Ronnie was trumped by the surfer dude...
From: [email protected] [mailto:[email protected]] On Behalf Of ssp Sent: Friday, May 21, 2010 8:02 AM To: [email protected] Subject: Re: [COWs] clincher tire deal/tubes and tire discussion http://www.sheldonbrown.com/tires.html Hydroplaning Car and truck tires need tread, because these vehicles are prone to a very dangerous condition called "hydroplaning." This happens when driving fast in very wet conditions, which can lead to the tire riding up onto a cushion of liquid water. When this happens, there is a sudden and total lack of traction. Cars can hydroplane because: Bicycles canNOT hydroplane because: A car tire has a square road contact, and the leading edge of the contact is a straight line. This makes it easier for a car tire to trap water as it rolls. A bicycle tire has a curved road contact. Since a bicycle leans in corners, it needs a tire with a rounded contact area, which tends to push the water away to either side.. A car tire is quite wide, so water from the middle of the contact patch can have trouble escaping as the tire rolls over it, if there are not grooves to let it escape. A bicycle tire is narrower, so not as much water is in contact with the leading edge at once. Car tires run at much lower pressure than bicyles. The high pressure of bicycle tires is more efficient at squeezing the water out from under. Cars go much faster than bicycles, again leaving less time for water to escape. At high bicycle speeds, hydroplaning is just possible for car tires, but is absolutely impossible for bicycle tires. Even with automobiles, actual hydroplaning is very rare. It is a much more real problem for aircraft landing on wet runways. The aviation industry has studied this problem very carefully, and has come up with a general guidline as to when hydroplaning is a risk. The formula used in the aviation industry is: Speed (in knots) = 9 X the square root of the tire pressure (in psi.) Here's a table calculated from this formula: Tire Pressure Hydroplane Speed Miles per hour Hydroplane Speed Kilometers per hour P.S.I. Bars 120 8.3 113 183 100 6.9 104 167 80 5.5 93 149 60 4.1 80 129 40 2.8 66 105 Squirm(sure you are familier with squirm) Knobby treads actually give worse traction on hard surfaces! This is because the knobs can bend under side loads, while a smooth tread cannot. The bending of knobs can cause discontinuities in handling; the tire grips OK for mild cornering, but as cornering force exceeds some critical value, the knobs start to bend and the traction suddenly goes to Hell in a handbasket. interesting perspective on flat tire prevention Prevention Many flat tires are avoidable, but some are not. Some people seem particularly prone to them. This is often caused by poor road position: people who get an unusual number of flats often do so because they are riding in the gutter instead of the traffic lane. The main travel lanes of most roads are kept fairly clear of glass and other dangerous debris by passing motor traffic. Cyclists who travel in the normal traffic areas of the roadway benefit from this. Many cyclists, however, hug the curb out of timidity and an irrational fear of being struck from behind by a motorized vehicle. The area close to the curb is where all of the glass shards, sharp rocks and other junk winds up. If you ride too close to the curb, you greatly increase the risk of tire punctures. Riding too close to the curb also, paradoxically, increases your risk of being hit by a car! By cowering in the gutter, you reduce your visibility. You also encourage motorists to pass you even when there is insufficient room to do so safely. You also reduce your maneuvering room, and may have nowhere to go if evasive action is required. On Fri, May 21, 2010 at 7:48 AM, Ronnie Raper <[email protected]> wrote: Not hydroplaning makes sense from a physics standpoint as there probably isn't enough surface area of the tire in contact with the road regardless of water depth to provide enough lift against the weight of the bike & rider. In other words, the tire acts like a knife against the water instead of a spatula. Ronnie -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of ssp Sent: Thursday, May 20, 2010 4:19 PM To: CyclistsOfWilson-COWs Subject: [COWs] clincher tire deal/tubes and tire discussion ... any tube better than another? how about the self-sealing slime? anyone used this? seems thorn holes are often. interesting info about road cycling tires: did you know a road bike tire CANNOT hydroplane? http://www.sheldonbrown.com/tires.html continental GP-4000-s 700x23cc reg:$59.99 http://www.texascyclesport.com/store/viewItem.asp?idProduct=4310 buy 8 or more $33.37 which inc s/h steveT=2 jeffG=2 ssp=2 davidC=2 8 total so far, that meets the discount anyone else? tube: the conti tubes are $4.99 for the 36mm stem and $5.99 for the 48mm stem will ck on those prices to see how they compare ?? -- You received this message because you are subscribed to the Google Groups "CyclistsOfWilson-COWs" group. To post to this group, send email to [email protected]. 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