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Joko
8/25/2016 7:02pm
8/25/2016 7:02pm
After listening to the 8/23/16 Pulpmx show when Steve M talked about how their steel YZ250's frame would stretch 1/4" after its first time out, and JT saying it was be a noticeable change in handling, and the new KTM steel frames are changed 5x a season at the pro level makes me wonder if this is a real problem when considering owning a KTM for an extended length of time? I also recall reading RC would go through KX250 frames on a monthly basis. Is the stretch dimension realized from the centerline of the steering head to the centerline of the swingarm pivot? Can it be repaired or reinforced to prevent stretch? Most of us probably couldn't stretch a frame in a season, but maybe after 3+ seasons of use? What is the noticeable change in handling on a stretched frame ... Does it gets too raked out and doesn't turn as sharp?
Josh
The Shop
http://motocrossactionmag.com/home-page/bones-bacon-on-suspension-where…
Cause i had factory rider speed.
Nutjob!
Pit Row
Metal flexes, and keeping a track of it is it pretty hard , I know when I have scanned bikes in the past , getting good numbers is hard work. Measuring a bare frame is easy , you just need a point of reference that isn't going anywhere, and on a dirt bike , that is hard to do.
The way you measure it can make a huge difference to the perceived results as well
1/4 a degree of movement in the frame is nothing , but measure that at the end of the forks and its huge almost 5mm over 1.2metres.
that equates to 0.3mm movement in the headstock.
Road race boys here in stock classes get frames pulled to the steepest allowable angle ( think the tolerance is half a degree) to help them turn.
I just know people who do the same and think the frame has gone that much LOL.
We sold adjustable clamps here in the UK to pull in the head angle to get race geometry out of road frames, we built a bike for a guy , he built his van to take the bike, then bought a second bike and fitted his own clamps, couldnt understand why it was shit.. i asked him to bring them both over , the fact that the second bike didnt fit in his van wasnt enough to tip him off that the inserts were in backwards.
I measure for a living , and its easy to get weird numbers if you dont get everything right.
Anything that's being hammered, fatigues.
It's wise to retire things, before they fail.
And everything , can, and will fail when taken past it's limits. Nothing lasts forever.
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