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Only $10 for all 2026 SX, MX, and SMX series.
There is only compromise.
Think she's not so rigid or are her ultimate fatigue numbers pretty high?
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I have no idea about the FEA numbers, Pursang (www.pursangmotors.blogspot.com) have made their own aluminium frame. I would love to have their information and reference numbers for frame design.
Al elasticity is next to nothing compared to steel You cannot buy an Al shock spring, but you can get a Ti spring.
This argument came up back 10 years ago. My guess is that Al alloys with high levels of elasticity have high material cost and/or are difficult to form and weld.
Of course no one seems to give a hoot about $10,000 dirt bikes now.
I wonder how much this is mental, I assume a good rider can feel the difference, but I wonder if that extra rigidness really takes it's toll in some way? I was thinking using more flex in forks might give back the loss in frame, and be happy with 10 lbs less which might be a factor in many areas?
But, I know shit.
Huge difference in how they handled and the fatigue I felt after a long moto. I have chronic shoulder problems and truly believe I can ride a steel framed KTM longer and harder than any current Al framed bike due to the increased flex.
In regards to maintenance I'd much rather have an aluminum frame. Nice to be able to just Scothbrite it and look as good as new again.
Now for what I am pretty sure is actually going on with aluminum frames:
Aluminum "feels" rigid because it responds very violently to violent input. Aluminum does not have a very well damped response while relaxing from a situation in which it flexes from a load. The resulting response is vibration that is perceived as harshness by the rider. This phenomenon is not unknown to the automotive and bicycles worlds. Noise, vibration, and harshness engineering is a huge topic in the automotive environment as we realize how important it is to control system response as a method with which to achieve perceived comfort from the occupants of a vehicle.
An aluminum baseball bat is a wonderful example. Take two bats, same strength. One is aluminum, one is aluminum filled with a damping material. Which one feels crappy, which one feels better? The crappy one feels stiff, as if the force of the ball is being transmitted to your hands. The damped one feels softer and more controlled. The difference here is that the undamped bat responds to input in a much more violent manner which the body perceives as harshness. Slow down, control, or even eliminate this response, and the system feels much better.
It could be theorized from this that an infinitely stiff aluminum frame would feel great since it cannot flex and therefore cannot respond. As stiffness increases, the frequency/magnitude of the response can become more "harsh" in perception. Since infinite stiffness is not practical, the solution is to damp the material with some other material
Steel is far more damped when relaxing from high loads. Titanium is very well damped, and carbon fiber is extremely well damped by virtue of its non-homogeneous build-up. This is well documented in the bicycle world. There are light years ahead of motorcycles in their knowledge and ability to tune a machine through frame geometry and material.
Strength is not really the issue here, flex is not directly the issue here; the issue, in my opinion, is the response of the chassis material to loading. Aluminum responds very poorly.
Base frame concept is Already used by sidecar racing, the only thing holding me back is current economy
for me the only reason to buy a new bike is because frames bent (Never buy an ex prof bike) can't have enough frames lol
http://www.flickr.com/photos/90359349@N00/2809832932/sizes/l/in/photost…
Pit Row
they dont have the sss spec stuff but a lot better than the early models.....and after riding the steel vs the af 125 back to back in practice sessions the head angle seemed a lot different
i'll have to go for STEEL everytime, i'm riding an 04 yz125 and 250 ive tried later models and every manufacturer but i dont like the added vibration of the alu frame and i find they do break loose easier on turn in and under load....and i can't get on with the 4pigs even though i am probably going faster i get bored and loose the will to ride.....+ the thought if it does go bang is too much for me
did anyone have the misfortune to have a 98cr125? man that thing handled so badly... way rigid after riding an 07 which was an awesome bike i couldn't believe how badly they f'd it up lol
Deltabox is a Road (Race) frame !
Someone else has already said that they feel the AF YZ's were the best after having several. I personally feel the '04's were the best, not because of the steel frame so much, but because I feel the stock suspension set up was so good that it's the only bike I felt I could race without needing a revalve. I still have my '02 Yz's and they work great, but after getting the right suspension set up, all my YZ-F's and CRF's have felt just as good. Most people would call me crazy, but my '03 YZ450 is still on of my favorite bikes.
i think i'm going to stick with my steal arsenal for now .... never felt any extra benefit from an af model and even the kx with its steel perimeter frame is better IMHO
My first bike was a '98 RM125. I only ever rode the sand in it, but I (as well as my uncle who's been riding for years) thought it was a phenomenally turning bike. Had a nice plush softness to it.
My next bike was an '04 YZ250F. I pretty much hated this thing. Not sure if it was the suspension, the frame, the motor, or the carb tubing, but it was just not a good feeling bike. Didn't turn well, and it would swap anytime I came up short on a jump.
Then I went to the '06 YZ250F and liked that a helluva lot better. Turned better and tracked straighter.
My '09 YZ250 was still pretty solid, but I felt this bike was too rigid and didn't turn all that well. Coulda been tire choice, but stock suspension on that bike never really made me feel like I could point and shoot for my skill level.
My '04 CR250 turns amazingly and tracks real well, for the most part. Probably my favorite handling bike on the list.
Point being, I've rode a few of each, and I think there's too many other variables at play to give a real good assessment.
Still, that might just be a geometry thing. I don't think I'm fast enough to notice a difference between the two materials
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