Instability Carrying Top Box

[ST13Fred]

I made a comment on the NC700 owners forum that these will change the riding characterics, especially when loaded.
This should be generally true on any bike simply because its' high location/distance from CG.
Weren't the top boxes not available in the US and owners would buy them from European retailers Honda would supply.
But didn't European ST1300s' have a few high speed wobbles and crashes? .......perhaps motor cops?
I thought I remember reading this in the early 2000s'.

 

[ad.hom]

This topic has been covered to death already, but to remain polite about it...

Yes, UK Police felt that the risk of high speed instability, and the health effects on their officers for the ST1300, were simply too great, so they were pulled from service (they now ride BMWs). There was an investigation, where one specific UK Police force worked closely with Honda engineers, a bunch of things were tried, but nothing that resulted in the ST13's remaining in service.

I can't comment on top box availability in the US, but my bike (in the UK) has one, and it is often loaded. Yes, it's away from the CG, yes it makes the bike handle differently (even when it's empty, vs it not being on the bike). But I've gone out of my way trying to find the limit of grip on my tyres, and trying to reproduce the same wobble that the P spec bikes saw.

It turns out, that I'm just as good at reproducing the problem, as Honda are at fixing it (I don't think I saw it, it's much more likely that what I saw was poor tyre pressures and/or a high windscreen while playing in the wake of a big truck).

 

[pmatulew]

Also not that many of us riding "professionally" at speeds well in to the triple digit range.

 

[dduelin]

This topic has been covered to death already, but to remain polite about it...

Yes, UK Police felt that the risk of high speed instability, and the health effects on their officers for the ST1300, were simply too great, so they were pulled from service (they now ride BMWs). There was an investigation, where one specific UK Police force worked closely with Honda engineers, a bunch of things were tried, but nothing that resulted in the ST13's remaining in service.

I can't comment on top box availability in the US, but my bike (in the UK) has one, and it is often loaded. Yes, it's away from the CG, yes it makes the bike handle differently (even when it's empty, vs it not being on the bike). But I've gone out of my way trying to find the limit of grip on my tyres, and trying to reproduce the same wobble that the P spec bikes saw.

It turns out, that I'm just as good at reproducing the problem, as Honda are at fixing it (I don't think I saw it, it's much more likely that what I saw was poor tyre pressures and/or a high windscreen while playing in the wake of a big truck).

After the release of the Coroners Report in April 2007 blaming the ST1300 for the death of PC David Reeves, a Merseyside motor officer, the ST1300 was pulled from duty in number of UK jurisdictions but by no means everywhere in the UK and it later returned to duty in some of the jurisdictions that mothballed them after The Report. No one really knows what happened in the accident but the bike that crashed was on Avon Azaro tires which were not approved to use on the ST1300 in the UK and one of the Merseyside test bikes in the report exhibited a rear tire lateral run-out in excess of what is considered "normal". The Merseyside bikes had the full complement of police radios and lights weighing quite a bit and massed on and slightly behind the rear axle. The light pole extending vertically behind the radio compartment was also suspected of causing an oscillation from vortices streaming off of it at 100+ mph. I did read the report at the time and bookmarked a link to it but the report itself quickly disappeared to this date from general internet access. I surmise Honda settled a lawsuit and the report was "catch and killed" in the popular vernicular.

The Hondaline top box was never widely available in the USA and because the civilian ST1300 did exhibit a chassis weave at elevated speeds from the day of release in 2002 so it seems natural that American Honda did not offer a topbox as optional equipment when the bike came over here for the 2003 model year. A reported fix for the weave was implemented by Honda during the summer of 2002. The fix was a retorqueing of engine mounting bolts and in the UK a different swing arm pivot perhaps torqued to a different amount from 2002 factory settings. The latter was incorporated into North American import market bikes - the bike was delayed a model year coming in the US and Canada.

Plenty of us have mounted them [topboxes] and not been thrown off the bike to our collective deaths at elevated speeds but some bikes do weave and some don't. Lots of threads on the Pan Weave and purported causes and fixes.

 

[Upt' North]

Yes Pan Weave is well documented, but weave existed since the very first motorcycle and in fact you rarely get high-speed weave without low speed wobble. Motorcycles with approved tyres in good condition run at correct pressures, at normal speeds and loaded within spec will rarely have issues with w and w.
The question seems to imply that top boxes and police bike spec were complicit to induce weave, no police bikes I've seen have top boxes. The rear hump would have the radio base set inside together with light and horn drivers as far as I'm aware. Maybe a second battery on some models.
But, you are obviously correct Fred that any aerodynamic or loading change will alter the riding dynamics. Whenever I set off on a tour fully loaded and two up it takes a little while to get used to the dynamics but that would be little different to throwing three kids, Er'Indoors and half a tonne of luggage in the family motor.
I do remember a colleague who took a K100 out for an assessment ride and it nearly killed him, he was used to riding sports bikes on covert duties (probably Fireblades/VFR's etc) and the K100 took him by surprise when it started to bend itself in two and he exited road left at speed, although this was at high speed.
Upt'North.

 

[SMSW]

Plenty of us have mounted them [topboxes] and not been thrown off the bike to our collective deaths...

And how do you know this? We might be in a parallel universe where all of us died.....

 

[dduelin]

And how do you know this? We might be in a parallel universe where all of us died.....

Yes, that is true. An assumption on my part.

 

[etalors]

I made a comment on the NC700 owners forum that these will change the riding characterics, especially when loaded.
This should be generally true on any bike simply because its' high location/distance from CG.
Weren't the top boxes not available in the US and owners would buy them from European retailers Honda would supply.
But didn't European ST1300s' have a few high speed wobbles and crashes? .......perhaps motor cops?
I thought I remember reading this in the early 2000s'.

Also Remember. The top box loading capacity is limited to 10 lbs or 4.5 Kg. Loading it more than that, you take your chances. Especially riding near triple digits. Honda clearly stated in their response that an unevenly loaded or overloaded bike will contribute to the weave.

 

[dduelin]

Contemporary FJR and BMW GS models have placards or warnings in the manual against exceeding 85 mph with the saddlebags even on the bike.

 

[Larry Fine]

I have a theory based on observation: I had some wiggle with my hands off the bars on my NH750 when I had weight in the trunk. I noticed that the fork assembly didn't rotate about the steering neck; rather, the steering neck rotated about the fork assembly. This means the center of rotation was the mass of the front end.

So, if the front of the bike's frame is rotating around its center of mass on the vertical axis, the back of the frame is wiggling side-to-side, too. I'm thinking that adding mass to the extreme rear of the bike increases the moment, or inertia, of that movement. So, if the weight could be moved forward, the effect would be reduced.

I'm guessing that carrying a passenger would reduce the effect of that weight, while a lighter rider riding solo would have the most wiggle, so when riding alone, the heaviest object(s) should be packed in the saddlebags first, and on the back seat, behind the rider second, and lighter bulk would be best items to carry in the trunk.

 

[CruSTy]

At the risk of stirring up the nay sayers I would like to share my observations of the ST1300. I have 50+ years of riding experience on probably a hundred or more different motorcycles. Of all of them I experienced the worst aerodynamic instability on the ST1300. I have the OEM PAN top box installed. When I first got the bike in 2013 i was taken aback by how unstable it seemed in dirty air following large vehicles on the freeway. I had experienced buffeting and turbulence on other bikes but this ST1300 was really being tossed around. I initially found lowering the windscreen to its lowest position helped. Removing the Top box helped as well but did not totally resolve the issue. The second year I had the ST I tried some Windscreen angle modifications an the result was the issue is now gone even with the windscreen up and the top box on. I think the stock angle of the windscreen in the up position causes air to hit one side then the other of the rear of the bike at speed causing the bike to move sideways back and forth. This oscillation could be exacerbated by the rider attempting to correct for the sideways movement. Very happy with the windscreen angle I'm using for the past 5 years with the stock windscreen.

 

[W0QNX]

Terrible bikes for hauling anything.

 

[Larry Fine]

Terrible bikes for hauling anything.

And I thought I looked funny carrying my new seat home tied to my bike.

 

[caldercay]

I tried some Windscreen angle modifications

And you posted here about that mod, because I implemented the mod on the 2003.

That thread starts here

Windscreen Mod Article Thank you! | Windshields

https://www.st-owners.com/forums/showthread.php?7767-ST1300-Screen-Mod I have a two fold purpose for this post. 1. To say thank you to those who contributed to the Windscreen mod Article linked above. 2. To share my SUBJECTIVE OPINION/EXPERIENCE with this mod. I'm 6'3 and purchased my '07'...

www.st-owners.com

And the original

Article [13] - ST1300 - Screen Mod | ST1300 Articles

Hi guys, I've read loads of different threads on here about all the different screens available, and also some of the mods that have been done to improve the air flow and buffeting situation. My first decision on this subject was that I was going to have a go at improving the stock screen...

www.st-owners.com

 

[bdalameda]

I read something from an engineer at Honda regarding the "Pan Weave" problem. He said it was related to the engine mounts and tolerances on the mounts that allowed frame flex in certain situations. I am sure the top box could have contributed to the frame flexing as well. Honda made changes to the mounts and possibly frame tubing wall thickness.

 

[OkieRider]

Instead of carying the top box, you should firmly attach it to the platform behind the passenger seat. You will find the bike much more stable with both hands on the handlebars.

 

[ColinW1981]

Ah yes...a new Pan Weave thread. Methinks New Moly Paste and Best Oil threads should be started. Because in the last ten nanoseconds THINGS HAVE CHANGED! Someone needs to call BBC and have the Doctor investigate. Someone pass me some Guinness would you...

 

[larryg]

Also Remember. The top box loading capacity is limited to 10 lbs or 4.5 Kg.

I have the Honda top box, it's load max is 19.8lbs /9kg.


I only ride with the box on for trips, otherwise leave it off. I have never had any noticeable change in handling with the box on.
BUT - I don't (ever) ride 100 mph+. Doing that, box or no box, is just dumb, IMHO.

Since I have the Laminar Lip on my (stock) windshield I can ride, always, with the windshield all the way down. This gives a big difference in stability, over having it up.
Maybe that's why I don't feel any difference with the box on, I dunno.
And since the Lip directs the breeze up and over my head, I get no wind in my face with the shield down.
I wouldn't ride without it.

 

[Igofar]

Also Remember. The top box loading capacity is limited to 10 lbs or 4.5 Kg. Loading it more than that, you take your chances. Especially riding near triple digits. Honda clearly stated in their response that an unevenly loaded or overloaded bike will contribute to the weave.

The sticker on the rear rack on the bike states not to load beyond 10 lbs. How much does the topbox weigh?
I had several BMW F-650 single's (Retired from service loaner bikes) and when the small BMW top case was installed on ANY of them, it would change the handling enough to notice by making the front end light and twitchy, and hunt around on the highway, and this was when the cases were completely empty.

 

[W0QNX]

Terrible bikes for hauling anything.

Safety note for all. Please note the side bags are removed so no chance the bike was overloaded. The payload is also on the rear seat so 100% safe for all you guys that never speed or break the 10 lb weight limit on that rear rack. I also only went about 150 miles and kept one hand on the payload at all times.



Please post pictures of your moped all loaded up.