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Old 09-22-2011, 01:58 AM   #91
DRjoe
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certainly not boring
+1
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Old 09-22-2011, 08:09 AM   #92
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Old 09-22-2011, 12:51 PM   #93
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Originally Posted by thecosman View Post
Progress was smooth until the unthinkable happened. At this point I'll leave you all hanging again, but tomorrow I will continue on. I'll also start to put up more pretty pictures as this narrative stage is getting a bit boring for me to type and I assume for you all to read.

See you tomorrow....
You gotta stop doing that...I'm and oldish person and my heart can't take the suspense
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Old 09-22-2011, 03:20 PM   #94
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Getting Blindsided

Getting blindsided is never fun and the memory seems to get permanently imprinted on your brain. I remember being at a kayak expo buying a paddle (carbon/kevlar, nice!) and trying on a PFD when my phone rings. Is it a buddy of mine, Scott Kolb, who tells me to sit down. He had bad news. Very bad news. Apparently the Grand Prix commission had just released an announcement that the Moto2 class would be powered by as an as-yet unspecified spec engine. The press release can be read here. I've never been so devastated by a single sentence: 'The commission unanimously accepted the proposition of the MSMA to have a “One Make Engine Regulation” in the Moto2 class.'

For those who don't know the MSMA is the Motorcycle Sport Manufacturers Association, or Aprilia, Ducati, Honda, Kawasaki, Suzuki and Yamaha. Considering that the only 600cc engine configuration made by any of these companies is an inline 4 I knew quite clearly that my project as conceived was screwed. After calling everyone I could think of that had any contacts in the GP paddock (a very short list) it became apparent that this had been a done deal for a while and that Honda would be supplying the engines. Final announcements would be forthcoming.

Now I must admit to being a bit naive and idealistic in thinking that we could design a bike and hop right onto the world GP grid. Although I knew the design had good performance potential I figured to get a wildcard or two and if the bike's performance was good enough then interest from existing teams would be my ticket to play. Isn't being naive fun? The world is so straightforward. Not! This simple introduction to the intricacies of GPs showed me how the rule packages are negotiated in closed rooms by corporations with high secrecy then slowly released to the public. Now if this was production racing then I would not have a problem with that approach. The manufacturers produce street-legal sportbikes in high volumes so they must be able to have a say in the rule structure. However, since Grand Prix racing is by definition prototype racing there is no production facility depending on continuity of rule packages. However as is usual with most governing bodies, common sense is turned upside down. Superbike racing rulebooks, built around modified production motorcycles, were written by a body with no manufacturer input. Grand Prix racing rulebooks, built around race-only prototypes, were written by production motorcycle manufacturers! Weird, huh?

After coming to grips with harsh reality I had a choice: keep making my own bike and be a lone voice in the wilderness, or redesign around an inline 4 and attempt to get a grid position. I had been in talks with Barry Gilsenan of Celtic Racing, a top privateer AMA team and also one with a lot of international experience, both in getting European riders into the US and US riders into European series. He was interested in the project and had offered an invite to attend any of his team's test days once the bike was ready. If it was fast he would do what he could to get it out onto the international stage. Barry wanted to get back to the GP paddock and it was a good possibility that my bike could be part of the effort. After looking into applying for a grid position he was told point blank- don't waste your time. Apparently there was plenty of interest from European teams and nobody had any reason to bounce a European team for a relatively unknown US team. Talk about an ol' boys club!

I did still have the option to build a bike around a CBR600 engine (the chosen Moto2 powerplant) and hope that the Moto2 format would trickle down to national series where I would have a chance to participate. Lets see, on one hand I can continue designing the bike of my dreams. On the other hand I could build a bike around the least exciting engine style in the hopes that years down the line I'd be able to race it. Tough choice. After taking to my collector buddy it became apparent that as a collector he could give 2 shits about a bike built around a CBR engine. At least we were on the same page!

With his OK I continued on the current path. I'd make my V4 and go to whatever tracks I could and race wherever we could. One positive was that I did not have to design, fabricate, and sort a new motorcycle design on an extremely tight schedule.

This about covers the backstory of how I got to be designing a bike like this. it's been a lot of fun so far and now that the engine is getting close to completion there will be some fruits of my labor I can actually show people. i'll continue on from here with posts documenting progress along the way.

There is one open issue with the Moto2 approach. The initial spec engine rule for the Moto2 class was 3 years long which ends in 2012. The members of the sanctioning body (Dorna/FIM/IRTA/MSMA) are now writing the Moto2 rulebook for the next 3 years from 2013 -2015. They want to open the engine spec up to allow more manufacturers to participate but preliminary tendencies are to limit engines to ones that use production crankcases as a basis. This would still exclude me as my engine cannot be considered a production design under their requirements. I was at the recent Indy GP and spoke with Dorna technical director Mike Webb and he encouraged me to write him with costing information of my current engine to show that a bespoke design does not necessarily mean extreme costs. With the extended global recession going on the rule makers are extremely concerned with keeping the costs of being competitive from ballooning out of control. I understand this concern but, as usual, the mechanisms that they wanted to put into place would only create the appearance of low cost. Any teams with more resources would be able to spend them developing a better engine. I am in communications with Mike hoping to indicate concrete ways to keep costs down without imposing a production engine base. These talks are still ongoing and I hope will bear fruit. If it does you can definitely expect to see the bike on a GP grid in 2013. If not you'll hear my scream around the world and then see me at local races wherever we are allowed to.

That's all for now.
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Old 09-22-2011, 05:22 PM   #95
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Great story man...unbelievable!

Can't wait for you to take us through the design/build!

Way to go Chris!


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Old 09-22-2011, 06:33 PM   #96
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Quote:
Originally Posted by thecosman View Post
... Progress was smooth until the unthinkable happened. At this point I'll leave you all hanging again, but tomorrow I will continue on. I'll also start to put up more pretty pictures as this narrative stage is getting a bit boring for me to type and I assume for you all to read.

See you tomorrow....
To play on a popular saying from the site - This thread is worthless without narrative!
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Old 09-23-2011, 09:52 AM   #97
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Quote:
Originally Posted by Lutz View Post
To play on a popular saying from the site - This thread is worthless without narrative!
I agree, i went threw a lot of pics on his blog, but its really cool to get the back story. I know I know i rarely read threads i just look at pics. but this is so cool.
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Old 09-26-2011, 08:12 PM   #98
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Now where to start?

Now that I was on my own as far as fitting into a rule structure goes it was time to start the process of figuring out where to put what. I had a pretty decently evolved rolling chassis CAD model from the original single cylinder project and needed to see how many changes would be required to adapt it or the V4. Since engine weight and power out wiull be drastically different even if the engine fits between the frame rails I can't expect that the chassis pivot points and behavior will want to be exactly the same.



The chassis design uses the same techniques as the 2nd and 3rd versions. I've developed a sort of design program inside my Pro-Engineer CAD software that can generate the pivot point locations given the values and variations of several inputs, such as center of gravity locations, brake dive, on-throttle squat, braking and acceleration load transfer, etc, etc, etc. Notice how I never mentioned such things as 'trail' or wheelbase'. Variables like trail and wheelbase are derived properties and are generated by a bunch of equations that govern the bike's dynamic behavior. Actually, the equations do not describe the bike's dynamic behavior but it's quasi-static behavior. Quasi static behavior is much simpler than dynamic behavior and I feel it is more relevant to the design process for a motorcycle as its parameters tell you how the motorcycle generally reacts to inputs. I'm not even sure that anyone is actually doing meaningful dynamic analysis of complete motorcycles as part of the design process. It is that complex and makes car simulation seem like child's play.

So what I do is set up these equations then use the CAD program to graphically evaluate them on an accurate skeleton model of a preliminary design. This is an important point in that you need to start the program with an initial desig or 'guess' to allow it to proceed. if you give it a crappy initial design there is no guarantee the program will end up with a good final design. As with eny expert system it is important to use the operator's experience as valuable input. After running several optimization routines the result is a lot of intersecting lines laid over a stick figure drawing of the bike. At this stage all that is important is the side profile and life is simple. Once the engine shape and configuration is finalized then this stick figure will be stretched into the 3rd dimensions and that's where all the work comes in.



It looks very confusing but embedded in the curves and where they cross is information on how the bike behaves to rider and road input. I've hidden a few important lines and shown a very early model as this is where a hell of a lot of thought and IP has been generated and I don't want to lay it all out for anyone to see. From certain of these intersections I can construct the front control arm and rear swingarm geometry. Presto, you have a bike! Well, not that fast. What I have are pivot locations that will (hopefully) provide the behavior that was provided as input.

After the engine width information is added there is a TON of details to work through to make sure that the pivot locations do not deflect under loading, that all pivots move with low friction, that the parts can be manufactured with a reasonable tolerance and cost, and above all to make sure everything fits and is not too heavy. I end up getting and reworking a lot of accessory supplies from racecar fabrication shops like The Chassis Shop and Pegasus Racing. The mindset for a motorcycle is completely different to a car. For a car guy space is not a driving issue and an extra ounce or 2 is usually acceptable. For a bike both of these are of utmost importance. A bike that is too long or too heavy will create a chain of additional compromises that will result in decreased performance. Considering that the podium is usually decided by 1-3 sec at the end of a 40 min race that means you need to be at 99.5% out of the box and soon at 99.9%. There's no room for error so if every part is custom, every part needs to be though about from end to end to make sure it is everything it needs to be and nothing more. Its a lot of work but when it all works out damn it is pleasing!


In the next post I'll go how I used a similar technique to design the engine.
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Old 09-26-2011, 11:38 PM   #99
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If you don't mind, could you explain a few of the curves and lines in the stick figure drawing. It doesn't have to be an overly detailed description and some of the lines (ie. wheels) are pretty intuitive. In particular, what do the two curves, the first moving upwards from the front wheel, and the second from the rear wheel to the handle bars, represent?
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Old 09-27-2011, 12:16 AM   #100
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I'd also be quite interested to hear about the idlers in the driveline. Are the primarily for packaging, or for...... [insert the patented Jeremy Clarkson dramatic pause here] something else? Are they fixed-position, or spring-loaded? Adjustable?
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Old 09-27-2011, 01:25 AM   #101
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Hey Chris - you were on Cafe Racer TV this week! Didn't they do something just on you as well?

Anyway, I'd like to know what the curves mean as well. Care to take us through some of what you're attempting to accomplish/discover/control? I gotta say this is one of the more interesting threads I've read - it gives a whole new perspective on what's going on next door.

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Old 09-27-2011, 01:37 AM   #102
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Originally Posted by Roadracer_Al View Post
I'd also be quite interested to hear about the idlers in the driveline. Are the primarily for packaging, or for...... [insert the patented Jeremy Clarkson dramatic pause here] something else? Are they fixed-position, or spring-loaded? Adjustable?
I'm interested about the idlers too.

I'm trying to design a dual sport bike and I'm woried about the pull from the counter sprocket causing to much squat on acceleration and anti squat on engine braking because my counter sprocket centre will be about 110mm away from my swing arm pivot (thats as close as I can get the swing arm to the engine)
Will some fixed idlers like you have be the answer to lessening that effect?

I also wanted to make the swing arm pivot height adjustable so I could tune the squat but I haven't come up with away of making it possible whilst keeping it strong enough.
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Old 09-27-2011, 10:17 AM   #103
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Originally Posted by DRjoe View Post
I'm interested about the idlers too.

I'm trying to design a dual sport bike and I'm woried about the pull from the counter sprocket causing to much squat on acceleration and anti squat on engine braking because my counter sprocket centre will be about 110mm away from my swing arm pivot (thats as close as I can get the swing arm to the engine)
Will some fixed idlers like you have be the answer to lessening that effect?

I also wanted to make the swing arm pivot height adjustable so I could tune the squat but I haven't come up with away of making it possible whilst keeping it strong enough.
I was curious about those idles too. They might work on a rear suspension with almost no travel but as shown they would increase the pull on the counter shaft assy. Horst Leitner came up with a design in the early 80's that isolated the affect of chain torque on the rear suspension but it didn't catch on. Here's a pic -
http://www.americandirtbike.com/Lickley2.jpg
It in affect moves the chains pivot point to the counter shaft sprocket seperating out it's influance on the suspension.
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Old 09-28-2011, 02:40 AM   #104
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I was curious about those idles too. They might work on a rear suspension with almost no travel but as shown they would increase the pull on the counter shaft assy. Horst Leitner came up with a design in the early 80's that isolated the affect of chain torque on the rear suspension but it didn't catch on. Here's a pic -
http://www.americandirtbike.com/Lickley2.jpg
It in affect moves the chains pivot point to the counter shaft sprocket seperating out it's influance on the suspension.

Interesting photo is the idea to lessen the pull on the swing arm by transferring the load to the swing arm itself whilst also keeping a constant chain tension?


I was thinking that if placed in the correct position you could use two idlers like thecosmans to virtually get the same results whilst
keeping bulk down and chain to sprocket contact good.
I'm sure you would still end up with a bit of chain slack somewhere in the stroke but a lot less than normal.


Sorry to clutter your great thread cosman.
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Old 09-29-2011, 02:02 PM   #105
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curves and lines

To start off, a lot of the analysis I've done has its basis in a series of books by Tony Foale named 'Motorcycle Chassis Design'. the first book was relatively slim and not as in-depth as later editions but it was enough to get me hooked.



Tony is a holdover from the heydays of the 60s and 70s where most of the performance motorcycles sold consisted of a good engine in a crap frame. By making better frames than the factories he made a good living while making motorcycles go faster, a feat rarely repeated in the following decades! He is a very down to earth guy that tries to scientifically examine the dynamic underpinnings of motorcycle behavior in a manner that those with a smattering of math and a good dollop of curiosity can understand. Even though I have an advanced mechanical engineering degree it is not always easy to go from the generic F=m*a equations to something that both is easy to solve and still have relevance to the topic under investigation. Tony's book helped me to understand what is important and why and to concentrate my analysis on that information.

That said, the line drawing you see is a mishmash of his graphical construction techniques and some equations of my own. The specifics of what is what and why are secret. Sorry about holding out but this is a lot of hard won information that is the intellectual basis of what I am basing my project around. Giving a clear description is basically giving away my IP.

What I can say is they are controlling are the 4 main ways the rider can load the suspension while the bike is nearly vertical: front brake dive, rear brake squat, on throttle squat, and off throttle rise. Thinking about it for a second you can see how these areas have the potential for the biggest positive or negative bike behavior. When a bike is leaned over on a corner all the hard work has already been done: slowing the bike down and getting it leaned over. Once you are leaned over and on your cornering line the suspension has little to do with how fast a bike goes. It is about subtle input on the steering and trying to keep throttle and braking inputs as neutral as possible. However braking/corner entry and on throttle corner exit behavior are all highly transient with changing rider input.

It is here where I concentrate my analysis, and not just at one point but through suspension travel. This is an important point. When you read a bike's specs in a magazine there is no information on how these are measured. Is rake and trail measured fully topped out or with bike or bike and rider weight? Wheelbase is calculated with what sprocket sizes? Same goes for the swingarm angle, where in the travel is it measured? So the important question is not what is the trail or wheelbase, but what is its value as the suspension travel varies. So I am sort of creating a 3D bike response map that describes to me how each aspect of the bike's behavior listed above varies as a function of front and rear suspension travel. I look at the resulting surface and see where and if I want to change it. This is the point where experience and good luck come in. You can use this technique to design a crappy bike or great bike.

Tony has since updated the book with another much more in-depth edition and my bike was lucky enough to be featured in a section discussing rear suspension squat control. That is the purpose of those 2 idlers on the chain run and I'll go into them in more detail and answer some of your questions in my next post.

Anyone interested in how bikes work is highly recommended to pick up a copy of the latest edition. To be clear, I have no financial interest in Tony selling books. I only want to spread the word on how people can get a better understanding of what happens with the two spinning wheels underneath us. The latest version is a much bigger book and includes more math (jt's not required to understand the how, only the results) and some computer simulations to verify his thought experiments.

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