750 R1 wrote:
KZQ wrote:
750 R1 wrote:
KZQ wrote:
swest wrote: I was thinking it would slow the steering down a little like extending the forks.
Steve
Hi Steve,
Trail affects a motorcycle front a lot like a tiller on a boat moves the aft end of a boat, port and starboard. Trail is measured by projecting a line through the center of the stem bearing to the ground and dropping a plumb line from the center of the front axle and measuring the distance between the two. The larger the trail number the higher the required steering force is, at least at low speeds.
When I rode over some bumps in the asphalt yesterday, with only one rear tire, the bars were forcefully pushed left and right. I'm thinking, and of this I'm not a 100% certain, that less trail would mean less turning moment on the bars when traversing uneven pavement.
Bill
The first part here is correct, the second part where you say the bars wanted to pull out of your hands is caused by the trail being small for your intended purpose, if the bars want to slap from side to side, you want more trail, it will make steering slightly heavier, but it will take the "nervous" feel out of the steering. Lots of trikes have leading link front ends for this very reason. I'll just say, I'm no expert on trikes but what i'm saying is definitely relevant to bikes, I also see lots of trikes with raked fronts and large trail... Hope you get it sorted...
Thanks 750 R1.
My problem does not result from instability but rather from the changing geometry that happens when one rear tire rises more then the other. I've been reading over at Trike Talk and those folks say a trike should run 1.5" to 2" of trail. I just measured my set up and I've got 3.5". I agree more trail generally yields a steadier ride and requires more turning effort. But what goes down must also come up. If the turning effort is higher because of the trail setting then the torque required to resist the feedback from the terrain must also be higher. I'm not saying that any of you are wrong. Gawd knows I'm known for working by trial and error. My plan is to fit the fork tubes and front wheel from my KZ 550, which has an offset front axle, to my KZ 750 steering head and see how 2" of trail feels.
I'll let you know.
Thanks
Bill
Hi Bill, my experience is with bikes, ... I'm interested in this one, can't hurt to learn something new...
I'm in the same place - can't hurt to learn. My impressions from that one ride were that:
As one wheel rises the rear end wants to push the front sideways and the bars swing as a result. Trail or, as I first said, "tiller" has a lot to do with this.
The second impression I got was that the front forks were flexing. I'm thinking that they were the springs that supported the harmonic I felt. All of this happened at 20 MPH or less.
The way I see it, I could go for a leading link front end, something I have no experience with, or $ for. Or I could fit the spare front end I have from an 81 KZ1300.
The stock 750 tubes are 36mm the 1300 uses 41mm tubes. Gotta be a bunch stiffer. There'll be a lot of lessons learned matching the triple trees from the 1300 to the 750 head tube. Before I go there I've got a good front end from a KZ 550. It uses the same fork diameter albeit slightly different fork spacing and it has an offset axle. Mating the stock 750 trees with the offset axle from the 550 will give me less trail. If less trail gives me less reaction when one rear wheel rises I'll put the work into changing over to the 1300 trees and forks.
One note on an earlier comment someone made about raked out front ends on some trikes. Over at Trike Talk, those guys regularily fit TWO steering dampers to their chopperized trikes and a number of them complained about their dampers breaking because of the forces they are having to overcome.
Oh Well, I'm just working through the issues as they come up. The exhaust system in another project to be tackled. Ive decided that before I build a two into one using the stock head pipes I should look around for a MAC system like I have on my other 750. I would still have to modify it to lower the megaphone but I wouldn't have to fabricate a "Y" fitting that flows well.
Thanks for your interest!
Bill