Wobble caused by taller windscreen?
 

I changed the windscreen with a taller one ( 8cm taller from OTR ). On the first ride I went into some serious wobbling somewhere around 155km/h ( gps indicated )... I thought wind was causing it and tried later again in a more protected area - again the same... everything else is pretty much the same on the bike ( tires in pretty much same shape and not underinflated, suspension setup same, load same ) as other times when I didn't had any issues running long time at full throttle... Any of you experienced that with a taller screen?

I would not expect that the screen is the cause of this since it is not attached to the steer or front fork ...

:confused1:

Behavior of front fork / steering is a funky one... feeling something in it doesn't mean is caused by it... something not directly attached to it might induce odd behavior in it... and the screen is pretty much the only thing i changed that could ...

I've tried Puig 8cm higher screen and standard with TT spoiler and neither had any effect. Mind you I don't think I've ever got anywhere near 96mph (155kmh) on the speedo never mind indicated on gps!

What happens if you remove the screen? Or put the original back on?

I've got a tall screen on mine and fine 100mph+. Have you got a rack/topbox. That'll give you a very nice weave.

I had a H&B 45L topcase on, but i have it for the past 20k or so km, the only thing i changed regarding it was the rack and plate, switched to H&B from SW Motech... never felt anything funky and surely I did a lot of speed riding with it... i'm 100km from anything twisty so about every weekend i have to do about 200km of hi-speed riding...

I'll try it... I do like the taller widescreen but it's gonna be a total turn off knowing it can cause speed wobble considering I have to ride at least 100km of total boredom in any direction leaving home...

Trust me, you would if you'd live in the middle of a plain and any road remotely interesting would be 100km away.... it's just 1h or so you have done it zillion of times and you just want to get over it faster...

Is the box in exactly the same position? I had a cbr600 which I used a box on and it made no difference to the handling with it on or off where as with the xt I get terrible weaving if I have the box on. The higher screen must be causing the air to flow differently to how it was causing some instability.

Top boxes and top box loading are a cause of weaves at higher speeds and wobbly steering at lower speeds. Also include with worn tyres and soft rear suspension. The only bikes that I have ridden with topboxes and not effected are BM's as they are designed for luggage from the off and often ride better with all the bins on!

Maybe it's the combination of topbox and windshield: airflow now hitting the topbox at a different spot???

HJ

I'll test during the following rides. If that's the case then I'll either go back to the original screen or ride slower - I wonder which is the worst scenario out of these :)

I have the taller MetalMule screen and its never been a problem, I would imagine the concern is somewhere else :Christo_pull_hair:

Wheels need another balance, perhaps?

I had the usual noise and wind blast with the original screen and so got the taller Metal Mule version and loved it, until a silly old sod reversed into the bike in a petrol station, I replaced it with a second hand Screen 10cm taller than standard (Givi I think), it caused massive problems from the first ride with it, wobbles and serious turbulence, real buffeting around the crash helmet. I tried to learn to live with it and gave it a week of commuting, 85 miles a day around 60 of it motorway, no mater what the weather or which helmet I was wearing nothing improved so I took it off and put the original one back on, threw the Givi one to the back of the shed, anyway I found it again this weekend and thought I would try again bit this time with a little mod of my own, I put the original screen on top of the Givi, drew around it and then took a dremel to it, in all I cut about 35mm from either side at the top and about 5mm from the sides at the bottom, left the length the same, so a very tall narrow screen, tried it today on the commute, works a treat, no problems at all.
I will post some pics when I get a chance.

The screen I have is not branded, I'm not sure who produces it, I bought it from off-the-road.de.

After some thinking I'm convinced it's the cause of the wobbles - it's higher than the original by 8cm, i know other have no issues with that size but I think the causes come from it not being that rigid as the original and that fact induces flexes into it that are carried on the rest of the bike. The profile might also be a cause although I'm not sure how different profile you can shape up.

Another thing to consider when replacing the screen is the way the edges are finished. This one has some quite rough edges and I suppose rounder edges would be better both to turbulences and noise. It did came with a rubber to fit on the side but I didn't put it on and have no idea where it's now either to check if things get better with that on.