Design process of a new motocross bike (Pursang)

Tim507
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Tim507 8/3/2011 8:30pm
8/3/2011 8:30pm
Spartacus wrote:
The MK4 rocked with its fiberglass box fenders. [img]http://www.bultacopursang.com/images/m68_03.jpg[/img]
The MK4 rocked with its fiberglass box fenders.

The boat tail......have one stashed away............
DrSweden
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DrSweden 8/3/2011 8:40pm
8/3/2011 8:40pm
machine wrote:
You guys honestly think this is a good looking bike?....:sick: I guess beauty is in the eye of the beer holder. :P [img]http://motocrossactionmag.com/Uploads/Public/Images/1111%20AUGUST/pursang1.jpg[/img]
You guys honestly think this is a good looking bike?....Sick


I guess beauty is in the eye of the beer holder. Tongue



WTF dude, the guy is present and have more talent than us combined and taste is subjective. Maybe you can post a drawing of your dream bike so we can see your good taste and sick skills...
DrSweden
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DrSweden 8/3/2011 8:44pm
8/3/2011 8:44pm
Jim Palau-Ribes wrote:
Hi guys, I´m the guy who builded the Pursang. I´ve never had the time to reply and write in forums like Vitalmx because just building the...
Hi guys,

I´m the guy who builded the Pursang. I´ve never had the time to reply and write in forums like Vitalmx because just building the bike during my free time was enought to fullfill day and night. Better late than never so within the next days I can explain more about the project and some details of the process and brand as well. It´s really interesting to see your comments and see that the passion that moved me to do the project is shared by lots of people around.
Hey, I'm SOOOOO IMPRESSED. You did what some of us could only dream of. I think the bike looks cool, and the skills you have is mind boggling. What engine, wheels, forks etc did you use? Has any expert rider tried it? Obviously the bike "works" but is it competitive compared to other bikes? Has a magazine tested it?

You done, or more stuff waiting? Smile
Jim Palau-Ribes 8/30/2011 3:13am
8/30/2011 3:13am
Erick wrote:
Congratulations with the work you have done this far. I am very impressed with the professionalism of your work. I have a few engineering related questions...
Congratulations with the work you have done this far. I am very impressed with the professionalism of your work.

I have a few engineering related questions:

- Did you design the steering geometry (wheelbase, trail, swingarm length, swingarm location, fork offset and head angle) to replicate in someway the steering geometry of the original model? If not, on what data did you decide steering geometry?
- There is a picture where you analyse the rigidity of the frame, how do you know what kind of rigidity is good? Did you compare it to other similar models?
- Did you consider welds in the simulation?
- What kind of aluminium did you use for the different frame components? Did it require heat treatment?
- Are you planning to mass produce this model, or is it just a show/study model for further development?
- How about a two stroke? Wink
Hi Eric,

In relation to the geometry I checked different bikes and them measures and rode them to know more about the steering and how all these figures afects the riding. They were modern bikes so the original Pursang was just a starting point to make a tribute to those bikes and first was just an style exercise and was muting to a more engineering project. Because I´m not a professional rider I personally I wanted to have a bike lower, more like the twin shocks from the sixties and seventies and the Pursang 450 has a lower settings than the actual ones.

To know if the analysis on computer is what you are looking for, you need a "real" reference so it´s important to compare it with a 3D model that represents a real frame knowing if you want to have more or less rigidity.

All the aluminium parts have heat treatment.

About the production of the model...Now I´m improving the prototype and adjusting it while some "inhouse" riders are trying it on the track. Also I´m working on showing the project and in the business plan to find investment. I made some interviews for the press here in Spain and in the next months we will make some press tests.

For the moment I´m done but the versatility that gives me the frame because of the possibility of changing angle of the fork makes me think on making a flattrack model and Paris Dakar version as well ans a light road bike also.

But these last words are just more dream things, the "reallistic" target is a 2 stroke Pursang...this is a MUST for me!

The Shop

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motogrady
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motogrady 8/30/2011 6:24am
8/30/2011 6:24am
Beautiful job. Nice work.

As far as the name, it's not the only bike currently using "Pursang".

http://www.motorcycledaily.com/2011/07/md-eye-candygram-rad02-pursang/

Using the old names, that's fodder for a whole different thread.

"Pursang" = throroughbred (horse)
"Bonneville" = nice village
"Tiger" = large striped cat
"Hurricane" = circular storm with sustained winds over 75 miles per hour
"Thunderbird" = Native American mythical bird, a Ford, or cheap fortified wine
"Sabre" = light curved sword
"Trident" = three-pronged spear associated with Neptune
"Fury" = uncontrollable anger or psychosis
"Velocette" = small quick entity
"Monster" = something large, unnatural and threatening
"Tenere" = desert region in Africa
"Hammer" = a tool for striking
"Vegas" = Meadows
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jmar 8/30/2011 6:34am
8/30/2011 6:34am
Who cares what it looks like?

How does the bike perform?
kripple428
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kripple428 8/30/2011 6:56am
8/30/2011 6:56am
Pretty sick!!! But I really hope they change the look of the shrouds fenders etc. not diggin that at all
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kripple428 8/30/2011 6:59am
8/30/2011 6:59am
machine wrote:
You guys honestly think this is a good looking bike?....:sick: I guess beauty is in the eye of the beer holder. :P [img]http://motocrossactionmag.com/Uploads/Public/Images/1111%20AUGUST/pursang1.jpg[/img]
You guys honestly think this is a good looking bike?....Sick


I guess beauty is in the eye of the beer holder. Tongue



DrSweden wrote:
WTF dude, the guy is present and have more talent than us combined and taste is subjective. Maybe you can post a drawing of your dream...
WTF dude, the guy is present and have more talent than us combined and taste is subjective. Maybe you can post a drawing of your dream bike so we can see your good taste and sick skills...
My complaint is that tge shrouds are VERY small not allowing alot of grip if they made the shrouds bigger and make the side plates come down a little further and add more curve to the fender and it wod look better
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dboivin 8/30/2011 7:08am
8/30/2011 7:08am
Throw some dirt track tires on it and lower it...and you got an ideal look for dirt track. (cosmetics).
DrSweden
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DrSweden 8/30/2011 7:36am
8/30/2011 7:36am
kripple428 wrote:
My complaint is that tge shrouds are VERY small not allowing alot of grip if they made the shrouds bigger and make the side plates come...
My complaint is that tge shrouds are VERY small not allowing alot of grip if they made the shrouds bigger and make the side plates come down a little further and add more curve to the fender and it wod look better
For me that was more constructive critique and I'm totally ok with that. I just think its wrong when people flame just because they can and they don't have any good arguments or reason for doing it. Basically just pissing sux.
Jim Palau-Ribes 9/2/2011 2:56am
9/2/2011 2:56am


Here you can see the Pursang 450i prototype almost finished.
The bike performs really good on cornering and jumping on the tracks and riding on paths is a good fun too. I Still need to refine the suspension settings. The engine is a Sherco 4.5 injection and his guaranteed realibility is proved with several years of good results in competition (Enduro championships and a Sherco 4.5 injection finished a Paris-Dakar rally)

My colleages, few of them who are race in spanish championsips and I have been riding the bike and we are delighted with its performance. However I thing for professional motocross riders the engine would need a Kit to bring more power.

The next step is to involve a Pro rider to test it and fine tune the last details for competition and also to try the 2 troke version of the Pursang (just checking to fit a 300 c.c engine)
tbanks
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tbanks 9/2/2011 4:28am
9/2/2011 4:28am
I like it. I'm an engineer and I once thought about making my own bike. Then I realised everything I would have to do and that idea turned into just a dream. Laughing You have done an amazing job and I look forward to seeing a two stroke.
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Tbteam 9/2/2011 4:32am
9/2/2011 4:32am
I love innovation, therefor I love that bike.

I was always a Bultaco fan when i was a little kid, and this is a nice ode to that era.
Erick
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Erick 9/6/2011 3:36am
9/6/2011 3:36am Edited Date/Time 9/6/2011 3:40am
Jim Palau-Ribes wrote:
Hi Eric, In relation to the geometry I checked different bikes and them measures and rode them to know more about the steering and how all...
Hi Eric,

In relation to the geometry I checked different bikes and them measures and rode them to know more about the steering and how all these figures afects the riding. They were modern bikes so the original Pursang was just a starting point to make a tribute to those bikes and first was just an style exercise and was muting to a more engineering project. Because I´m not a professional rider I personally I wanted to have a bike lower, more like the twin shocks from the sixties and seventies and the Pursang 450 has a lower settings than the actual ones.

To know if the analysis on computer is what you are looking for, you need a "real" reference so it´s important to compare it with a 3D model that represents a real frame knowing if you want to have more or less rigidity.

All the aluminium parts have heat treatment.

About the production of the model...Now I´m improving the prototype and adjusting it while some "inhouse" riders are trying it on the track. Also I´m working on showing the project and in the business plan to find investment. I made some interviews for the press here in Spain and in the next months we will make some press tests.

For the moment I´m done but the versatility that gives me the frame because of the possibility of changing angle of the fork makes me think on making a flattrack model and Paris Dakar version as well ans a light road bike also.

But these last words are just more dream things, the "reallistic" target is a 2 stroke Pursang...this is a MUST for me!
First of all, thank you for your informative response Smile I am a fan of your work and very interested in the technical aspect as I am an engineering student at the TU/e

So how does the frame respond when the engine is mounted? It must have a big impact of the frame ridgidity. Have you analysed this too? It sure takes a lot of computer work Tongue And why did you choose aluminium for the frame instead of steel? I see the bike does not have a head stay, why is that?

How do you change the head angle? How did you place the bearings?

The swingarm of the bike, did you design/produced it yourself?

Are you saying that your bike has a lower height than other models?

About the two stroke, what engine do you plan to use? A Gasgas engine? Or a KTM?
Erick
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Erick 4/4/2012 2:33am
4/4/2012 2:33am
dboivin wrote:
Throw some dirt track tires on it and lower it...and you got an ideal look for dirt track. (cosmetics).
I guess you are right





More info and pictures from them: http://pursangmotors.blogspot.com/
robkinuk
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robkinuk 4/4/2012 2:44am
4/4/2012 2:44am
Did you take any inspiration from the CCM frame design from 2 years ago? They used a casting then used some industrial strength glue to bond it together. Looks a very interesting project, glad the "garden shed innovators" aren't dead!
mmcmx
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mmcmx 4/4/2012 3:34am
4/4/2012 3:34am
Shame Montesa is owned by Honda. Would love to ride a modern cappra!
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Moto_Geek 4/4/2012 3:37am
4/4/2012 3:37am
Would be interesting to see motocross bikes become more customizable and interchangable.

Pit Row

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Spartacus
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Spartacus 4/4/2012 4:47am
4/4/2012 4:47am
also to try the 2 troke version of the Pursang (just checking to fit a 300 c.c engine)

also to try the 2 troke version of the Pursang (just checking to fit a 300 c.c engine)

also to try the 2 troke version of the Pursang (just checking to fit a 300 c.c engine)

Woohoo
Neil_Romero
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Neil_Romero 4/4/2012 5:35am
4/4/2012 5:35am
Bravo!
What an endeavor. Love seeing something truly unique.
throttle77
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throttle77 4/4/2012 6:12am
4/4/2012 6:12am
Congrats on producing such a cool bike. I find it very unique and the frame looks well thought out.
reded
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reded 4/4/2012 8:07am
4/4/2012 8:07am
With a modern front fender and deeper shrouds this thing would look F'in killer! I like the bike and can appreciate everything it took to make it a reality.
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exsarg 4/6/2012 7:17pm
4/6/2012 7:17pm
reded wrote:
With a modern front fender and deeper shrouds this thing would look F'in killer! I like the bike and can appreciate everything it took to make...
With a modern front fender and deeper shrouds this thing would look F'in killer! I like the bike and can appreciate everything it took to make it a reality.
agreed. i seen a pic in mxa a few months back. absolutley love it. the tank is unreal. i would love to try one.gotta have ohlins front and rear
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LowPsi 4/6/2012 9:33pm
4/6/2012 9:33pm Edited Date/Time 4/6/2012 9:38pm
mmcmx wrote:
Shame Montesa is owned by Honda. Would love to ride a modern cappra!
It's not a shame:

Today Bultaco is this: Bultaco Backpacks


and MONTESA HONDA is this................ WORLD CHAMPIONS X 26

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Whorehay 4/6/2012 10:19pm
4/6/2012 10:19pm
that is pretty awesome work!!!

I have a bunch of friend who build vintage bikes and I have been trying to get them to step outside the reproduction and make a "new" bike. There is so many amazing options for new products its good to see people putting the work in and making something truly unique.
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KAWboy14 4/7/2012 6:16am
4/7/2012 6:16am
machine wrote:
You guys honestly think this is a good looking bike?....:sick: I guess beauty is in the eye of the beer holder. :P [img]http://motocrossactionmag.com/Uploads/Public/Images/1111%20AUGUST/pursang1.jpg[/img]
You guys honestly think this is a good looking bike?....Sick


I guess beauty is in the eye of the beer holder. Tongue



that thing looks like something from Pep-Boys!
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Supermoto Al 4/10/2014 12:41am
4/10/2014 12:41am
machine wrote:
You guys honestly think this is a good looking bike?....:sick: I guess beauty is in the eye of the beer holder. :P [img]http://motocrossactionmag.com/Uploads/Public/Images/1111%20AUGUST/pursang1.jpg[/img]
You guys honestly think this is a good looking bike?....Sick


I guess beauty is in the eye of the beer holder. Tongue



Not only do i think this bike is a good looking bike, but better looking than any bikes on the market today. Not covered in plastic. The lines are simple and straight forward. I would buy one today if they were in production.
Supermoto Al
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Supermoto Al 4/10/2014 12:48am
4/10/2014 12:48am
Jim Palau-Ribes wrote:
[img]https://4.bp.blogspot.com/-DWBzE01m_1o/TmCfM-R-OCI/AAAAAAAAAaQ/QqwBc5_kG7o/s1600/IMG_1067.JPG[/img] Here you can see the Pursang 450i prototype almost finished. The bike performs really good on cornering and jumping on the tracks and riding on...


Here you can see the Pursang 450i prototype almost finished.
The bike performs really good on cornering and jumping on the tracks and riding on paths is a good fun too. I Still need to refine the suspension settings. The engine is a Sherco 4.5 injection and his guaranteed realibility is proved with several years of good results in competition (Enduro championships and a Sherco 4.5 injection finished a Paris-Dakar rally)

My colleages, few of them who are race in spanish championsips and I have been riding the bike and we are delighted with its performance. However I thing for professional motocross riders the engine would need a Kit to bring more power.

The next step is to involve a Pro rider to test it and fine tune the last details for competition and also to try the 2 troke version of the Pursang (just checking to fit a 300 c.c engine)
Jim.

This is by far the coolest looking bike I have ever seen. I am so impressed with this bike! I made a profile on this site just to tell you how much I love this bike.

Now every time I'm looking at bikes online my thoughts are always "it's not anywhere near as cool as the pursang 450i".

Honestly, I think this is the coolest bike I have ever seen. I am very picky, and this bike hits the spot.

If I could have just one bike, it would be the one you have created. Bring this bike alive!!!
Bultaco
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Bultaco 4/10/2014 3:53am
4/10/2014 3:53am
Erick wrote:
I guess you are right [img]https://farm8.staticflickr.com/7038/6838816866_5f45a5ecc5_b.jpg[/img] [img]https://farm8.staticflickr.com/7083/7023430735_92f3bd4472_b.jpg[/img] More info and pictures from them: [url=http://pursangmotors.blogspot.com/]http://pursangmotors.blogspot.com/[/url]
I guess you are right





More info and pictures from them: http://pursangmotors.blogspot.com/
Love this. This the first modern flat tracker that that reminds me of the old Champion framed short trackers of old. A good thing. Good luck with your project Pursang. I am impressed.
wired4speed 4/10/2014 4:38am
4/10/2014 4:38am
Nice thread....Beautiful bike. All I can say is that I wish I had that talent. I'm even amazed by the engineering and the dreams of builders generations ago.

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