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Discussion Starter · #1 ·
Hey all, just purchased a 2008 VN2000, it has been converted to a trike with a MotorTrike kit, it's a great ride, done fairly well. That being said, it has one issue I'm trying to correct. The steering is VERY heavy whether traveling in a straight line or a curve at anything over 20mph. Unreasonably heavy in fact. My assumption is that the rake and trail has been altered when the trike kit was installed. I have been raising the rear end with the bags, to some effect, and am looking at lowering the front 2 inches. I had wondered if there was a tripple tree kit that would reverse some of the problem, but most kits i have seen are to increase the rake angle instead of reducing it. I need to increase the rear tire size to correct the speedometer, which should help some. Any other thoughts? Thanks guys!
 

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Make sure the neck bearings are tightened to speck. If you can slide the forks up, that should give you sharper steering. You could try contacting the company that made the kit, and ask for any suggestions. They may know something. Other than that, converting to an Earl's Fork assembly would be the best way to run a trike, so many possibilities in set up. :)

Earl's Fork:

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Discussion Starter · #3 ·
Make sure the neck bearings are tightened to speck. If you can slide the forks up, that should give you sharper steering. You could try contacting the company that made the kit, and ask for any suggestions. They may know something. Other than that, converting to an Earl's Fork assembly would be the best way to run a trike, so many possibilities in set up. :)

Earl's

I will look into that. Not sure about sliding the forks up because of the chrome covers, but anything is worth trying. It's a lot like wrestling with a bear, and I'm not a small guy. I can't imagine that someone that weighs a buck and a quarter could ride it for long, if at all. I'm 270, and after 250 miles yesterday i felt like i had spent 5 hrs on a weight machine. I know it will always have a bit of resistence, but this thing is 2 hands full.

Jeff
 

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Discussion Starter · #6 ·
I will try to get some pics and figures on here tomorrow evening. The bearings are without slack but free turning, so i think that part is ok, no detent at center from wear. It's gotta be a geometry problem.

Thank you guys!
J
 

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Discussion Starter · #7 ·
Ok, got a pic, and some rough measurements to start with anyway. I had to do them old school with a protractor and plumb weight, so not down to the mm but should be close. The angle of the forks appears to be 32 deg. The amount of trail appears to be approximately 8". Still doing some other figuring but feel free to jump in if you have any good advice.
Thanks
Jeff
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Discussion Starter · #8 ·
On further reading, the factory rake was said to indeed be 32°, with a trail of 7.2". My measurements were rough, so i defer to those numbers instead. While reading some other articles i came across one that was an experiment on rake and trail using a BMW R75/5. Factory numbers on it were 27° and 3.2", with less than stellar handling and significant shaking with bumps and ruts. They built a rig to change the rake to 15° and 0°, and 5 riders over 2000 miles of riding evaluated the changes. Steering was much lighter and nimble with no wobbles even from 100mph down to idle speeds hands free at 15°. At 0° the changes were little more than at 15. The takeaway from that i think is that the closer one can get to say, 20 to 25 the better, with a diminishing return probably beyond that. I am wondering if a person could reverse the bottom plate to gain some ground on it. Food for thought!

Jeff
 

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Just by looking at it, (and for the record, I have designed a few recumbent bikes and trikes), the rake on your bike looks really large. This means that you are getting a lot of wheel flopping, which is O.K. on a chopper, but on a trike, not good. The heavy steering is because the wheel is scrapping on it's entry into turns with the contact patch in the wrong area for the trike set up. I wonder why the trike kit manufacturer did not take this into consideration when they manufactured it. A "mule" set up would define what angles would work best for the trike conversion. I built a "mule" frame to set the Ackerman" and Castor and Camber on my bikes. Cannondale bikes (when they were in business, a private company) were so impressed with my recumbent bike, they gave me $3000 dollars worth of parts to help me with my projects. I let them measure up my bike. My recumbent was designed before theirs. I learned a lot about this stuff by actually building them. My trike was a tadpole set up (2 wheels in the front) with dual disc brakes and independent rear suspension, 24 speeds.

Changing the fork angle using different plates, or custom ones could cost some big bucks. If you're committed to this bike, and you really really love this bike, then go for it, turn it into the bike you want. Funny how Harley runs their forks almost parallel with the neck, just a slight angle, with the neck slightly leading on the bottom and back on the top of the neck leading. On your bike, if you reversed it, you would be decreasing the rake. This is just an observation, it's something I would try if everything could line up without anything hitting. A crazy idea, just throwing it out there. Modifying the front end of a bike can open up a can of worms. A custom springer front end might be the most inexpensive way to go, either way you're going to be spending big bucks. Too bad the forks won't slide up a little, that may alleviate the issue a big. I don't know that bike enough to know this, you would have to try and your own risk. I just lowered my ZZR1200 1" inch front and back.

This is a pic of the trike I designed, my "Mule'. I could cruise easily at around 20 to 24 mph on this, I had to machine, and weld a lot of parts for this thing:


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Discussion Starter · #10 ·
Thank you for that info. I had considered building or having built a girder front unit, that i could properly address the math of a more ideal setup. Plus it could give more wiggle room for the fender. As long as it is paterned to accept the brake calipers and upper hardware, it might just be a simple, if expensive, fix. I will do some research in that direction. I was a machinist and engineer for a few years back in the day. Might be worth a try... thank you!

Jeff
 

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I was a machinist, I did it manually first, then ended up programming and designing fixtures for 4, up to 8 axis CNC machines. So in plain speak, I would seriously considering turning the triple trees 180 degrees, to see what angle you actually come up with. The bike is sitting on a new rear end, and that has obviously changed the rake a lot. If you have a CAD program, or could get me a dimensional drawing, I could draw it up and tell you what the end results would be. A hand drawn picture with the actual angles (on center lines please) would be enough. The fork tube diameters would not matter, just the dimensions of the triple trees,( the rake on the frame, of the forks, and steering stem). I have designed a lot of parts for people and helped them find alternatives that sometimes a CAD program will show you. I use Rhino3D NURBS CAD program primarily. I can import around 60 different formats.

If I could find a drawing, or picture from a manual, I could use that as a background bitmap and get the dimensions by reverse engineering it. Personally, I would try reversing those triple trees to see how it comes out. In my mind's eye it seems like it could work. In any event, buying a triple tree off of EBAY would allow you to have a welding shop change the rake angle, by cutting and re-welding.

I like the custom front end idea better. I would also contact the kit manufacturer as raising the bikes mount on the kit would have the same effect as decreasing the front end rake. That kit may have adjustments, and if the frame is mounted such that it is lowering and increasing the rake, there may be adjustments back there to align the kit to make the bike handle properly. I just can't imagine a kit being sold that would handle so bad, and those kits usually have lots of adjustment points. You problem may lie in the rear of the bike. :)
 

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Discussion Starter · #12 ·
Yes, i agree with you on the rear end, and that may in fact be the place to start. It has coilover primary shocks and airbags to supplement. The shocks measure just over 13.5in, at full extension. They restrict the rear from going any higher. I had been looking at putting taller coilovers or air shocks in place of them, as there appears to be plenty of travel in the mechanism. I just don't want it sticking way up in the air is all.

There is a girder style front end out there that can be custom ordered to your needs,called the Relic. With some creativity i think it could be used with all the factory hardware such as the calipers and fender. I will get the trike up on ramps and investigate.

Jeff
 

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For testing purposes, you could take out the rear suspension shocks and put in a hard mount struts, lowered in length and see at what point the bike gives you the handiing you want. At that point, you may have to just replace or cut the springs to the proper length that you figure out works. You will know right off at low turns if lowering the rear end gives your bike the stand you need. Make the struts strong, and use a very flat parking lot of road to check the handling out, as the bike might be bouncy because of the lack of suspension. All the obvious stuff that comes with experimenting. :)
 

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Discussion Starter · #14 ·
Ok, so i reached out to Motor Trike, got a response back but unfortunately the conversion is very outdated and was not a big seller apparently. They did not, therefore, make a rake kit for my model. Very gracious people, so i have also reached out to a custom triple tree manufacturer for their products, waiting to hear back from them. They had some info on their website, i read up a little.

I am wondering if i am going the right direction with the rake and trail. It was my thought that bringing it to a mor vertical stance would lessen the amount of power it takes to turn the bars. Some of what i read seemed to be the opposite on a trike, so i am confused, and not changing anything until i get some clarity on the subject.
 

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Research is your friend. A more vertical rake would make your bike steer quicker. That's rooted in virtually everything that has a rake, in a car, it would be the castor. I wish I could get a blueprint that I could bring into my CAD program and analyze the rake, swinging it back and forth and telling you something more definitive. A tighter angle will not make your trike harder to steer, too small of a rake, and it could become twitchy. When I made bicycles, a designer, who makes world class custom bicycles, told me that if the neck of the bike, lowers, or raises, when going from back and forth range, it is wrong. The idea is for the center neck to stay at the same height through the range of motion. This can be done by offsetting the wheel to placing the axle mount in front or in back of the fork leg lower. Some bikes have it on the bottom. This is why you see such a variety of this set up. An Earl's fork set up alleviates the problem because the angle of the fork can by adjusted by the for mounts, and this gives you great variability. If you could find a Earl's fork set up for your bike, you would probably end up with the best options. You can set up an Earl's fork to actually rise, stay neutral, or dive, under severe breaking. That is why some many sidecar enthusiasts use the. The sidecar company "Hannigan" sells a unit that they use for their $40K plus side cars rigs. They may be able to give you some info on how you could price this and see if it is a viable option. Do you run a motorcycle tire, or car tire on your trike. If I had a trike, I would be trying to find a proper car tire to use on it. Just some thoughts I wanted to throw out there. If I had a trike, and could find this Earls fork set up, some times called leading for, I would go that route. There are some Ural sidecar Earls forks on EBAY right now. :)

Here's a couple of links you may find interesting : Sidecar Leading Link


This company will build "bespoke" units of leading edge forks, but they are in the U.K. Leading Link Forks Custom Made for Sidecar Outfits, Trikes and Motorcycles

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Discussion Starter · #16 ·
Wow, ok, gotta keep it short but thank you so much for the links and your input. I do know however it gets done I am installing a damper just to be on the safe side. I will get back on here as soon as i get more up on the situation. Thank you again!

Jeff
 
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