Thinking about building a trike

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...

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

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 have trail calculators that help when using different front ends, wheel sizes and forks clamps and stuff, but Like I said, not with trikes, I know a couple of guys that race sidecars, but not trikes. The trail figures you quoted there are very small, are you sure they were for telescopic forks and not leading link front ends..? 1.5 to 2 inches of trail is dangerous on a 2 wheeler, you'd be tank slapping everywhere. Have you got a set of shorter shocks or maybe just some shorter solid bars you could try just to see what lowering the rear achieves..? I'm interested in this one, can't hurt to learn something new...

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

Bill, I was thinking setting the shock mounts back a couple inches would be the quick and cheapest way of telling what direction you would like to go. Also don't most trikes have independant suspension in the back?
Steve

swest wrote: Bill, I was thinking setting the shock mounts back a couple inches would be the quick and cheapest way of telling what direction you would like to go. Also don't most trikes have independant suspension in the back?
Steve

Hi Steve,
I can't move the shock mounts without making the wheel base longer and redesigning the whole thing.
Modern trike conversions have independent rear suspension but it wasn't that long ago that 8" Ford differentials were regularly used.
Thanks
Bill

Did a bit of reading up on trikes today, the ones that had small Trail numbers like 1.5 inches to 2.5 inches, had raked frames, 35 to 42 degrees {these rake numbers were just the ones talked about, not a rule of thumb}, They also recommended girder or springer type front ends with this kind of rake, which makes sense, I also found a bit on of insight on rake and trail for trikes, mainly about trail...

international.widowssons.com/forum_posts.asp?TID=4935

Just something to read...

Found this while poking around.
Steve

I'm needing to select some wheels. I'm presently using some cheap trailer wheels and tires. They're only temporary. I'm not too particular about the style of wheel. However I do need it to fit these specs:
15" diameter
5 by 4.75 bolt pattern
4" or 5" rim width
Here's my problem I need one wheel to have an offset or backspacing that is 1.25" different than the other. In other words, I need to pick out a wheel that comes in a range of offsets. I did find one wheel that came with offsets of - 19mm to +19mm but it was $750.00 each.
I've been all through Summit Racing's website with no joy.
Any suggestions will be greatly appreciated.
Bill

swest wrote: Found this while poking around.
Steve

Thanks Steve,
That's apparently a rigid DNA belt or chain drive axle. It has a differential but not independent suspension. It's the same axle I have.
One feature I will definitely be building into this trike will be a fender design that prevents, or mostly prevents, the rider or passenger from getting their foot or leg from being run over.
Have you ever been pushing a bike with saddle bags around in a garage and had the saddlebag clip you in the calf? Imagine the hazard that an exposed wheel presents.
Bill

GOD yes. I think some bodywork in that area would save you. I noticed the stabilizers going to the hubs. I had trouble finding a chrome 16" 8 lug wheel for my truck. Being a 69, finding used ones were out. I went to America's tire with a pic and they found it for me. $99. Had to dirty it up to match the others I have on the truck. :lol:
Steve

I've been busy lately but not neglecting my trike. Last time I was working on the steering stability issue. I ended up deciding to fit a steering damper and see how it might work before I get into changing the steering geometry. I was determined to make the installation functional and not appear to be something quickly bolted on. I chose the longest damper available and this installation makes use of all the travel.



I welded up an exhaust pipe, no muffler yet. The pipe is 16 gauge stainless and just joins the two head pipes over to the right side. I haven't found a muffler that pleases me yet. I need something pretty short with a inlet diameter of 1.75".




What do you think?
Bill