "sometimes it's better to keep a low profile until something is proven". But that works both ways (it's not proven that it's too weak is it?)

And I won't try to sell a single one until we've done a lot of testing on track with it, including data logging and stress gauges. So the we'll see and I promise that I'm man enough to admit to my errors but then I first have to find them.

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kind regards,

MJ

Maarten

I wish you only good will. If my observations are unfounded then I would be happy to put my hand up
and say sorry. Regarding the crash "Bullshit" this was my first thought from the first time I saw the drawings. What class do you intend the use this bike in? European organisers are notoriously reluctant
to accept non standard chassis except in Supermono as I have found to my cost with my work.
If it's a "Norton" or "Paton" this does not apply of course.

Maarten, I share Dave's opinion. And I agree with your 'bullshit'; it would be foolish to build a crash-proof racing bike.
In case anyone wants to travel crash-proof, I can recommend this:
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Maarten,
My intention was not to say "bad design". I don't have the knoweledge you have.
I tried to draw my concerns on your picture.

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Angelo

Dave Pearce a écrit:

Maarten

I wish you only good will. If my observations are unfounded then I would be happy to put my hand up
and say sorry. Regarding the crash "Bullshit" this was my first thought from the first time I saw the drawings. What class do you intend the use this bike in? European organisers are notoriously reluctant
to accept non standard chassis except in Supermono as I have found to my cost with my work.
If it's a "Norton" or "Paton" this does not apply of course.

Don't get focused on the B-word But I didn't know how else to put it, haha.
I'm happy with comments and I listen to them (as you know!--> think about the ER70-S filler rod) but I'd like them to be founded as good as possible offcourse.
The bike is made for hobby-riders that are looking for something diferent + more lightness + more adjustability to cancel out excess- or lack off anti-squat.
There is a "moto2" class in the ONK championship that also should accept this frame because the reglementation looks like that one of the supermono.

Frits Overmars a écrit:

Maarten, I share Dave's opinion. And I agree with your 'bullshit'; it would be foolish to build a crash-proof racing bike.
In case anyone wants to travel crash-proof, I can recommend this:
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Wich part of Dave's opinion do you share Frits? I'd like to know. Do you also think that it's going to be to weak?

Polux rsv a écrit:

Maarten,
My intention was not to say "bad design". I don't have the knoweledge you have.
I tried to draw my concerns on your picture.

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Angelo

I understood these concerns teh first time but like I said I don't share them.
The parts will flex offcourse, as will everything... But we did take it all into account so I'm not affraid of flexing inside of the plain of the cnc parts.
The most rearwards and almost vertical "rib" of takes most of the torque from the upper crossmember and uses that force to counteract the one that starts from the bottom crossmember.

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My only concern is the lateral flex, perpendicular on the plain of the cnc parts. So viewed from te back; the sideways flex.
It will be strong enough not to break but I'm hoping it won't flex too much and loose grip at the rear or start to chatter because of that. Only the track will tell.

MJ-Works a écrit:

Wich part of Dave's opinion do you share Frits? I'd like to know. Do you also think that it's going to be to weak?

Maarten, I already expressed my concerns earlier, before Dave did. I wrote:

Citation :

Your craftsmanship is superb, but the ribs around the swing arm fixing look rather fragile. The chain will try to pull the engine backward and the force exerted by the suspension triangle will try to twist the lower transverse tube.

This was the opinion I share with Dave:

Dave Pearce a écrit:

Maarten, I wish you only good will. If my observations are unfounded then I would be happy to put my hand up and say sorry.

Hello Maarten,
in your simulation, have you been able to determine the self frequency of your raw part (both each half and assembled) as you know those (bitches) bikes generate vibrations that can get in tune and manifest themselves in chattering. I'm not criticizing whatsoever your design choices but would rather advise you to think about using piezo to try and record vibration frequencies while datalogging. I don't know wether that kind of measuring is currently done (except in motoGP most probably) and the type of probes you may use to fulfill the job. I thought about piezos because that's what we use in our physics labs at school...

Keep it up!

alextatic a écrit:

Hello Maarten,
in your simulation, have you been able to determine the self frequency of your raw part (both each half and assembled) as you know those (bitches) bikes generate vibrations that can get in tune and manifest themselves in chattering. I'm not criticizing whatsoever your design choices but would rather advise you to think about using piezo to try and record vibration frequencies while datalogging. I don't know wether that kind of measuring is currently done (except in motoGP most probably) and the type of probes you may use to fulfill the job. I thought about piezos because that's what we use in our physics labs at school...

Keep it up!

Hello,

I think we can still do that. I didn't do it yet because last time we've put a lot of time into that and on track it reacted completly different (with my supermono).
That's why I said that currently my only real worry with this frame is indeed the chatter! We didn't do a simulation for that so we will have to wait and see!
Thank you for the tip of using piezo, I'll have a look at what's possible. I'm planning on using strain/stress gauges on the aluminium and some tubes of the steel part to check the movement under load on track.

Interesting times ahead! I still need to learn a lot...

Kind regards,

Maarten

When I read some of this I wonder how I have ever managed to build a solitary chassis with just a
welding torch and a few simple tools. Even the might of HRC fucked up last year. What planet is Mr Alextatic from ? Has he ever been in a workshop ? . Just get on with it and stop trying to blind us all with science ( Bullshit). Its time to leave your capsule if you dare.

Times have changed dude , you can work in a workshop with few "simple" tools and be an engineer calculating stuff that no one think about

welcome in our world



.

To Dave,

considering the lightweight objective pursued by Maarten and the incredible lean angle permitted by moto Dunlop tyres I believe (though I might fool myself) that this type of phenomenon might occur. In my young age I welded frames as well but it was 25 years ago and our bikes were working more vertically...

Dave Pearce a écrit:

When I read some of this I wonder how I have ever managed to build a solitary chassis with just a
welding torch and a few simple tools. Even the might of HRC fucked up last year. What planet is Mr Alextatic from ? Has he ever been in a workshop ? .  Just get on with it and stop trying to blind us all with science ( Bullshit). Its time to leave your capsule if you dare.

I've also built chassis with simple tools and a welding torch. And they worked better than I could have dreamed about and I enjoy the building part of it all the most. It's a passion for me to create things with my hands that I've tought about every day and night before- and during the proces!

BUT it's also interesting to hear about other peoples vision on how to do things. This is allways something you should be open minded for.

A good friend of mine once told/learned me to the use of a chair in the workshop.
While you are building you should sometimes take out the chair (+a cup of coffee), sit down and just have a fresh look at what you are building instead of just completing the steps you've decided to take in the beginning. This might spark better plans based on the part you've allready built and hat you've learned in the proces.
Just to say I'm happy with everyone's vision on how to work on a project.

I personally like simplicity but I also try to push (my own) boundries with every build. Because like I said I mainly do this for the "building" part of it all.
Look at the suspension setup on my supermono; everyone told me it wouldn't work and I've proven in the races that is does work.
I wanted that system because of the packaging advantages and how the forces went trough the frame and I've proven that it works just like I hoped it would work.

We missed out on a good face to face talk in Croix because of my injection failing but we'll surely have it in the future!

kind regards,

Maarten

Today we did the first testride on cicuit zolder!

Made this 380 gram subframe

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--> this make sthe total weightsaving on frame + subframe 5.5 Kg lighter than stock R6!!

A Few pictures of today:

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The best news is that she preformed beyond expectations! We are very pleased to announce that despite the cold weathter and the noise limit we've accomplished good laptimes and did some good testing! Everyone was very ppleased and the bike got a lot of attention (despite not being fully finished yet) what's also a plus. We're in love!

GRTZ

MJ

Great ! Your child is born ! So touching !

Just lovely.
Great job, this see-through frame is a real jewel.

Hey guys,

Soooo you guys told me that the frame wasn't crash proof???

Today had a big crash at assen because of an oil leak on track and the bolt on footpegs broke but the chassis is stil in perfect condition
No cracks or torsion on the aluminium or the steel part.

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greets!

MJ

At least you had a reason to celebrate!

MJ-Works a écrit:

Soooo you guys told me that the frame wasn't crash proof? Today had a big crash at assen because of an oil leak on track and the bolt on footpegs broke of but the chassis is stil in perfect condition.

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But I'm glad everything is OK, Maarten.

Frits Overmars a écrit:

MJ-Works a écrit:

Soooo you guys told me that the frame wasn't crash proof? Today had a big crash at assen because of an oil leak on track and the bolt on footpegs broke of but the chassis is stil in perfect condition.

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But I'm glad everything is OK, Maarten.

Thanks! The guy after me that slipped has been sent to the hospital and is in a coma...pfff