New Frames?

TSCHAM101
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TSCHAM101
This may be a weird question...

Bowers recently acquired 2 new 450's for outdoors even though his bikes were brand new for supercross.

Why do pro's need new frames after maybe 20 hours of riding them??

What wears out on them?
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Honda Man 66 5/8/2019 7:50am
5/8/2019 7:50am
They stretch. I know a fast A rider who back in the day would measure the distance between the swing arm pivot and the front axle on his bikes when they were new, and compare it to the measurement after a year. It would be an inch longer.
#434
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#434 5/8/2019 7:55am
5/8/2019 7:55am
Honda Man 66 wrote:
They stretch. I know a fast A rider who back in the day would measure the distance between the swing arm pivot and the front axle...
They stretch. I know a fast A rider who back in the day would measure the distance between the swing arm pivot and the front axle on his bikes when they were new, and compare it to the measurement after a year. It would be an inch longer.
Was your buddy an A rider in the 80s?
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TSCHAM101
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TSCHAM101 5/8/2019 8:20am
5/8/2019 8:20am
Honda Man 66 wrote:
They stretch. I know a fast A rider who back in the day would measure the distance between the swing arm pivot and the front axle...
They stretch. I know a fast A rider who back in the day would measure the distance between the swing arm pivot and the front axle on his bikes when they were new, and compare it to the measurement after a year. It would be an inch longer.
Does that inch make a world of difference to the top pro's?? Couldnt they make up the difference by sucking up the rear axle slack? (for us budget guys)

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yz133rider
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yz133rider 5/8/2019 8:32am
5/8/2019 8:32am
Honda Man 66 wrote:
They stretch. I know a fast A rider who back in the day would measure the distance between the swing arm pivot and the front axle...
They stretch. I know a fast A rider who back in the day would measure the distance between the swing arm pivot and the front axle on his bikes when they were new, and compare it to the measurement after a year. It would be an inch longer.
TSCHAM101 wrote:
Does that inch make a world of difference to the top pro's?? Couldnt they make up the difference by sucking up the rear axle slack? (for...
Does that inch make a world of difference to the top pro's?? Couldnt they make up the difference by sucking up the rear axle slack? (for us budget guys)
Its going to have more flex also once stretched and worn...and what if your already all the way forward in the axle for handling...now what.
alien
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alien 5/8/2019 8:36am
5/8/2019 8:36am
1/8th of an inch in frame stretch is huge, it's not the wheel base that changes but the head angle. Steel frames were bad about stretching in just a few hours of SX practice and racing. When the front end starts pushing in turns when it didn't before it was time for a new frame if you wanted the bike to handle like it did when it was new.
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TSCHAM101
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TSCHAM101 5/8/2019 9:03am
5/8/2019 9:03am
alien wrote:
1/8th of an inch in frame stretch is huge, it's not the wheel base that changes but the head angle. Steel frames were bad about stretching...
1/8th of an inch in frame stretch is huge, it's not the wheel base that changes but the head angle. Steel frames were bad about stretching in just a few hours of SX practice and racing. When the front end starts pushing in turns when it didn't before it was time for a new frame if you wanted the bike to handle like it did when it was new.
Is there a way to order a new frame? Or do you need to buy new bikes?

Is that why all the top amatuers also buy new bikes every season?
Muscle-Milk-KTM 5/8/2019 9:16am
5/8/2019 9:16am
alien wrote:
1/8th of an inch in frame stretch is huge, it's not the wheel base that changes but the head angle. Steel frames were bad about stretching...
1/8th of an inch in frame stretch is huge, it's not the wheel base that changes but the head angle. Steel frames were bad about stretching in just a few hours of SX practice and racing. When the front end starts pushing in turns when it didn't before it was time for a new frame if you wanted the bike to handle like it did when it was new.
TSCHAM101 wrote:
Is there a way to order a new frame? Or do you need to buy new bikes? Is that why all the top amatuers also buy...
Is there a way to order a new frame? Or do you need to buy new bikes?

Is that why all the top amatuers also buy new bikes every season?
You can buy a new frame like any other part, might be on back order for a couple of weeks.

TSCHAM101
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TSCHAM101 5/8/2019 10:18am
5/8/2019 10:18am
Do average joes ever do this? or only top amateurs and pros?
rob162
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rob162 5/8/2019 11:03am
5/8/2019 11:03am Edited Date/Time 5/8/2019 11:34am
Buy a new frame and swingarm. After you put about 60-70 hrs on your bike give or take on your riding abiltys. Now only switch the new frame and arm over. Don't do anything else. No new tires, tru wheels, rebuild suspension. Nothing! It will feel like a whole different bike. Now add all new bearings and frame mounts and oh boy. Axles do wear out to. Not often but they do streach and fatigue also.

This is why it's so hard to do great resto's on old bikes. Even a bike as new as a 2010 will almost never feel exactly like a new bike no matter what you do.
Honda Man 66 5/8/2019 11:11am
5/8/2019 11:11am
Honda Man 66 wrote:
They stretch. I know a fast A rider who back in the day would measure the distance between the swing arm pivot and the front axle...
They stretch. I know a fast A rider who back in the day would measure the distance between the swing arm pivot and the front axle on his bikes when they were new, and compare it to the measurement after a year. It would be an inch longer.
#434 wrote:
Was your buddy an A rider in the 80s?
This was around 2000. He was referencing steel frame bikes. He rode two different brands.
cwtoyota
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cwtoyota 5/8/2019 11:19am
5/8/2019 11:19am
TSCHAM101 wrote:
Do average joes ever do this? or only top amateurs and pros?
Not so much with modern aluminum frames, but back in the day the regular Joe probably didn't know it was happening slowly over time.

It wasn't uncommon for professonal race bikes to have little tabs and gussets added into the frames back in those days.

My first full sized bike was a 1989 RM250 and I was a beginner class kid.
After a few years owning that bike, I noticed it was getting harder and harder to put the upper engine mount on because the bolts didn't line up so well anymore. A little farther down the line and the back of the cylinder was cracking because the frame was flexing enough to pull on it. I stripped it down to the frame, pulled it back into shape and welded a bunch of little tabs in to gusset the frame. Then I had an old-timer buddy weld up the small crack in the transfer ports on the aluminum cylinder.


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