Just a Hint...
- Thread starter Mellow
- Start date
Joe,
Sue (BES) had some of the same issues but was able to fix them, thread: https://www.st-owners.com/forums/showthread.php?t=31843
If you are really going to sell it, I am going to be home 16 June to 15 July (Mom is having a knee replaced) how much do you want for it? I would love to have it in Europe with me, it's the right color too!
JD
Sue (BES) had some of the same issues but was able to fix them, thread: https://www.st-owners.com/forums/showthread.php?t=31843
If you are really going to sell it, I am going to be home 16 June to 15 July (Mom is having a knee replaced) how much do you want for it? I would love to have it in Europe with me, it's the right color too!
JD
I like Kreis's trailer as well, but he must be a really busy guy.
JD
JD
OP
OP
I saw a special yesterday on Gulf Coast Oil Rig development in strong currents.... oddly enough, it made me think of this situation.
Here's a video of what happens when you place a cylinder in water..
http://www.youtube.com/watch?v=cA-zJwVqzxg
The vortices that form, will cause the cylinder - if not anchored - to move from side to side.
What they did was add what they call strakes to the base.
http://www.redwingengineering.com/ocean_engineering.html
I'm not engineer and yes, these use water vs air but I have to thing there is a correlation.
If I were selling these trailers, I would be doing a bit more product development/design to see what could be done to make them more stable.. maybe a spoiler, maybe some body molding of some type to break up the air.. not sure... again, I'm not engineer, I'm just a guy doing a lot of guessing.
Here's a video of what happens when you place a cylinder in water..
http://www.youtube.com/watch?v=cA-zJwVqzxg
The vortices that form, will cause the cylinder - if not anchored - to move from side to side.
What they did was add what they call strakes to the base.
http://www.redwingengineering.com/ocean_engineering.html
I'm not engineer and yes, these use water vs air but I have to thing there is a correlation.
If I were selling these trailers, I would be doing a bit more product development/design to see what could be done to make them more stable.. maybe a spoiler, maybe some body molding of some type to break up the air.. not sure... again, I'm not engineer, I'm just a guy doing a lot of guessing.
BakerBoy
It's all small stuff.
Helical strakes are a common method on smoke stacks too. Look at most modern factories with a stack, and you'll see them. The strakes or equivalent would have to be on the bike, as far forward as possible ...not too attractive... so such does have to be designed into the bike IMO.
OP
OP
So I have to ask... do you think the little fins on the ST1300's saddlebags are cosmetic or any chance they are there to break up the air flow? They are also on the Hondaline Top Box that also is designed to move left and right to compensate for rough air.Helical strakes are a common method on smoke stacks too. Look at most modern factories with a stack, and you'll see them. The strakes or equivalent would have to be on the bike, as far forward as possible ...not too attractive... so such does have to be designed into the bike IMO.
Considering Kreis' and my homebuilt trailers and comparing them to the Uni-go, the biggest difference I see is length. I really feel that the Uni-go drawbar is too short. I suggested this to Sue and even told her that I would extend the drawbar for her.
Could fabricate an adjustable sleeve to allow testing with different lengths to see what changes have the desired effects.
I also think the hitches are too tight. Any movement involving the trailer is transmitted to the bike. With a bit of "wiggle-room" in the hitch, some it this energy will not be sent to the bike. Negative aspect of the loose hitch is that you will sometimes feel a slight "clunk" when transitioning from side to side.
My "I-Lean" trailer, with the aerodynamics of a brick and a sloppy hitch, pulls rock solid up to triple digit speeds. I'm not sure how I lucked out and got this right the first time, but somehow I did! I'll give Kreis the credit, since my trailer is loosely based on his!!
Could fabricate an adjustable sleeve to allow testing with different lengths to see what changes have the desired effects.
I also think the hitches are too tight. Any movement involving the trailer is transmitted to the bike. With a bit of "wiggle-room" in the hitch, some it this energy will not be sent to the bike. Negative aspect of the loose hitch is that you will sometimes feel a slight "clunk" when transitioning from side to side.
My "I-Lean" trailer, with the aerodynamics of a brick and a sloppy hitch, pulls rock solid up to triple digit speeds. I'm not sure how I lucked out and got this right the first time, but somehow I did! I'll give Kreis the credit, since my trailer is loosely based on his!!
BakerBoy
It's all small stuff.
I'm pretty sure that those little ridges are there for cosmetics. Although if they were longer and taller (protruded more), they could have slight influence.
Eddie generators (spoilers/strakes) typically approach an aspect ratio of ~10 ... meaning width of object (such as a smoke stack or bike's width) to protruding height of the spoiler/strake approaches 10:1. My guess is those ridges have aspect ratio of ~400.
To solve this problem, the spoiler/strakes have to be as far forward as possible and as large as practical. Or, you can get away with less aspect ratio of the whole rig is longer; ie much longer hitch length. The whole idea is to allow the trailer to be in totally roughened air or smooth air, not just in the cyclic vortex that sheds off the bike. It is much like following a semi trailer... very close (unsafe) you're out of the eddies, very far you're also out of the eddies, but at a certain distance you're in the eddies and your bike slowly gets buffeted left and right. Using that analogy to the bike's trailer, it is positioned in the cyclic vortex shedding off the bike, and the bike either has to make the air a lot dirtier (more turbulent) to change the vortex shedding, or the hitch needs changed to significantly move the trailer's position. A foot hitch change is likely not enough, but could help slightly.
My guess is that a BMW RT has no such trailer buffeting issues... those jugs sticking out probably make a great turbulent condition behind the bike.
bdalameda
PaleoCyclist
Joe
What tire pressure are you running in the trailer. I was advised to not run over 25 psi and 22-24 is probably about right. This is for suspension and to prevent bouncing. It could improve your situation as well. A steering damper would probably help a lot. Not sure if anyone has ever added one to an ST1300. It may be a interesting project to add one. Also a stiff sidewall rear tire would help. As the oscillation of the trailer starts it can wag the rear of the bike back and forth on the flexible sidewall. Maybe a bias tire would be best. Just thinking out loud. My new(to me) Unigo is very stable at any speed on my St1100. I have run it slightly over 100 mph several times without issue. Where I live on near my home there is an area that there are pretty severe cross winds and wind gusts. I rode through this area several times to see if the cross winds would effect the trailer and so far it is tracking very well. This has to have something to do with the geometry and or aerodynamics of the ST1300 with the Unigo. My bet is on geometry. The ST1300 is known to be less stable than the St1100.
Dan
What tire pressure are you running in the trailer. I was advised to not run over 25 psi and 22-24 is probably about right. This is for suspension and to prevent bouncing. It could improve your situation as well. A steering damper would probably help a lot. Not sure if anyone has ever added one to an ST1300. It may be a interesting project to add one. Also a stiff sidewall rear tire would help. As the oscillation of the trailer starts it can wag the rear of the bike back and forth on the flexible sidewall. Maybe a bias tire would be best. Just thinking out loud. My new(to me) Unigo is very stable at any speed on my St1100. I have run it slightly over 100 mph several times without issue. Where I live on near my home there is an area that there are pretty severe cross winds and wind gusts. I rode through this area several times to see if the cross winds would effect the trailer and so far it is tracking very well. This has to have something to do with the geometry and or aerodynamics of the ST1300 with the Unigo. My bet is on geometry. The ST1300 is known to be less stable than the St1100.
Dan
OP
OP
Yeah, all the tire pressures are what they should be so that's not the issue as far as I can tell. Not sure a steering dampener will help as it feels like the problem starts at the rear. Pretty much ready to sell it.
Joe, have you talked to Mark at Uni-go? I was there a week ago Saturday and was telling them about yours and BES's problems and at that time they had not heard of these problems. You might want to talk to them (if you haven't) and maybe they can help....beats selling it...if it can be fixed.
While I was there, two BMW riders came in towing their Uni-go's and I asked them if they had experienced any of these described problems...neither one has experienced excessive wiggle (mellow weave
) while pulling the trailer...but both of them did say they don't go over 70 mph while pulling it either. If you decide to sell it...the bidding war on this site could be a lot of fun!
OP
OP
That makes no sense.... If I never went over 70 I wouldn't have the issue...Joe, have you talked to Mark at Uni-go? I was there a week ago Saturday and was telling them about yours and BES's problems and at that time they had not heard of these problems. You might want to talk to them (if you haven't) and maybe they can help....beats selling it...if it can be fixed.
While I was there, two BMW riders came in towing their Uni-go's and I asked them if they had experienced any of these described problems...neither one has experienced excessive wiggle (mellow weave
If you decide to sell it...the bidding war on this site could be a lot of fun!
I haven't talked to Mark... Not really sure what they are going to do.. none of the parts are bad so other than the same suggestions here I don't see what he can do.
I'm still pissed that it took 3 months to get the thing... I was going to cancel my order as I just decided I didn't need a trailer that bad but they'd already shipped it so I'd have to eat 500 getting it back to them.
I would not care to sell it to an ST1300 owner.. I just don't feel it's right for the bike... we'll see.. I don't have a lot of time to mess with it with my workload at the moment so it will just sit there collecting dust 'til I can play with it more.
bdalameda
PaleoCyclist
Joe
Try a simple experiment. Take about 10 lbs of weight and add it to the draw bar. I was thinking of a large tow chain and wrap it around the bar. Pad the bar to keep from scratching it. Try riding it with the weight added. This could help quite a bit. If this works you could have soeone fabricate a piece of steel to permanently attach a weight. Your trailer is acting much like a small trailer I had in the past that would go into a weave oscillation over about 60mph. the weigh changes the center of gravity but also acts as a damper.
Dan
Try a simple experiment. Take about 10 lbs of weight and add it to the draw bar. I was thinking of a large tow chain and wrap it around the bar. Pad the bar to keep from scratching it. Try riding it with the weight added. This could help quite a bit. If this works you could have soeone fabricate a piece of steel to permanently attach a weight. Your trailer is acting much like a small trailer I had in the past that would go into a weave oscillation over about 60mph. the weigh changes the center of gravity but also acts as a damper.
Dan
Dinkie Diesel
------------Jeff------------
Now that you posted that YouTube vid I am inclined to think that that is the biggest factor. Tires, weight distribution, tongue length, caster angle, etc. all probably have less affect than the swirling air coming off of the ST. I have ridden at ultra-legal speeds following another ST. I got a slight back and forth buffeting like following a semi only much, much less severe.
Just use some huge radiator clamps and clamp something about the size of a bowling ball to your Staintunes.
You don't have highway wings do you? That really disturbs the airflow when you stick your feet out in the breeze. Don't give up!
Just use some huge radiator clamps and clamp something about the size of a bowling ball to your Staintunes.
You don't have highway wings do you? That really disturbs the airflow when you stick your feet out in the breeze. Don't give up!
Sorry to hear that!
My trailer looks like it has a longer wheelbase than the Unigo. I mean the distance between the rear wheel of the MC and the wheel of the trailer. And I still get some tail wagging when overtaking semis. Then again, the ST1300 has always been aerodynamically sensitive.
One thing I remember the manufacturer telling me is to watch the tension of the vertical pivot. I am not sure how the Unigo is attached to the bike, but he was very specific about my trailer. The bolt acting as vertical pivot has to be snug, but if I tightened it too much, I would get more weaving. The tire pressure was a factor too.
Strictly for research purposes, have you tried pulling the trailer with the side bags removed from the bike? I'm not suggesting that is an adequate solution to the problem, but it may help you to isolate the problem. If it pulls straight behind the different profile of a bagless ST, then you'll know its a uni-go problem that is specific to the ST rather than a problem with the trailer itself.
I've got a uni-go myself that I have not pulled yet, so I'm very interested in your situation.
I've got a uni-go myself that I have not pulled yet, so I'm very interested in your situation.
OP
OP
I'll add that to the list of thing to try thanks.
Tankereng
Site Supporter
Good luck...hope that forever ends the wrath of the Wobble-go Motorycle trailer....4:
4:
OP
OP
Well, my videos didn't come out. My SD card had issues and what I did capture I deleted thinking I'd saved it off so no video at the moment.
There is still an issue even with the dampener installed however, that issue appears to be at the 100mph range so that's a good thing.
I'm going to see if unigo will send me a new wheel. The one there looks fine and I don't see any issues with it but at this point I don't know what else to try. The dampener is nice and as soon as a wobble starts it actually corrects it and keeps it from getting out of control...
At the moment I can't do much more testing as I need to get the bike ready for my next trip. In fact I'm probably selling it as I'm tired of dealing with something that should work better.
I think if you have a unigo, the dampener is a must as it should help you get past some of the wobble you get when passing 18 wheelers.
There is still an issue even with the dampener installed however, that issue appears to be at the 100mph range so that's a good thing.
I'm going to see if unigo will send me a new wheel. The one there looks fine and I don't see any issues with it but at this point I don't know what else to try. The dampener is nice and as soon as a wobble starts it actually corrects it and keeps it from getting out of control...
At the moment I can't do much more testing as I need to get the bike ready for my next trip. In fact I'm probably selling it as I'm tired of dealing with something that should work better.
I think if you have a unigo, the dampener is a must as it should help you get past some of the wobble you get when passing 18 wheelers.