"Bump Steer" as related to the "Darkside" and other black arts.

[Ricky-D]

It seems that the term "bump steer" appears in most of the threads that deal with "darkside" conversions.

I went and Googled the term and found it singularly relates to automotive conditions of steering wheel, suspension, and front end configuration.

So much for "bump steer", although there is a lot of authoritative sounding comments on past threads that would make the posters sound like they know what they are talking about.

My feeling is that the use of the term is fallacious and is mainly used as scare words to detract from the advantages of changing to the "darkside" by those feel strongly against the practice.

***

[SANDMAN5]

"Fallacious"????? Why bring sex into it?

[Ken Tarver]

Ricky-D, I'm darkside on my wing and valkyrie and I don't get it...I don't get what they call "bump steer",  I steer/counter steer as I always have...what the heck do they mean?

Ken

[Ferris Leets]

Bump steer refers to the jolt when the flat tire comes up against an edge that is parrellel to the direction of travel.  The bike will jump towards the down side of the edge.  It depends on who you ask whether htis is a minor problem or a deal killer.  The effect is only really noticable as a bump at parking lot speeds.  At road speds it manifests as a tendency to wander off ot the ridges in the road.  At low speed if you are not expecting it you could loose control for a few feet.
    My self.  It is something you get used to and/or avoid those edges.  Not a big effect on my riding.

[MarkT]

Good to see that the expert "Ricky-D" has taken up the role of board and prose police.  I stand corrected from his expert googling, having used the expression his expertise objects to, "bump steer" as applied to the effect of a car tire on my Valkyrie's line in turns.  Looks like I need to create a new lexicon as Mr Expert's googling and thought process can't apply a little understanding to how this could apply. Since I am now officially among the "fallacious", just a modicum of explanation, to apply to my use of Mr Expert's narrowly defined and googled term, as posted on my web site and somewhere on this board MONTHS ago: my meaning was, the car tire would cause my bike's line in the turn - even "sweeper" - can I use that term Mr Expert? - to change when I rolled over a bump.  I would have to make a steering correction to restore the line I intended, directly caused by the effect of the bump on the suspension and tire.  Or roll off the road.  Jeez, I can't call that "bump steer" because Mr Expert found some other definition for the expression via a google.

I really don't want to go down this path again.  Just prefer to stay out of the argument; I no longer care - but apparently Mr Expert wants to re-whip this dead horse.

I can see the argument baiting Ricky-D needs to be added to my short Ignore list - and so he is.

[Daniel Meyer]

Well, the phenomenon is there...it's the tendency for the motorcycle to steer "downhill" on a surface that isn't flat. Does it with every tire. It's more pronounced the fatter or flatter the profile of the rear tire is.

Doesn't have to be called "bump steer". Pick a name. Heck, we can call it "Bob" I guess, but that might be confusticating...especially if you are Bob.

I'm pro-darkside...at least on my bike. I've got more than 140,000 miles of experience with it on Valks alone. I'm free with my information about how it's done, but my stand on most other questions is if you have to ask me if it's right for you, the answer is "no".

The arguments for AND against it have gotten increasingly irrational and I generally don't participate anymore. Pity. There's lots of good info to be had on these boards if we'd quit debating the stuff like it's a presidential candidate (misdirection and irrelevant but scary info).

The "Bob", which henceforth I will refer to as "bump steer" I don't really call a negative...every motorcycle on the planet does it. It's a tendency, not a requirement...in other words, the bike will want to go...you don't have to let it. Fatter the rear tire, the more the tendency. Doesn't have to be darkside.

[donaldcc]

"bump steer" the use of the term is fallacious ***

  ALWAYS thought "bump steer" was fallacious (: tending to deceive or mislead).  Why would people always be talking about a cow?    A "bump steer" is a brahma bull, right, with the big "bump" on the back?  ???

[Willow]

"bump steer" the use of the term is fallacious ***

  ALWAYS thought "bump steer" was fallacious (: tending to deceive or mislead).  Why would people always be talking about a cow?  

Now you've done it!  The terms steer and cow are mutually exclusive.    


Oops!  Sometimes can spell.  Often can't type.

[Oss]

that steer needs to see the dermatologist....too much sun  that bump looks nasty

this one looks better and 2 car tires also

[donaldcc]

Now you've done it!  The terms steer and cow are mutually exclusive.    

OH DARN! Always forgot to look between their legs to see whats there.  I am usually looking and fantasizing about rib eyes or porterhouse, not mountain oysters.  

[Jess Tolbirt]

thats not a steer thats a bull as best i can tell,, steers have no uh, er uh nutz,,,,that bull looks like there is something hanging down there,,

[BigAl]

Maybe they meant Bum Steer.

I heard that once on a western about a bad Steer they were bringing to market.

Car tire guys are so sensitive,

[Gryphon Rider]

Here's how I experience what I have called "bump steer" for lack of a better term.  I didn't coin the term:
When in a sweeper corner and I go through a noticeable dip which momentarily compresses the suspension, the bike tends to want to stand up slightly and thus moves out slightly in the corner.  This is because the tire's contact patch is inside (relative to the corner) the centre line of the bike.  It's not something that puts me off running a car tire, but it is something I need to keep in mind, just like I need to be aware that going through a compressive dip while leaned over reduces my cornering clearance, even with a narrower motorcycle tire.

I hope I sound authoritative, like I know what I am talking about.  If my description of this phenomenon scares anyone away from running a car tire, they will probably be happier staying with a motorcycle tire, which I have no argument against.

[sugerbear]

my input:

i don't care WHAT you call the movement of any tire. i like my car tire and will not go back.
but..........just for fun. is the car tire dem or rep, left wing or right wing?

no..... no.............i'm serious, which is it. just so i'll know which one to vote for

[Valkahuna]

I suppose you could make a point that it is both. 

The frugal aspect such as long life and low initial cost in comparison to a M/C tire could be fiscaly conservative, or Rep. 

On the other hand, some would consider it a radical thought, making it a Lib, or Dem. 

my input:

i don't care WHAT you call the movement of any tire. i like my car tire and will not go back.
but..........just for fun. is the car tire dem or rep, left wing or right wing?

no..... no.............i'm serious, which is it. just so i'll know which one to vote for

[Ferris Leets]

I  tend to vote conservative so I  would have to go to the fiscal conservative definition.  It has my vote.

[Ken Tarver]

thanks everyone.....now i understand, it's the same effect I had with a MT

[Disco]

I just had a thought... 

The next time someone asks if that's a car tire on my Valkyrie, I'm going to ask them if my Valkyrie is a car.  They will say no, and I will say that, because my Valkyrie is a motorcycle, the tires mounted on it are motorcycle tires. 

Case closed.

[FryeVRCCDS0067]

When someone asks me if that's a car tire on my motorcycle I tell them it used to be, now it's a motorcycle tire.

"Bump Steer" otherwise know as "Bump Stare" is allowing your eyes to become fixated on that bump you do not want to hit causing you to perfectly center-punch it.

Darkside is merely the shadowed side of said bump.

[Rio Wil]

The "Bob", which henceforth I will refer to as "bump steer"

So Daniel.....if it is the manly term of "Bob" for a Valkyrie, should it be "bobbie" if on a Vespa, or on a BMW shall it be "Robert" and a Harley, maybe "Booooobie"....ah heck, just trying to be fallacious