Modern Vespa

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?

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.

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.

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

I mean sheet metal flexes so I'd assume the whole frame flexes. Steel bicycles flex a bunch too. Totally normal and fine.

Yes i am probably worrying too much.
It moves maybe a mm or so back or forth.

It's fine. Carry on.

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.