Need help in picturing this....
Given -
GS paralever arm = 365mm
most other R paralevers arms= 385 mm
For a GS if you put in the longer paralever arm would that decrease the trail of the front wheel?
Wudo sold an adjustable paralever arm, just not sure the lengths..
Is the paralever arm your talking about the rear or front. I thought the paralever referred to the rear suspension.
If it's the rear, length would have at most a minor affect, depending the angle in relation to the ground and if it raised or lowered the rear end of the bike. Probably not worth the trouble.
If you are talking about the lower front arm. a longer lower one would cut the trail. A longer upper would add to trail. One way folks eliminate trail on the newer bmw front ends is to move the pivot points where the upper and lower ball joints are mounted.
I'm investigating this (moving the pivot points) approach for my k1200rs.
my question refered to the rear. Kinda like standing the bike on it's nose was what I was thinking.....
How does changing ball joints work if the steering angle is fixed...having a hard time picturing it...
Changing the rear has some effect on trail on the front. Changing the lenght on the arms on the front has little to no effect. Changing its lenght is like "raking" a frame. (not to be confused with what people often wrongly call raking the front end with "raked" triple tree's)
If you want to change the trail on the front one way to do so is by relocating the ball joint. We make a different ball joint mount for this as does Side-effects and Hannigan sidecars (at least for the R1100GS) We have it for both the R1100 and the much more difficult to make R1150GS.
When you move the ball joint back you move the front wheel forward thus reducing trail. On our kit we also move the ball joint up some so that the front of the bike does not drop when the wheel is moved forward.
Jay Giese
Dauntless Motors Corporation
www.dauntlessmotors.com
866-638-1793
Moving the ball will make a difference in steering (trail). Raising the rear of th ebike will make a difference in static rake which also changes trail but it is not much of a difference in real life riding. Raising the ball location as Jay does makes a lot of sense. Too much forward change in the fork tube angle can create a potential issue with the upper pivot area on GS Rigs.
Ok...it makes sense until I start thinking about the headset (where the steering tube rotates in the frame). That is a fixed angle and does not rotate. How do you then change the trail with a fixed frame/fork angle?
Just can't picture it, I am sure it will be completely obvious soon, but now.....
I have just found a interesting way to reduce the trail on the bmw with telelever front arm without changing the angle of the fork. To do so, the steering angle must be straight up, this angle is the line between the bearing bolt located in the upper fork brace and the ball joint in the lower bridge. To change this line, once again without changing the angle of the fork, the ball joint must be relocated. A sidecar company does this work in Europe. To achieve this trail reduction, they manufacture a new longer lower bridge and in the same time, to straight up the steering angle, they also change the location for the ball joint on the A arm (telelever), shortening the A arm (cut and rewelded)to the same distance they have lenghten the new lower bridge. In other words this pivot will move backward, and the trail is then reduce. My telelever is already on its way to Europe for this modication, will then get back the modified A arm and the new lower bridge in about a month or so. Then I will keep you updated with the new rig's handling and pictures.
