My silly windshield

Ishrub said:

Do any parts of your screen and ahem LIP flex, shudder or flutter at that 90mph or approaching it? That is a very deep secondary screen or lip and a big distance between your main screen and the lip as well, both of which may reduce the laminar flow effect and cause air turbulence or uneven distribution and or pulsing of air flow as the lip may be acting as a screen itself rather than a laminar lip. i.e. The airflow is being pushed by the front of the lip rather than forming a laminar air flow up the back surface of the lip so that it emerges above your main screen and smooths or reduces the air flow behind the screen where your head is. The idea is the pushed up laminar flow prevents air rushing into the low pressure area behind your main screen. There would be a pretty big wind load on the single mount too with that size of lip.

If it was mine I would reduce the mounted height and depth of the lip by cutting the bottom portion off about in line with the current mounting hole and drill another one or three holes to experiment different mounting heights so the top edge of the lip is lower than the main screen top edge. It would also be worth putting two or three more holes in the main screen to give an even bigger range of mount heights. The third link below suggests having the lip top edge higher than the main screen top edge but with at least half the lip depth below the screen top edge to allow a laminar flow to occur. It also states that some may benefit by having the lip top edge below the screen top edge. You could then adjust the lip top edge height down to below the screen top edge in stages and see if it affects the issues you are experiencing. The benefit is you may even get a big improvement below 90mph. I would also try adjusting the angle of the lip in relation to the screen by tilting it forward so the lip top edge is further from the screen than the lip bottom edge



Some basic explanations of the effect being sought.

Laminar LIP Review - webBikeWorld

Laminar Lips

http://www.laminarlip.com/proddc.php

http://www.laminarlip.com/whyneed.php

Click to expand...

Ishrub said:

Do any parts of your screen and ahem LIP flex, shudder or flutter at that 90mph or approaching it? That is a very deep secondary screen or lip and a big distance between your main screen and the lip as well, both of which may reduce the laminar flow effect and cause air turbulence or uneven distribution and or pulsing of air flow as the lip may be acting as a screen itself rather than a laminar lip. i.e. The airflow is being pushed by the front of the lip rather than forming a laminar air flow up the back surface of the lip so that it emerges above your main screen and smooths or reduces the air flow behind the screen where your head is. The idea is the pushed up laminar flow prevents air rushing into the low pressure area behind your main screen. There would be a pretty big wind load on the single mount too with that size of lip.

If it was mine I would reduce the mounted height and depth of the lip by cutting the bottom portion off about in line with the current mounting hole and drill another one or three holes to experiment different mounting heights so the top edge of the lip is lower than the main screen top edge. It would also be worth putting two or three more holes in the main screen to give an even bigger range of mount heights. The third link below suggests having the lip top edge higher than the main screen top edge but with at least half the lip depth below the screen top edge to allow a laminar flow to occur. It also states that some may benefit by having the lip top edge below the screen top edge. You could then adjust the lip top edge height down to below the screen top edge in stages and see if it affects the issues you are experiencing. The benefit is you may even get a big improvement below 90mph. I would also try adjusting the angle of the lip in relation to the screen by tilting it forward so the lip top edge is further from the screen than the lip bottom edge



Some basic explanations of the effect being sought.

Laminar LIP Review - webBikeWorld

Laminar Lips

http://www.laminarlip.com/proddc.php

http://www.laminarlip.com/whyneed.php

Click to expand...

Bob R said:

Sounds like the air is spilling off of one side more than the other and when that happens the pressure on the other side is putting more force on the bars. I guess there is a reason wind tunnel testing or at least computer modeling is used for these things. Does it always fall off to one side the first time it starts the wobble?

bob

Click to expand...