Darkside conversion for R1200 BMW bikes & late K's with newer Final Drives

[Roundworld]

There is also a 155/60R15 which is slightly smaller at 22.3" diameter if you really want to get maximum drop and lower gearing in your bike.
That tire would put the rear axle about 1.65" (42mm) lower than stock. But remember by dropping the rear axle that far without altering the front ride height it will also result in the head angle changing by around 1.6-degrees (reduced steering angle, and increased trail).


If I put the car tire and used the 155/60R15 and increased the trail would that also then make the steering better as if I put an easey steer? Just a thouhgt or am I off base

[Roundworld]

No worries, looks like you had a blast. I have two questions one how soon can I get the conversion with the rim? and two, If I put the car tire and used the 155/60R15 and increased the trail would that also then make the steering better as if I put an easy steer? Just a thought or am I off base. Also I saw that you make the trail reduction bracket. I wanted that as well.

Someone told me that while it would help, that while one is in a turn the trail is reduced do to the compression of the front spring and there by negate having it. Is this true?

Roundworld

[BMWzenrider]

Originally Posted by Roundworld

If I put the car tire and used the 155/60R15 and increased the trail would that also then make the steering better as if I put an easey steer? Just a thouhgt or am I off base

For easier steering with a sidecar rig you want to REDUCE the trail of the front wheel.
That is what the various "easy steer" modifications do.
(also known as trail reducers...)


Trail is what makes the front wheel want to stay going in a straight line because the contact patch literally "trails" behind the point where the steering axis intersects the ground.
In the following diagram the red dashed line is the steering axis, and you can see how dropping a line from the front axle shows that the wheel is "trailing" behind the point where the steering axis intersects the ground.



For a two-wheeled vehicle more trail means that the bike is more stable because the front wheel doesn't want to flop over as readily when the bike is tilted off of vertical at speed. For a sidecar more trail simply means that the friction of the tire has a longer lever arm to resist steering inputs at the handlebar. Reducing the trail shortens the lever arm of the centering force on the front wheel, making it easier to turn.
The diagram shows how the trail is usually reduced for a TeleLever front suspension by the addition of an adapter to push the wheel farther forward in the suspension.

Some high-performance sidecars have center-hub steering with extremely small (or no) trail for a lighter feel at the bars with the wide car tires that they use up front.

So in the case of a sidecar rig, increasing trail by going to a much smaller wheel on the back without also reducing the ride height at the front will make it HARDER to steer.

Does that explain it adequately?

[BMWzenrider]

Originally Posted by Roundworld

No worries, looks like you had a blast. I have two questions one how soon can I get the conversion with the rim? and two, If I put the car tire and used the 155/60R15 and increased the trail would that also then make the steering better as if I put an easy steer? Just a thought or am I off base. Also I saw that you make the trail reduction bracket. I wanted that as well.

Someone told me that while it would help, that while one is in a turn the trail is reduced do to the compression of the front spring and there by negate having it. Is this true?

Roundworld

As you can see in the diagram in my previous reply, if you compress the front suspension (drop the front end), you would increase the steepness of the steering axis. And yes, that would reduce trail.
Of course, for a sidecar this is not necessarily a bad thing...

Of course, even with a sidecar, if the trail figure gets too low the steering can begin to feel a bit vauge. I like to have some trail left so that I am still getting feedback from the front wheel.
(center hub steering is a whole 'nuther kettle-o-fish, so the trail figures for those are not related to what we are talking about.)

-----

As far as the trail reducer brackets that I made for myself, it was designed to work with the R1200RT/ST/Roadster.

The R1150GS & R1200GS has a different type of lower steering cross-member. Rather than one which bolts to tabs on the slider, the later model GS lower bridges have a clamp ring which the fork sliders slip into. So my adapter would not work for one of those bikes.
I have not taken the measurements to see if my trail reducer plate will fit on the R1100GS or any of the other Telever from ends which use a bolted on lower bridge...

When I designed the bracket I went to a place which does laser and water-jet cutting to cut my blank, and I had a couple of extra blanks made so that I could experiment with less offset/reduction if I wanted to.
However, the first offset chosen worked so well that I never did anything else with the extra blanks.
So I would be able to offer a reducer for a R1200RT or one of the stable-mates.

-----

As far as the rear wheel conversions, I don't currently have any of the adapter hubs on hand, so it would take several weeks to get all the parts together, the anodizing done, etc.

To be honest, it has been months since anyone has shown any interest, and I have been trying to decide if it would be worth the investment of having another batch of hubs machined up only to have them sitting gathering dust for who knows how long.
I haven't even checked to see if the prices at my anodizing shop, machine shop, and parts suppliers have changed since the first batch was made.

Ideally, I would like to know that I have at least 2 people interested/commited before investing the time/money to do another batch of hubs.
Even then, I will be sitting on part of my investment while I wait for other buyers.
SantaRosa?
GAS GUY?
Anyone else with a serious interest???

[Roundworld]

Great thanks, I think I finally understand how all this works. by moving the front wheel back that moves the bars forward and so the plate moves the bars back to the original place?

If you are selling the trail reducer then I would like to get one form you. You said that yours was perfect so one just like yours. Do you have all the pieces for the conversion or do I need to get some other pieces? Also did you compress the front spring or replace it? And how much?

I have a 2005 R1200RT with a Hannigan sidecar

[BMWzenrider]

Originally Posted by Roundworld

If you are selling the trail reducer then I would like to get one form you. You said that yours was perfect so one just like yours. Do you have all the pieces for the conversion or do I need to get some other pieces? Also did you compress the front spring or replace it? And how much?

I have a 2005 R1200RT with a Hannigan sidecar

PM sent...

[TWOISBEST]

I find this hub arrangement quite interesting. I have 2005 K1200LT, with four wheell lugs and one center lug. Your words indicate that this will work with LT, however the hub arrangement would look a slightly different. I would like to install the hub arrangement on my bike. Are you still deploying new ones ?

[BMWzenrider]

Originally Posted by TWOISBEST

I find this hub arrangement quite interesting. I have 2005 K1200LT, with four wheell lugs and one center lug. Your words indicate that this will work with LT, however the hub arrangement would look a slightly different. I would like to install the hub arrangement on my bike. Are you still deploying new ones ?

When I mentioned my adapter hub being able to work on LATER model K-bikes, that means the ones with the open center final drive only.
Not the K1200LT, sorry.

The basic design for the K-LT is the same, but as you pointed out it is a four-bolt hub rather than the five-bolt hub on later models. However, unlike most of the R-bikes which use the K-LT final drive, the LT has a brake rotor/tone-ring which stays on the final drive when the wheel is removed. That makes it MUCH easier and less expensive to do a wheel conversion.

Claude Stanley ("Claude" over in the Hacks forum) has done numerous wheel conversions for the K1200LT.
If you are interested, just drop him a PM or look up his webpage to contact him directly.
http://www.freedomsidecars.com/

Claude is a great guy and will be able to get you set up!
Hope this helps.

[TWOISBEST]

I sort of figured it was not the same. If I knew the width of the hub, I might try and make it myself. I assume the lug bolts are pressed in place. The whole idea is very impressive anyway. I visited Claudes place during the BMWOA rally last year very good people. Thanks for the help.

[treetop333]

Originally Posted by BMWzenrider

As you can see in the diagram in my previous reply, if you compress the front suspension (drop the front end), you would increase the steepness of the steering axis. And yes, that would reduce trail.
Of course, for a sidecar this is not necessarily a bad thing...

Of course, even with a sidecar, if the trail figure gets too low the steering can begin to feel a bit vauge. I like to have some trail left so that I am still getting feedback from the front wheel.
(center hub steering is a whole 'nuther kettle-o-fish, so the trail figures for those are not related to what we are talking about.)

-----


As far as the rear wheel conversions, I don't currently have any of the adapter hubs on hand, so it would take several weeks to get all the parts together, the anodizing done, etc.

To be honest, it has been months since anyone has shown any interest, and I have been trying to decide if it would be worth the investment of having another batch of hubs machined up only to have them sitting gathering dust for who knows how long.
I haven't even checked to see if the prices at my anodizing shop, machine shop, and parts suppliers have changed since the first batch was made.

Ideally, I would like to know that I have at least 2 people interested/commited before investing the time/money to do another batch of hubs.
Even then, I will be sitting on part of my investment while I wait for other buyers.
SantaRosa?
GAS GUY?
Anyone else with a serious interest???

I would be interested