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Old 10-11-2009, 08:25 PM   #21
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I tried out the new Superbiike slicks this weekend. John said the rear hot pressure should be 25lbs off the track. I wasn't running a warmer so I set it cold at 22. I figured for 3 lbs heat growth on the track. I came back in and it was at 30 lbs. It grew 8 lbs! I spoke to John about it and he clued me in. I didn't expect more growth in cooler weather, but I understand it now. Just one more thing to keep in mind.
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Old 10-11-2009, 09:00 PM   #22
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Quote:
Originally Posted by Mr Richards View Post
I tried out the new Superbiike slicks this weekend. John said the rear hot pressure should be 25lbs off the track. I wasn't running a warmer so I set it cold at 22. I figured for 3 lbs heat growth on the track. I came back in and it was at 30 lbs. It grew 8 lbs! I spoke to John about it and he clued me in. I didn't expect more growth in cooler weather, but I understand it now. Just one more thing to keep in mind.
You need to get that smaller rear sprocket, and back that up un the swingarm. How did the rest of the day go?
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Old 10-11-2009, 09:07 PM   #23
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Ahh, I see what yall are saying now, off the warmers temp (say 22) in cold temps will exceed the desired off the track temps whereas in higher temps the same setting won't jump as much because of the closeness in degrees in which they begin. I was referencing last track setting (warm/hot) off warmer which in colder temps will always require an additional 1lb or 2...
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Old 10-11-2009, 09:36 PM   #24
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An interesting study in tire presure, ambient temperature, track temperature and greenness of track. I had plenty of time to think about it as I slid through the grass on my in Turn 9 about 10am on Saturday. There is plenty of tire help from anyone at the track, especially John, none of which will do you any good if you don't let the feckers warm up a bit.

If anyone has any pics of a yellow SV hitting the dirt I would be delighted to see them.
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Old 10-11-2009, 09:53 PM   #25
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Wow, I saw you out there on nine. Glad you are ok.

-Curt
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Old 10-11-2009, 10:30 PM   #26
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I've done a lot of messing with pressures and tires through the years - I have had the best luck with softer compound tires when the temp are down than with pressure changes.
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Old 10-11-2009, 10:53 PM   #27
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I would have loved to have seen this.

I'M THERE FOR A REASON PEOPLE!!!
i know and i even talked to you for a few min. i totally got caught up with someone else and i forgot to follow up with you.

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After you suggested the pressure drop, my bike stopped sliding the rear out between 5 and 6.
thats exactly where i was sliding! coming out of 5 and out of 6.
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Old 10-11-2009, 10:58 PM   #28
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I've done a lot of messing with pressures and tires through the years - I have had the best luck with softer compound tires when the temp are down than with pressure changes.
Actually your right to a point. The problem is, most people can't afford 2 or 3 sets of tires. Most people try to get multiple trackdays out of one set, and this is a tough time of the year to do that. Weather variations, and different tracks demand different compounds for optimum performance. The pressure changes just help people make the best out of what they have.
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Old 10-11-2009, 11:21 PM   #29
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One thing that I have found to be both useful and inexpensive for the track is a cheap non-contact temperature gauge for checking tire temps. It is easy to get one for $30 or less from most R/C hobby shops or R/C websites and even the cheap ones are usually accurate to about +- 3 degrees. They can be used to check ambient temp, track temp, and tire temp to get some idea of how the three are affecting what is going on.

From checking these three different temps at TWS (Texas World Speedway) this past Saturday and on previous occasions it is apparent that the ambient air temp can have a lot of effect on tire temps. In the morning the ambient air was between 55 and 59 degrees until mid-day and ground temps were about 5 degrees higher. Tires were coming off the warmers at about 170 degrees. After a full session running a little slower than my typical pace I would check tire temps immediately after coming off the track and the rear was typically around 140-150 with quite a bit of variability across the tire and the front was about 130-135. Cold pressures were 24.5 rear and 28 front (31 and 31 while hot) on BT-003s .

For comparison purposes, on a day where ambient is more like 85-95 and ground temps are 120 or more the tires will often come off the warmers at 180 and fresh off the track (with a pace that is 3-5 seconds faster) the rear will be 175-180 degrees and the front will be about 150-160 degrees.

Having made these temperature measurements in ambient temps between 50 degrees and 100 degrees I usually see that once the air temp starts to drop below about 80 degrees that operating tire temps will tend to start falling at about the same rate as air temp does.

It is also interesting to measure the difference in temperature across the tire from left to right where I often see a differential of 10 to 15 degrees between the more loaded side and the less loaded side.

This has all been done using BT-002 or BT-003 which were hard rear and medium or hard front. Id be interested to see if other people have experienced similar tire temp results as air temps drop.
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Old 10-12-2009, 02:43 PM   #30
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i was out there both sat and sun,tyres were off the warmers at 30/26 and just off the track at 31/26.i set these pressures as per John and they were dead on.i have to say the 003's felt the best for me on the cold.
i also noticed the track was way faster on sunday,well til noon anyways.
only had one minor slide out of 11 sunday,not too bad.
i had a harder time keeping the front tyre down on wheely hill than i had B4.
i was on the gas as soon as i came out of the paddock,but waited til the group was gone to avoid waiting and letting the tires go cold.
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Old 10-12-2009, 02:45 PM   #31
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Quote:
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i was out there both sat and sun,tyres were off the warmers at 30/26 and just off the track at 31/26.i set these pressures as per John and they were dead on.i have to say the 003's felt the best for me on the cold.
i also noticed the track was way faster on sunday,well til noon anyways.
only had one minor slide out of 11 sunday,not too bad.
i had a harder time keeping the front tyre down on wheely hill than i had B4.
i was on the gas as soon as i came out of the paddock,but waited til the group was gone to avoid waiting and letting the tires go cold.
I had GREAT power all day Saturday courtesy of the cool air. From an average of 154 on the front straight (measured via gps) to 159. Dang near had a 160... 159.8....
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Old 10-14-2009, 09:26 AM   #32
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Strange...

I ran 28 front and 26 rear, BT003 med front hard rear, off the warmers, on Saturday and never slid once.
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Old 10-14-2009, 09:31 AM   #33
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Strange...

I ran 28 front and 26 rear, BT003 med front hard rear, off the warmers, on Saturday and never slid once.
That tells me your suspension is setup better. It is loading the tires properly and your riding smooth.
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Old 10-14-2009, 09:41 AM   #34
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John,
I was on my third rear tire for that front and quite a lot of heat cycles. It still looked decent, however. I actually lost 1 psi coming off the track in the morning sessions.... off the warmers at 29 psi... returning at 28.

The new tire felt better; I can't help but wonder how much of that was psychological.

-Curt
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Old 10-14-2009, 11:06 AM   #35
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John,
I was on my third rear tire for that front and quite a lot of heat cycles. It still looked decent, however. I actually lost 1 psi coming off the track in the morning sessions.... off the warmers at 29 psi... returning at 28.

The new tire felt better; I can't help but wonder how much of that was psychological.

-Curt

New tires will always feel better.

#1. There is a definate grip and flex advantage to fresh rubber.
#2. Your mind thinks it is better, so it will be.

The psi loss off the track, was that with the new tire or the old tire?
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Old 10-14-2009, 11:07 AM   #36
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New tires will always feel better.

#1. There is a definate grip and flex advantage to fresh rubber.
#2. Your mind thinks it is better, so it will be.

The psi loss off the track, was that with the new tire or the old tire?
That was on the old tire.
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Old 10-14-2009, 11:10 AM   #37
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Quote:
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That was on the old tire.
Without being there and looking at it in person. My theory is that the old tire, with excessive heat cycles, was not flexing enough to build heat or maintain the heat from your warmers. Esspecially with the weather conditions we had last weekend. Tire flex and mid-corner bump compliance are going to be the first charictaristics that suffer from heat cycles.
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Old 10-14-2009, 11:41 AM   #38
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John, I was getting movement on the front tire when riding over the tar snakes just prior to the transition in turn one. Nothing crazy enough to warrant slowing down, but definite movement that I had not felt previously.

Anyway, I have no tire complaints. I was simply getting more movement than I am used to, or comfortable with. I started this thread asking how racers compensate for colder track temperatures and it looks like dropping a couple of PSI is the answer.

Thanks to everyone for the responses.

-Curt
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