"I would not ride a TW32 on the street."
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  1. #1
    Senior Member Malkop's Avatar
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    I pulled this one up from Beewerk's street riding tyre thread below. It seemed important enough to warrant seperate attention, instructive as it is about the safety of our ride.



    As I said down there, I bought maybe the last of the now discontinued TW32s. It may be old stock but is to all intents and purposes new. I have been doing some hardcore riding on it over rock and have been riding it a little on paved roads with no problem. Many of our forest tracks are clay so when it's wet you want the most aggressive tread you can get. The inch of tread on the blocks gives me confidence of clearing thorns and other tyre hazards. After some hard testing, the little nipples are still on the tyre, so am confident that the compound is not degraded.



    Would the problem come with wet conditions? The retired Yamaha mechanic who had the FM Cdi and the know how to get my derilict TDub running warned that they plane on wet roads which he noticed when road testing them after warranty services. This he put down to the wide tyre and knobbly combo. They would have been stock TW 34s so, the problem may be worse with the 32s.



    Any experiences or opinions to share. qwerty I'd appreciate some of your characteristically insightful technical elaboration on this point.



    Am off to do a 30 km fun ride on Sunday which is an annual fundraising event hosted by farmers up the road at their country club. I've never done it but its in amazing country with varied mountains, rivers and forests with some optional very technical bits. Its the TDub's sort of race - uncompetitive and was told that "you can time yourself if you want to". Ha and win the tortoise prize! She is filled with clean racing fully synthetic oil but there is no race



    Am glad to have the 32's on. Some rain is predicted for the weekend. But to ride there its 50% tarmac but some lovely dirt roads. I could load the TW on the truck to go and take the family but would rather ride there and back. It is roads not streets that I'd be riding so will not be going against querty wisdom completely.



    Have a great weekend.

  2. #2
    Senior Member biglefti's Avatar
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    All tires will plane given the right conditions. The two most critical are speed of travel and depth of the water. Knobby tires will have more resistance to planing than street tires because there is so much more are for the displaced water to exit from. Second, I have only experienced planing once in my life below 55 mph. I doubt you will have any issues if you just use common sense.

  3. #3
    Senior Member Malkop's Avatar
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    Thanks big guy. Turns out that family want to come so no issue for now, so bike on the truck for Sunday. I am going to get the spare back wheel to put to a the slicker tyre and smaller sprocket anyhow. That makes sense since the knobbly puts down so much friction and want the longer legged gearing for commuting on the paved world to put the TW to work saving me money and the planet's warming. But am still wondering about qwerty's statement . . . . . . ?

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  5. #4
    Senior Member TW2007's Avatar
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    There are three types of hydroplaning, that can occur: viscous, dynamic, and reverted rubber ( this last one should not be an issue with the TW)



    Viscous Hydroplaning is caused by oils, painted surfaces, etc which can create a loss of traction. And is very common on freshly wetted surfaces.



    Dynamic hydroplaning tries to estimate the minimum speed at which hydroplaning can occur in standing water and that is a function of tire pressure. Formula is Minimum Total Hydroplaning Speed equals 8.6 times the square root of tire inflation pressure. In other words the higher the tire pressure the higher the speed at which dynamic hydroplaning occurs. The TW with 22psi will start to hydroplane at apprx 40 mph or faster and at 16psi at about 34 mph or faster. These are ball park figures but explains some of the relationships that exist. With total dynamic hydroplaning the tires wedge up on the water and the tires can spin down or actually stop spinning making braking impossible. The loss of gyroscopic forces as the wheels spin down has a negative impact on balance, and the use of poor braking technique could cause the bike to take a nap.



    Mike



    Anyway that's one piece of it!



    Note a bicycle with 70psi tires would start to hydroplane (dynamic) at approx 71.9 mph but could get wiped out by viscous hydroplaning at a much lower speed.
    The TW200 may be slow but the Earth is patient.

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  6. #5
    Banned qwerty's Avatar
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    Quote Originally Posted by TW2007 View Post
    There are three types of hydroplaning, that can occur: viscous, dynamic, and reverted rubber ( this last one should not be an issue with the TW)



    Viscous Hydroplaning is caused by oils, painted surfaces, etc which can create a loss of traction. And is very common on freshly wetted surfaces.



    Dynamic hydroplaning tries to estimate the minimum speed at which hydroplaning can occur in standing water and that is a function of tire pressure. Formula is Minimum Total Hydroplaning Speed equals 8.6 times the square root of tire inflation pressure. In other words the higher the tire pressure the higher the speed at which dynamic hydroplaning occurs. The TW with 22psi will start to hydroplane at apprx 40 mph or faster and at 16psi at about 34 mph or faster. These are ball park figures but explains some of the relationships that exist. With total dynamic hydroplaning the tires wedge up on the water and the tires can spin down or actually stop spinning making braking impossible. The loss of gyroscopic forces as the wheels spin down has a negative impact on balance, and the use of poor braking technique could cause the bike to take a nap.



    Mike



    Anyway that's one piece of it!



    Note a bicycle with 70psi tires would start to hydroplane (dynamic) at approx 71.9 mph but could get wiped out by viscous hydroplaning at a much lower speed.
    Getting deep. Send fresh air. Water skis are solid, no air at all, yet they hydroplane at relatively slow speeds, like 12mph. That air pressure formula is bull. In a given tire carrying a given load at a given speed through a given depth of water, air pressure does make some difference. An over-inflated tire will crown the tread, lift the edges of the tread, and allow water to escape more easily out the sides. An under-inflated tire would have the opposite effect.



    One can certainly hyproplane on oil, but oil on the road would have to be more than just a thin film to cause hydroplaning. Oil is slippery, technically called "low friction coefficient". When drive, steer, or braking forces exceed the coefficient of friction, control is lost. Oil reduces the coefficient of friction, so the rider must reduce drive, steering, and braking forces appropriately to avoid skidding.



    How the heck can paint on the road contribute to hydroplanning? Unless the paint is still wet, it is impossible since dry paint is a solid. Hydroplaning occurs only on the surface of a liquid. Paint on the road is slippery because the water acts as a lubricant and reduces the coefficient of friction.



    I doubt a TW will go fast enough to hydroplane with a fairly new TW32 or TW34 on the back. Ever. The tread on both tires is way to deep and open to hydroplane. I've been 70+mph in a downpour with a TW204 and did not hydroplane.



    When tires age the rubber becomes hard, wears slower, and has a lower coefficient of friction. Hardening is a normal degradation of rubber. This phenomenon has absolutely nothing to do with hydroplaning. However, it has lots to do with loss of traction. This is one reason I will not run old tires on the street. Offroad in soft terrain such age-hardened tires work quite well and have a long life expectancy as long as not dry rotted. However, if you can drag a peg on dry pavement, there is still plenty of traction for normal riding on wet roads.




  7. #6
    Senior Member TW2007's Avatar
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    Quote Originally Posted by qwerty View Post
    Getting deep. Send fresh air. ……………….


    Yup!



    Cancer and chemo can cause weird mental aberrations………..



    But I'm thankful I can still fog a mirror without loosing traction ……….
    The TW200 may be slow but the Earth is patient.

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  8. #7
    Banned qwerty's Avatar
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    Quote Originally Posted by TW2007 View Post
    Yup!



    Cancer and chemo can cause weird mental aberrations………..



    But I'm thankful I can still fog a mirror without loosing traction ……….
    Understand completely. I did the cancer thing last year. I hope you can keep fogging mirrors for a long while.




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