OP
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Enthusiast
skipper st125
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Location: York,uk
 
Enthusiast
skipper st125
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Location: York,uk
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I have a p200e frame I have been working on.
It has a brace welded between the headstock and frame.
I have welded new legshields to the frame tube.
I have cut the frame brace.

If i pull really hard on the heastock whilst holding the brace the frame flexe's. Not much and is hard to do.
Is this normal/acceptable or should it be completely rigid?
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@orwell84 avatar
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Ossessionato
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Location: northern New York
 
Ossessionato
@orwell84 avatar
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I honestly don't know. I have never tried to flex the legshield/headset. I would imagine that it would have some amount of flex. Just look at how much the floor flexes when the weight is loaded/unloaded on the stand. I am currently restoring a p200e chassis that is pretty straight. There is evidence of flexing in a number of places that appear to be from use but not damage.

I would take some measurements to check if it's straight and the dimensions are correct. Make sure your plug welds have made sufficient penetration. Check to see if you left out any welds that the factory would have used. You could always add some if in doubt. Other than that, you should be good.

Hope this helps.
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parallelogramerist
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parallelogramerist
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That flex is normal. That's why lots of the track bikes (largeframe, smallframe, Lammy) have them installed (if and when the rules allow it). In order to combat the flex in my T5 track bike, i had the frame dipped in acid, then i welded up every single seam in the body...then also welded in a brace between the steering neck and the frame. My frame is absolutely rock solid now.
OP
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Enthusiast
skipper st125
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Location: York,uk
 
Enthusiast
skipper st125
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Thank You,
For the replies.

The leg shields spot welds were drilled out.
The new ones were mig welded on.

I would prefer not to attach a brace.


Robbie
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Molto Verboso
1958 Allstate 177VMC, 1962 Allstate, Yamaha Vino 70cc
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Location: Philadelphia
 
Molto Verboso
1958 Allstate 177VMC, 1962 Allstate, Yamaha Vino 70cc
Joined: UTC
Posts: 1769
Location: Philadelphia
UTC quote
I mean sheet metal flexes so I'd assume the whole frame flexes. Steel bicycles flex a bunch too. Totally normal and fine.
OP
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Enthusiast
skipper st125
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Location: York,uk
 
Enthusiast
skipper st125
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Yes i am probably worrying too much.
It moves maybe a mm or so back or forth.
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parallelogramerist
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parallelogramerist
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wreckless robbie wrote:
Yes i am probably worrying too much.
It moves maybe a mm or so back or forth.
It's fine. Carry on.
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Hooked
1952 allstate (early), 1958 allstate, 2009 S150, 2001 ET2
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Hooked
@slowpoke avatar
1952 allstate (early), 1958 allstate, 2009 S150, 2001 ET2
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Location: CT
UTC quote
wreckless robbie wrote:
Yes i am probably worrying too much.
It moves maybe a mm or so back or forth.
Frame flex is normal and not going to hurt steel. The amount of flex your talking about is within the tolerance of metals "endurance". The flex causes no harm. I have a VNA with a frame brace and it rides like a road bicycle due to the brace.
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