Just a thought on the 2007 frame/handling


60 replies to this topic
  • bajamoto

Posted November 30, 2007 - 11:25 AM

#41

Dude, CAN YOU READ???

http://www.aluminum....&ContentID=7648


Honda CRF250R
Lest Yamaha garner all the credit for its aluminum motorcycle technologies, it should be noted that rival Honda has an equal appreciation of the metal’s design possibilities.

The company recently completed development of the fourth-generation aluminum frame on its acclaimed CRF250R motocross model. Almost a decade after the debut of the first aluminum CR frame, Honda engineers continue to marvel at the metal’s design versatility.

“Many riders seem to think that aluminum frames are bound to feel [stiff], but the CRF250R’s frame has been tuned to offer a very natural feeling,” head designer Eiji Adachi says. “By adding a bit of thickness here and trimming a little bit off there, we have balanced lightweight agility with frame rigidity. Aluminum has a lower specific gravity compared to steel, so these adjustments are easier to achieve than with comparable steel frames.”

One of the great advantages to working with aluminum, Honda notes, is that designers can add or take away material to add strength or flexibility in specific areas. In the case of the CRF250R, the main spars of its frames are rectangular in cross-section, which permitted Honda engineers more design latitude than that available to round-tube-steel fabricators. That allowed Honda designers to vary the thickness of the top and bottom sections of the box, vis-à-vis the sidewalls, simply by specifying a change in the extrusion dies. This helped make the frame members resistant to up-and-down flex while still allowing side-to-side resilience—both in precise increments.

Honda engineers also took advantage of aluminum’s “tunability” to incorporate into the frame a forged aluminum steering head. The most visible distinction of the new frame are the main spars connecting the steering head and the swingarm pivot. These lightweight aluminum extrusions are shorter, narrower, and feature thicker walls than Honda’s third-generation aluminum frame.

[COLOR="Red"]The upgrades to the frame change its “flex characteristics”[/COLOR] to create a chassis that feels softer on bump impact and improves cornering over previous designs, Honda says.

No doubt those are qualities that any enthusiast of motocross—where jumps of 100 feet and cornering at 40 mph are not uncommon—can appreciate
.

  • 917 rider

Posted November 30, 2007 - 12:04 PM

#42

okay so i read... :busted: 08 :busted: :ride: :lol: 06. :worthy: :goofy: :D Bubba, Ricky. :D :D :lol:

And do you have an 07? no you have an 06 and now an 08.

And what does your ramblings have to do with frame flex?

:cry: :cry: :lol: :lol:


you said the results speak for themself,he did not win those races cause he was on a 08 it was because the top riders was not there,i did not say you was right our wrong.you are just getting carried away,if the flex was differnt you would never no it none of us would ,the end result is a few changes to help the bike steer better and a verrrrrrrrrrry small amount of flex.i do have a 08, i said i have spent some time on a 06 and i buy a new bike every year which ever one i feel like.you talk big but i wonder do you spend most of your time reading what every body else thinks instead of getting on a bike and finding out for yourself ,if you read i just asked about early alm.frame hondas and nobody liked them cause they was to stiff then they fixed them by adding more flex?:lol: yourself, you brought up racing and the results.what does that have to do with frame flex smart guy, langstons results was the same just lesser riders.:thumbsup:

  • bajamoto

Posted November 30, 2007 - 12:14 PM

#43

you said the results speak for themself,he did not win those races cause he was on a 08 it was because the top riders was not there,i did not say you was right our wrong.you are just getting carried away,if the flex was differnt you would never no it none of us would ,the end result is a few changes to help the bike steer better and a verrrrrrrrrrry small amount of flex.i do have a 08, i said i have spent some time on a 06 and i buy a new bike every year which ever one i feel like.you talk big but i wonder do you spend most of your time reading what every body else thinks instead of getting on a bike and finding out for yourself ,if you read i just asked about early alm.frame hondas and nobody liked them cause they was to stiff then they fixed them by adding more flex?:busted: yourself, you brought up racing and the results.what does that have to do with frame flex smart guy, langstons results was the same just lesser riders.:thumbsup:


all right smart guy. go back and read the title of the thread. then read what this debate is about next time before you jump in with some random post that has nothing to do with the thread.

ironcally you are fighting with me but agreeing with my argument. I agree with your comments on the racing and Grant winning. If Ricky or Bubba were there he would have not won... But rider confidence is a huge part of racing. If you aren't happy with your bike then you wont win... Grant wasn't happy, he didn't like the 07, he said it himself. He loves the 08.

Bubba is a perfect example. Hated his bike, fired his Mech and crashed and burned when he had the Moto in the bag. Alessi too, hated his suspension so they grabbed the spring off their Euro bike and POW he was riding better then ever.

My point is that bike frames have flex, some are too stiff and others are too soft. You agree with me on that.

My other point now is that race results have everything to do with frame flex. Racer hates the bike performance = not comfertable on bike, factory makes changes, racer likes changes and is happy.

yamaha told grant they weren't going to mess with his 07 since the 08 was about to come out. and they told him the minor frame changes made on the 08 were address the frame flex issues he was describing to the mechanic.

Now i have a race on sunday so i need to go prep my 2007 YZF...

:busted:

  • tw557

Posted November 30, 2007 - 12:20 PM

#44

Dude, settle down. Maybe you read too much. Believe me, I do not believe everything I read. If I did then I would assume if my 06 is pointed at a tree when I take off there is no way to not hit it. I am keeping a bit of open mind to this situation but trying to understand the situation instead of just believing a marketing paragraph. I would like to see any info on how the flex works. If the frame does flex how does this actually help the turn? I have been a design engineer for years and the marketing people put so much fluff into statements its almost unethical at times. I had a design that had a bump in its motion ( bad design) marketing put a spin on it as a Anti premature closing device. All I'm saying is MY GUT FEEL is the spoke wheels and flexable tires will flex pretty darn far before the frame has enough force on it to flex. When I have straighten roadrace aluminum frames it took pretty much hydrauling force to bend most frames ESPECIALLY if the motor was installed. Let's face it, None of us KNOW FOR SURE what happens with the whole frame thing. Hell the manufactures don't know either. Does this mean yamaha has found the perfect flex now and they never will never do any more research. In a couple more years we will here "we improved on the frame flex for better handling" There is no doubt that flex effects handling but I mostly believe that too much is WAY more of a detriment the too much.
We don't have to get rammy about all this. I just like thinking about all the possiblities and come to some opinions on interesting stuff.

  • 917 rider

Posted November 30, 2007 - 12:22 PM

#45

bubbas mech. quit for another job where you racing at?langston said that to sell more blue bikes period

  • bajamoto

Posted November 30, 2007 - 12:24 PM

#46

bubbas mech. quit for another job where you racing at?



in the desert, so steering doesn't even matter, just power and stupidity which as you can see i have plenty of both.

and you don't just quit working for the best rider in the world for another job... little more to that story then a new job.

  • 917 rider

Posted November 30, 2007 - 12:29 PM

#47

well there best friends though and he went for more money and power on the new team.anyways have fun and good luck:ride:

  • bajamoto

Posted November 30, 2007 - 12:32 PM

#48

Dude, settle down. We don't have to get rammy about all this. I just like thinking about all the possiblities and come to some opinions on interesting stuff.


i have some time right now as you can see... sorry about the hyper posts, Raining in So Cal and had too much coffee...

and i actually work in marketing where i take tech jargin and rewrite it into marketable material on a daily basis.

i deal with flex of materials a great bit just not in Moto.

There is truth to everything i write and i am sure Yamaha is no different. The fact that they are admitting publically that the 07 didn't handle as well as the 08 is enough evidence to me that changes needed to be made.

the information you seek is probably top secret and not for the publics eyes. yamaha just came out with this frame and have many bugs to work out.

Honda is ahead of the game on the frame while Yamaha is ahead on the engine.

KTM is about to kick some serious butt, too bad their budgets keep them from getting the big name pros...

and Ricky wins on anything. too bad he retired but it's cool he did at the top.

In the end money wins you races. but sometimes bike design does too...

  • bajamoto

Posted November 30, 2007 - 12:35 PM

#49

well there best friends though and he went for more money and power on the new team.anyways have fun and good luck:ride:



thanks, sorry about the rude post. just got fired up on this thread.

and i think the point of it was lost long ago...

money sucks...

  • SoundChaser

Posted November 30, 2007 - 01:04 PM

#50

[quote name='grayracer513']I have done this on more than one motorcycle. 3 of the frame projects I undertook at the shop I was working at involved complete new road racing frames for 2 Kawasaki triples and one of the first of their 1000cc 4's.

Gray - Those Kawi Triples, now there was a monster of a bike. I had a `72
H2 and that thing screamed. :thumbsup: Wish I still had it !

...no back to your original programming.

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • grayracer513

Posted November 30, 2007 - 01:10 PM

#51

...changes were made. There are race proven results that show this.

...changes were made to the head tube area of the frame from 07 to 08 that allow the bike preform better in turns.

More than a dozen chassis related changes were made, but the one that makes it corner better is the change to the frame stiffness? Good logic.


The upgrades to the frame change its “flex characteristics”to create a chassis that ...improves cornering over previous designs, Honda says.


From what I have read the rigidity of the frame DOES impact cornering characteristics, it is not just the geometry of the frame. In a logical context it makes sense to me.

Again I simply ask for anyone to explain, "How?" No such explanation has yet been made. When you read it somewhere besides a brochure or a magazine article, and there is enough detail on the mechanism by which it has such an effect to make it more than a gratuitous assertion, please forward that here, so we can understand it.

I bet a little frame flex is help full when getting kicked sideways in woops and landing from jumps a little side ways. As I look at this logically though the thin spoked wheel has got to flex alot more then a frame. And first the tire will need to flex to almost pulled off the bead to flex the rim. The big problem with a flexing frame is it has no dampening effect. It is like a shock or fork with ONLY springs. The frame is just a big leaf spring with no dampening. So as it flexes one way it will try and flex itself back to the opposite side backand forth till it all energy is dispersed. ...

Someone gets it.

I don't understand why some of you people cant get this.Bajamoto has shown more than enough evidence to support that frame flex and how rigid a frame does affect how a motorcycle handles......

It certainly does. and most of its effect is negative unless very carefully controlled. Flex CAN make the bike FEEL softer, smoother running, and cover for shortcomings of inadequate suspension in terms of shock absobtion. What no one has explained one more time, is how allowing a frame to flex makes it CORNER better.

The discussion has gotten fairly well off track, and some of you are getting a little cranky. Let's go back for a second to the first post to see what the subject actually was:

the main handling difference between the ’07 and ’08 model is the amount of flex in the frame.

My response to that is that is simply untrue, and that if the '06/'07 frame were replaced by an '08 frame and clamp set, with no other changes to an '06/'07 the difference would go unnoticed by almost anyone riding the bike. That's what I said, and continue to say.

Feel free to have the last word, but if the discussion continues, it will need to stay civil and focused, or it will be closed. Deal?

  • bajamoto

Posted November 30, 2007 - 01:21 PM

#52

My apologies gray.

I think you were bringing other discussions from previous threads into this one. I was taking your 2nd response at a litteral value.

I can't prove to you anything. I am not and engineer. But i can show evidence from other similar applications of frame flex having positive and negitive effects on handling of any vehicle, Bikes, Cars, Motorcycles, Dirt Bikes.

My point is simply that Flex is there and plays an important role. Engineers try to eliminate it or add it to correct problems that adjustments to Suspension, Geometry, Ergonimics and other factors can't fix.

Of course a company like yamaha would much rather make a new clamp mold or redesign the suspension before touching the frame but sometimes things just don't work and more drastic measures need to be implemented. Like going back to the drawing board on Frame Design...

We have all made our points. we are all talking about our own thing. nothing is relevant and this debate is one that even top designers and engineers disagree on.

In conclusion, Gray, you know your stuff and i enjoy reading your posts and pretty surprised i was even able to come up with a argument agaisnt your theroy.

  • JohnnyOfast

Posted December 01, 2007 - 03:11 PM

#53

Again I simply ask for anyone to explain, "How?" No such explanation has yet been made. When you read it somewhere besides a brochure or a magazine article, and there is enough detail on the mechanism by which it has such an effect to make it more than a gratuitous assertion, please forward that here, so we can understand it.



Not that I claim to know the answer, but here's how I see it.

I never even entertained the possibility that frame rigidity effected cornering until MXA started spout'n about it. To me it makes sense cause when manufacturers were using steel frame's they had the geometry pretty much where it should be. When the transition to alum was made they carried over the same geometry #'s from the steel frame yet it didn't work the same, it pushed. Reason being steel flex's more than alum. Especially first year bikes where the manufacturer was worried that the alum frame would self destruct so they built 'em like bridge abutments. Honda learned it first cause they started with that god awful '97 frame that had no flex and was incredibly unforgiving. From what I understand the geometry was based on '93 CR geometry yet it still pushed. So through the years they have realized the frame needs to flex a certain amount and that has now been "fed into" the frame.

In support of my point I offer 2 examples:

1) the 1993 Honda CR250 was supposed to be one of the best cornering bikes ever and it had a steel frame that flexed like a noodle. The suspension was crap though cause of all that frame flex.
2) The '94 to '98 KX250 line of bikes didn't corner all that great but the suspension was awesome cause the frame was so boxy and rigid.

It seems somewhere in the good handling equation a certain amount of frame flex is neccessary. As to answer the question of how I think you would have to delve into metallurgy and the combination of different flexing members of the machine from tires, spokes, triple clamps, frame and swingarm and I don't know how you could quantify those properties. It would be very complex.

No disrespect intended, just debating what to me is a very interesting subject.

  • lightestYZF

Posted December 01, 2007 - 04:51 PM

#54

Both sides are right in this discussion. What needs to be understood is the difference between the types of flex. A lot of the "flex is bad" argument comes from flex related to the back wheel. Flex especially from engine power applied to the rear wheel makes a bike feel like it has hinge in the middle. Anyone old enough to have ridden a Suzuki TM400 Cyclone absolutely could attest to feeling that type of frame flex. The "flex is good" comes from when loading the front wheel while slightly leaned over. Even just a little movement (even thousands of an inch) side to side at the steering head get magnified at the front wheel. What does this do - it shifts the center of the wheel very slightly to the opposite side of turn. This causes a slight change in the acting center of gravity of the bike. The center of gravity shift is to the inside since wheel center went out so the bike "falls" into the turn more. So this type of flex does help turning. Is that good or bad - it depends on many other factors especially rider technique. So many people think the steering geometry (rake and trail ) decides how a bike handles but really you need to understand all the weight shifting that is going on. Like on the 2002 Honda CR450F every one said put 20mm clamps on to fix the handleing. That really added trail which should add stability but instead really made the front wheel shift out more in a turn so it fell in better and it also changed the weight bias of the bike to more on the front wheel so it got more front end traction. That brings me to the real handling issue with all the Yam 06-08 bikes which is mass centralization. Yam has centralized the weight which means less is transfered to the front in braking. So less traction on the front in normal braking. The rider has to compensate by being more active or really getting their foot out by the front axle. These type of riders have no problem with how the Yams handle. Also helps to shift weight of bike itself by moving the axle all the way back (something both Langston and Everts did).

  • grayracer513

Posted December 01, 2007 - 05:42 PM

#55

In support of my point I offer 2 examples:

Let me offer two more for consideration: The steel 2005 RM250, a notoriously good turning bike, and the aluminum 2006 RMZ450 another one. Figure that one out. :thumbsup:

As to answer the question of how I think you would have to delve into metallurgy and the combination of different flexing members of the machine from tires, spokes, triple clamps, frame and swingarm and I don't know how you could quantify those properties. It would be very complex.

No disrespect intended, just debating what to me is a very interesting subject.

And non to you, either, but for how, we need to see what flex is occurring, and what its affect on dynamic geometry is.

lightestYZF, you have arrived at a flawed conclusion with regard to side load of the fork in a turn. Any such load would not occur as a result of banking since that is canceled by centrifugal force so the the load is very near vertical.

  • lightestYZF

Posted December 01, 2007 - 05:59 PM

#56

Gray I actually proved this once accidentally using a 72 125CZ. The steering head nut came loose and most of the ball bearings came out of the top bearing so I had lots of steering head flex. The bike was turning great that day but making an alarming clunk of course when the front end unloaded, of course with a 125CZ even full power did not unload the front much :thumbsup: I fixed the steering head went out and no longer was able to get it to catch the same inside lines I had been using.

  • rr558

Posted December 08, 2007 - 04:20 PM

#57

Please post any quote you can find in which I said that.

What I have said repeatedly is that frame flex in a motorcycle is inherently a bad thing.


Go ride a 97 cr 250 and tell me frame flex is bad, that thing is so stiff its unridable. Honda has put more flex in every frame since.

  • hi everybody

Posted December 08, 2007 - 10:26 PM

#58

GUYS!!! I found a $20 solution that helps my 07 handle WAAAY better...at least to me...





more practice at hangtown:busted:

  • 917 rider

Posted December 09, 2007 - 05:55 AM

#59

Go ride a 97 cr 250 and tell me frame flex is bad, that thing is so stiff its unridable. Honda has put more flex in every frame since.


they were bad in the rough stuff and off jumps not in the turns imo

  • RCannon

Posted December 09, 2007 - 06:26 AM

#60

There was something interesting in a recent Dirt Rider article. They claimed to have updated their long term KX450 F, a 2006 model, but adding the spacers and longer bolts that the 07 came with. The 07 apparently has spacers and longer bolts in a lower motor mount that is supposed to allow more flex to happen...





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