Large Top Box - is it me?

[TarTripper]

Got the bike back after the rear shock change and now for the first time I've been riding it with the large BMW top box fitted.

 

Now I think I'm starting to notice a slight instability at 75 mph or higher. The bike seems to roll left and right a bit when I'm cruising on a freeway. It's only a slight roll and the instability, if that's what it is, is not divergent.

 

Is it me, or has anyone else experienced this?

 

Before you ask the top,box is lightly loaded and I'm sticking well below its 110 mph speed limit.

[TEWKS]

Steady as she goes, here!

 

 

Pat

[biometrics]

Tire Pressure correct? Sounds like your rear tire may be a bit low... I always run 40F-42R... it solved a lot of my unsteadiness at speed.

[mneblett]

The large trunk on my K16 (same as the large wethead box, IIRC) also wags the bike around at higher speeds.

 

One way to check whether it is the box is to carry a passenger -- when a passenger is present the airflow the box sees is completely different, so it doesn't generate eddys that push the rear of the bike around.

[TarTripper]

Thanks guys, both good ideas to investigate. Interesting about the K16 top box. I rode one for 3500 miles this summer but didn't notice any wobble - pillion or no pillion.

[marcopolo]

...Before you ask the top,box is lightly loaded and I'm sticking well below its 110 mph speed limit.

 

Is the limit really 110 mph? On my '06, the recommended maximum speed with the top box installed is 80 mph (if I recall correctly). If so, has it really gone up 30 mph?

[Teddy]

...Before you ask the top,box is lightly loaded and I'm sticking well below its 110 mph speed limit.

 

Is the limit really 110 mph? On my '06, the recommended maximum speed with the top box installed is 80 mph (if I recall correctly). If so, has it really gone up 30 mph?

 

It says 180km/h on the lid of my large top box (approx 110 mph) I too notice a slight instability at higher speeds too especially when there is a bit of wind around. All my BMW's over the years have done this with a top box on, my R1150RS was especially bad even @ 110km/h on the freeway and it was markedly worse when following large "B Doubles".

It's probably nothing to worry about and the bike just moves around a bit more.

Teddy

[TarTripper]

Yes, I think wind is the antagonist. It was fine today in still wind conditions.

[simonB]

I have the large top box, with the top box and luggage fitted I have not experienced instability at freeway speeds. The majority of my riding has been UK dual carriage way and motorway riding for nearly 2000 miles and I haven't experienced any issues with stability in normal, rain or wind conditions.

 

the only issue I came across was over judicious use of the throttle whilst trying to over take a truck, whilst exiting a roundabout. The result was a little too much throttle causing the front to go light and my heart to try and exit my mouth at the time! fortunately the traction control kicked! lesson learnt - don't pin the throttle on a roundabout exit whilst the road is drying out!

[AndyS]

Nah, nail it. That's why you have traction control. See if you can get a bit of rear wheel drift before TC kicks in!