Rubber on the road??

[Ratman]

I was told that at 140 MPH there is only 1/4 inch of rubber on the road. I thought my BS meter was going off, But I don’t know for sure, so I asked even with Z rated tires? Was told yes.

What can this group contribute so I may sound like I know what am talking about.

 

[Ignacio]

Absolutely, completely true! The FJR is a lot like a dragster in that tires baloon to huge diameters and skinny contact patches as they exceed 100. Can't you tell that the bike is six inches taller at 140? Combine Yoshimura's law of lightened objects and the FJR ownly weighs 12 pounds at that speed.

But seriously, I think (and I hate to answer if I'm a fish and you're trolling) it's total BS. 1/4"? 1/4" by what? A contact patch is measured in area--usually in square inches. And, I think it's closer to 10 square inches for the FJR.

Of course it's dependent on load, tire pressure, maybe some with speed and centrifugal force. It's also dynamic with load on front and rear through acceleration (like wheelies) and deceleration (think stoppies) as well as increased loads in corners through g-force side load.

I'd try here and here for some reading.

 

[Scab]

Either way you look at it, there is just not a lot of rubber on the road for a motorcycle. This is all fine and dandy, as long as you are going straight. Besides, if you are planning on running at 140 mph, do you really want the answer to that question? Please, just leave me with my false sense of security.

 

[BugR]

It's the same when it's parked in your garage

Chris

 

[Afast03nNJ]

"Z" rated rubber does not ballon at 140 MPH. If you run the correct speed rated tire for the speed and load range your riding on, the contact area remains pretty much the same.

There's a reason tires are rated for load and speed.

 

[Toecutter]

As long as it's rubber and not plastic, metal, or skin contacting the road, at any speed, who cares?

 

[tontofjr]

I remember once being told that the contact patch is about the size of a credit card

and if you lose that contact patch you need at least 2 credit cards to pay the damage bill

 

[falcon]

I remember once being told that the contact patch is about the size of a credit card

That actually sounds about right. But the force of the weight on the bike on the contact patch is the same if you're moving or standing still (unless you are on an incline), so the contact patch area won't change much if at all.

 

[Mike-H]

AND....this is going to change the way you ride how? :blink: :blink: :blink:

 

[FJRMGM]

on one of the motorcycle show on Two Wheeled Tuesday last week they talked about contact patch on the bike.

Basically said the front patch is about the size of first three fingers on your hand and the back is the size of your palm.

Any way you measure it -it's not much.

 

[radman]

Well I checked, and damn if he isn't right. On my way to work this am, I decided to see if my cousin had gotten into Uncky's stash again, so I brought along the tape measure, and on a long lonely stretch of 35E, cracked the throttle, and at 140 set the cruise. Bent over the side of the bike, deployed said device, and sure as shit, 1/4", just as advertised. Of course, with my fat ass hanging off the bike like I was Gene Autry avoidin' Injun arrows on the range, that 1/4" was all sidewall as the bike began a left turn that had to be seen to be believed. When I'm out of the hospital, I'm gonna try checking the right side, maybe thats different. More to come.

 

[SkooterG]

Well, I for one, hope they don't let you out of that mental hospital anytime soon.

 

[HIGHLANDER]

I'm thinking there may be a litle more tire on the road at high speed. When I'm up over the ton the bike feels like it hunkers down and sqauts a little more, might just be my ass sucking up to the seat, but with the aerodynamics of the bike it seems it squats, and maybe it increases tire patch contact. I can't see the factories designing a shape that would lift the bike at high speed.

 

[Ratman]

I’ve been reading this site since I was a 04 waiter and I am all ways amused by the witty repartee, it is all way a pleaser to read the responses by such a talented bunch of riders..

Meet you on the road some were..

 

[double_entendre]

I was told that at 140 MPH there is only 1/4 inch of rubber on the road. I thought my BS meter was going off, But I don’t know for sure, so I asked even with Z rated tires? Was told yes.What can this group contribute so I may sound like I know what am talking about.

Not necessarily relevant to the FJR in specific, but according to a MotoGP FAQ I read, the total contact patch size was approximately one credit card. Wikipedia says each tire has a contact patch the size of an average human hand.

YMMV. B)

Bob

Rancho Cucamonga, CA

 

[FJRski]

On the average, it depends on how your rebound is set and how big the shreds are...

 

[rublenoon]

Points for your consideration:

FJR at rest in vertical with rider [180 lbs] and assuming a 50:50 front:rear distribution and tires at 40 psig pressure. Wet bike weights 580 lbs [530 + oil + fuel + coolant], rider @ 180 lbs, and misc gear in/on bike @ 40 lbs for a total static weight of 800 lbs. Two tires at 40 psig each and with equal share of the total weight results in 10 square inchs of contact area for each tire. Ten square inches area may be represented as 2"wide by 5 " long or 2.5" wide by 3" long or a square with approx 3.17" per side.

FJR at 140 mph [warm day near sea level] and the same static conditions and weight of 800 lbs. Now the wind drag results in lift [on the leading edge] for this study the front, the lifting rotates the bike about its CG and loads the back tire. Depending our your favor of drag calcs/method, one will see the dynamic weight is approx 670 lbs. Of which approx 50 to 70 lbs on the front and the rest on the back. The front tire contact area is 60/40 = 1.5 square inches and the rear tire contact patch is 610/40 = 15.3 square inches.

One of the many reasons rear tires are larger than fronts.

rublenoon

 

[Grumpy]

Points for your consideration:
FJR at 140 mph [warm day near sea level] and the same static conditions and weight of 800 lbs. Now the wind drag results in lift [on the leading edge] for this study the front, the lifting rotates the bike about its CG and loads the back tire. Depending our your favor of drag calcs/method, one will see the dynamic weight is approx 670 lbs. Of which approx 50 to 70 lbs on the front and the rest on the back. The front tire contact area is 60/40 = 1.5 square inches and the rear tire contact patch is 610/40 = 15.3 square inches.

One of the many reasons rear tires are larger than fronts.

rublenoon

Maybe not? Windshield up and built in aerodynamics could be putting more force down on the front end? Unknown at this point.

 

[zorkler]

contact patch *%$##$&* who gives a &^%$#* at that speed