Landracing Forum
East Coast Timing Association => ECTA General Chat => Topic started by: wrongway on July 20, 2009, 01:24:35 PM
-
I am sure some of 'all have seen my bike with the car tire running at Maxton. After building the new motor , I wanted to get some miles on it before the race in maine. So I made a video of the rear tire going thru some sweepers near the house to check out sidewall flexing and contact patch.
http://www.youtube.com/watch?v=Xi1shYlklFM (http://www.youtube.com/watch?v=Xi1shYlklFM)
Roy
-
Roy, after seeing that video how do you feel about being under full acceleration and having to lean the bike over like that to stay straight because of a heavy cross wind?
Todd
-
Roy, after seeing that video how do you feel about being under full acceleration and having to lean the bike over like that to stay straight because of a heavy cross wind?
Todd
that isnt an issue at all.... the lean angle on the video is much greater than leaning into a crosswind....
compare the angle between the sidewall and the horizon... the bike is going more than twice the recommended speed for the corner:-) You wont see anyting like that at Maxton
I dont think the lean angle on a crosswind is much more than the lean angle riding on a road with a crowned surface.
I really do have complete confidence with this setup.
Roy
-
What camera is that again? I like the quality of the video.
I know we've spoken about the car tire in the past. I personally feel that it is the wrong answer to the question.
Good luck in Maine, maybe I'll see you there. :-)
Shane
-
What camera is that again? I like the quality of the video.
I know we've spoken about the car tire in the past. I personally feel that it is the wrong answer to the question.
Good luck in Maine, maybe I'll see you there. :-)
Shane
the camera is a winbook 8321... great camera for 70 bucks .
Roy
-
LMAO...... lets see a trip down deals gap.....
kent
-
How dose it feel ? If you did not know the bike had a car tire what would you think of it?
I love the sparks from grinding the header the beginning of the video. :evil:
-
:roll:
-
The 3 fastest bikes on pavement have all ran ran both Maxton and Texas.
They have all 3 proved successful in acceleration, deceleration, crosswind and turning stability.
They all 3 have more then double the horsepower of your Kawasaki.
All 3 of them run readily available off the shelf motorcycle tires.
The two fastest run the same stock sized motorcycle tires that came on your Kawasaki.
The contact patch is considerably less on a car tire then on a motorcycle tire if you lean at all.
I don't see the risk versus reward factor being in your favor, and think you can go faster without it.
Either way, good luck.
Todd
-
From a performance point of view I can't see any advantages. I would think worse handling, less grip, and more drag. Or have you found it to be better than a motorcycle tyre somehow?
-
From a performance point of view I can't see any advantages. I would think worse handling, less grip, and more drag. Or have you found it to be better than a motorcycle tyre somehow?
much better traction compared to a motorcycle tire on any surface except a well prepped dragstrip.
Roy
-
I don't see the risk versus reward factor being in your favor, and think you can go faster without it.
Either way, good luck.
Todd
I wouldnt expect the speed to be any different between the motocycle tire and car tire at loring. Speeds were similar at maxton with both.
But I think I can run a longer wheel base without spinning with the car tire.
Roy
-
:roll:
-
I am sure some of 'all have seen my bike with the car tire running at Maxton. After building the new motor , I wanted to get some miles on it before the race in maine. So I made a video of the rear tire going thru some sweepers near the house to check out sidewall flexing and contact patch.
http://www.youtube.com/watch?v=Xi1shYlklFM (http://www.youtube.com/watch?v=Xi1shYlklFM)
Roy
So, this is what you can possibly expect in shutdown after a 200 mph run, should you take the wrong line and have to adjust it late:
(http://www.warp12racing.com/images/roylean.JPG)
While your plan may be to keep the bike completely upright and perpendicular to the road surface, I am afraid that you will have to lean it to some degree at some point. And it may not be when you plan.
Shane
-
So, this is what you can possibly expect in shutdown after a 200 mph run, should you take the wrong line and have to adjust it late:
(http://www.warp12racing.com/images/roylean.JPG)
While your plan may be to keep the bike completely upright and perpendicular to the road surface, I am afraid that you will have to lean it to some degree at some point. And it may not be when you plan.
Shane
that lean angle in that picture is around 30 degrees and going into a corner. If you had to turn that hard at 200 you would be off track in a hurry. The camera is facing rearward and here is a pic further into the corner
(http://www.zzrbikes.com/albums/WrongWay/D_Side_test_0001.jpg)
the amount of leaning to make a correction would not get the tire on the side like this. I have made a dozen passes at maxton with this setup without any issue, I havent felt uncomfortable going thru the turn onto the runway even with nitrous. The video was to show that the bike was capable of making turns, not just a straight line setup.
Roy
-
Years back I ran a Firestone Drag slick (car tire) on a fuel Kawasaki laydown drag bike. I was fine as it was straight away all the time and then on a run when it got a bit out of shape at the big end, I apparently lost the contact patch because of lean angle and it was a rodeo ride ... "I saw Jesus at a 1000 feet" ... happy ending but I converted to a bike drag tire laid out on a wide rim and it was a world of difference. Car tires have sidewall flex as the they are designed to work in pairs ... be careful with car tires on bikes ...
-
that lean angle in that picture is around 30 degrees and going into a corner. If you had to turn that hard at 200 you would be off track in a hurry. The camera is facing rearward and here is a pic further into the corner
(http://www.zzrbikes.com/albums/WrongWay/D_Side_test_0001.jpg)
the amount of leaning to make a correction would not get the tire on the side like this. I have made a dozen passes at maxton with this setup without any issue, I havent felt uncomfortable going thru the turn onto the runway even with nitrous. The video was to show that the bike was capable of making turns, not just a straight line setup.
Roy
It is good to hear that you have made 12 runs with incident, but that does not prove that the design is safe. It merely means that you have not crashed thus far.
Every machine has a solid safety record up until the point that it doesn't.
I certainly hope it works out well for you. I personally do not feel it is safe for Maxton.
Shane
-
I've never been on a LSR motorcycle so this is just my input, for what it's worth.
Motorcycle tire design and automobile tire design are based on different physics principles, we should all agree on that. Likewise motorcycle rim design and automobile rim design are also based on different physics principles.
I would worry more about the strength and longevity of the motorcycle rim than the performance of the tire (but I would worry about the tire).
Years ago I mounted a 15X10 Indy race tire on a thrust driven bike. The idea was to have an Air Show machine that would race a Bede Jet down the run way.
We were fortunate to run into some very intellegent tire engineers before I rode the bike for the first time.
In this day and age there is no reason to run a car tire on a bike, except for looks. Look at the bike tires that are that are being used in the dragracing Street Bike Shootout class. These shootout tires go from zero to 180 plus MPH in the low 7 second range and the bike have NO WHEELIE bar....no street tire made can offer traction like that on a bike.
If you really want to learn about motorcycle tire construction read the book by Ray Taylor: Motorcycle Tire Basics or follow this link.
http://ezinearticles.com/?Motorcycle-Tire-Basics&id=530176
Good Luck
Buzz
(and if I add a pun.....keep the rubber side DOWN!
-
Roy, I am glad that this setup has worked for you so far, but automotive tires are not engineered to run on their edge like that. Maybe it is ok for running the 1/4 mile but too much can happen in the 1 mile plus we are at speed in Maxton. I also don't see why you feel you need it based on what others are running. I don't know if you are running Loring but I personally would feel better seeing you back on a bike tire in September. I would also like to see a rule change next season that covers this.
-
"""much better traction compared to a motorcycle tire on any surface except a well prepped dragstrip.
Roy"""
guess i should be getting some for the salt.........
wish i would have known of this sooner.....
ps....how did you get your nickname...?
-
"""much better traction compared to a motorcycle tire on any surface except a well prepped dragstrip.
Roy"""
guess i should be getting some for the salt.........
wish i would have known of this sooner.....
ok , maybe not good for the salt .... maybe I should have said "paved surface"
Roy
ps....how did you get your nickname...?
-
Quite few guy on 1800 Goldwings use a car tire on the rear. They seem to like the run flat tire design the best.
And , yes some have been on the Tail of the Dragon with no problems
-
An 1800 Goldwing is a compact car, isn't it? :?
-
An 1800 Goldwing is a compact car, isn't it? :?
Compact car?
-
Roy,
GREAT video!
We have had some pretty strong sidewinds at Texas, but simple solution.
Got a big sidewind, just don't run if there is any doubt of stability (which i know you don't have doubts anyway)
I have run at Texas in heavy 15-20mph gusting sidewinds and it is spooky as hell, AND mph is down.
Better off sitting back, have a few beers and then run when the wind dies down ;)
-
i would much rather have a strong sidewind on pavement versus getting smacked with it on the salt at the 3-4...then the big lean to keep it straight feels almost safe...LOL
-
For me, a steady strong sidewind is OK, not great, but not spooky.
But a strong gusting sidewind makes this ole scairdy cat pucker a bit.
I cannot even imagine what its like on salt.
Don't they stop the races when the wind gets "bad"???
-
For me, a steady strong sidewind is OK, not great, but not spooky.
But a strong gusting sidewind makes this ole scairdy cat pucker a bit.
I cannot even imagine what its like on salt.
Don't they stop the races when the wind gets "bad"???
I think they wait for a couple of cars to spin out due to wind first! :evil:
-
I will post a few more videos this week.
1. on an Interstate changing lanes - this should be more than a correction at the track and show what the contact patch and angle is in a race situation.
2. The same run as the original , but with a motorcycle tire. I am guessing that the motorcycle tire will have a small contact patch.
The reason for this testing was to be able to run a longer wheel base without spinning. Stock wheel base bikes wheelie easily and if the bike is lowered the headers or oil pan take a hit if you come down too hard. Add more power and the wheelies get worse.
I don't think anyone will say that doing tall wheelies on the track is a good idea, and I don't want to tear up my stuff either.
Add some wheelbase and the wheelies aren't as bad , and go far enough , they are impossible. But the problem is that longer wheel base means less traction on the rear and then tire spin is an issue.
At the drag strip this is taken care of with ultra soft compound tires, clean and smooth surface , and allot of rubber and VHT. Soft compound tires don't last long on at Maxton or the street, so unless you want to replace tires often, that is not a great option. And that is how I got to the point where I am trying car tire ....
(http://216.77.188.54/coDataImages/p/Groups/89/89919/folders/48363/2387894web-wheelie.JPG)
-
(http://216.77.188.54/coDataImages/p/Groups/89/89919/folders/48363/2387894web-wheelie.JPG)
Just curious, Roy...what do you think caused the above scenario...not enough wheelbase...or poor control over power delivery? Just something to think about when you are not busy figuring out a way to utilize a dump truck tire. :-D
Shane
-
needs a wheelie bar
-
Not very smart racing a M/C wearing tennis shoes.....but...Hey, what do I know......been only in this game for the last 58 years...
PS. A good pair of gloves would also be a good idea..............................................................................
-
:roll:
-
Roy, I can appreciate your reasoning, and I like your outside-thinking. But what about Rich Yancy's stock-wheelbase, motorcycle-tire, 260mph bike? And Charlie Anstaett's 64", motorcycle tire, 259mph bike? Do you really need the wheelbase? I ran my ZX10 to 225mph at 60" wheelbase without a boost controller.
-
"Don't they stop the races when the wind gets "bad" "
Trouble is -- with 7 or more miles of course, the weather is different in different places. And the old "notch" in the mountains, tho miles away, has an intermittent effect, too.
On another note (and not being one ever accused of termperence) -- having a couple of beers and waiting for the weather to change is a good idea, if you're waiting 'til tomorrow.
Stan
-
......uh never did get an answer as to how Shane got his
nickname...........
Joe
-
Stan, the wind speed is a call we make depending on the type of Vehicle. For stream liner bikes it's 6 mph in a cross wind. For cars 8 to 10 mph. For most others above 12 mph is where we start watching and notifing the starters of the conditions down course.Many vehicle only run to the 3 mile and are not effected like the long course vehicle that the notch does. Most of the fast vehicles alway ask for a report if they think the wind is a problem. ,One thing the drivers and riders must remember a head wind or a tail wind turns into a cross wind when they turn out. Seen many spins dou to this.
-
......uh never did get an answer as to how Shane got his
nickname...........
Joe
Shane=Warp12 or Roy=Wrongway? Thought you were wondering about Wrongway or are you just flabbergasted over the tennies & no gloves while admiring that outstanding display of throttle control? :?
(http://i129.photobucket.com/albums/p224/DahMurf/Smileys/batting_eyelashes.gif)
I know I know..... bad girl... back to your corner! (http://i129.photobucket.com/albums/p224/DahMurf/Smileys/hide.gif)
-
(http://216.77.188.54/coDataImages/p/Groups/89/89919/folders/48363/2387894web-wheelie.JPG)
Just curious, Roy...what do you think caused the above scenario...not enough wheelbase...or poor control over power delivery? Just something to think about when you are not busy figuring out a way to utilize a dump truck tire. :-D
Shane
The camera was in my lane :-o who need a picture with a boring 6" wheelie
Roy
-
Roy, I can appreciate your reasoning, and I like your outside-thinking. But what about Rich Yancy's stock-wheelbase, motorcycle-tire, 260mph bike? And Charlie Anstaett's 64", motorcycle tire, 259mph bike? Do you really need the wheelbase? I ran my ZX10 to 225mph at 60" wheelbase without a boost controller.
I guess the question would be is when are these bike under full power ? I think I saw in one video clip that the turbo bike tune up was backed down from it peak to run at maxton.
Charlie told me he only got 1 or 2 passes per tire when I spoke to him last year. So yeah , they get down the track. But I dont think that means that improvements cant be made.
Roy
-
:roll:
-
I tried a car tire at Bonneville back when we only had wire wheels and tubed tires. The square profile is NOT a good idea. Todays radials are so good there is NO reason to use anything else. You have not had a problem but you are rolling the dice and if you lose, we all lose. I guess the rules should be changed to protect us all. Larry
-
As per the picture......I am wondering what dragstrip would allow him to race a 1/4 mile at speed wearing the gear, (or lack of it) as shown in the picture.......and "Wrongway" if you are stupid enough to race
as shown in the picture.........your opinion or input regarding a "car tire" means nothing to me..............
Sorry, I have a mean streak (just for today....I think)
-
I don't know shit from shinola, but the tone of the remarks about Roy's tire experiment remind me 110% of comments about Bill's 240 when he started using it.
-
I don't know Subaru from shinola, but the tone of the remarks about Roy's tire experiment remind me 110% of comments about Bill's 240 when he started using it.
Bill's bike has went very fast. But I bet a lot of people still feel the same about that tire. Is it for good reason? Perhaps yes, perhaps no. But I don't think that we should wait until a catastrophic failure occurs in order to invoke the critical thought process, particularly when safety is the issue.
Shane
-
Bill Warner's tire is a Z rated MOTORCYCLE tire designed with a radiused sidewall which safely allows lean. Bill has been leaning that bike alot recently with no issues other than he probably would go even faster upright. The square car profile loses contact patch as it is leaned (see video) which is OK until the bike is upset by a bump and then there is no guarantee the tire will allow the bike to self center. I am all for innovation but this is more like Fred Flintstone. :roll: larry
-
Entropy, granted, I'm sure there are doubters of Bill's tire choice however it is still a motorcycle tire. Anyone running over 186mph is pushing the approved limit of the available motorcycle tires as it is. I don't see that Bill did anything dramatically different he just thought outside the box a little and used a wider tire.
The car tire is an entirely different story. In my opinion (yeah I know the @ saying) but he's trying to adapt a tire for use in a manor for which it was not intended as a bandaid to an entirely different set of problems all while there is superior and proven equipment available. Now don't get me wrong, we're all about innovation and fabrication. Heck there's not a metric bike that has left our shop that's not secretly sporting a Harley part {gasp} but never when there is a better, proven, readily available item to be had.
For all we've seen go on at Maxton I just don't get why a car tire would be allowed on a bike at the track. Yeah I get that so far he hasn't gone fast enough for it to matter but it's only a matter of time. Some of our best riders have taken out cones heck some of our not so great riders have too... ahem... but the point being, as was said above, if this little experiment fails as it is destined to do as he continues to try to push the limit, we ALL suffer! The trees are gone, the cross winds are stronger, conditions & the track change not to mention the wildlife. You can't just count on going straight and making one {hopefully} controlled turn.
I don't understand stating that the fastest bikes had to dial it down. What kind of comparison is that? Yes they had to in order to keep the power to the ground and the wheel from spinning so what I wonder is why doesn't he just do that? So far the majority of the riders don't do as well with an extended swing arm at our track because they can't hook up with it hanging out there. Many many people have proven you don't need to launch hard enough to stand the bike up and in fact if you're trying to go fast, standing the bike up only slows you down.
I don't know, I just don't get it. Why where motorcycle tires even designed if car tires were adequate or even superior? How much more horse power needs to be used and how much more speed obtained before the motorcycle tires are proven?
I dunno, maybe I'm just a dumb girl cause I don't get it! :roll:
-
OK , so a superior tire requires a waiver saying that I know I am running beyond its limits , but the car tire is legal by ECTA/SCTA rules on a car up to 225 mph.
The car tire is rated at 1250 lbs at 50 psi
the superior motorcycle tire is rated at 800 lbs at 42 psi
the weight of my bike and rider is 770 lbs . That means that the superior MC tire is running at 96% of its rated capacity and beyond it rated speed but the car tire is running at 61% of its rated load and under its rated speed....
If I have to sign a waiver that I understand I am taking a risk , I would rather be on a car tire.
Roy
-
:roll:
-
the superior motorcycle tire is rated at 800 lbs at 42 psi
the weight of my bike and rider is 770 lbs . That means that the superior MC tire is running at 96% of its rated capacity
Not to pick nits, but unless you are on a mile-long wheelie, your total weight would be divided across both front and rear tires.
In any case, the car tire is rated for a vehicle with 4 wheels that doesn't lean, so I'm not sure it's a fair comparison.
-
I don't have a dog in this fight other than the fact that I would not like to see anyone run and get hurt because of a safety concern that was not corrected before said vehicle was allowed to make it's run.
Seems to me that John and other very experienced riders and inspectors have voiced opinions and concerns.
The last line of defense against any of us starting or making a run with a "potential safety issue" is the tech inspectors and starting line officials.
If I was the guy in the video with the car tire, If I showed up with the car tire to a LSR venue on a bike, I would make sure to have an extra rim with approved motorcycle tire mounted and ready to go,,, as if I read between all the lines,,, that setup poses a "safety concern"...
My advice, don't run the car tire on the bike, and carry a bike tire mounted and ready !!!!
OK I'm outta here....
Charles
-
Not to pick nits, but unless you are on a mile-long wheelie, your total weight would be divided across both front and rear tires.
In any case, the car tire is rated for a vehicle with 4 wheels that doesn't lean, so I'm not sure it's a fair comparison.
I dont know about that , the torque applied to the rear wheel is also trying to lift the nose... Under full power the rear tire has most of the weight unless you have some aero down force or have enough lift to limit the torque applied.
and under most conditions , the car tire on a bike is flat and not leaned over.
here is a video of the bike on a highway crossing 2 lanes. This is more aggressive than the correction on the track so it should give you an idea what the bike will really see on a run.
http://www.youtube.com/watch?v=7oDxk0HkE4o (http://www.youtube.com/watch?v=7oDxk0HkE4o)
Roy
-
Roy,
I enjoyed your video but it was like watching a scary movie, I just kept waiting for something bad to happen.
I believe "nothing ventured, nothing gained". You tried the car tire set up and survived, you sought feed back on your idea and you would be wise to heed the advice from several very experienced land speed racers.
If you want to increase your rear tire's contact patch, you might consider getting a ZR motorcycle tire shaved. It will still have a relatively round profile , there will be greater contact and it will be a proper motorcycle tire for your motorcycle application. Nate Jones supports our sport and offers a quick turn around.
Good luck.
-Scott
-
Sure Roy, there's more weight on the rear than the front tire under power, but not ALL the weight. So the 96% capacity claim is an overstatement. And yes, most of the time the tire is flat. But I think the issue is that some of the time it's not.
I really don't know, it may be perfectly fine to run a car tire on a land speed bike, I'm not a tire engineer. I just don't see the need- people are doing very well with motorcycle tires, so to me it's a suspect solution to a problem that doesn't exist.
Dean
-
I am not trying to convert the Land Speed world, just sharing info on tests. I understand most dont want to go this route, but I am willing to show test runs and share info.
And if there is going to be a rule change before the Loring event , please let me know.
I have not seen any negative results from my runs at Maxton, so I have no reason to change.
Roy
-
I run a very small very low powered bike . The 250cc four stroke. I have thought of using a front tire from a motorcycle on the rear to reduce drag . As it is I run the max recommended tire pressure to get the tire on a point . judging from the dirt on the tire I ride on about three inches of rubber. It looks to me like Roy has a lot more rubber on the ground . BUT he is going twice as fast .
Is the concern hear that the bike will loose control or the tire will fail?
-
i agree w/ most replies; put a motorcycle tire on
your bike . way less chance of any problems.
franey
-
Is the concern hear that the bike will loose control or the tire will fail?
The concern is that the rider will fail with that tire on his bike, where as safe and specific designed tire will allow him the room for error and prep him for higher speeds should he and his bike be able to obtain them.
Todd
-
Is the concern hear that the bike will loose control or the tire will fail?
The concern is that the rider will fail with that tire on his bike, where as safe and specific designed tire will allow him the room for error and prep him for higher speeds should he and his bike be able to obtain them.
Todd
I think I have demonstrated the the car tire is capable of maintaining control in situations more extreme than is seen at the land speed events with the videos. Safe runs at Maxton ( and I am sure there were with alot of eyes on it ) also show that the bike can run down a not-so straight track with no issues. Running a car tire on a drag bike is not a new idea and prostock bikes have run a car slick for decades without any handling issues.
While you may believe that there maybe a potential for not being able to control the bike , I dont think there are any facts support that.
-
your statement...."I think I have demonstrated the the car tire is capable of maintaining control in situations more extreme than is seen at the land speed events with the videos"............
is interesting...........
your obviously speaking from your experience............
which in the land speed world is...?
records...?speeds.....? the only response to your speeds
has been...."very fast"..........define very fast............
...........situations more extreme than seen at land speed events.........really...?
when the rear wheel is spinning.....say when coefficient of friction is exceeded......
and the rear wheel begins oscillating....ie sliding left and or right......what do you
think the edge of the tire does or will do............that video would be enlightening.......
modified to remove inhappy smiley faces that for some reason are automatically generated
to certain keystrokes....
-
your statement...."I think I have demonstrated the the car tire is capable of maintaining control in situations more extreme than is seen at the land speed events with the videos"............
is interesting...........
your obviously speaking from your experience............
which in the land speed world is...?????????????????//
records...???speeds.....??? the only response to your speeds
has been...."very fast"..........define very fast............
I don't think i have ever said very fast. My car is faster than my bike :-)
I did set a naked record in MF/1650 at 189 year before last.
...........situations more extreme than seen at land speed events.........really...??????
when the rear wheel is spinning.....say when coefficient of friction is exceeded......
and the rear wheel begins oscillating....ie sliding left and or right......what do you
think the edge of the tire does or will do............that video would be enlightening.......
I don't think I have ever seen that on pavement ... I do record some wheel spin at maxton , but much less with the car tire. I cant imagine ever running this on the salt.
Roy
-
While you may believe that there maybe a potential for not being able to control the bike , I dont think there are any facts support that.
You're right Roy, and that's one of the reason we have not banned it from being ran yet.
You originally asked me about running this tire last year sometime. I told you there was no specific rule in the book keeping you from it (barring the president, race director, chief tech or chief starter saying no). So I said lets see how you and the rest of the organization feel about it if you're set on running it, just make sure to have a standard motorcycle tire mounted on hand in case we deem it unfit for use for whatever reason.
I commend you for bringing it to light here, although I think your "data" thus far is more harmful then helpful to your cause, and we will continue to discuss and and try to make a final decision on it.
Also remember your reasoning of running it was that you were spinning your tire in 6th gear and needed better traction, I will say again that your bike didn't have enough power to spin a decent motorcycle tire. And I also said that there are many MC tires that will stick much better then that car tire at Maxton due to the course surface and layout, as well as me believing you can go much faster without it for the fact of additional weight early in the run and additional drag at the important end.
At the speeds you've obtained there's no major concern for issues so far as long as your runs are fairly uneventful. Best case scenario is you go continue to go averagely fast for the type of bike you're riding, but worse case scenario is what we're worried about.
Discussion will continue to take place both publicly here and privately with the organization and I will keep you in the loop if something changes of course... thanks again for bringing this issue back to lighta nd do keep that back up tire handy for any reason you may want to decide to use it.
Todd
-
I agree with everything said except that at +9" over , the bike tire will spin.
Roy
-
I agree with everything said except that at +9" over , the bike tire will spin.
Roy
Your bike is 9" over?
-
Regardess of all opinions, you gotta admit that Roy is always thinking.....and he usually goes pretty damn fast........ sometimes the hard way!
Keep it up, Roy, and continue to go fast!
-
I agree with everything said except that at +9" over , the bike tire will spin.
Roy
Your bike is 9" over?
sorry , 8"
I have the roaring toyz 2"-8" extensions.... I try to run it as far back as I can or as far back as I need to to stop the wheelies.
Roy
-
Black hole of knowledge here-- Is there a point at which contact patch begins to resist acceleration even if the bike still making power? Obviously, a car tire on my bike would just mean I could take the side stand off.
-
Black hole of knowledge here-- Is there a point at which contact patch begins to resist acceleration even if the bike still making power? Obviously, a car tire on my bike would just mean I could take the side stand off.
At the drag strip i saw less than a 2 mph change going from the stock setup to the heavier rim and car tire. At maxton I saw no difference in speed.
Roy
-
sorry , 8"
I have the roaring toyz 2"-8" extensions.... I try to run it as far back as I can or as far back as I need to to stop the wheelies.
Roy
At what hp level did wheelies begin to significantly impact your top speed? What was your bike configuration and highest speed achieved at the time you decided to add wheelbase?
-
Roy,
I went 207mph faired and Deb went 209mph faired (and 202mph naked) on less then 215hp with a bone stock wheelbase and we never had the front wheel off the ground on any of those runs. Not only has her bike always ran a standard 190/50-17 motorcycle tire, but it is a Bridgestone OEM STOCK MOTORCYCLE STREET TIRE.
One of Scott Guthries bikes with twice the hp of your bike (conservatively), never broke the tire loose once on a pass that went over 250mph (again, a standard 190mm tire).
Some of the 250+mph runs on Rich Yancy's bike were done with the wheelbase SHORTER then stock!
I know the tires and the run history very well on Charlie's bike, enough to know you heard what you wanted to hear about it only being able to make 2 passes per tire.
What I'm getting at is that the rider is more important then the tire in the situations and justifications you are trying to explain. I think you are trying to put a bandaid on a papercut that wouldn't bleed if you just left it untouched and quit dragging paper across your hand.
Just a couple FYI's concerning wheelbase, wheelies, spinning and rider control.
Todd
-
Some of the 250+mph runs on Rich Yancy's bike were done with the wheelbase SHORTER then stock!
What do you gain by going to a shorter wheelbase, or was this a byproduct of another change for some other reason?
-
I run a very small very low powered bike . The 250cc four stroke. I have thought of using a front tire from a motorcycle on the rear to reduce drag . As it is I run the max recommended tire pressure to get the tire on a point . judging from the dirt on the tire I ride on about three inches of rubber. It looks to me like Roy has a lot more rubber on the ground . BUT he is going twice as fast .
Is the concern hear that the bike will loose control or the tire will fail?
Just out of curiosity, what tires are you running? I would think you would be hard pressed to find a narrower tire than the 125 GP slicks
-
Roy,
I went 207mph faired and Deb went 209mph faired (and 202mph naked) on less then 215hp with a bone stock wheelbase and we never had the front wheel off the ground on any of those runs. Not only has her bike always ran a standard 190/50-17 motorcycle tire, but it is a Bridgestone OEM STOCK MOTORCYCLE STREET TIRE.
I have had similar results to Todd and Deb. Riding Racheal's Turbo, I went 207 and Racheal went 211 mph. The bike is stock wheelbase with a regular old 180/55 Dunlop Qualifier. As for hp, well, enough to go 211 mph. :-D No wheelie's to speak of.
Shane
-
Some of the 250+mph runs on Rich Yancy's bike were done with the wheelbase SHORTER then stock!
What do you gain by going to a shorter wheelbase, or was this a by product of another change for some other reason?
Shorter bike means more weight over the driven (rear) tire.
Better traction..just not for the thread starter, his bike has too much power and needs a sport touring compound car tire for his much slower bike with about 1/3rd the hp of much faster bikes on the same track.
J
-
Just curious....read a little article recently about tire size changes when vehicle weight doesn't change. It basically said that at normal pressures, the contact patch for wider tires doesn't get bigger (to any significant amount) because the patch gets shorter as it gets wider. The explanation said that the vehicle weight (pounds per square inch) actually stays the same if the pressures are similar.
I found it interesting, because in my younger years we learned to run VERY skinny tires (and a little taller) on our 4x4s in the winter snow (grew up in Colorado). We didn't get stuck near as much, and the cars would run much straighter on slippery surfaces.
Wouldn't the contact patch be more dependant on tire pressure, than tire width (assuming there's some curvature in the tread)?
I'm curious to hear what works best for tire pressures (mc tires, on the salt)....I never gave it a lot of thought, to tell the truth, just ran them pretty hard.
Regards, JimL
-
I run a very small very low powered bike . The 250cc four stroke. I have thought of using a front tire from a motorcycle on the rear to reduce drag . As it is I run the max recommended tire pressure to get the tire on a point . judging from the dirt on the tire I ride on about three inches of rubber. It looks to me like Roy has a lot more rubber on the ground . BUT he is going twice as fast .
Is the concern hear that the bike will loose control or the tire will fail?
Just out of curiosity, what tires are you running? I would think you would be hard pressed to find a narrower tire than the 125 GP slicks
I use a 130 70 17 on a 3.50 inch rim I was thinking of going to a 120 70 17 front tire on the rear.
-
I use a 130 70 17 on a 3.50 inch rim I was thinking of going to a 120 70 17 front tire on the rear.
While that tire is numerically smaller, you may find that it has an increased contact patch once installed on the rim. In drag racing, sometimes a smaller than oem width tire is used because it can spread out flatter once mounted.
Just something to consider.
Shane
-
Just curious....read a little article recently about tire size changes when vehicle weight doesn't change. It basically said that at normal pressures, the contact patch for wider tires doesn't get bigger (to any significant amount) because the patch gets shorter as it gets wider. The explanation said that the vehicle weight (pounds per square inch) actually stays the same if the pressures are similar.
I found it interesting, because in my younger years we learned to run VERY skinny tires (and a little taller) on our 4x4s in the winter snow (grew up in Colorado). We didn't get stuck near as much, and the cars would run much straighter on slippery surfaces.
Wouldn't the contact patch be more dependant on tire pressure, than tire width (assuming there's some curvature in the tread)?
I'm curious to hear what works best for tire pressures (mc tires, on the salt)....I never gave it a lot of thought, to tell the truth, just ran them pretty hard.
Regards, JimL
Jim,
Do you happen to have a link for the article?
I remember a similar discussion with Sumner about his weight formulas and motorcycles, but in the end I was still scratching my head. I can't find the thread at the moment.
I do know that contact patch is dependent on tire diameter, taller tire has a bigger contact patch.
-
It wasn't on the net...it was in one of the multitudes of trade papers, magazines, technical junk-mail....that pile up at our regional office. It might have even been in a tire-flyer ad. I agree with the concept that the taller tire has a longer contact patch, but on a round section tire I'll believe it gets narrower...meaning maybe the same contact (pretty close) if tire pressure is the same between the two tires (unless maybe way over-inflated?)
I am convinced that the taller tire seems to track straighter...I got a used motorhome that has 19.5" wheels, where my old one had 16.5"; the tires are really tall and very skinny...and it's a LOT less work to drive straight than the smaller, wider aspect tires were. Of course...it's a big difference between 58mph cruise speed and 158!
This whole concept has me scratching my head, hoping to someday build a lakester and trying to figure out tire sizes. I think I'll go with whatever I can get free or "inifo" as they say in the streets! :lol:
Very interesting thread...still learning I hope.
Regards, JimL
-
It wasn't on the net...it was in one of the multitudes of trade papers, magazines, technical junk-mail....that pile up at our regional office.
It may have been in a racecar engineering magazine - I remember an article on tire size. I will dig through my stack sometime this weekend and see if it is in there.
-
Roy, I found a photo of a pit bike you could build over the winter