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2389
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11/9/2011
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Denver Metro, CO
US
Edited Date/Time
5/19/2022 7:01am
I am passively looking for KTM 350SX-F and 450SX-F bikes.
I am committed to *trying* the orange Kool-Aid later this year, but have been hearing a lot about the frames "stretching" lately (biased by a pro mechanic I talked to who brought it up + listening to Keefer podcasts --- which I love, BTW).
So, if I were to buy a ***USED*** 2019+ KTM350/450SX-F, what's the max number of hours I should entertain given the apparent frame-stretching nature of these bikes?
Also, what's a real-world number of hours I can expect to replace the frame, in general?
I'm a Vet B/C rider, so under my use/stress it seems I'd be able to ride a frame a looooong time (100, 150, 200+ hours?), but I have no idea.
I'd love to hear hear thoughts from all you guys "in the know!"
I am committed to *trying* the orange Kool-Aid later this year, but have been hearing a lot about the frames "stretching" lately (biased by a pro mechanic I talked to who brought it up + listening to Keefer podcasts --- which I love, BTW).
So, if I were to buy a ***USED*** 2019+ KTM350/450SX-F, what's the max number of hours I should entertain given the apparent frame-stretching nature of these bikes?
Also, what's a real-world number of hours I can expect to replace the frame, in general?
I'm a Vet B/C rider, so under my use/stress it seems I'd be able to ride a frame a looooong time (100, 150, 200+ hours?), but I have no idea.
I'd love to hear hear thoughts from all you guys "in the know!"
For anyone who is going to opine about 3-4 yr old KTM steel frames stretching.. also tell us what you think about guys with their 25 yr old steel frame 2-stroke builds!
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Please weigh-in with your thoughts on handling changes vs. time & recommended frame-replacement intervals.
As I understand it, too, you're a KTM guy --- so any frame-related advice you have in assessing a used KTM is greatly appreciated (it seems I may have to buy used given I can't find new currently).
I don't doubt that there are some small high stress spots on the frame that locally yield and stay that way, but it would happen rather quickly (first few rides) and wouldn't amount to much of anything as far as noticeable "stretch". So we can pretty much ignore that as it's always going to be there and almost not worth mentioning (same goes for an aluminum frame).
But a frame "stretching" over time means it continuously is yielding a little more every time it is ridden. I really doubt that is happening and that would rather quickly lead to a big failure. Various people say it is, though, which makes me wonder how they know. Are they measuring it? How and where are they measuring?
There are A LOT of other variables that can change to throw off what they might be measuring. I've heard of an axle to axle measurement from one person. It's easy to mistake a change there for the frame stretching when in reality it's just inconsistency in measuring (different shock settings, different fork heights, chain stretch (not really stretch, it's actually wear!) causing the wheel to have been moved back, bearing slop, bushing wear, etc. They must have measured that when the bike was fairly new and compared that months (years?) later and determined the frame stretched. But how much also changed during that time that may actually be the cause of the different measurements?
It also seems to be a steel frame only thing for some reason. But aluminum can yield too, so it's odd that you don't hear about frame stretch on an aluminum framed bike...
So in other words, I don't think it's really happening to any appreciable extent. The only ones who would really know would be KTM (not the race team, the manufacturer) as I doubt anyone else has properly measured it. It would take a fairly serious effort to measure any difference (raw frame on a CMM or similar), not just a tape measure.
Anyway, when looking over a used bike, be sure to look closely at the frame in the high stress areas - head tube welds, etc. Cracked paint/powdercoat is a bad sign and indicates a failure.
When Keefer and others refer to KTM frame breaking in and then later losing some of their desired handling characteristics/specialness, what do you attribute this to?
A fresh bike is what many would think of a good bike. But just because it's broken in doesn't mean it got worse; I'd argue that it got better and more consistent. Of course as it goes from "broken in" to "worn out" it's going to get worse.
The first few hours is so bad, to the extent i want to hand the bike back. Specially riding my previous bike (have dual of everything).
So something is settling 😄
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