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warren
human power expert

USA
4899 Posts

Posted - 01/17/2013 :  18:20:34  Show Profile  Visit warren's Homepage  Reply with Quote
Someday I will build a trike. Because it's winter and I am bored, I will just write about it. Because I iz Warren, it will not be your run-of-the-mill cruciform tadpole trike. It will be designed for a body, and have full suspension.

There are so many ways to do trike suspension, it's mind boggling . The one I have see that I like the best is this one:


I'm not sure what this design is called, but it looks like it could be made light, and it only uses one shock unit. That rack and pinion unit would need to be replaced but otherwise it looks like something I could build. Does anyone know where a schematic drawing of this type of suspension is?

-Warren.

Jeff Wills
human power supergeek

USA
1209 Posts

Posted - 01/17/2013 :  19:18:35  Show Profile  Visit Jeff Wills's Homepage  Reply with Quote
Looks like a run-of-the-mill double-A-arm suspension to me. The single-shock arrangement is neat, and probably results in a lot of roll resistance. (Not rolling resistance.) This could be good for handling, but bad for comfort: imagine what happens when one side hits a bump where the other does not.

Any book on basic suspension geometry will get you started. Start with a design that has zero roll resistance in the rear (one rear wheel) and infinite roll resistance in front (two front wheels) and see what it gets you.

__________________
Jeff Wills
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OpusthePoet
recumbent guru

USA
678 Posts

Posted - 01/17/2013 :  20:42:51  Show Profile  Visit OpusthePoet's Homepage  Reply with Quote
From what I could tell it's a parallel equal-length A-arm suspension. Good point for a trike is the roll center is at the same height as the rear roll center, good for keeping all three wheels actually on the road, bad part is there is no camber change as the vehicle rolls in a turn. This will cause reduced grip as the vehicle makes harder turns unless the wheel is run at a large negative camber angle, which causes accelerated tire wear. This setup is good for a vehicle with low performance aspirations compared to the potential of the tires, or that has low grip tires. Either way a vehicle that does not corner very hard.`

Opus

My gas is up to $0.99 a burrito, $5.99 for premium and I'm only getting 10 miles to the regular burrito. Dang $0.99 burritos are smaller now.
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warren
human power expert

USA
4899 Posts

Posted - 01/18/2013 :  06:12:37  Show Profile  Visit warren's Homepage  Reply with Quote
That design is used in small formula race cars, so I imagine it is designed to handle well in corners, but probably is not designed for rough roads.

Would the McPherson strut type of suspension used on velomobiles like the Quest be a better way to go?

-Warren.
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Garrie L Hill
human power supergeek

USA
1457 Posts

Posted - 01/18/2013 :  07:46:08  Show Profile  Reply with Quote
Paging Rick Wianecki!!! Show them what you're currently developing.

Garrie "carbon based lifeform" Hill
HPRA Co-Dictator of the East
for pics of some of my time and money sucking projects
http://garriehill.winkflash.com/
and
http://s58.photobucket.com/albums/g277/cfbb/
and videos
http://vimeo.com/5513519


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rickmantoo
recumbent enthusiast

USA
244 Posts

Posted - 01/18/2013 :  15:52:06  Show Profile  Reply with Quote
Warren

I think the McPherson strut type of suspension is great from a packaging point of view on a trike that is going to be used for a velomobile. They are fairly easy to make. That being said I have been working on using transverse carbon leaf springs. Garrie has made several versions of the springs so far and I think we are getting closed to something that will work. More when we get a actually rideable vehicle.



Rick
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Speedbiker
human power expert

USA
2466 Posts

Posted - 01/18/2013 :  17:25:25  Show Profile  Reply with Quote
What about dampening and preventing wind up when braking?
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warren
human power expert

USA
4899 Posts

Posted - 01/20/2013 :  08:26:34  Show Profile  Visit warren's Homepage  Reply with Quote
Looks very cool, Rick. I'll be interested to hear how it performs. I'm thinking the CF arms should be self damping. What I am most curious about is cornering. How many layers of CF are in those arms Garrie?
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warren
human power expert

USA
4899 Posts

Posted - 01/20/2013 :  08:28:47  Show Profile  Visit warren's Homepage  Reply with Quote
Rick, is that a new trike frame or the one from your Velo?
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harv
recumbent enthusiast

339 Posts

Posted - 01/20/2013 :  14:54:43  Show Profile  Reply with Quote
Have you looked at Stein Trikes suspension?
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rickmantoo
recumbent enthusiast

USA
244 Posts

Posted - 01/20/2013 :  15:23:27  Show Profile  Reply with Quote
Warren
That is a new trike frame, but it will fit in the velomoble.

Rick
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warren
human power expert

USA
4899 Posts

Posted - 01/20/2013 :  16:02:50  Show Profile  Visit warren's Homepage  Reply with Quote
I love the Stein trikes Mad Max suspension.



Availability and price are other issues.
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Ivo.M
Starting Member

Germany
19 Posts

Posted - 01/22/2013 :  12:00:33  Show Profile  Reply with Quote
Check out the Leitra front suspension, there you have double A- arm leaf springs.
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Loki
Starting Member

USA
43 Posts

Posted - 01/23/2013 :  10:03:15  Show Profile  Reply with Quote
Here's an easy to build suspension that also works well at my riding speeds. I have 1400 miles on it with no noticeable wear. It does not have camber change which is nice for higher speed cornering. It is an independent front suspension, the neat linkage system in the first post is only independent to the extent that something bends or twists.
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alevand
human power supergeek

USA
1899 Posts

Posted - 01/24/2013 :  05:36:43  Show Profile  Visit alevand's Homepage  Reply with Quote
The first picture would be cool for the TerraCuda. The carbon leafs are neat too, would they need a drag brace to keep from twisting? If decided to build a suspension trike, I would consider leaning.

C:
Tony Levand

Edited by - alevand on 01/24/2013 05:37:13
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warren
human power expert

USA
4899 Posts

Posted - 01/24/2013 :  09:33:45  Show Profile  Visit warren's Homepage  Reply with Quote
Yes, I was thinking about the leaning thing again the other day when I should have been sleeping. Trikes are low mainly because narrow wheelbase trikes corner without crashing when they are low.

The trike I build would be used for commuting. On roads. With cars. Being driven by drivers who may be only peripherally viewing the road in front of them. Because of that I need a vehicle that is car height. A seat height of around 18"+ works well for that. Because the trike would be (mostly!) human propelled, it needs to stay narrow. A tilting trike is the best way to do that. I am envisioning a tadpole trike with an 18" seat height and 26" wheels, using a parallelogram tilting mechanism with a disk brake based lockout mechanism. A suspension would certainly complicate this arrangement. I think the tilting effect plus fat tires may be enough to negate the need for a traditional suspension. Thoughts?

-Warren.
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alevand
human power supergeek

USA
1899 Posts

Posted - 01/24/2013 :  10:43:01  Show Profile  Visit alevand's Homepage  Reply with Quote
I like it when the wheels tilt. Maybe the parallelogram tops and bottoms could have carbon leaf springs.

C:
Tony Levand
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Speedy
recumbent guru

USA
759 Posts

Posted - 01/24/2013 :  11:28:42  Show Profile  Reply with Quote
http://www.youtube.com/watch?v=QOyunGuPwE0

the first prototype of this was made in my home shop
based on a version I made in 1986
also has been applied to a recumbent
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rickmantoo
recumbent enthusiast

USA
244 Posts

Posted - 01/24/2013 :  19:13:04  Show Profile  Reply with Quote
Warren
Here is a drawing I started several years ago when I first started thinking about the carbon leaf trike. This predates my velo. Features long arm rear suspension and carbon leaf front. The concept is not fully developed so there are thing drawn that will not work.


Rick W
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Jeff Wills
human power supergeek

USA
1209 Posts

Posted - 01/24/2013 :  20:49:57  Show Profile  Visit Jeff Wills's Homepage  Reply with Quote
quote:
Originally posted by rickmantoo

Warren
Here is a drawing I started several years ago when I first started thinking about the carbon leaf trike. This predates my velo. Features long arm rear suspension and carbon leaf front. The concept is not fully developed so there are thing drawn that will not work.


Rick W



I like your design, Rick- it's something I'd like to see, also.

I think the hard part of developing this concept is figuring out the steering linkage. It's got to do so accommodate all sorts of motion: steering, leaning, and suspension deflection while keeping the wheels parallel. There's bound to be a gotcha in there somewhere.

__________________
Jeff Wills
All my bikes:
http://home.comcast.net/~jeff_wills/Gallery/index.html
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alevand
human power supergeek

USA
1899 Posts

Posted - 01/25/2013 :  04:38:35  Show Profile  Visit alevand's Homepage  Reply with Quote
I like the 26 inch wheels all around, but big turning radius. I think with a leaning trike, the CG can be moved back to put more weight on the rear wheel.

C:
Tony Levand

Edited by - alevand on 01/25/2013 04:41:24
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rickmantoo
recumbent enthusiast

USA
244 Posts

Posted - 01/25/2013 :  08:33:38  Show Profile  Reply with Quote
Jeff

I understand what you are saying about the complexity of the steering and geometry. I built a leaning tadpole trike a while back, so I sort of have a feel for what is involved.

http://www.wisil.recumbents.com/wisil/wianecki/leaning_trike.htm

Tony

I agree with you the seat should be moved back. The main concern is the heels of the feet hitting the parallelogram arms. Warren would not have a problem. You and I would have to be careful

Rick
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rickmantoo
recumbent enthusiast

USA
244 Posts

Posted - 01/25/2013 :  16:41:50  Show Profile  Reply with Quote
So I revised the drawing a little , moved the seat back and lowered the cranks some, simplified the frame some. I am starting to like the concept more and more. Might have to build one.


Rick
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mikeatlbch
recumbent enthusiast

USA
200 Posts

Posted - 01/26/2013 :  15:59:07  Show Profile  Reply with Quote
When you talked about traffic height and leaning, Bill's Stites Design Chamelion came to mind.
http://www.velovision.com/showStory.php?storynum=436
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Jeff Wills
human power supergeek

USA
1209 Posts

Posted - 01/26/2013 :  16:29:44  Show Profile  Visit Jeff Wills's Homepage  Reply with Quote
quote:
Originally posted by rickmantoo

Jeff

I understand what you are saying about the complexity of the steering and geometry. I built a leaning tadpole trike a while back, so I sort of have a feel for what is involved.

http://www.wisil.recumbents.com/wisil/wianecki/leaning_trike.htm



Yep, I'm thinking the same things. Adding carbon leaf springs adds a couple complications to the movement:
1. the outer suspension ends are moving in an arc that's not the same as the tie rods. The amount of toe will change when the suspension hits a bump. Maybe good, maybe not.
2. What happens when you're leaned over and you hit a bump that pushes the wheel vertically? Does the spring flex more? Does it go over-center?

I start thinking about this and my head hurts. I'd still like to try it... after I finish the streamliner. I should be done in a couple decades, give or take.


__________________
Jeff Wills
All my bikes:
http://home.comcast.net/~jeff_wills/Gallery/index.html
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warren
human power expert

USA
4899 Posts

Posted - 01/26/2013 :  20:05:22  Show Profile  Visit warren's Homepage  Reply with Quote
Makes my head hurt too, Jeff. Now that we have fired Rick up, let's see what he comes up with.
I still have a project backlog, so maybe by the time I'm ready to build, Rick will have it perfected. He already has the leaning part and the suspension part perfected, now all he has to do is combine them!

Warren
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