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I’m surprised the factory level teams don’t have a frame dyno to break them in under controlled conditions
New Factory Edition comes pre broken in
I’m jealous you can buy 2 brand new bikes!!
For the average dude setting up your suspension right and maybe gearing is the single biggest improvement you can make.
This formula hasn’t changed since Adam was a boy and Eve was a twinkle in his eye..
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someone should probably tell these building engineers making these 100 foot skyscrapers that metal gets softer the more it flexes, some of those sway a few feet with the wind.
Bending a coat hanger back and forth just a bit does indeed make it weaker. Well, technically, fatigue damage builds up over time and it will eventually break.
If it's aluminum, it doesn't matter how little you bend it, it will eventually break. May take millions or hundreds of millions of bends back and forth, but it will.
Steel is more complicated. You would have to bend it to a point of stress beyond the endurance limit for the particular alloy, but if you did that, it would break just like the aluminum one eventually. But if you didn't stress it past the endurance limit (say just bend it a little bit back and forth), it would never break.
So you're not wrong in that respect, however, the strength/fatigue damage, etc. doesn't have any appreciable effect on the stiffness of the coat hanger. And that's what's important for feel. But in your clamp/swingarm/frame combo, you've also broken in bearings, bolt holes, etc. (everywhere where something else bolted on/joined up), which might make a difference.
I would never step foot in a 10 story building that sways a few feet in the wind lol
I meant 100 story
I agree with you on that for sure lol.
I'm an idiot and looked at the second photo and thought, awesome somebody did a different paintjob on their frame besides powdercoating it black.
I remember when everyone on Vital was a lawyer….now, everyone is an engineer. 😂
/s/ El Capitan, Esq.
I put on some smooth jazz and rub cocoa butter into my triple clamps for 35-45 minutes. If I don't then the bike is UNRIDEABLE.
On the point of material properties changing over time, steel can soften over time with fatigue without yielding, granted I don't know the chromoly used in mx frames but they could be susceptible to cyclical softening as well as hardening.
I would say that it would soften below an amount that most people would feel, especially when compared to the rest of the components working through their individual stressing and bedding processes, but the frame itself could gain different "feel" from localized increases and decreases in strength over time. https://fcp.mechse.illinois.edu/files/reports/FCP_Report009.pdf
Unless I'm missing something, I'm not seeing anything in that paper that suggest a change in modulus for pre-yield cyclic fatigue stress. Seems they're subjecting the specimen to a strain of about 0.13-0.40%, but the yield strain for 1018 steel is about 0.15%. I wouldn't be surprised at all to have the material's plastic modulus change in relation to fatigue damage level.
It is hard to tell as the data and plots are rather poorly presented, often without axis labels and multiple plots in a single graph without a y-axis... For example, figure 22 seems to show a slight decrease in modulus over time for cyclic fatigue at a near yield stress level (assuming the y-axis crosses where the plot crosses the x). But we don't see a significant change in modulus (slope) until 20k+ near yield cycles.
Regardless, we should be looking at pre-yield on anything relating to motocross frames and break-in/change in feel. Any portions of the frame that see stresses above yield will be really tiny relative to the rest of the frame, and largely out of the structural "feel" portion (should be localized to brackets, mounts, etc. and not on the down tubes or other major structural areas). If a large portion of the frame is seeing near yield stresses on a regular basis, then we've got bigger problems than break-in, we've just got break!
Hey, so I did some digging and emailing... This is what I got back from a company who does FEA and stress testing on mountain bikes, when asked if a frame will, "soften" or "break in" over time.
"No, the stiffness will not change from day one of riding a bike to day 200. It won't even change over a few years of riding. However, the welds will fatigue over time until cracking one day, but that has no relation to the stiffness or compliance of the bike. So no, there is no "break in" and the bike will feel the same until it breaks."
Sooooo, with that said, we can now say, "Let the bike parts break in 10 hours" :-). We are on the same page now that it's the bearings, bolts, pivot points that are "loosening up" which is making the bike feel "broken in"?
Link to video of Faction Bikes Studio doing a test, start @ 4:40
Well, if FEA was the determining factor of authority, you could have just listened to me all along!
I keep seeing the acronym FEA thrown around. Maybe this helps.
Finite Element Analysis is classic mechanical physics applied to a large number (finite) of individual elements. The force enters the closed system, acts upon it, then passes the results to the next element. Think about dividing a frame into 15-30 thousand tiny cubes. Finite element analysis is not telling anyone anything new, it was created as a way to analyze abnornal shapes. See above in the Luxon clamps. The squares you can see in the lower clamp are the elements.
I am quoting you not because I think you don't know but because you are the last to mention it.
Well, it's not just FEA, they do long term durability testing in machines. They put the product in machines and run frames through simulated years of riding in just a few days. I can't deny results. But does make me understand the other parts of the bike that are becoming more "free" feeling.
I will chose my words more wisely from now on about "break in". Hahaha!
Now we are getting somewhere 👍…. Next up: KTM”s fixed rear axle block vs Floating axle block kits… real or fiction?
Pit Row
My 24 450 felt pretty good at about five to six hours.
I'm an old fat vet rider, but I can feel the bike settle in to corners A LOT better after a bit of break in time - some of the KTM's reputation for harshness comes from suspension set up I think - IMO you have to throw away the proven settings from the older gen bike and start new.
I think MXA pulls some stuff out of their ass and make it sound like it is based on controlled, documented research when in reality it is a few people's opinion: Moisman , Stapleton and some REM regular amateur vet guys. They are good riders and pretty fast for locals, but I'm not taking their opinion as the last word on anything.
People usually believe you if you sound like you know what you are talking about - MXA has used this approach as their business model for years, and lot of riders are buying what they are selling, no questions asked because of the tone of authority that they use in their reviews.
The only person there with an advanced education that I know of is Weisel, and his PhD is in Gerontology (he can be the subject of his own Thesis now I think?) and for the most part I think they are backyard engineers, but the articles make it appear like they are ex-Nasa or something.
I have seen stuff posted to this board by members that somehow later shows up on their web site appearing as if they were the authors...
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On the flip side of KtM stiffness…. I have put over 100hrs on every late model KTM I have owned, pretty much all Mx and lots of whooped out sand tracks, with new plastics and a decent detailing, you would be hard pressed to guess the hrs on these bikes… they hold up and stay tight…
I have no dog in this fight but after reading through this thread I saw the press release from KTM about the 2024.5 450sxf factory addition. They make it sound like they’ve changed the frame to allow for more “flex”. Misinformation/ fake news?? I’m far from an engineer or metallurgist so I have to take the word of the folks that are in the know and this just muddied the water for me. As I’m in the camp that the entire bike “breaks-in” not the frame itself. 🤷🏻♂️
450SXF
factory editions have officially been released with updated chromoly steel frames. The frame has varied wall thicknesses and cutaway sections (as pictured ei) to increase flex and reduce weight. The shock has new low-friction linkage seals and the linkage ratio has new settings with a smaller
linkage bolt to also improve flex.
Why is everyone trippin about the word flex. The new KTM is designed to feel less shitty on a rough track vs. the old frame.
You're spot on. Materials flex. Frames are designed to withstand the force of the loads the rider is applying and not yield/stretch/break. Think about standing on a 2x4 vs a 2x6. They might both hold you just fine but the 2x6 is going to be stiffer.
Just paypal me the money instead and I can write you an encouraging email. That's about how effective that 'mod' is.
Dont let it muddy the waters for you, they can build a frame to flex a certain way from new but the argument here is it doesnt flex more or less the more its used.
They cut huge holes in the upper engine mounts on the 24.5 KTM too. There is also a pretty decent sized hole right in front of where the upper shock mount bolt is that used to be solid. You cannot see it in the picture above but you can in the powder coat frame pics earlier in the thread. If you want bare frame pics of the 2023 frame there are frames for sale on ebay with extensive pictures so you can compare to the new frame. I am curious what the smaller diameter linkage bolts will do. Things like that and the upper engine mounts will probably fit on the 2023-24 frames.
Im dumb as well lol
I think what we’ve learned from this thread is that Flex is OK and it’s not a problem for them to build that into the design of the frame. What I’ve learned is that even though the bike flexes over hours of use, it will still keep it same character from day one today 200 or day 1000 until a weld might break or crack.
Or a Doctor.
I'm not sure about frame stiffness, I think most actually get it backwards like the Honda CRF frame being super flexible and Kawasaki/Yamaha actually having stiff frames, but I'll argue about the tire pressure. I can tell a difference of several psi in my tires.
Post a reply to: Paging Keefer, or ML. KTM race team question