HEADS UP!!!

Site upgrade in progress... Core site functions are working, but some non-critical features/functions will be temporarily unavailable while we work to restore them over the next couple of weeks.

Please post any bugs you encounter, but before you do, check to see if it's already listed.

Thanks for your patience while we work to improve the community.

Sign in to follow this  
Followers 0
Ice67

Just a thought on the 2007 frame/handling

61 posts in this topic

From what I have read, the main handling difference between the ’07 and ’08 model is the amount of flex in the frame. For ’08 the KX450F has a spacer and longer bolts on the front engine mount to add flex. Would this work to help the ’07 Yamaha handling?

Share this post


Link to post
Share on other sites

Here are a couple quotes from Grant Langston on the MXA website.

MXA: What was it in your program that seemed to turn your season around this year?

GL: “The new frame on my bike. People thought I must’ve been training harder, but in fact I think I did less. When I was struggling like I was earlier in the year, that’s actually when I was training harder because I was trying to compensate for not doing as well.

MXA: How did the frame change things for you and will there be any changes in your bike for 2008?

GL: The frame had more flex in the front end and I put a lot of emphasis on the front wheel so everything improved from that. The biggest change for next year will be the # 1 plate on the front of the bike.

Share this post


Link to post
Share on other sites

In Dec. TWMOTO he says the same thing. He struggled with the 07 from the start. and the mods the factory made that he liked were not legal. Chad Reed who rides with his weight back more didn't have the same problem whith the bike. Couldn't understand why Grant didn't like it.

Then the 08 came out... Grant loved it, and major changes were in the frame flex and the front end.

It depends on how you ride. I ride weight forward and am having a terrible time getting my bike (07 450) to perform right. Rode a 08 KTM SX and loved it.

Working on how i ride and trying to get my weight back since buying another bike isn't in the cards.

Share this post


Link to post
Share on other sites

grayracer,from the comments you seem to continually make about the differences between the 08 and 07, you must know something that everyone else doesnt know.Form what I have heard and read is that yamaha redesigned the frame to feed more flex into the head tube area,the steerer tube was shortened by 5mm to lessen the span between the bearings and triple clamps.The ribbed gusseting (inside the frames down tubes)was reduced in height to take some stiffness out of the chassis.This is a direct quote from mxa mag. You seem to think they only did an offset change.Since you seem to know it all explain how the changes in the frame are not going to be an improvement in handling.

Share this post


Link to post
Share on other sites
My, but we have a combative attitude this evening, don't we?

http://www.thumpertalk.com/forum/showthread.php?p=5523758#post5523758

it is fair to note, regardless of the agro nature of the post from edge, different strokes for different folks.

I am one of those that notices every little vibration, noise, mis alignment, etc.

I am a very picky rider. If my front end is just 1 degree off i go nuts, bars just slightly bent my whole day is ruined. This is a very exspensive problem.

:thumbsup::busted:

If you can ride with your weight back the rush from the power of the YZ is unmatched and provides for much more YAHHHHOOOOO!! factor then a Honda. But that is just my 2 cents...

Share this post


Link to post
Share on other sites

grayracer,

That's also incorrect in my opinion. The frames were made less rigid because they were stronger than they needed to be, and that allowed them to be strategically lightened without giving up adequate strength or suspension control.

In my opinion you are wrong.I dont see yamaha reducing the amount of material being used at the head tube and frame tubes to just reduce weight.All you have to do is look at the first honda aluminum frames to to see what Im taking about.Look how bad the early hondas with the overly rigid frames handled.Yes,you are correct about how an overly rigid frame will affect suspension,but a overly stiff frame will also affect handling without a doubt..I believe yamaha is trying to improve the handling of their 450 by making frame changes,but Im getting to many conficting reports to believe it has helped.I would love to stick with yamaha,but I did not care for the way my 07 yz450 handled,and if the 08 handles the same I will not be buying an 08yz450.

Share this post


Link to post
Share on other sites

You're entitled to your opinion, but if you are saying that there were no geometry changes to the Honda chassis you mentioned, then you're wrong about that as well. If you believe that frame flex contributes favorably to handling in any way, perhaps you can explain how.

Share this post


Link to post
Share on other sites

A quote from the Kawasaki web site:

Frame

New engine mounts moved 10mm farther from the engine for a slight decrease in torsional frame rigidity to quicken turning and increase rear wheel traction.

In the latest Dirt Rider, they upgrade a ’07 KXF 450 with the ‘08 motor mounts and say it is an improvement. I am not an engineer, but I think there something about the increased flex that helps the handling.

Gray, I am not trying to say you’re wrong. I brought up this topic because I have issues with the ’06, ’07 handling, but I would like to get a leftover ’07 if I can solve the problems. I rode YZF’s from 1998 to 2005. I like the Yamaha brand.

I hope this topic stays on point.

Share this post


Link to post
Share on other sites

I'm not saying that it doesn't help, either, only that the geometry change is more significant, and that any change a difference in frame flex would make is going to be very subtle, if the additional flex is not so great that it causes problems.

Quite often, the belief by a test rider that a modification should improve handling will influence the results of a test. I wonder if a group riding the two Kawasakis in a blind test would single out the more flexible one as handling better?

Share this post


Link to post
Share on other sites

I have "heard" alot about this and gray shot me down awhile back also on this. Here is what I do know for a fact go ride a 06 or 07 with 24mm clamps. Then go ride an 08 same deal basically right WRONGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGG.

Something changed My bro and law has 3 sets of clamps for his 07 and my 08 is on rails compared thats why his is for sale now. Something changed gray, I want to know what it is:excuseme:

Share this post


Link to post
Share on other sites

OK, look. I have given a reasoned explanation of how frame flex is non-conducive to good handling character. What I want to hear from anyone who can provide it, is the same kind of rational fact-based analysis explaining specifically how allowing the frame to flex in any particular way improves handling. Once I see that, we can have a discussion about it that gets somewhere. Until then, there are only assertions that it helps.

The fact that A was done, and now condition B exists does not logically show that A caused B, particularly when so many other things were done simultaneously with A. :thumbsup:

Share this post


Link to post
Share on other sites

Grayrecers response:

BUT, you can only allow a little before the wheels start steering themselves. If you've ever ridden some of the early Japanese road rockets at speed in a wavy corner, you know what that can be like. Any improvement to handling in an MX bike from adding in flex will be very, very subtle, and totally unnoticeable to most riders

This is the part that has me intrigued. Is this self steering what some like? I have an 06 with just no complaints at all. Just amazing how many 06 reviews it either won or got glowing remarks about it. And no way shape or form do I believe in the night and day difference to an 08. I just do wonder if there is a flex that can happen to NOT keep the wheels in line and let the rear sort of come around a little. Sort of like a car with soft sidewall tires on the rear that lets the car tail steer alittle. But on the other hand, do we really run these bikes into a turn hard enough to make it flex. I'm thinking a bunch of people on here complain about the steering at pretty slow speeds anyway. I would think you need A class , berm pounding speed to get things to flex. I just love my 06 with and without 24mm offsets and I almost hate to check this forum out. Makes me think I should just sell for scrap price. I do wish I had the chance to ride the new bikes though.

Share this post


Link to post
Share on other sites
OK, look. I have given a reasoned explanation of how frame flex is non-conducive to good handling character. What I want to hear from anyone who can provide it, is the same kind of rational fact-based analysis explaining specifically how allowing the frame to flex in any particular way improves handling. Once I see that, we can have a discussion about it that gets somewhere. Until then, there are only assertions that it helps.

The fact that A was done, and now condition B exists does not logically show that A caused B, particularly when so many other things were done simultaneously with A. :thumbsup:

Thats why I ask Gray :busted: because i dont know how a dog barks much less a bike handles. But the 08 does handle good. I love you gray

Share this post


Link to post
Share on other sites
OK, look. I have given a reasoned explanation of how frame flex is non-conducive to good handling character. What I want to hear from anyone who can provide it, is the same kind of rational fact-based analysis explaining specifically how allowing the frame to flex in any particular way improves handling. Once I see that, we can have a discussion about it that gets somewhere. Until then, there are only assertions that it helps.

The fact that A was done, and now condition B exists does not logically show that A caused B, particularly when so many other things were done simultaneously with A. :thumbsup:

from what i understand...

allowing a the frame to flex in a particular way allows the rider to drive harder forward into a turn with their body weight. The increased flex will absorb the weight transfer of the rider and keep the bike for reacting as dramatically. thus improving the turning capabilities for that particular rider.

It has been mentioned that Chad Reed had NO PROBLEM with the 07 or the 08. It was Grant who had the problem. back to the different strokes for different folks. Chad rides weight back, Grant rides weight forward.

Stiff frames are more responsive and less forgiving and require more precise reactions from the rider. Soft frames are more forgiving and allow a rider to be more sloppy in their riding style.

To say that a softer or stiffer frame doesn't affect handling would be ignoring the basic principles of suspension... softer = loose, harder = stiff...

It all adds up. If you don't agree then fine, your choice. But i assure you that changes in the charactoristics of frame flex affect performance of the bike. Whether it is positive or negitive depends on the riders style and their sensitivity and overall bike awareness.

Share this post


Link to post
Share on other sites

Once again, you have listed a set of attributes that belong to the suspension components, not the frame.

Weight transfer entering corners is handled by the suspension. The forks may dive as much as 7-8" (from the top) during this maneuver. How much do you think the frame moves?

The earlier Kawasaki example is instructive because, finally, there was a small bit of specificity in it; they said they wanted torsional flex. This means that the entire chassis was more easily twisted lengthwise so that the front and rear wheels are out of line with each other on in two different, skewed vertical planes. As I said earlier on, allowing some degree of this could prove useful in MX when the bike slides into an obstacle, or lands sideways, by absorbing some of the shock of such an event. The suspension has no ability to do this, since it moves only through the vertical. However, the designer must avoid allowing the wheels to be deflected from their assigned longitudinal (lengthwise) planes even while letting it twist. Failing in that leads to the self steering I spoke of before.

Because a motorcycle is a bank-to-turn chassis, it is loaded primarily on the vertical at all times, unlike a car. Lateral loads tend to be incidental. A frame too willing to respond to them can be quite thrilling if they occur at speed, believe me.

tw557's comments regarding the ability of most people to bring a frame to flex are worth thinking about.

Other that the conjecture I offered above, and the repetition of what "they say", I still see nothing definitive explaining the benefits of a flexing frame.

Share this post


Link to post
Share on other sites

Another thought on frame flex. If i planned to do a frame flex measurment that duplicated real life action I would mount the rear tire top and bottom and pull on the bottom of the front. Since I didn't actually do this I can only assume the outcome, but I bet the tires and wheels themselves would flex pretty darn far before the frame would move measurably. And like Gray said almost all the force is vertical into the frame not torsional. And I really have trouble believing the frame flexes fore to aft while the front suspension is not fully bottomed. I bet without a motor mounted in the frame you could see some flex but mounting the motor has got to really make the frame ridgid. Let 2 lbs of air out of your tires will cause more flex then the frame can do.

If you read Yamaha also claims to change bottom triple clamp strength to help with flex. lower forged triple steering clamp is lighter—for enhanced handling feel.So to keep the theory of believing everything yamaha claims, everyone should talk about that. And I REALLY doubt us guys will ever feel that change.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
Sign in to follow this  
Followers 0