Author Topic: Going to the Darkside.  (Read 18534 times)

Offline VirginiaJim

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Re: Going to the Darkside.
« Reply #20 on: March 17, 2016, 12:05:36 pm »
+1
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Offline datsaxman@hotmail.com

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Re: Going to the Darkside.
« Reply #21 on: March 19, 2016, 01:34:55 am »
SHEESH. 

My 2008 C14 with the CAR TYRE on it and the "REAR ONLY" tyre on the FRONT is parked outside in the hotel lot as I type this.  Guilty as charged.  Still. 

Feel free to ignore the comments from folks who have no experience with running a CT, but seem pretty sure they know ALL ABOUT IT.  Hell, ignore this post if you like.  But I have well over 100,000 miles on CT in the last five years alone, so maybe you will find something useful here.  I do not know it all, but I am a scientist at work and when I got interested in "the CT thing", I read everything I could find, started talking to everybody that had tried it, and started measuring tyres and such. 


First, the rear tyre on the front thing.  The idea is to find a REAR tyre in the FRONT size.  Folks, read that a few times before you get out the flamethrowers, ok?  The main difference between F and R?  NOT the rubber compounds...NOT the carcass construction...sometimes the tread patterns are similar, sometimes quite different...the main difference is the tread is much thicker on the REAR.  So you put a REAR (in the correct front size) on the FRONT in order to extend tire life.  I have a 130/70R17 right now.  Yeah, I know...

Next, the main event...CAR TYRE on a C14.  I have two C14s.  Pirelli Angel GTs on one, Bridgestone BT45 REAR on the front, and the evil CT on the rear of the other.  I have almost 80,000 miles on CTs on the C14, and ran a CT for over 35,000 on my C10 before that.


There are lots of "FAIRY TALES" about contact patch size and shape, rim shapes. tyre sizes, safety,  cornering, and $$.  Some of them are already in this short thread.  There are a few facts, too.  The 100,000 miles is a fact.  We live in the mountains, so EVERY ride begins and ends with high speed twisties.  I wear out the edges on the fronts and throw away lots of center rubber every time.  I ride at a pretty good pace, but do not race on the street.  Wore another set of footpegs out last year and had to get new.  (the CT and the REAR on the front are taller than stock, so there is even more ground clearance than stock!).  I do not ride like a beginner or somebody on a bike that can't corner decently.  Or a guy on a Gold Wing.  The CT does not handle like a Moto Tyre, but it is not so different either.  It takes a little getting used to.  I ride a lot, and do not own a car.  All weather, even when that kinda sucks.  The CT is the least of my worries.

I can go around corners as fast as I want to anytime, and I usually like faster better than slower.

Facts! 

I do not run a CT because I am cheap, but because the heavy duty carcass is so strong.  After my last two Moto Rears picked up nails, and then failed SUDDENLY, in the dark, a long way from home, I decided to take a chance and try the CT for a long distance competitive rally I was going to be doing.  I expected the CT to suck, and to be a bad idea, and to change it out right after that rally.
But I tried it anyway.  You can see how that worked out...

I expect the CT will stay on the rim a lot better than a Moto Tyre in the event of a sudden blowout (that last bit is opinion).  But I have not had such a blowout.  My last CT had three small nails in it when I took it off.  I did not even know they were there.  Still had about 2mm tread depth, but it was time for a new one.  It still held air, and I had gotten a little too comfortable with the reliability of the CT.  I have to remember to check the CT all the time so that does not happen again.  A Moto Tyre might have been fine like that too, but I expect it would have blown out on the interstate from the first nail.  I REALLY hate getting flats at night, or in the rain, or a long way from home.  I carry a compressor, sealant in a can, and "gummy worm" tyre plugs all the time.  I only seem to use them on Moto Tyres on other people's bikes these days. 

I have begun to think of the CT as "a better, safer tyre that lasts a long time".  It stopped being an experiment a long time ago.  The CT rubber is actually SOFTER than any of the Moto Tyres I have measured (flame me after you have measured lots of tyres with a durometer like I have, ok?).  A physicist will tell you that softer rubber will give you more traction, and that the tyre contact patch size and shape DO NOT MATTER ONE BIT. 

I AM a Physicist. 

I measured tyre contact patches on the two C14s.  One with the CT, one with the Angels.  The contact patches are almost exactly the same size for both C14s (no surprises there).  Then I got some heavy tie downs to hold the bike up, and measured the contact patches with the C14s leaned over.  Not exactly like flying through a corner at speed. but I had a budget of $0, and an afternoon, and some quadrille paper.  I was a little surprised when the contact patch went from short and wide to long and thin as I pitched the C14 with the CT over, AND STAYED THE SAME SIZE.  No matter what the angle!   

Oh, by the way... I (still) DO NOT RECOMMEND RUNNING A CAR TYRE ON A MOTORCYCLE TO ANYBODY.  You should probably take your C14 to the Kawasaki dealer and have them put on approved tyres in the correct sizes every time. 

I do recommend making informed decisions, not based on hysteria. 

Folks can say what they like, but lots of folks are just making **** up.  Which is fine, but you should know that.  The stuff you will hear about contact patches and tyre edges and traction is mostly just guessing, and mostly just wrong.  But it is late and I have posted all that on this forum before.  Search for it if you like, or send me a message if you want to read more.


dat
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Offline T Cro ®

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Re: Going to the Darkside.
« Reply #22 on: March 19, 2016, 05:52:57 am »
Great post datsaxman....

Tony P. Crochet
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Offline gPink

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Re: Going to the Darkside.
« Reply #23 on: March 19, 2016, 06:46:37 am »
Yes it is. Makes me wonder why they even manufacture motorcycle specific tires at all any more.
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Offline T Cro ®

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Re: Going to the Darkside.
« Reply #24 on: March 19, 2016, 08:46:03 am »
Yes it is. Makes me wonder why they even manufacture motorcycle specific tires at all any more.

For the 99.7 % of the riders who would prefer a properly fitted tire you silly rabbit....
I'm most appreciative that at least it is from actual use and not repeated mantra...
Tony P. Crochet
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Offline Conrad

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Re: Going to the Darkside.
« Reply #25 on: March 19, 2016, 08:48:36 am »
Yes it is. Makes me wonder why they even manufacture motorcycle specific tires at all any more.

For the 99.7 % of the riders who would prefer a properly fitted tire you silly rabbit....
I'm most appreciative that at least it is from actual use and not repeated mantra...

Just a guess on my part but I'm thinking that Mr Pink's statement above is/was dripping with sarcasm.    ::)     ;)
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Offline martin_14

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Re: Going to the Darkside.
« Reply #26 on: March 19, 2016, 12:47:25 pm »
The CT rubber is actually SOFTER than any of the Moto Tyres I have measured (flame me after you have measured lots of tyres with a durometer like I have, ok?).  A physicist will tell you that softer rubber will give you more traction, and that the tyre contact patch size and shape DO NOT MATTER ONE BIT. 

I AM a Physicist. 

I measured tyre contact patches on the two C14s.  One with the CT, one with the Angels.  The contact patches are almost exactly the same size for both C14s (no surprises there).  Then I got some heavy tie downs to hold the bike up, and measured the contact patches with the C14s leaned over.  Not exactly like flying through a corner at speed. but I had a budget of $0, and an afternoon, and some quadrille paper.  I was a little surprised when the contact patch went from short and wide to long and thin as I pitched the C14 with the CT over, AND STAYED THE SAME SIZE.  No matter what the angle!

I'm not a physicist, but an engineer, but I'll tell you the same: contact patch size and shape do not matter for grip... theoretically, in static conditions. When the wheel is rolling, drag, drift angle, temperature and a few other factors (to give you a hint, a computer model of a tire has around 300 factors, some measured, some calculated) influence the grip and hence the outcome of your cornering.

Pros don't use car tires. Just like ophthalmologists don't do lasik.

Another bit of anecdote: when a new bike is about to go on sale in Germany, it is released with a couple of tire models, which are selected among a pool of at least 3, but usually 6 different tires. The test drivers can tell the minute differences between those tires. Warm up times, drift characteristics and low and high speed stabilities are just a couple of 70 or so different things they look at.
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Offline Deziner

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Re: Going to the Darkside.
« Reply #27 on: March 19, 2016, 01:46:04 pm »
I'm not a highly educated guy but I like to think that I have a bit of sense, so I am confused. If contact patch size has little to no effect, why do high performance vehicles have comparably larger tires? I understand that a smaller, stickier tire could conceivably have better traction than a larger "slicker" tire. Given 2 tires of equal rubber compounds, wouldn't the tire with a larger contact patch afford better traction? If not, why would race cars not use skinny tires to reduce wind and rolling resistance?
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Offline just gone

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Re: Going to the Darkside.
« Reply #28 on: March 19, 2016, 01:46:55 pm »
Great post datsaxman....

I'm most appreciative that at least it is from actual use and not repeated mantra...

+2

Offline Deziner

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Re: Going to the Darkside.
« Reply #29 on: March 19, 2016, 02:03:16 pm »
I was also involved in the custom motorcycle industry when builders were putting those ridiculously wide rear tires on bikes with really narrow front tires and it was learned that due to the huge difference in the radius of the tread area handling anomalies abounded. (Don't bother to rant about how ill handling those types of bikes are due to a multitude of other factors. When a tire with a tighter tread radius was installed the bike handled better.)
God does not subtract from a man's life the number of hours spent riding a motorcycle

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Offline PH14

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Re: Going to the Darkside.
« Reply #30 on: March 19, 2016, 02:13:27 pm »
I'm not a physicist, but an engineer, but I'll tell you the same: contact patch size and shape do not matter for grip... theoretically, in static conditions. When the wheel is rolling, drag, drift angle, temperature and a few other factors (to give you a hint, a computer model of a tire has around 300 factors, some measured, some calculated) influence the grip and hence the outcome of your cornering.

Pros don't use car tires. Just like ophthalmologists don't do lasik.

Another bit of anecdote: when a new bike is about to go on sale in Germany, it is released with a couple of tire models, which are selected among a pool of at least 3, but usually 6 different tires. The test drivers can tell the minute differences between those tires. Warm up times, drift characteristics and low and high speed stabilities are just a couple of 70 or so different things they look at.

I don't know...my eye doctor had lasik done.  :stirpot:

Offline datsaxman@hotmail.com

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Re: Going to the Darkside.
« Reply #31 on: March 19, 2016, 09:09:08 pm »
Lots to do, and little time right now...here we go...in no particular order...

First, I am ALWAYS impressed and glad that the collective response to the CT thing is so...civil.

THANK YOU ALL FOR THAT.  It matters, and is appreciated.

** Wide Tyres: For straight line stability, for longevity (lots of very sticky rubber), etc.

** Why Don't Racers Use CT If They Are So Great?  Non Sequitur!  Race bikes have no lights, brakes and tyres that are wasted after 40 minutes, cannot idle without overheating, etc.

** Lots Of Variables To Traction: The most important are 1) Coefficient of Friction between the two materials in contact (how sticky the tyre is here, plus how rough and clean the road is)...2) Normal Force pushing the two surfaces together (the weight on the tyre here).  The other zillion variables are essentially noise here.  This is not NASCAR or NHRA, but street touring motorcycles, possibly being ridden vigorously. 

** Wide Tyres Do Not Handle As Well As Skinny Tyres.  TRUE.  The difference between a shagged front and a fresh one is WAY MORE than the difference between the CT and a Moto Tyre.  That is my opinion.  yours may not agree.  Assuming you have tried a CT.

As always, I heartily recommend you only run the officially sanctioned tyres available at your local Kawasaki shop, and have all tyres and replacement parts installed by them as well. 
DO NOT RUN CTs ON MOTORCYCLES!!


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Offline MAN OF BLUES

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Re: Going to the Darkside.
« Reply #32 on: March 19, 2016, 11:23:45 pm »
Lots to do, and little time right now...here we go...in no particular order...

First, I am ALWAYS impressed and glad that the collective response to the CT thing is so...civil.

THANK YOU ALL FOR THAT.  It matters, and is appreciated.

** Wide Tyres: For straight line stability, for longevity (lots of very sticky rubber), etc.

** Why Don't Racers Use CT If They Are So Great?  Non Sequitur!  Race bikes have no lights, brakes and tyres that are wasted after 40 minutes, cannot idle without overheating, etc.

** Lots Of Variables To Traction: The most important are 1) Coefficient of Friction between the two materials in contact (how sticky the tyre is here, plus how rough and clean the road is)...2) Normal Force pushing the two surfaces together (the weight on the tyre here).  The other zillion variables are essentially noise here.  This is not NASCAR or NHRA, but street touring motorcycles, possibly being ridden vigorously. 

** Wide Tyres Do Not Handle As Well As Skinny Tyres.  TRUE.  The difference between a shagged front and a fresh one is WAY MORE than the difference between the CT and a Moto Tyre.  That is my opinion.  yours may not agree.  Assuming you have tried a CT.

As always, I heartily recommend you only run the officially sanctioned tyres available at your local Kawasaki shop, and have all tyres and replacement parts installed by them as well. 
DO NOT RUN CTs ON MOTORCYCLES!!


dat
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 :stirpot: :popcorn: :popcorn:

as I put Tires on my bike, and ride on Tires
I have to say your post is kinda spot on...
especially because the term I use for those doughnut things is not spelled with a "Y".. I use tires, not Tyres..
so there is no "Y" in my choice of what to mount.
I do not need to experiment to find something.
I have enough sense to make a decision, based on dimensional facts, and design intent, and fully knowing that even though you CAN spoon a car tire onto a Bike rim, the seal area of the rim, was not designed for the dimensions and intimate mating of a car tires dimensions relating to that bead area.
yes, I actually ran a car tire on my old Harley.. back when.
Putting one on a modern bike is kinda moot.

thanks for your test results, and if one person can change mindset of a populace, it goes a long way.

I do agree on your safety statement " DO NOT RUN CTs ON MOTORCYCLES!!"

so, there it is in a nutshell... :thumbs: :deadhorse: :hitfan: :stirpot: :deadhorse: :thumbs: :chugbeer: :doh: :doh: :doh: :hitfan:

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Offline martin_14

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Re: Going to the Darkside.
« Reply #33 on: March 20, 2016, 05:14:27 am »
so... tires or tyres?
Y'm so confused...

Regarding Deziner's question about why some things are done in a particular way in competition, it has a lot more to do with regulations of that particular motorsport than with what is needed on the street, for layman like you and I. An F1 car (I have no clue about Nascar or such) idles at 4000 rpm, so that'd give you an idea of how purposeful those vehicles are, and how useless they become as soon as you take them out of the environment they are meant to be in. Another tidbit of F1 cars: 50% of the suspension travel comes from the tire itself (look at the high sidewalls). And so on. You can't really take things from competition and straight on the street. That's why I said "pros" don't use CTs. I'm sure there are advantages to CTs and they could be used in some type of competition. But on the street... for us...
All that said, I'd love to ride with datsaxman and see what I might be missing, to be honest.
« Last Edit: March 21, 2016, 12:48:27 pm by martin_14 »
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Offline VirginiaJim

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Re: Going to the Darkside.
« Reply #34 on: March 20, 2016, 07:03:22 am »
This has kinda morphed into a general CT thread so I'm moving it over to the Open area..
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Offline datsaxman@hotmail.com

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Re: Going to the Darkside.
« Reply #35 on: March 21, 2016, 05:39:37 pm »
Martin,

Great idea!  That is quite a commute though...


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Offline datsaxman@hotmail.com

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Re: Going to the Darkside.
« Reply #36 on: March 21, 2016, 05:57:37 pm »
Yes, the only real factual concern I had about the CT - spell it whichever way you like and it changes nothing - was the bead retention area of the wheel.  Simply put, the car wheel is a different shape from the MC wheel.  Each has a standardized shape, and the round rubbery pneumatic thingies are designed to take advantage of the shape. 

** Also, as a separate issue of no concern to Concours owners, 15" car wheels are actually different diameter than MC wheels.  It is a small small difference, but I would be very concerned with 15" fitments.
**

Bottom line, I tried the CT on the moto wheel.  YES, I WAS VERY NERVOUS ABOUT BEAD SHAPE DIFFERENCES!!  Again, a lot of miles later, there have been zero problems. 

They do not leak enough to say so.  I check pressures every week or so.  Sometimes it needs a few PSI and other times it does not. 

The CT is not difficult to install.  Some folks tell scary stories about CTs - or even MTs - not seating and exploding at shops with very high inflation pressures.  NEVER overinflate ANY pneumatic CT or MT.  Pressurized air is a BOMB, looking to explode if you are not careful.  Big truck shops have heavy steel inflation cages, and explosions HAPPEN.  I put the pneumatic thingies myself with four 18" irons, rarely needing them all (but always needing three), and Ru-Glyde for the slippery stuff.  The CTs always seem to seal right away, 40-45-50 PSI maximum.  I run the CT at 40-45PSI, as it does not seem finicky about exact pressure.  Some folks say it is hard to get a CT mounted on a moto wheel at a shop, but I already have been putting the MTs on the moto wheels for too long to worry about it. 

Anyway...and as always...thanks for the discussion, and the several PMs. 

Purolator PSL 14610, Rotella T6.  Hahahahaha....


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Offline gPink

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Re: Going to the Darkside.
« Reply #37 on: March 21, 2016, 06:28:27 pm »
I've gotta say...this has been one of the most civil car tire threads I've seen.
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Offline maxtog

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Re: Going to the Darkside.
« Reply #38 on: March 21, 2016, 07:23:58 pm »
I've gotta say...this has been one of the most civil car tire threads I've seen.

+1
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Offline Rhino

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Re: Going to the Darkside.
« Reply #39 on: March 22, 2016, 05:14:27 am »
I've gotta say...this has been one of the most civil car tyres threads I've seen.

FIFY  ;D