Cyrox = a shit and dangerous tyre

[racefactory]

Just want to warn people not to buy the Bridgestone Cyrox tyre.

This has to be the worst piece of shit ever made and bridgestone should be ashamed. Of course everyone feels the rear sliding from time to time and I have put a few down recently to what I thought was cold weather and hard to spot slippery surfaces but today something happened that brought me to my senses...

Tyres warm, lower pressures to bring heat into them, fairly good weather, going around a smooth well surfaced bend at about 60kmh, not turning fast at all, absolutely nothing special with the lean angle... rear end just starts coming around drifting. A real in helmet 'woah shit!' moment.

I have heard Vtec talk about the drifting abilities of the cyrox but never though they could be this shit. Even with shitty stock GN250 tyres i have never had close to such an experience. Stay away from them, they are fucking dangerous...

[White trash]

Funny. I have to dissagree with every single point you've made.

I religiously ran the Cyrox on the back of my VJ21's (I've owned 3 of them) and found them to be without a doubt mint. Especially in winter where you tend to encounter a few wet roads. Only dry weather tyre I prefered was the Yokohama 003. Now THERE was a tyre but about 7 times the Bridgestone price. Horses for courses.

[boman]

Just want to warn people not to buy the Bridgestone Cyrox tyre.

This has to be the worst piece of shit ever made and bridgestone should be ashamed. Of course everyone feels the rear sliding from time to time and I have put a few down recently to what I thought was cold weather and hard to spot slippery surfaces but today something happened that brought me to my senses...

Tyres warm, lower pressures to bring heat into them, fairly good weather, going around a smooth well surfaced bend at about 60kmh, not turning fast at all, absolutely nothing special with the lean angle... rear end just starts coming around drifting. A real in helmet 'woah shit!' moment.

I have heard Vtec talk about the drifting abilities of the cyrox but never though they could be this shit. Even with shitty stock GN250 tyres i have never had close to such an experience. Stay away from them, they are fucking dangerous...

And how old are these tyres you are riding on? Age does evil things to tyres.

[racefactory]

I don't actually know but there is a shitload of tread on them... seem almost new.

[AllanB]

Bowman, saw the avatar, no idea what this thread is about anymore ........

[racefactory]

It's not about riding cock.

[MSTRS]

I don't actually know but there is a shitload of tread on them... seem almost new.

Amount of tread is no indication of the tyre's age, just it's use. Have a look on the sidewall for the Julian code...4 numbers inside an elongated circle. Tell us what they are

[mouldy]

Cyroxs' Bridgestones budget radial for small bikes , seen them worked quite hard round Puke on an NC30 but wouldn't put them on a Gixxer 7 but they I didn't think they made a 180 so have you got an old J then ?

[Ronin]

Amount of tread is no indication of the tyre's age, just it's use. Have a look on the sidewall for the Julian code...4 numbers inside an elongated circle. Tell us what they are


Juilian code

http://image.guardian.co.uk/sys-images/Arts/Arts_/Pictures/2008/05/22/jul460.jpg

[p.dath]

Amount of tread is no indication of the tyre's age, just it's use. Have a look on the sidewall for the Julian code...4 numbers inside an elongated circle. Tell us what they are

+1. Tyres older than 7 years probably shouldn't be used - but they are still sold as "new" since they have never been used.

Been a lot of people having accidents in the USA where the sale of "old" "new" tyres is more common.

[p.dath]

This articles says how to read tyre age, and the danger of using "old" tyres, even if they have never been used.

http://abcnews.go.com/Video/playerIndex?id=4826897

[p.dath]

Tyres warm, lower pressures to bring heat into them, fairly good weather,

This is way outside of my area, so please excuse my ignorance.

When at the track they tell us to deflate our tyres, but that is when we are travelling at many hundreds of km's per hour, accelerating as hard as we can, and braking as hard as we can. We are basically (in my case at least) pushing a street tyre much harder than what it is on the street. So the tyre is running hotter than would it would normally, so you have to compensate by lowerng the pressure to begin with.

My impression is that for normal road use, if you are not accelerating or braking hard continuously (as in applying forces along the length of the bike), you should run at the manufacturer rated pressure. They allow for the tyre to get to a certain temperature, so that it has a certain level of inflation.

If your deliberately underflating the tyre on the street then it may never get inflated to the correct pressure, because there is not enough force to get it hot enough. Sure it may heat faster, but may never get to the intended pressure it was designed for.


As I said, this is too far outside of my area, but do you think underflating the tyre could have impacted its performance while travelling in the 60km/h area you indicated? I would imagine the tyre wouldn't be very hot at all to touch in those circumstances.

[Robert Taylor]

I question such a statement when there is so much relevant information that has not been forthcoming to substaniate bagging the product.

Tyre pressures?

Age of tyres ( as has been questioned )

Suspension setup ( which has more of an impact on ultimate grip and rider feel than many people realise )

And a myriad of other factors that knowledgable and experienced readers may come up with.

A few years back we had a customer who complained that the tyre we fitted to his bike was faulty. We had recieved only the wheel to change the tyre. We insisted on checking the bike and found that the twin shock rear end had lost much of its damping and that the bike was using up 70% of its rear stroke as it was being ridden two up most of the time with some luggage on predominantly rough roads. The suspension was therefore frequently bottoming out and frequently overloading the tyre.

He got his way with a replacement at manufacturers cost as he was prepared to make a lot of noise to anyone that listened even though it was proven beyond all doubt what the root cause of the problem was.

My point being that tyre problems are very often caused by suspension. Also changing to a different brand of tyre can often dictate a quite different suspension setup.

It is my opinion that tyre manufacturers are all too often unfairly maligned.

[vtec]

Horses for courses. Had a BT090 on the front and a Cyrox on the rear the first time I ever went on the track, at Pukekohe on my CBR250RR about 5 years ago. Gave good notice of slides but not much grip. Probably fine for most road users on the road. I only run good stuff on sportsbikes now, because I don't like having to allow for average grip.

[Owl]

We are basically (in my case at least) pushing a street tyre much harder than what it is on the street. So the tyre is running hotter than would it would normally, so you have to compensate by lowerng the pressure to begin with.

Sounds a little "back to front" to me? Less pressure should = more heat.

[p.dath]

Sounds a little "back to front" to me? Less pressure should = more heat.

The tyre is designed to run at an ultimate level of pressure to get the right shape. The manufacturer has to estimate how hot the tyre is going to get, subtract off that estimate, and that becomes the recommended cold tyre pressure.

A street tyre on the track is going to get much hotter, and would end up being over inflated. Hence the need to deflate the tyre before you begin, so it runs at the correct inflated hot pressure.

Deflating a street tyre for use on the street indicates you think the manufacturer has miscalculated the running pressure and expected heat. Possible, but in this case we were only talking about 60km/h zones. Not really much possibility to develop a lot of heat.
So sure, the under-inflated tyre may heat more rapidly, but probably wont get to the correct operating pressure as it will never get hot enough.


I'm not a tyre expert, but the manufacturer who designed my tyre is, so personally I'll stick to using the recommended pressure on the street.

[MSTRS]

Rule of thumb is a 10% increase in pressure from cold to hot. If you are getting less than 10% then your cold pressure is too high. And vice versa.
More heat tends to mean more grip, and I believe that is the reason for dropping pressures for track use. The trade-off is your tyre/s wear noticeably on the track.
Manufacturer's recommended pressures are more to do with tyre life than the best grip.

[Robert Taylor]

The other thing to consider is riding on wet roads, the tyre pressure has to be high enough to keep the rain grooves as clear and as functional as possible.

[Owl]

So sure, the under-inflated tyre may heat more rapidly, but probably wont get to the correct operating pressure as it will never get hot enough.

Don't take my word for it and do your own experiment. Run your rear tyre with very little pressure and go for a ride. Then see for yourself which tyre gets hotter!

[Neshi]

not sure you understand what he's saying.. You could let the bike run on nothing but rubber, and that would get hot as hell.. doesn't mean it will get the right amount of pressure in the tire now will it?

there is the combination between the volume of air that goes into the tire + the heat of the rubber (and thus the air inside, which expands) = tire pressure, and grip.

[Robert Taylor]

not sure you understand what he's saying.. You could let the bike run on nothing but rubber, and that would get hot as hell.. doesn't mean it will get the right amount of pressure in the tire now will it?

there is the combination between the volume of air that goes into the tire + the heat of the rubber (and thus the air inside, which expands) = tire pressure, and grip.

In road racing we play with pressure all the time to manipulate tyre temperature and grip. If ( within sensible limits ) the tyre pressure is lower the tyre is more ''busy'' flexing and distorting under acceleartion and bump inputs etc. That raises core temperature. During winter racing we will also very often go to FIRMER springing and valving calibration to work the tyre even harder to get some more temperature into it. Lower temps equal less grip

[t3mp0r4ry nzr]

brings back good memories of sliding the MC22. Fun tyre!

[motorbyclist]

So sure, the under-inflated tyre may heat more rapidly, but probably wont get to the correct operating pressure as it will never get hot enough.

I'm not a tyre expert, but the manufacturer who designed my tyre is, so personally I'll stick to using the recommended pressure on the street.

good call running recommended for street use but can you find a source for this theory you've got about tyre pressure? I'd like to have a read as it's the first i've heard it about despite track days and years riding.... and robert isn't correcting it so I won't rip into it...

It's just that an underinflated tyre will heat until pressure raises enough to reduce the heating enough to reach a steady state. A tyre that is flat or severely under-inflated simply overheats before reaching the desired pressure

my experience/learning/understanding has been that for road tyres, low pressure means more bending, thus heat, which gives a hotter tyre faster to help it better stick to the road sooner. Conversly, low pressure means more rolling resistance and increasingly undesirable handling as the tyre moves under you and the round profile is deformed. Pressure too high or too low can both be detrimental to tyre life, and as the tyre heats, so does the air and thus pressure (thus the pressures quoted are for "cold" tyres to ensure the correct profile and balance of tyre life, traction and fuel efficiency.




Tyres warm, lower pressures to bring heat into them, fairly good weather, going around a smooth well surfaced bend at about 60kmh, not turning fast at all, absolutely nothing special with the lean angle... rear end just starts coming around drifting. A real in helmet 'woah shit!' moment..

did you go back and look for diesel or other friction modifiers you may have missed? hard on the gas? what state is the suspension like?

I'm just saying this because I see/hear a lot of "oh that product is shit" based on an individuals sole experience where there hasn't been any effort on their part to see why the product might be failing or if others have had the same problems. Often the individual was either "doing it wrong" or using the product outside it's operating parameters; you wouldn't run a nylon shinko on a gixxer750 and expect strong performance, but many adventure riders swear by them for their (alledged) combination of wet and dry performance and long life....

but really, if you're using even half of a 750 you need to have decent tyres that are of a known age/condition. When I bought my rvf, the bt95 on the rear was an absolute shocker but should otherwise have been a suitable tyre (and since fitting new tyres things have been good, and correctly setting the rear preload helped further)

[p.dath]

good call running recommended for street use but can you find a source for this theory you've got about tyre pressure? I'd like to have a read as it's the first i've heard it about despite track days and years riding.... and robert isn't correcting it so I won't rip into it...

It would be safe to say your knowledge would exceed mine.

My presumption is that the tyre has an ideal shape when being used. My presumption is that the manufacturer goes to a lot of trouble when designing the tyre, it's curvature, how it deforms under pressure, etc.

And my presumption is that the shape of the tyre is greatly affected by the pressure inside of that tyre.

I could be wrong ...

[racefactory]

Sorry to cause a big stir up fellas!!!

Just had another drift today and had a good think about it, thought hmm that rear tyre is a bit on the skinny side isn't it? Did some reading and result- found out someone has put a 140/70 on instead of the 160/60 like it should be!!!

Interesting read from your posts anyhoo!

Yes I went back to check the road the first time i realized something wasn't right.

Sorry to Mr Bridgestone as well. I still swear by your bt090!

[motorbyclist]

Did some reading and result- found out someone has put a 140/70 on instead of the 160/60 like it should be!!!


this is a gsxr750 right?

160 still seems too skinny... should be a 180 isn't it? is it from this decade or the 80's? an older classic model would make sense at those sizes.... nice. :)

[motorbyclist]

It would be safe to say your knowledge would exceed mine.

My presumption is that the tyre has an ideal shape when being used. My presumption is that the manufacturer goes to a lot of trouble when designing the tyre, it's curvature, how it deforms under pressure, etc.

And my presumption is that the shape of the tyre is greatly affected by the pressure inside of that tyre.

I could be wrong ...

unfortunately the manufacturer can only spec the available tyre size to best work with their machine for their set of requirements - thus those who have a different performance target (ie racers) changes to pressure and even profile can be made. Provided the user is actually taking a responsible and reasoned approach (ie safe and scientific) I'd say that the good advice from the racing/riding community shouldn't be ignored... of course i've also heard some wild theories in the past that don't seem to based on anything but wild conjecture ;)

can't go far from wrong following what the manufacturer manual says though :)

[pc220]

good call running recommended for street use but can you find a source for this theory you've got about tyre pressure? I'd like to have a read as it's the first i've heard it about despite track days and years riding.... and robert isn't correcting it so I won't rip into it...

It's just that an underinflated tyre will heat until pressure raises enough to reduce the heating enough to reach a steady state. A tyre that is flat or severely under-inflated simply overheats before reaching the desired pressure

my experience/learning/understanding has been that for road tyres, low pressure means more bending, thus heat, which gives a hotter tyre faster to help it better stick to the road sooner. Conversly, low pressure means more rolling resistance and increasingly undesirable handling as the tyre moves under you and the round profile is deformed. Pressure too high or too low can both be detrimental to tyre life, and as the tyre heats, so does the air and thus pressure (thus the pressures quoted are for "cold" tyres to ensure the correct profile and balance of tyre life, traction and fuel efficiency.




did you go back and look for diesel or other friction modifiers you may have missed? hard on the gas? what state is the suspension like?

I'm just saying this because I see/hear a lot of "oh that product is shit" based on an individuals sole experience where there hasn't been any effort on their part to see why the product might be failing or if others have had the same problems. Often the individual was either "doing it wrong" or using the product outside it's operating parameters; you wouldn't run a nylon shinko on a gixxer750 and expect strong performance, but many adventure riders swear by them for their (alledged) combination of wet and dry performance and long life....

but really, if you're using even half of a 750 you need to have decent tyres that are of a known age/condition. When I bought my rvf, the bt95 on the rear was an absolute shocker but should otherwise have been a suitable tyre (and since fitting new tyres things have been good, and correctly setting the rear preload helped further)

I think this theory was introduced by pirelli. To figure out the best tyre preasure for your tyre, set your preassure when tyre is cold. Then run the tyre for an hour of normal riding/driving then re check the preasure, the warm tyre preassure should be within 5% of cold preasure. Well something like that. Was a few years ago that I was taught this so not sure of the finer details , there is a good chance i am way off the mark.

[MSTRS]

I think this theory was introduced by pirelli. To figure out the best tyre preasure for your tyre, set your preassure when tyre is cold. Then run the tyre for an hour of normal riding/driving then re check the preasure, the warm tyre preassure should be within 5% of cold preasure. Well something like that. Was a few years ago that I was taught this so not sure of the finer details , there is a good chance i am way off the mark.

Correct. Almost.
About 10% increase is right. And about 15-20 minutes should be enough runtime.