Does asymmetry affect bike behavior?

Ulrich

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I am a new Super Tenere owner, I bought it used a month ago with about 7.5K km on the clock. The previous owner fitted the bike with some useful accessories including Givi Trekker Outback side cases: the smaller one on the left, and the bigger one on the right. I like everything about them, but I have been noticing that the motorcycle tends to pull to the left, especially at speeds above 70-80 km/h. It took me quite a while to figure out that this behavior might be related to the asymmetry of the cases. Or, more precisely, to the asymmetry of front surfaces of the cases that produces uneven drag. The way I nailed the cause was quite simple: after clearly feeling the bike’s tendency to steer to the left, I removed both cases and — what a relief, the motorcycle goes straight again without me having to slightly push on the right handle all the time in order to compensate that behavior with counter-steering. And when I say “slightly”, I really mean it because it’s a very minor issue which is barely noticeable for the first 30 minutes on the highway, but after hours of riding, the tension in my right arm builds up and it’s just not right. So, even though it’s a subtle thing with the steering, it is still annoying.

Has anyone riding with asymmetrically sized cases noticed anything like this?
 

Cycledude

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Yes I always hear that your supposed to try to have a balanced ride.
I have never worried about that and have never noticed any issues from it.
If it was really as important as many claim Yamaha would have designed it so both saddlebags were the same size.
Unless I’m on a big Trip my left saddlebag is usually empty and the right saddlebag is completely full.
 

Longdog Cymru

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I have a pair of 37 litre Givi Dolomiti cases, they are equal size although the exhaust side sits about 1” further out. I load them pretty equally and my bike tracks straight and true.
 

Sierra1

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I'd be more apt to look at external causes; road crown & wind. I haven't measured, or even looked, but I THINK that the outside edges of the boxes/bags are going to be real close to the same distance from the bike's centerline. Or, as Longdog has measure....1".
 

jbrown

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The asymmetric OEM Yamaha panniers don't seem to influence my bike's straight line stability. No pull either way for me, with or without the bags.
 
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Don in Lodi

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The OEM are actually symmetrical, the left one has a cut out for the exhaust, both inside edges are the same distance from the center line.
 

jbrown

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The OEM are actually symmetrical, the left one has a cut out for the exhaust, both inside edges are the same distance from the center line.
I think we have a different idea of symmetrical. :) I'm looking at the boxes, which are clearly not the same, while you are looking at where the outside edge is.
 

Don in Lodi

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Yep, different view. Cut-out boxes vs square boxes. I like cut-outs. The asymmetrical design is when the left rack is is pushed outside the muffler bump and you mount a small square box on that side, say a 35 liter, and the tucked in rack on the right lets you install a large square box on the right side, say a 42 liter, and the outside dimension winds up being close to equal, though it looks kind of odd from the rear. An interesting practice for symmetry with square boxes is to make the right hand rack bumped out as far as the muffler rack for same size boxes. Leaves a gap on the right side that can be filled with a tool roll or fuel cell.
 
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Longdog Cymru

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That's why I'll go for a Bumot rack. I've seen it on a KTM this weekend, and they offer a lockable tool box for the side opposite the exhaust. Best looks (as symmetrical as it gets) and use of available space in my opinion.
I would have gone for Bumot too, but I had my Givi kit for £400 less, (bought from this forum), but the Bumot gear is superb.
 

bnschroder

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Or mount your bags on Hepco Becker racks - the left side is nice and tight to the exhaust and the right side almost the same distance from center so it looks pretty symmetrical.



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Ulrich

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I run different size GIVI Outback bags loaded down for 7K mile View attachment 59603Alaska trip 600+ on dirt, no pulling during the entire trip. Mostly 80MPH+ on the Highway
Wow, my set-up is either the same or very similar, please see the pic below.

Thanks for your thoughts, everyone! As I mentioned, this steering issue is very, very subtle, it is barely noticeable, but it does increase at higher speeds, and I do have to counter-steer by slightly, but constantly, pushing the right handle. After hours on the highway, the fatigue in my right arm and shoulder builds up, and by the way, I never had that feeling on my previous bike which was a Transalp 700 with Givi E41 panniers. The issue disappears completely when I remove both cases -- I immediately feel that the tension in my arm goes away. So, the logic suggests that the cases do have something to do with that...

My idea is that this asymmetry produces uneven drag, i.e. the air resistance is different on the sides of the bike: it is higher on the right where the bigger case is, and lower on the left, so it causes the bike to kinda "twist" :) The counter-steering effect makes it pull to the left, not to the right. I am quite sure it has nothing to do with the weight of the cases, as long as it is roughly the same.

It does not bother me that much, I think I'll get used to it. I was just wondering if anyone else has ever noticed this.
 

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Sierra1

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....As I mentioned, this steering issue is very, very subtle, it is barely noticeable, but it does increase at higher speeds, and I do have to counter-steer by slightly, but constantly, pushing the right handle.....
And that is what makes ME lean (no pun intended) toward the road crown. Depending on how pronounced the crown, even in a car I have to steer ever so slightly to the left. That being said, I just noticed where you live. My hypothesis only works if you drive on the right side of the road.
 
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Baja Explorer

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Wow, my set-up is either the same or very similar, please see the pic below.

Thanks for your thoughts, everyone! As I mentioned, this steering issue is very, very subtle, it is barely noticeable, but it does increase at higher speeds, and I do have to counter-steer by slightly, but constantly, pushing the right handle. After hours on the highway, the fatigue in my right arm and shoulder builds up, and by the way, I never had that feeling on my previous bike which was a Transalp 700 with Givi E41 panniers. The issue disappears completely when I remove both cases -- I immediately feel that the tension in my arm goes away. So, the logic suggests that the cases do have something to do with that...

My idea is that this asymmetry produces uneven drag, i.e. the air resistance is different on the sides of the bike: it is higher on the right where the bigger case is, and lower on the left, so it causes the bike to kinda "twist" :) The counter-steering effect makes it pull to the left, not to the right. I am quite sure it has nothing to do with the weight of the cases, as long as it is roughly the same.

It does not bother me that much, I think I'll get used to it. I was just wondering if anyone else has ever noticed this.
You are not going at warp speed !!!
 
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