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my name is NYSLIM and I ride Tufo's because they are the fastest.
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At 220psi how can you dispute that Tufo's have lower rolling resistance then the best clincher or tubular at 130psi?
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Re: my name is NYSLIM and I ride Tufo's because they are the fastest. [NYSLIM] [ In reply to ]
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Talk to Erik, he can fill you in.


Steve

http://www.PeaksCoachingGroup.com
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Re: my name is NYSLIM and I ride Tufo's because they are the fastest. [NYSLIM] [ In reply to ]
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OTOH, if you race in the 40-44 age group, and plan to do TTs in Michigan or Natz, don't bother asking Erik. Just stick with the Tufos at 220;)


Steve

http://www.PeaksCoachingGroup.com
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Re: my name is NYSLIM and I ride Tufo's because they are the fastest. [NYSLIM] [ In reply to ]
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how does 220psi make them fast?
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Re: my name is NYSLIM and I ride Tufo's because they are the fastest. [NYSLIM] [ In reply to ]
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My question is how the hell do you get 220 psi into a tire?

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Elivis needs boats.
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Re: my name is NYSLIM and I ride Tufo's because they are the fastest. [Schwingding] [ In reply to ]
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Well, first you had better have an "iron taint"!

"I really wish you would post more often. You always have some good stuff to say. I copied it below just in case someone missed it." BarryP to Chainpin on 10/21/06

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Re: my name is NYSLIM and I ride Tufo's because they are the fastest. [S McGregor] [ In reply to ]
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What happened to Erik?

You can get 220 psi into the tire with a special pump.

220spi makes it faster because it does not deflect over the surface imperfections on the road.
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Re: my name is NYSLIM and I ride Tufo's because they are the fastest. [etocaj] [ In reply to ]
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Agreed on the Iron-taint but you can offset this with a TitanFlex.
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Re: my name is NYSLIM and I ride Tufo's because they are the fastest. [NYSLIM] [ In reply to ]
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"220spi makes it faster because it does not deflect over the surface imperfections on the road"

You mean slower, right?

"I really wish you would post more often. You always have some good stuff to say. I copied it below just in case someone missed it." BarryP to Chainpin on 10/21/06

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Re: my name is NYSLIM and I ride Tufo's because they are the fastest. [etocaj] [ In reply to ]
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No I meant faster...

http://www.sheldonbrown.com/brandt/rolling-resistance-tubular.html

http://www.rouesartisanales.com/article-1503651.html
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Re: my name is NYSLIM and I ride Tufo's because they are the fastest. [NYSLIM] [ In reply to ]
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If you ride exclusively on smooth steel, then you'll do great with 220psi. On actual roads your performance will vary.
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Re: my name is NYSLIM and I ride Tufo's because they are the fastest. [Pooks] [ In reply to ]
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Why?
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Re: my name is NYSLIM and I ride Tufo's because they are the fastest. [NYSLIM] [ In reply to ]
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I hope you are joking, but just in case you arent........

The graph goes up to 130psi, but you are assuming that as pressure increases beyond that rolling resistance also decreases. This may be the case on a smooth track or a metal drum where the testing is done, but what happens on real pavement surfaces is beyond that point the rolling resistance may actually start to climb.

You might want to research some of Joshatzipp's replies on rolling resistance where he says that they found beyond a certain pressure on typical road surfaces that rolling resistance actually increased.

Kevin
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Re: my name is NYSLIM and I ride Tufo's because they are the fastest. [flying wombat] [ In reply to ]
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I'm not joking. Why would the higher PSI do anything but increase rolling resistance? That doesn't sound right and the graphs indicate the trend toward the opposite whereby the psi increase will decrease resistance.
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Re: my name is NYSLIM and I ride Tufo's because they are the fastest. [Schwingding] [ In reply to ]
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My air rifle pump can go up to 250 bar. I pumped up my Tufos to 3600 psi and now ride 33 times faster (3600 psi/110 psi=33).
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Re: my name is NYSLIM and I ride Tufo's because they are the fastest. [NYSLIM] [ In reply to ]
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When you ride at a high PSI on "regular" roads you will feel like you are bouncing. And you are. This bouncing means that energy is being lost in the "vertical plane". You want a lower PSI because you are absorbing more of the imperfections in the road(not bouncing) and thus your forward progress is greater.

"I really wish you would post more often. You always have some good stuff to say. I copied it below just in case someone missed it." BarryP to Chainpin on 10/21/06

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Re: my name is NYSLIM and I ride Tufo's because they are the fastest. [NYSLIM] [ In reply to ]
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Simple, rolling resistance is a balance between 1. contact patch of rubber (provides drag) and 2. when the tire encounters a bump in the road it forces the riders weight upwards slightly which adds drag. When you increase pressure you reduce number 1 which drops rolling resistance, but you also increase number two which increases rolling resistance. The pressure which leads to the lowest rolling resistance will be one that balances number 1 and number 2 optimally. This will depend on your weight, the suppleness of the tires tested and the road surface that you ride on so there is no optimal pressure for everyone and every surface.

Kevin
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Re: my name is NYSLIM and I ride Tufo's because they are the fastest. [etocaj] [ In reply to ]
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If that was true then why not use tires at 80psi?
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Re: my name is NYSLIM and I ride Tufo's because they are the fastest. [NYSLIM] [ In reply to ]
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80psi is what Discovery ran at Paris-Roubaix. When they won the TTT in '04 in the rain they were at 100.
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Re: my name is NYSLIM and I ride Tufo's because they are the fastest. [eganski] [ In reply to ]
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Ok, maybe you are right. I have to consider this.
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Re: my name is NYSLIM and I ride Tufo's because they are the fastest. [NYSLIM] [ In reply to ]
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Did you actually read the articles you referenced?

Why not use them at 80 psi? Because there is clear evidence that they are faster at a higher pressure.

Why not ride them at 220? Because there is no evidence that it helps. You are extrapolating without any justification for your assumption that the trend will continue. In fact, if you look at more of Sheldon Brown's articles, he states that the gain in increasing pressure is so small as to be outweighed by the negative effects such as a harsher ride and loss in traction when cornering (you're not planning on riding on the track or that roller drum, are you?). He doesn't even explore the possibility that excessive vertical deflection of a highly pressurized tire might result in a lower speed.
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Re: my name is NYSLIM and I ride Tufo's because they are the fastest. [NYSLIM] [ In reply to ]
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Total momentum remains the same. Some is converted to up-and-down bouncing, leaving less going forward. High pressure slows tires down.

Instead, proper pressure allows tire to squish over bumps. It loses far less forward momentum.


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Re: my name is NYSLIM and I ride Tufo's because they are the fastest. [NYSLIM] [ In reply to ]
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"If that was true then why not use tires at 80psi?"

Again you need to balance contact patch versus tire deformation over a bump. Unless you are a featherweight 80 will give you too much contact patch and increase the drag. You want enough pressure to reduce the contact patch without causing too much displacement.

for an extreme examples a mountain bike on rocky terrain may run 30psi or less in the tires to reduce drag. A track cyclist racing on the boards may run 180psi in silk tubulars to gain the least drag.

Kevin
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Re: my name is NYSLIM and I ride Tufo's because they are the fastest. [Ashburn] [ In reply to ]
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Ash,
Do you think that the 220psi tire will act the same way in reference to a surface imperfection that is concave instead of convex? It would seem that the bump in your illustration will act like a ramp and cause the tire to fly through the air with zero rolling resistance. You also must agree that a squishy tire is a loss of power. I just wished there was a study that pitted the 220psi against the 130 on a "real road" surface.
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Re: my name is NYSLIM and I ride Tufo's because they are the fastest. [NYSLIM] [ In reply to ]
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One way to think about it in your "consideration" time out...

Think in terms of suspension (like on a car or mountain bike). Not only do you have to absorb all of the little bumps in the road as you go in a straight line, but a lack of suspension drastically reduces the quality of braking and turning. A long straight course on butter smooth new pavement can get a little benefit from higher pressures, but if you are on a rough course with lots of corners (like St. Croix) 200 psi would rattle your teeth out and you would have to either slow down a ton or increase your risk of crashing in a lot of places. The point of suspension is to actually maintain a good contact patch on the ground (rather than trying to reduce it like high pressure does) and to isolate the passenger from the road surface. You can adjust the pressure (suspension) for conditions, just like a race car has different needs than a 4x4 truck. One bike shop trick is to vary the tire pressure for test rides depending on what angle you are taking to sell the bike. Unless the parking lot has a lot of pot holes some shops run the pressure a little low because it makes the bike feel comfortable and the braking/turning is nice at parking lot speeds. If a customer is looking for something that is "super high performance/racy/stiff) then they will put in more air. If you are doing a test ride comparison you may want to ask the shop to make sure that the tire inflation is the same for both bikes so you can compare apples to apples. A stiff frame will feel plush compared to a flexy frame if the stiff frame is running 90 psi and the flexy frame is running 140 psi.

The reason we don't all ride around at 80 psi (or less) on our road/tri bikes is because you have an increased risk of a pinch flat when you hit holes in the road. If you run REALLY low pressure on a road bike you would also lose lateral stability in the tire for turning (like an old Ford LTD land yacht vs. a BMW M3 sport sedan). In general most people will have better overall performance and increased comfort riding their tires around 100 psi compared to 140+.
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