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Old 07-16-09, 05:42 PM   #1
UnsafeAlpine
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Trike Engineering

My friends and I were looking at a trike sail passed up the other day and I asked one of my friends how they steer. Apparently, the question was too difficult for a rocket scientist, so I decided to ask here.

My curiosity stems from an engineering standpoint. Do trikes with two steering wheels have differential steering? If they do, how does it work? If they don't, what happens to the handling at speed?

Thanks.
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Old 07-16-09, 08:40 PM   #2
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Very much similar to automotive steering with tie rods, etc.
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Old 07-16-09, 09:25 PM   #3
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You're presumably talking about tadpoles trikes, with the two wheels in front.

The short answer is: tie rod linkage with Ackerman correction.

There are many variables: kingpin angle, steering knuckle angle, wheel camber, caster, track, wheelbase, etc., etc., etc.

Ricky Horwitz has a great overview on this. As an engineer, you'll appreciate it.

http://www.hellbentcycles.com/Trike%...0%20part-1.htm

I'm not an engineer, but I've read a lot about recumbent design. The technical aspects can be extremely interesting. If you're interested, check out the homebuilders' section (under "specialty discussions") in the forums at bentrideronline.com. Many very knowledgeable people there.

Eric
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Old 07-20-09, 05:10 PM   #4
globalrider
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the simplest answer is: Ackerman steering makes the outside wheel turn a tighter radius than the inside wheel as it will cover more ground.
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Old 07-20-09, 07:33 PM   #5
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Quote:
Originally Posted by globalrider View Post
the simplest answer is: Ackerman steering makes the outside wheel turn a tighter radius than the inside wheel as it will cover more ground.
I think you mean the outside wheel turns on a longer radius to cover more ground with the inside wheel turning more sharply to cover less.
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Old 07-26-09, 11:41 AM   #6
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Quote:
Originally Posted by UnsafeAlpine View Post
My friends and I were looking at a trike sail passed up the other day and I asked one of my friends how they steer. Apparently, the question was too difficult for a rocket scientist, so I decided to ask here.

My curiosity stems from an engineering standpoint. Do trikes with two steering wheels have differential steering? If they do, how does it work? If they don't, what happens to the handling at speed?

Thanks.
Some of the answers are more complicated than the initial question, and they don't clarify anything due to an apparent lack of understanding of what they are talking about.

In short, the trikes steer just like a family car does.

"Differential steering" could apply to a lot of different mechanisms, but with experience, people can use braked differential steering at speed to produce the same steering effect even though neither front wheel is powered. One trike that I know of called the Sidewinder does use differential steering, but it is the exception, not the norm.

For those that like big terms, it's "Ackerman COMPENSATION", not "correction" or "steering", and on a trike, Ackerman compensation is a moot point unless you spend all your riding time at walking speeds. When cornering on a trike at speed, even while leaning to the inside of the turn, the inside wheel will be unweighted enough that any concerns about alignment or tire scrub are minimal. For anyone that has actually looked into Ackerman compensation on anything, there is no "perfect' setting. As soon as you turn your wheels, the alignment is off and gets further askew the further you turn the wheels. Of far more import is caster and scrub radius.

Last edited by 25hz; 07-26-09 at 11:46 AM.
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