Top Box Aerodynamics

[Sportznut]

OK, I have been reading older posts about riding solo with the Givi top box. Sounds like it could cause some handling issues at higher speeds. I am planning my first long distance trip (about 2500 miles) on my ST so I want to get it dialed in as much as possible before I leave.

I tried riding solo on the Interstate w/box mounted and it was not too bad but I did notice some turbulence. There was a heavy traffic so there was a lot of dirty air.

I was wondering if I put something (a packed bag/tour pack?) on the pillion seat if it would help prevent the issue. Hoping to force the air around the Givi instead of in front of it.

Have any of you tried that or something else? Thoughts?

Thanks

 

[dduelin]

The problem that MAY arise at triple digit speeds is the weave. The 110 mph and up weave is not the same as the light steering and "happy feet" feeling the ST1300 has when riding at highway speeds. This is worse in dirty air of large vehicle or truck traffic. The light steering is simply a characteristic of the ST1300 and is completely normal. Depending on tires, tire pressure, windshield choice, and load configuration it might be slightly better or worse. Conventional wisdom is to add significant preload to the rear shock, maintain proper tire pressures, and keep a light grip on the bars and go ride. The weave is completely different.

 

[PQ11]

Driving with a top case is a bad idea. Under strong winds, it causes disturbing turbulences. If you can travel without, it is much better. On mine, I installed a top rack on the Givi case. It was a very bad idea...

Best thing is to low your luggage as much as possible. When travelling with my body, we had that installation for 1000's miles and never experienced any inconvenient with wind effects. Travelling solo, I prefer pack on the back saddle and use the bag as a backrest sometimes.

I changed my bike for a 1300 three years ago, and it is the same packing set that offers best comfort and efficiency.

 

[Art Franz]

I ride with a Givi. Haven't used or ridden with a Hondaline, so con't comment on them. Givi's a nice box but:

1) They're just up too high, IMO. So they catch wind, make the bike top-heavy feeling, change aerodynamics. Some compensation is possible - I always ride single, so I 'stack' my tent, sleeping bag, duffle bag on the rear seat in front of the top box. That seems to help somewhat with the wind issues. Also helps with my second point -
2) They're always 'loose'. If you watch a guy riding an ST with a top box, they're always wobbling back and forth. Standing still, grab the top box and it's not solid. It's like it needs a good brace or two to really anchor it to the bike. I've compensated with that as well, I've attached a grab loop on each side of the top box, and then I bungee the stuff in front of the top box to the top box and across, down to the tip over bar on the opposite side.

Top boxes definitely have their place, there's lots of room for storage when you're touring, but I never have it on unless there's a specific need for it. I use mine whenever I'm on a long distance run, but only for the storage capacity it has.

 

[peegee5344]

I use a Bestem box,, and have for 6 years.. never had a problem with weave, wobble or whatever,, and as many of us are aware,, those quick twists of the wrist to pass put you into triple digits pretty quickly and no troubles.
On my long trips I strap a Cabela waterproof duffle to the seat behind me as you see here and again, stable. 55,000 km's and still a long way to go.

 

[PQ11]

With a passenger, one of the solutions is a rear bag adapted on a small platform. When travelling solo, it is simple to pack right behind our back. And a spider bungy makes miracles in all situations.

 

[pepollock]

Top boxes are a bad idea. I have a Givi V46 on my Beemer RT and had a Bestem on my ST13. When you gotta carry stuff, or want to be able to lock it up, you need a top box. I never had stability problems with either rig but I'm a codger and tend to ride at moderate speeds (yeah, right) The problem with top boxes is they put the weight very high and out behind the rear axle where it levers some weight off the front wheel. Better to strap a seat bag on the passenger seat if you can. I'm not convinced the aerodynamics are that important since by the time the air flows around the fairing/windshield and the rider it is pretty turbulent already. Maybe filling in the space between the rider and the top box would take some pressure off the front of the box. Might be worth experimenting with it if you are having stability problems.

pete
Or you just try bacon. It fixes everything.

 

[Rider33]

I find a good seat bag to be a lot more flexible on long trips: holds a ton, makes for a perfect back-rest, doesn't tend to agrivate side-wind issues, and comes off completely when you want it in about 5 seconds:

That's an Arerostich Moto-Fizz Medium seat bag by the way. Fully extended you could likley hide a body in there.

 

[Byron]

Here is what I've observed regarding riding with a top box. I ride solo and without anything on the rear seat the box will cause a wiggle with high high winds, high speeds (more above legal speeds) or cross winds. With a duffel or bag on the rear seat buffeting is reduced considerably with head winds but you still get blown with side winds as you have a bigger profile. I've never had this diminish my enjoyment of a ride and having what you need with you is better than doing without.

Summer time if not on a trip I generally ride without the top box but winter time with the box as the extra storage is great for storing the extra gear you wear once stopped.

 

[Skunkape]

I never noticed any difference on either of my STs (one with Bestem and one with Givi) with the top box on or off. I did however notice instability near semis, especially car haulers. I also noticed at highway speeds that the air sucked me forward and tried to suck my wife off the back. Personally I feel the ST's aerodynamic "issues" are more to do with the front than the rear. I never tried different windshields. Costs too much to experiment.

My current bike is pretty much naked except for a small windshield. It weights a couple hundred pounds less than the 1300 and doesn't get blown around nearly as much. Even with these aero-bricks. Aerodynamics is 50% science and 50% voodoo. JMHO and observations.

 

[04strider]

I also have a Bestem top box, and it has stayed on the bike for the last 30k miles, best box for the money that can be had IMO. It regularly sees 100+, and I have never experienced any weave, or handling issues with it installed. I like the lockable convenience being there whenever I need it. I do get some buffeting around trucks, but I don't think this can be fully attributed to the top box. Just one of those things, ride loose and don't fight it, and all is OK. I also ride solo, but keep the rear shocks on a high preload, I think this improves the handling as well as giving more ground clearance in the twisties. For me, I wouldn't have the bike w/o a box for trips, just don't put the heavy stuff up there.

 

[Superzuki]

I have a Honda Pan-European top box with a rack on the top. I've never had any handling issues.
When loaded it gets light in the front when I take off fast. I keep the box on all the time, loaded or empty.

 

[sennister]

I have an E52 and I can count the number of times I have ridden with it off the bike on one hand. I use it all the time for commuting as it is more convenient. On a trip I have added bags to the rear seat and I don't know that I have noticed a huge difference. Sure I get some stability issues in high winds and high speeds but on a long trip it isn't nothing to set the cruise at 70-75 sit back and keep a loose grip on the bar with one hand for hours at a time. Don't fight the bike or it will wear you out. Just go with the flow.

 

[STOC# 889]

I ride with a Givi. Haven't used or ridden with a Hondaline, so con't comment on them. Givi's a nice box but:

snip
2) They're always 'loose'. If you watch a guy riding an ST with a top box, they're always wobbling back and forth. Standing still, grab the top box and it's not solid. It's like it needs a good brace or two to really anchor it to the bike. I've compensated with that as well, I've attached a grab loop on each side of the top box, and then I bungee the stuff in front of the top box to the top box and across, down to the tip over bar on the opposite side.

.

I put some foam under the Givi box and that takes the slop out.

 

[Sportznut]

Thanks everyone. This is very good feedback. I think I will put a packed bag (I always pack too much anyhow) on the rear seat, pack the box light, balance my load, loosen my grip, keep the speed down in traffic, and be cautious when I am on the road without traffic.

 

[Blrfl]

2) They're always 'loose'. If you watch a guy riding an ST with a top box, they're always wobbling back and forth. Standing still, grab the top box and it's not solid.

That's done on purpose. Every time wind hits the box, that energy is transferred to the most-flexible point in the mount. If that point is the mounting hardware, repeated stress will eventually cause it to fail. The Hondaline box has rubber in the mount to absorb it with the side effect of having a bit of slop. Givi's Monokey mount use a two-bolt arrangement that forces the lower plate to bear a lot of that stress and I think is the reason why we've seen a few of those mounts crack or fail at the point where the bolts are.

Solid causes breakage. That's why bridges are made of steel and not aluminum: the steel can flex enough to absorb an ever-changing load. Aluminum is brittle and can't.

--Mark

 

[mean13]

I have a Besteem box and have had 0 problems. Quit yer whinning and ride!

 

[DonMac]

Tallest Clearview windshield. Fully loaded panniers and Givi top box. No pillion but a small dry bag on the rear seat. 125 mph on occasions and no weave for 5000 miles. I believe you are over thinking the issue.

 

[nhdiesel]

I've had a Shad top box on for nearly 60k miles and never had a problem. I've ridden without it a few times and didn't notice any change. I've had mine heavy, light, empty, bag mounted on the seat in front of it...no change. I've been up to 130 mph with it, and I frequently run at 80-90 on the highway.

If you want to go with a bag to hold a lot for an extended trip I would highly suggest the Revpack Excursion Pack. I've had mine for 11 years. Its been on my old ST1100 (bought it for that bike), KLR650, and ST1300. Its great to go on the pillion seat, and packed right acts as a kind of backrest. It works with or without a top box. Here is my bike loaded with top box & Excursion Pack:

From their site:

 

[roginoz]

My topbox is a Hondaline, but I think it's similar enough to the Givi for my experience to apply (Givi makes the Hondaline box, by the way.) Over 75,000 miles with the topbox on, the vast majority of it one-up. The bike is stable from zero to 120-plus, and handles our Kansas crosswinds as well as anything.

Use the topbox for light items that you want with you all the time: raingear, compressor and tire plug kit, spare gloves, bike cover, etc. This is a center of gravity consideration, not an aerodynamics issue. Adjust your rear preload properly, keep the tire pressure at 42 psi, and check the tightness of the steering stem bearings every now and then (or replace them with tapered roller bearings.) Cupped tires will play hell with your handling, too. Don't try to get the 12,000th mile out of a rear tire.

It's normal to have some instability when passing large trucks, more so on the downwind side - it's them, not the bike. Speed up a bit, keep a light hold on the bars, and pass as soon as possible.

There's nothing unsafe about the topboxes. Well, no more unsafe than being on two wheels in the first place.