Luggage rack modification (sliding)

[rusche]

So I've found that with my tall windshield, and Givi trunk, it makes the bike noticeably less stable at speed, especially in crosswinds.

I've found that its possible to remove the rear luggage rack mounts, and flip them forwards, allowing the trunk to be mounted almost 6" forward of the regular position. This makes the bike much more stable at high speeds and in crosswinds. The downside to this is I cannot carry a passenger, or remove the seat without first removing the rack.
It makes a great setup for long solo trips, but becomes an inconvenience if I wish to carry a passenger.

Has anybody built/seen any kind of sliding rear rack? Im considering building a new mount for the Givi, that allows it to mount in a regular rearward position, or pull some pins and slide forward. That way it is easily swappable. I have welder/chopsaw/drill press, etc. Im a mediocre fabricator, but have the skills to do the job I believe.
Any ideas or suggestions? Id like to build the rack in a way that adds the least amount of height as possible to the trunk, since the goal overall is aerodynamics and stability.

Heres the only picture Ive got with the trunk moved forward. Its incredible how much of a difference it makes.

 

[paulcb]

How fast do you go? My ST11 is rock solid, at least up to 125 mph, with a top box and 20" tall screen. I don't count crosswind, as any bike moves around in that.

 

[rusche]

Usually we cruise 80-90 mph. Ive recently replaced steering head bearings with new tapered. It took several adjustments to get them correct, but Im pretty confident now they arent overtight.
My rear tire is an Avon Storm that is very squared off. I know this likely contributes to the problem. Im ordering new tires in the next few weeks.
Ive added a Laminar lip to the large shield and its seemed to help, although doesnt fit quite perfect.
I know there are other things I can do to add a little bit of stability, most of the problems are in dirty air.
However moving the trunk forward does make a very noticeable improvement in all speeds/winds when touring, thus the reason for attempting to build a different mount.

 

[ST Gui]

However moving the trunk forward does make a very noticeable improvement in all speeds/winds when touring, thus the reason for attempting to build a different mount.

Just about any mount you might add would increase the height of the trunk potentially negating some of the improvement. A design to maintain the factory height could be a near major undertaking.

I thought one member here did do a sliding rack/trunk but I'm not all that confident in my memory.

You could start with a couple of aluminum plates with slots for travel. One is bolted to the trunk and one is bolted to the rack. A threaded screw or two with knob or hex key to lock it in the riding position once maintenance is done.

Would you want to be able to carry a passenger? That might require more structural integrity and engineering. Just spitballin' here. I have no idea as to the viability of my imaginings.

 

[Ron]

There is a rack system for sell on Ebay. It's from Ukraine. Shipping is a "little" steep but may be able to combine shipping for less. Just an idea. The 3 Givi attachment parts used to be available from Givi but haven't checked lately. Some one from here ordered a set up a year or 2 ago. Maybe they'll jump in.

https://www.ebay.com/itm/Honda-ST-1...ash=item3abe75ec71:g:OjMAAOSwoJZXSASV&vxp=mtr

https://www.ebay.com/itm/Complete-r...ash=item3ab54ed03d:g:HCAAAOSwAYtWNGpV&vxp=mtr

https://www.ebay.com/itm/Complete-r...ash=item3ab54ed03d:g:HCAAAOSwAYtWNGpV&vxp=mtr

 

[Al st1100]

Just about any mount you might add would increase the height of the trunk potentially negating some of the improvement. A design to maintain the factory height could be a near major undertaking.

I thought one member here did do a sliding rack/trunk but I'm not all that confident in my memory.

You could start with a couple of aluminum plates with slots for travel. One is bolted to the trunk and one is bolted to the rack. A threaded screw or two with knob or hex key to lock it in the riding position once maintenance is done.

Would you want to be able to carry a passenger? That might require more structural integrity and engineering. Just spitballin' here. I have no idea as to the viability of my imaginings.

I think the problem would be securing the front of the slides. The slides would react like a diving board if the front isn't solid. The other problem is there is nothing to bolt or secure the front to.

 

[jamalc6996]

My Givi trunk is rock solid at high speed. I've did triple digit speeds with my trunk on without issue.

 

[Andrew Shadow]

You are correct. They posted pictures of it as well- I can't find the post or the pictures.

I thought one member here did do a sliding rack/trunk but I'm not all that confident in my memory.

 

[Upt' North]

I wouldn't do anything with rack alterations until you've fitted decent matched tyres.
Mines rock steady at any speed, any road and any load. Tyres can make a massive difference.
Hope it helps.
Upt'North.

 

[Loki WRX YZF]

I wouldn't do anything with rack alterations until you've fitted decent matched tyres.
Mines rock steady at any speed, any road and any load. Tyres can make a massive difference.
Hope it helps.
Upt'North.

I agree.

I would also make sure that your suspension settings are not the problem. A bad combination of too hard, too soft, too high or too low can create a great deal of instability, especially at speed. And that is taking into consideration that the difference is felt with the top case on versus off.

Not only the weight, but the shape of the case will cause differences in the aerodynamics compared to a pillion passenger, and that difference can cause either down force or uplift at the rear. If downforce is applied, then the rear suspension will have to soak that up. If it’s uplift, then the rear will be light and feel as though it’s being blown around. Suspension settings can be made to accommodate that, if I’m not mistaken.

 

[rusche]

I wouldn't do anything with rack alterations until you've fitted decent matched tyres.
Mines rock steady at any speed, any road and any load. Tyres can make a massive difference.
Hope it helps.
Upt'North.

I agree with you, however the 'issue' has been present since the tires were new. Its hard to call it an issue. I probably wouldnt have even noticed it if I hadnt removed the trunk for one long day trip that didnt require packing. The bike was noticeably more stable at cruise, thats what led me to playing around with flipping the mount

Im familiar with some mild suspension tuning, but the front doesnt have any external adjustments, I rebuilt fork seals last season and filled with 10wt, IIRC.
The rear is equipped with an older Progressive shock. Preload is adjustable. I have not checked sag or anything, the previous owner was similar to me in size, and the bike handles like it is on rails.

Sometimes I wonder if the Large Clearview shield also contributes to the feeling. I have outfitted it with a Laminar lip that has made a difference.

 

[rusche]

Also the bike is noticeably more stable with the trunk in the factory location and a pillion. Ive wondered if the gap between myself and the trunk causes different aerodynamics, and thats why it feels more stable with the trunk forward.

 

[Al st1100]

Usually we cruise 80-90 mph. Ive recently replaced steering head bearings with new tapered. It took several adjustments to get them correct, but Im pretty confident now they arent overtight.
My rear tire is an Avon Storm that is very squared off. I know this likely contributes to the problem. Im ordering new tires in the next few weeks.
Ive added a Laminar lip to the large shield and its seemed to help, although doesnt fit quite perfect.
I know there are other things I can do to add a little bit of stability, most of the problems are in dirty air.
However moving the trunk forward does make a very noticeable improvement in all speeds/winds when touring, thus the reason for attempting to build a different mount.

Question ? how tall are you and how tall is the windscreen? Do you look over the screen or thru it? I'm 6'5" and I use a 4" over, I can ride with my face shield up and get no wind on my face. From the pics looks like you have a good sized screen which may be some of the problem.

 

[rusche]

Question ? how tall are you and how tall is the windscreen? Do you look over the screen or thru it? I'm 6'5" and I use a 4" over, I can ride with my face shield up and get no wind on my face. From the pics looks like you have a good sized screen which may be some of the problem.

Im about 5'10". I look through the screen in traffic, over it in the highway. Its in the middle I guess. I believe its a Clearview Large. Its a big screen. I have a stock screen and a middle height screen that came with the bike.
I prefer a very upright position to avoid back pain (Mechanic by trade) and have added 1" risers to the Heli bars the previous owner added. Im not that tall, but my riding position on the bike seems taller than normal due to the taller handlebar configuration, I think this is why Ive been more comfortable with the larger shield.

 

[Al st1100]

Im about 5'10". I look through the screen in traffic, over it in the highway. Its in the middle I guess. I believe its a Clearview Large. Its a big screen. I have a stock screen and a middle height screen that came with the bike.
I prefer a very upright position to avoid back pain (Mechanic by trade) and have added 1" risers to the Heli bars the previous owner added. Im not that tall, but my riding position on the bike seems taller than normal due to the taller handlebar configuration, I think this is why Ive been more comfortable with the larger shield.

Your screen is too big. You should be looking over the screen at all times
and still not get wind in your face. Just for verification measure your screen and check the sites to see what you have. I have the same set up you do and I'm 6/5

 

[rusche]

Your screen is too big. You should be looking over the screen at all times
and still not get wind in your face. Just for verification measure your screen and check the sites to see what you have. I have the same set up you do and I'm 6/5

Ill go get a measurement on my medium shield today. Not sure of the brand, came with bike. I remember I had it mounted when I first bought the bike, and I loved it. But after the 1" bar riser it was just enough to cause a head bobble. Maybe I'd be better off if I tried mounting my Laminar Lip on the medium shield. I originally mounted it level with the top of the large shield trying to add a little downforce. Going for a several hour ride today, maybe I'll throw the medium shield on for giggles see how much difference there is

Despite all that I would still love to engineer a way to slide the trunk forward, I had an idea of mounting a backrest to my trunk and sliding it forward using it as a drivers backrest for long solo trips. Supporting the front of the box will prove to be the biggest problem however. There are lots of options for the slides.

Edit: The Medium shield is a CeeBaily 19.5". The Clearview is a 24". Maybe a 22" would be better suited to me.

 

[John OoSTerhuis]

I think the problem would be securing the front of the slides. The slides would react like a diving board if the front isn't solid. The other problem is there is nothing to bolt or secure the front to.

The forward mounting bolts for the passenger grab handles have been used by a number of STriders for support, e.g. IBR aux fuel tanks. IIRC Adam Koczarski had a great setup on his ST1300 for a quick change to move his topcase back when his wife rode with him. Sorry, can’t find a pic or link just now... may be on his website somewhere.

John