A question (or two) for Brad

[newrider3]

Out of all your designs, which one would you say is the fastest? Which takes the least energy to ride long distances? Which one is just the most comfortable? Thanks!

[Radical Brad]

Hello!

Fastest for short rides = Marauder.
Fastest for long rides = HighRoller
Least energy = SilentSpeedster!
Most Comfortable = LodeRunner

This will all change this year when I bring out new designs and try some fairings as well.

Brad


Out of all your designs, which one would you say is the fastest? Which takes the least energy to ride long distances? Which one is just the most comfortable? Thanks!

[jimFPU]

This will all change this year when I bring out new designs and try some fairings as well.

Brad
Which some of us are anxiously awaiting....Fighter II, Fighter II, Fighter II, Fighter II, Fighter II, Fighter II, Fighter II, Fighter II, Fighter II, LOL!!:1eye:

[newrider3]

Thanks, Brad. What is your definition of a long or a short trip?

[Radical Brad]

A long trip to me is more than 2 hours on the bike non stop.
A short trip is when I go out there to do nothing but get from A to B as fast as I can.

SF-II..... yes, hopefully there will be time this year. Is is a "spare time" project, so we will see what happens once the deep freeze ends!

Brad

[Locutus]

Brad, sorry to "hijack" this thread from Newrider, but I'd like some input from you specifically. (Anyone else feel free to chime in.)

I'm trying to finalize steering on the Street Fox. I have a couple of female ended 12" solid rods. They're a little too long to connect in the middle at one point. So my question is this: If I were to cross tie rods in the middle like this:

http://i59.photobucket.com/albums/g292/Locutus59/Workshop/img036.jpg?t=1241050203

...would it affect the Ackerman steering compensation? If so, how? Would it be better to take a chunk out of the middle of each rod and weld them back together to make them shorter? Or would the best option be to only use one of the 12" rods, run it over closer to the wheel on one side, then tie the two wheels together at the Ackerman points with a drag rod?

[savarin]

Hi Loc,
I believe that configuration will actually lock up on each bolt or at the most only allow movement in one direction.
Its well worth having a play with Peter Elland's ackerman spreadsheets to plan your ackerman as you will find a huge discrepancy form within very small differences in all the components.
Mind you, a caveat in all this is that large diversions from perfect ackerman seem to be fine in practice.

[TheKid]

Mind you, a caveat in all this is that large diversions from perfect ackerman seem to be fine in practice.


And smaller diversions are often recommended. There are respected builders who comment on geometry. For instance, 25HZ seems to be more concerned with toe-in than Ackerman, Ricky Horwitz seems to prefer a little anti-Ackerman.

[Gerald_G]

Hello!

Fastest for short rides = Marauder.
Fastest for long rides = HighRoller

Brad

Just curious why you might not suggest the marauder for long rides ? Is it a comfort issue ? Or a gear carrying thing ?

[Radical Brad]

Looking at your drawing, I would say yes it will work. It will take some fiddling to get the wheel scrub down though. When I design new steering systems, this is how I do it...

1) Toss away all spreadsheets and time tested formulas (important!!!).

2) Actually build the thing using my initial best guess of angles.

3) Roll the trike around and test for wheel scrub at all steering angles with the tie rods first removed to get perfect tracking and then compare against the initial test unit.

4) Cut and adjust to reduce wheels scrub and maintain perfect ackerman angles at all steering positions.

5) Repeat step 4 until the system is perfect, even if it takes all day.

So far this is the only way I have found to design a new steering system that is reliable. All attempts at using formulas and spreadsheets have resulted in mediocre steering systems that usually drag a wheel after 20 or so degrees of steering.

I think you can do this with your system and win.

Brad

[savarin]

I must admit Brad I agonised for ages over the ackerman on my trike (still coming along when I can do a bit) and eventually I got it.
Even following the spreadsheet info it had to be adjusted somewhat. Next time I'm going your way now I understand all the little nuances.
I found toe in the be ultra important and over about 5/6mm it made the outer wheel actually turn more than the inner and scrub like the blazes.

I still dont think Loc's steering will work in that incarnation as one of the tie rods has to pass between the other at some stage.
If we look at the drawing and work from the left hand side.
If the centre steering is turned anti clockwise it can work, if however its turned clockwise the left hand tie rod can only get almost to the the position its in now and no further as it will lock up on the right hand side tie rod.
I know mine do if I turn beyond the maximum allowed and is why greenspeeds keep those rod ends so far apart on the cross over to give enough room.
They will turn beyond the max in one direction but stop when the cross over locks up on the other tie rod end.
I believe he has to cut the rods and remove one of the arms on the steerer so one arm works both tie rods or place those arms out further to get sufficient movement on the cross over.
Just my thoughts on the subject but I've only done it once so far:jester:

[Locutus]

Thanks, everyone for your feedback. There seems to be a bit of confusion on my idea of crossing the tie rods. My intention is to offset them vertically, so that they don't run into each other. Perhaps another view would help:

http://i59.photobucket.com/albums/g292/Locutus59/Workshop/img039.jpg?t=1241139138

This is obviously not to scale and somewhat simplified, but should give you the general idea. I would compress this in practice so that there's JUST enough clearance.

But I'm also thinking that getting the Ackerman right with this setup might be a more complicated affair than if I use a tie rod and drag link setup. In that scenario I'd have the ackerman tabs tied directly to each other, and only one tie rod connected to the control arm:

http://i59.photobucket.com/albums/g292/Locutus59/Workshop/img041.jpg?t=1241140534

Again, not to scale, and I'd have to fiddle with it for Ackerman and clearance.

(See article):

http://www.hellbentcycles.com/Trike%20Design%20101%20part-2.htm

[TheKid]

All attempts at using formulas and spreadsheets have resulted in mediocre steering systems that usually drag a wheel after 20 or so degrees of steering.


With all the variables possible, these formuli are merely guidelines. Wheelbase, track, actual tire size, weight distribution etc., etc,. etc. all affect the steering geometry. Let's say you build a trike and tweak it until there's no ill steering effects. It's adjustable for X- seam and seat angles. Now another rider gets on your trike. This rider is 20 lbs. heavier and 6 inches shorter than you are. The BB and seat is adjusted to suit this rider. He or she may very well experience wheel scrub and/or pedal steer, due to a variable in weight distribution, riding style, and other variables. I agree with Brad, tweaking the steering to suit you is the only way to go.
These formuli may be a good place to start, but I wouldn't follow them religiously.

[savarin]

Thanks, everyone for your feedback. There seems to be a bit of confusion on my idea of crossing the tie rods. My intention is to offset them vertically, so that they don't run into each other. Perhaps another view would help:

http://i59.photobucket.com/albums/g292/Locutus59/Workshop/img039.jpg?t=1241139138


"Ah Ha" he says, as the light bulb eventually turns on. No problems, totally ignore what I said about the lock up.
I never considered off setting so much as I was hung up on the ground clearance for my pivot so only off set a minimum amount to get enough clearance for the rods.
So many variables and so little time.