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STAND AND FIGHT!
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13,499 Posts
Discussion Starter #1
I have both bikes and switch back and forth, almost every day.

I handle the LowRider much better, by comparison the B-Rod feels so low and quick,
as to be demanding and unforgiving, certainly if I tried to ride it equally hard in corners.

This really puzzles me.
Anybody have any analysis or discussion as to the specs of the bikes predicting this difference in handling?
I couldn't find the lean angle specs.

2005 LowRider Technical Specifications:
Length (ft) 7.83
Wheelbase (in/mm) 65.5 / 1663.7
Rake (degrees) 32
Trail (in/mm) 5.1 / 129.5
Ground Clearance (in/mm) 4.6 / 116.8
Length (ft/ft) 7
Length (ft/in) 10
Dry Weight (lbs/kg) 623 / 282.6

2005 VRSC-B Technical Specifications:
Length (ft) 7.8
Wheelbase (in/mm) 67.5 / 1715
Rake (degrees) 34
Trail (in/mm) 3.9 / 99.1
Ground Clearance (in/mm) 5.6 / 142.2
Length (ft/ft) 7
Length (ft/in) 10
Dry Weight (lbs/kg) 596 / 270.3

This pix I think was the first time I really realized how different the rake and trail are.
The bikes are as near perfectly upright as I could get them on the kickstands and running.

 

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"Ain't quite right"™
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11,255 Posts
"normal" raked bikes looks smashed to me now.
 

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Just passing thru
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6,636 Posts
I would say the difference in trail is why.



TOO LITTLE OR NEGATIVE TRAIL

With too little or negative trail (steering axle mark behind the front axle mark), the bike will handle with unbelievable ease at low speeds, but will be completely out of balance at high speed. It will easily develop a fatal high-speed wobble. EXTREMELY DANGEROUS!

NORMAL TRAIL

Normal trail is somewhere between 2 and 4 inches. The bike will handle easily at both high and low speeds. Flowing smoothly through curves without swaying or wobbling. If you use a very fat rear tire, you should keep the trail as close to 4 inches as possible.

TOO MUCH TRAIL

If the trail is more than 4 inches the bike will handle sluggishly at high speeds. It will seem almost too steady. You will have trouble balancing the bike at lower speeds or on winding roads. It will feel generally sluggish and clumsy.
 

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STAND AND FIGHT!
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13,499 Posts
Discussion Starter #5
According to your description of the general bike geometry handling rules,
which I have no doubt is accurate, the bike with the higher trail should be
the more sluggish one at lower speeds, but it is actually the more stable one.

Maybe it's just me, and yet, there was once a thread where some V-Rod riders said
they wouldn't want to have to take the license test on the V-Rod.

Your figures are a bit different than the current year line up
I knew the Dyna frame had changed significantly in 2006 or 2007, but I am surprised that the V-Rod changed.


.
 

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I {Heart} Hookers.
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31,321 Posts
According to your description of the general bike geometry handling rules,
which I have no doubt is accurate, the bike with the higher trail should be
the more sluggish one at lower speeds, but it is actually the more stable one.
Trail is just part of the deal, Nathan, as rake effects turning as well, as does a wide rear tire.

The difference between a 190-50x17 rear tire on my race bike and a 190-55x17 (slightly taller, more crest) was a night and day difference in handling. The slight increase in rear ride height made a difference as well.

The Dyna has a higher center of gravity, less rake and narrower tires, all aiding in its turning abilities.
 

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Just passing thru
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6,636 Posts
Your right Nathan. I know that the trail is the single most noticeable change to the handling but as Dave said and you know there are many factors.

I know the vrod has offset triple trees. I'm not too sure on the effects of that on handling. I think you have a 180 on the rear of the v? The width of the tires I know has an effect on the force needed to turn but I'm not sure if it reduces the ability of the bike to turn. After all, most all the best handling Jap bikes have 180 width rear tires. Why dont they run 130's or less?

Dave I always had thought that the lower center of gravity would produce better handling but it does make sense that the higher center of gravity would allow for quicker turns.
 

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I {Heart} Hookers.
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31,321 Posts
Dave I always had thought that the lower center of gravity would produce better handling but it does make sense that the higher center of gravity would allow for quicker turns.
Lower center of gravity would make a bike feel more planted and balanced. Turning is all geometry. Another handling factor is "Center of mass" which is why you see sportbike engines/trans all tucked into one space, with very little weight beyond that "mass".

My race bike was 3.7" Trail and 23.5* rake. It was altered even more by raising rear ride height (axle to tail, not ground to tail) 22mm, lowering the front 5mm, (decreasing trail), and achieving a 13* swingarm angle for better "out of corner" acceleration without pushing to the outside. (Due to rear suspension compression under acceleration and lost rear ride height)

Perfect example: Drag bikes. Low, long and stable. With ungodly amounts of rake and trail, they can't turn to save their rider's life.....

The irony: The Dyna series started off as an FL (Read:Touring) frame with a set of Sportster forks hanging off them. It was never a "handling" machine by standards, but recent frame improvements have changes a lot, as have modern tire upgrades and suspension advancements. It's a decent handling bike for its heavy weight.

Another factor that's not been talked about is suspension preload, compression and rebound. All this plays into factoring a bike's handling in corners as well, because your geometry changes as a bike's suspension compresses with weight in a corner too.

HOW a bike acts during cornering is just as improtant as its geometry.

You can't narrow it down to any one factor.
 

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STAND AND FIGHT!
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13,499 Posts
Discussion Starter #10
If you could look at riding each bike, and getting the feedback from the feel and
manuevering and adjusting in millisecond time slices...

It FEELS like the LowRider's mass is so much higher,
that there is more time to move the bottom under it
to keep it balanced.

And a clearer feedback signal that allows more constant correction.

Imagine trying to balance 2 different sledgehammers of equal weight in your palm,
by the handle with the head up.

Imagine how much harder one would be if the handle was only 1 foot long,
and the other one was 3 feet long.

With the longer handle you could more clearly see the direction you needed to move the bottom
to keep the mass centered, and with the longer handle, and so the longer arc before the head's mass
was so far over as to be unrecoverable, you'd have more time to react.

This is my gut feel for the difference.
 

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I {Heart} Hookers.
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31,321 Posts
Imagine trying to balance 2 different sledgehammers of equal weight in your palm, by the handle with the head up.

Imagine how much harder one would be if the handle was only 1 foot long, and the other one was 3 feet long.



This is my gut feel for the difference.
Your thought process is on track, but the mechanics is different. What actually changes isn't actually the LENGTH of the handle, rather one is like having Popeye (big forearms) moving the big, heavy hammer side to side, and the other, more like Olive-Oil....:thumb

The change in rake a trail is almost the leverage and indirect force to move that hammer.

What's most important regardless of how it works, is what the rider feels. In racing, it's often said that no matter what the number-crunchers tell you it SHOULD feel like, you need to listen to how the rider SAYS it feels. On paper, everything looks good.....
 
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