The terrain I am riding on usually dictates the amount of tire pressure i run. Car or bike tyre .Any where from 15psi to 35psi . Cheers Ian
Don't shut up QUITSTIK you have made some interesting comments. Good discussion can help us all to think more and learn more. No One is beyond learning and ANYONE who thinks they know it all is obviously deceived in a bad way .
Thanks Clude, I do enjoy the debate. Before I continue let me state that I am NOT against car tires on motorcycles, in fact I am an advocate. I have been a member of the darkside since '07. Let me give you a little back ground info, in '09 I was involved in an accident on my motorcycle. It was one of those situations that as an MSF instructor I had always tried to avoid and taught to the students to do the same. NEVER get caught up with a large grouping of cars and NEVER allow yourself to get boxed in with no out. I was on a four lane road with a speed limit of 55mph and had passed through a controlled intersection that is notorious for bad accidents. As is my normal habit I was in the left hand lane to avoid cagers that have a tendency to pull out in front of you with no regard to safety. It was at this point that I became boxed in with traffic on all sides, there was a car in the turn lane going in my direction that was acting erratic. I had a safe margin between myself and the car in front of me, in fact I had slowed down to about 35-40mph when suddenly the car ahead veered into the right hand lane cutting off another vehicle. A pickup truck had stopped in the left travel lane in an attempt to make a left hand turn even tho there was a turn lane available. I hit both brakes in a controlled manner but even at the low rate of speed and about three car lengths I managed to slam into the back of the pickup rather hard. Had it not been for the fairing that I had installed on my bike I would have ended up in the back of the pickup but as it were, I was tossed backwards by the fairing. The bike, a '98 Honda VT1100C with saddle bags and a car tire on the rear. Everything on the bike was in perfect operation including the brakes front and rear. In the course of braking I had bent the rear brake lever. At the time of the accident I had been riding with the car tire for over two years and 30K miles in all types of weather including snow and ice so I felt confident in my abilities and those of the tire/bike. Now as to the cause. In my research I have come to the conclusion that it was a lack of hysteresis. Hysteresis is one of those things that tire manufacturers take into consideration when designing a tire. Heat in a tire is not necessarily a bad thing in fact it is needed but to much and the tire breaks down faster, to little and the coefficient of friction for the tire pretty much goes out the window. The later was the case for my situation. I was ten miles from the house on a good dry clear road traveling at the posted speed limit of 55mph. Under normal circumstances with a bike tire on the rear at the speed I was traveling just before the accident the tire would have reached a normal operating temperature and stopping would have been achieved. Hysteresis is the act of deflection/deformation that a tire goes through when rolling that creates heat in the tire that will result in a normal coefficient of friction between the tire and road surface. Most people do not notice this when driving but you do not need to apply the brakes to slow a vehicle down on a flat road. Friction will slow you down considerably just from the weight of the vehicle, rolling resistance of bearings and of tires on tarmac as well as other factors. A car tire is designed with hysteresis derived from the weight of the vehicle and tire pressures. When you keep all things constant but remove just one element from this equation all other factors become moot. We can all agree that a motorcycle, even with a hack and a full load will never exert the pressures on a car tire that a car will, unless of course you have a pachyderm as a monkey. My point of this lengthy dissertation is that when one variable is changed another must change along with it to keep the values constant. The variable that we change by the very nature is weight/force on the tire, to match that, tire pressure must change to bring some balance back into the tire design.
I did not mean to label you as anti car tire quitstik, your info's great, and your temp thesis is good also, now I just gotta get some weight on my 17 pound Mini Schnauzer Justin LOL.DB
Googled Hysteresis in tires, los of interesting reading, Wiki's seems the best easiest:http://en.wikipedia.org/wiki/Rolling_resistance I ended up with 29 front and 28 rear at the end of today's ride, the radials seem to deform about the same however much air's in them example 16-28 look about the same but I can't be sneaking over ugly rocky places without some air in the tire, I think I'd be courting disaster.DB
Thanks Dave. Your rig/tire setup is the schnizzle. When I grow up I want a setup like that. Seriously, I would love to build a rig with nothing but car tire contact patches, I have even contemplated building one from the ground up.
There's much to think about here. I was once into rally cars. Mostly in the 60s. We learned fast about the European tires not lasting but helping the little cars stay planted. At the time some thinking was all about mere tread design or the actual pattern of the cuts in the tire's contact area. The term ''tire compound'' changed our thinking. I once believed that only extreme riders needed extreme tires. Well once a very careful rider finds themselves in that split second extreme riding crash NOW situation, then we all become that extreme rider. Here we are trying to use a tire on a lighter vehicle than it may have been designed for. We do so wanting to ''look cool'', get more miles between tire changes & even thinking we are going to be safer out there waiting for that ''extreme riding'' experience that is waiting for us just around the corner or at that intersection. Maybe more contact is not better....w/o the other factors which we forget we do not have on a sidecar. Having sat through a few lectures about asphalt abrasive factors in auto accident collision investigation, I can say paved surfaces are not all alike & even surface temps will affect any tires ability to ''grip'' the surface we pass over. For me, the bottom line is be careful, I'll not trust in my tires to correct my riding ignorance. Much thanks to '' guitstik ''
The one thing I've figured out about sidecars is that (with the exception of Urals that come from the factory with a standard setup) it's a world of customizations and trial & error. That's one of the things I love about hacking. I rarely see another hack here in New England, but when I do me and the other driver invariably compare notes and tales. The power of my GSA can easily overwhelm the front MC tire, and several times on spirited rides I've felt it skitter sideways a bit. That style of riding also wears them down prematurely. Sure, I could slow down and could have gone with a slower rig, but it's what I do for fun. Look cool? Hardly! I love the look of spoked wheels on my rig. But I don't like having to source a replacement front tire halfway thru my summer adventure, and I don't like worrying if the nearly bald tire will get me home from Iowa especially if the weather turns sour. I don't think any of us are looking at car tires to "correct our riding ignorance" as you so delicately put it. Rather we are looking at the challenges we face and are making risk-based decisions to better meet our needs. I'll never ride without a helmet and other protective gear, but I'll not tell a helmetless rider he or she is wrong. I figure they went thru a similar risk-benefit analysis and reached a different conclusion. Or that my years serving in a military ER colored my way of thinking a bit. At the start of every riding season I repeat the exercises in the Yellow Book, practice evasive maneuvers and emergency (never panic) stops. When I get the car tire setup on my front end I'll do it all over again to learn how the change impacts handling before heading out on public roads. My safety is my responsibility.
Come on Wolfie lighten up a bit ! You own a Buell and I believe almost every model Eric designed had a safety recall ], at least you got the best of the breed the Austro-Canadian motor.This is motorcycling or a branch there of, Hannigan is probably the only one of the US manuf who could defend his design in a court of law if he had too.The Euro rigs are much more sophisticated have big tires, sidecar wheel drive, centerhub steering, builders who have there designs certified by the EU, our stuff looks like junk in comparison.Am I the only one who looked at this thread ?:http://www.advrider.com/forums/showthread.php?t=779654&highlight=smiling+swordfish We even have folks who tell their sidecar customers that big tires and swaybars are dangerous, we'll leave them nameless as they only issue these cautionary tails in their shop not on public forums. We are either a large group of cheap bastards,scared of our own mortality, or rugged individualists looking for adventure. or crashing bores !!!!!!!!! If you end up with a boring miserable life because you listened to your mom, your dad, your teacher, your priest, or some guy on television telling you how to do your shit, then you deserve it. ― Frank Zappa The fear of death follows from the fear of life. A man who lives fully is prepared to die at any time. ― Mark Twain No offense meant just checking to see if any of you guys are awake.DB
http://insideracingtechnology.com/tirebkexerpt1.htm THEN: Hysteretic Losses in Rolling Tires P. R. Willett 1 1The Olympic Tyre & Rubber Co. Pty. Ltd., Melbourne, Australia Abstract A relationship between the observed energy losses for a tire that has reached a state of thermal equilibrium when operating at a constant speed, and the viscoelastic properties of the tire components has been formulated. The analysis was carried out by systematically varying tire components and operating parameters, using the Vibron Viscoelastometer and tire test wheel dynamometer. The investigation was carried out for 6.95–14 cross ply passenger tires. From the derived dependence of the tire energy losses on viscoelastic properties, the effect of changes in tire tread compound, ply rubber and tire cord on the tire energy losses can be predicted. This enables the design of a tire with the properties to meet desired service characteristics. Dunno about all this but this ol racer has been around a few rings over the years. This discussion can be a good one and Not a bad thing but.....We are talking sidecars here on this forum. I doubt very seriously if anyone is going to travel too awful far off into" Hysteretic land" without getting hysterical about it. Honestly There Is No offence meant here but we need to get real.
Claude, this is about "getting real". You happened to pull that excerpt from a paper on racing tires, what about the study they did in that same year about the drastic tire failures at the Brickyard 400? Hysteretic's is not JUST about race cars but about ALL tires even motorcycle. Here is an article about bicycle tires http://www.schwalbetires.com/tech_info/rolling_resistance . As a tire rolls it deforms the faster it deforms because of speed causes an oscillation in the tire deformation and contraction along with rolling resistance creates heat. This heat is good because it allows for traction but to much heat causes the chemical chains in the tire compound to break down leading to degradation. Let me postulate this idea, "I am going to go out and slap any old sidecar on just any old motorcycle and not worry about all that "junk" about lead and toe or steering angles". In all reality that would just be foolish for someone to make a flat statement such as that because of all the implications that would go along with it. I bet you could give me whole litany of reasons NOT to do that and I would listen. I am not telling you to listen to me but just hear out some of the ideas that apply. I believe that there were several factors that lead up to my accident. When I first put the car tire on I ran it with 35psi and gradually lowered it to get a ride that I felt comfortable with. There was a learning curve that I was going through not only with the pressures but with the car tire its self, meaning that I was extremely cautious. When I finally settled on the pressure I was happy with (12-16psi) I ran it that way for over two years so I was extremely comfortable with it. By the way all of this came from the experienced riders on the darkside.com site. At the time of the accident I had just started to do some empirical testing of pressures and related temperature so I had 35psi in the tire again. I would run it at that pressure for a week and check the temp after my 35 mile ride (going to work). The idea was to drop the pressure each week keeping track of ambient temps and tire temps/pressure and graph the results. I figure that what happened is that I had become so accustomed to the tire being on the bike that I never thought twice about the drastic change in behavior that the pressure would have. Do not get me wrong, I am not saying that the accident would never have happened if I had been running the pressure I was used to or even had I been using a bike tire, all of this is conjecture but it is an educated one. Another thing to think about, yes we are talking about side cars but also about car tires on bikes as well. Just because we are putting a car tire on does that mean that we MUST run the rated pressure? How about we go ahead and install suspensions from cars as well, after all the tire is considered a suspension component, pneumatic. Talk about a harsh ride, it would probably handle like a cement block. I am not trying to be argumentative or to scare anyone away from using car tires but I would like you (everyone) to think and be aware that there is more to this than just slapping a care tire on your rig and going. By the way Calude, I hope this little debate won't affect me getting a good deal on a side car Wolfgang, Knowledge is a good thing when applied correctly but it can also create fear as well as abuse when not. I became to comfortable and complacent and so I think I was just as much at fault as the tire, maybe more so.
Not dissing your earlier comment in your post but just focusing on the words you wrote below: You wrote: Another thing to think about, yes we are talking about side cars but also about car tires on bikes as well. You may be talking about solo bikes but I am not and after all this is a 'hacks' section here . I am quite sure that you know the lateral forces generated by a dual track vehicle are Not the same as with a single track vehicle. This is why I am Leary of running lower pressures in most cases on sidecar outfit. Nothing against a few pounds up or down but to go down drastically should be avoided. The exception could be in rough terrain at slower speeds possibly but that isn't the point. Safety is number one! You wrote:Just because we are putting a car tire on does that mean that we MUST run the rated pressure? Never said that just said that it is very questionable in most cases with the machines we are dealing with here to drastically drop the air pressure. We do not want to have a tire bead break with a sudden deflation period! You wrote: How about we go ahead and install suspensions from cars as well, after all the tire is considered a suspension component, pneumatic. Talk about a harsh ride, it would probably handle like a cement block. Do you have a sidecar outfit? Have you had one? As far as car type suspensions go it has and is being done. I am kind of surprised you seem to be unaware of this. Some have run and still do run double a frame suspensions. This has been done on the sidecar and the front of the bike. Center hub and what we refer to as true center hub front ends are also quite common. Center hub, for those who may not be familiar with the term means that the steering axis and the center of the tire at ground level intersect thus leaving no scrub radius. The difference between center hub and true center hub only refers to how this zero scrub radius is arrived at but that is another discussion. These types of suspensions are not typically seen on the types of outfits that usually are discussed here. Many of these guys do run lower air pressures but they are also running wider (195's on front and 205's on rear)lower sidewall type tires. Maybe one of my HPS friends here would want to elaborate more on this. You wrote: I am not trying to be argumentative or to scare anyone away from using car tires but I would like you (everyone) to think and be aware that there is more to this than just slapping a care tire on your rig and going. you wrote: By the way Calude, I hope this little debate won't affect me getting a good deal on a side car I do not really see this as a debate actually. Yes, We are in the sidecar business. There are around 7 in this country that do this full time. Most get along very well and try to compliment one another. Products differ here and there but I think I am right in saying that we all try our best to provide a product that is , number one safe and handles well as well as being able to do the job it is meant to do. Shop around...study this and other forums and continue to do some research. Feel free to call any of the sidecar suppliers anytime.
When I read his comment, I interpreted it as being related to spring rate, not component configuration. If you put a car or dump truck spring on a sidecar (assuming same leverage ratio), it's going to be wildly stiff. It's not something anyone would do. A similar thing happens with tire pressure. If you put the "rated" pressure in a car tire on a sidecar, you're going to get a stiffer ride than that same tire on a car. I think a good bit of that scientific study stuff could be condensed down to something fairly simple, though slightly over simplified: The more pressure, the less heat. The less heat, the less traction. Then again, there's the other side of the coin: Too much heat and the tire will come apart. And: Too little pressure, and the sidewall or bead seal will fail. The key is to find that happy place between too much pressure, and too little.
Dave, I thought I did but it seems that I need an interpreter. I guess that my wife is correct when she tells me that I have a tendency to over complicate matters. So now I am going to have to find an alternate way of explaining to my daughter the correct procedure when implementing the vector correction illuminated indicators as she starts learning to drive.
There are scientifc papers that explain those things in simple photon physics and neurological terms: http://www.sciencedirect.com/science/article/pii/S0022437512000047 http://www.zahniser.net/~physics/index.php?title=Turn Signal Interference Of course it's all different for sidecars since they are non-symetrical, so we need a new thread to discuss how best to implement them on our rigs.
Back to the tire pressure and heat issue... A while back I tested a product called Tire Balls. The purpose of this product is to keep you going after you get a puncture. Every minute of lost time is important in racing! The idea is that a nail or other puncture will only knock out one "ball". All the others will shift a bit to take up the gap from a flat ball, and you just keep on riding. These balls are like round inner tubes, but they are made of thin plastic rather than rubber. You pump them up, pop them in the tire, then mount the tire as usual. In my early testing everything was great, no problems! In a later test I was out in the Death Valley area in July, riding dirt and pavement. After a fast run on the pavement I noticed the rear tire seemed to be getting out of balance. It eventually went pretty much flat. I limped back several miles to my truck on that flat rear, pretty much destroying the tire in the process. When I took the tire off the rim, all I found was a huge clump of melted and mangled black plastic. The rear tire had gotten so hot, those tire balls completely melted. The point is, what worked great one day in one set of conditions turned into a complete mess in other conditions. The heat buildup in the tire on pavement on a very hot day turned a good setup into a bad setup. I was probably getting GREAT traction with that hot soft rubber. But take that same setup on a dry but freezing road and I could be sliding all over the place on cold hard rubber. BTW, I think Tire Balls are a great product that works great in the right conditions. My rig and conditions just were not the right place for them.
