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Dr Matt

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Post Tue Feb 19, 2008 7:34 pm

Gemm wrote:it's soft, and deflects underfoot!

now that reminds me of another question - is the hardness of the surface being spot tested for entire test strip, or it it being sampled in regular patters over the entire area?

For the uninitiated - Hanson is not only soft a squidgy, its different softness and squigness as you go around the track. Which is why a race line on Hanson is 3 meters wide as you proceed through the northern bank - the squidginess changes make it extraordinarily difficult to hold a straight line.

Gemm wrote:with 110psi in tyres

wow, did they puncture or what?
what is the effect on the results from running "proper" track pressures of 200+psi?
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LukieSpookie

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Post Tue Feb 19, 2008 7:59 pm

Gemm wrote:
LukieSpookie wrote:See picture below for a type A.

http://www.quackenbushairguns.com/000_0217Durometer.jpg

Basically...some schmuck went there and poked one of these at the ground. Most unscientific test ever.


No I have to disagree Luke, it's not the most unscientific test ever... they were given data (which you have seen) which used a standard bike and standard position with standard athlete, with 110psi in tyres, with SRM cranks, doing standard speeds. The power thru cranks required to maintain the steady speeds over a certain number of laps was used to measure the difference in power requirements to maintain the same. SO the major difference between tracks was obviously the surfacings first, and all other things like track geometry, atmospheric conditions, rider line etc all secondardy (and considered neglibible for the puurposes of the test).

Negligible differences were recorded in power reqd for a set speed between Edwardstown and Superdrome, despite the large difference in skid resistance measurements (which is a function of surface roughness (micro and macro texture) first and materials second), which leave the MASEEEEVE power difference required between Hanson and the other tracks being down to the softness of the surface... which is what Matt and Pud and everyone picked up the first time you walk or ride on it... it's soft, and deflects underfoot!

But not giving the Durometer readings leaves a lot of qns.... as getting a Shore of 99-100 would be easy for hardwood/asphalt no matter which Shore scale, but a Shore scale of 50 varies big time between OO, A & D scales:
http://icrank.com/cgi-bin/pageman/pageo ... e.html&t=2

:shock:


Oh that data! It all makes sense now... I retract my previous slander of the validity of the test. I think that maybe they should cut a chunk out of the track and do a compression test on it, measuring the deflection.

Its pretty obvious the answer really...i mean who rides around on 20psi in their tyres? Riding on rubber would be like riding through wet cement.
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Gemm

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Post Tue Feb 19, 2008 8:05 pm

LukieSpookie wrote:Oh that data! It all makes sense now... I retract my previous slander of the validity of the test. I think that maybe they should cut a chunk out of the track and do a compression test on it, measuring the deflection.

Its pretty obvious the answer really...i mean who rides around on 20psi in their tyres? Riding on rubber would be like riding through wet cement.


They have used to separate bits of the same stuff in the lab as well as insitu testing, that is in the report.

And Matt, the difference between 200psi and 110psi across the three different surfaces will make a bee's dickteenth of SFA in terms of deflection...
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Dr Matt

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Post Tue Feb 19, 2008 8:28 pm

Gemm wrote:And Matt, the difference between 200psi and 110psi across the three different surfaces will make a bee's dickteenth of SFA in terms of deflection...

defection of the surface or of the tyre?
cheers
Matt..

with the right tools, I can do anything
with the wrong tools, you'll have to give me a minute ... and a new right shoulder ... and a new upper spine ...

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Gemm

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Post Tue Feb 19, 2008 8:46 pm

Matt D wrote:
Gemm wrote:And Matt, the difference between 200psi and 110psi across the three different surfaces will make a bee's dickteenth of SFA in terms of deflection...

defection of the surface or of the tyre?

Both, as the tyre is a constant.
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Dr Matt

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Post Tue Feb 19, 2008 9:01 pm

Gemm wrote:Both, as the tyre is a constant.

dammit, I coulda sworn my thumb deflects a tyre with 110psi quite a lot more than the ones with 220 :twisted:
dont tell me I'm going to have to start using a gauge :cry:
cheers
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with the wrong tools, you'll have to give me a minute ... and a new right shoulder ... and a new upper spine ...

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Gemm

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Post Tue Feb 19, 2008 10:11 pm

Matt D wrote:
Gemm wrote:Both, as the tyre is a constant.

dammit, I coulda sworn my thumb deflects a tyre with 110psi quite a lot more than the ones with 220 :twisted:
dont tell me I'm going to have to start using a gauge :cry:

That's not what I meant, I meant Newtons law, equal and opposite reactions and all that. the tyre and tyre pressure is the constant across all three tracks. The contact patch is a different matter....... :lol:
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Nomorespeedhumps

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Post Wed Feb 20, 2008 2:07 am

Gemm wrote:
Matt D wrote:
Gemm wrote:Both, as the tyre is a constant.

dammit, I coulda sworn my thumb deflects a tyre with 110psi quite a lot more than the ones with 220 :twisted:
dont tell me I'm going to have to start using a gauge :cry:

That's not what I meant, I meant Newtons law, equal and opposite reactions and all that. the tyre and tyre pressure is the constant across all three tracks. The contact patch is a different matter....... :lol:


She's right, friggen engineer's always using fact to prove their right....
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Dr Matt

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Post Wed Feb 20, 2008 7:46 am

Gemm wrote:The contact patch is a different matter....... :lol:

which is precisely the point I'm persuing in a roundabout way. :roll: I'm confident it makes bugger all difference on the properly hard tracks, but I'm thinking that more PSI in the tyre means a smaller contact patch, which on the crumb rubber becomes important as fewer square inches means more pounds per sq inch, which means with high pressures you dont so much float over the rubber but sink into it more.

I'm also concerned that the council+surface contractor has focussed entirely on the speed/performance penalty of the soft surface, which in reality is a very minor niggle. Vastly more importantly is how the soft surface affects the handling of the bikes - and on the crumb rubber it's very negative - and not dissimiliar to riding on tyres with 40 or 50 psi in them.
cheers
Matt..

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with the wrong tools, you'll have to give me a minute ... and a new right shoulder ... and a new upper spine ...

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Gemm

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Post Wed Feb 20, 2008 10:41 am

Matt D wrote:
Gemm wrote:The contact patch is a different matter....... :lol:

which is precisely the point I'm persuing in a roundabout way. :roll: I'm confident it makes bugger all difference on the properly hard tracks, but I'm thinking that more PSI in the tyre means a smaller contact patch, which on the crumb rubber becomes important as fewer square inches means more pounds per sq inch, which means with high pressures you dont so much float over the rubber but sink into it more.

I'm also concerned that the council+surface contractor has focussed entirely on the speed/performance penalty of the soft surface, which in reality is a very minor niggle. Vastly more importantly is how the soft surface affects the handling of the bikes - and on the crumb rubber it's very negative - and not dissimiliar to riding on tyres with 40 or 50 psi in them.


I don't think the tyre pressure is really making all that much difference, as the deflection is happening in the track surface rather than the tyre. So what is probably more of an influence on the contact patch is tyre width rather than the tyre pressure. Eg imagine trying to ride on Hanson on a pizza cutter width tyre, you'd hav no chance of steering due to the excessive deflection. ... but we may agree to disagree, at the end of the day we have to be convinced that the remedial treatment will work over the entire track by whatever means....

Gemma
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David

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Post Wed Feb 20, 2008 1:09 pm

The whole thing is a load of horseshit....why can't the council just admit they f*cked up and rip it up and lay a proper surface down? All they have been doing in the last two years is wasting time and more money doing all this testing. Can't someone just chuck a few gallons of diesel all over the track and they'll have to rip it all up anyway!?!

Having said that, I don't think it's necessarily a bad thing that Hanson has been out of commission, at least from a track racing point of view. Typically when Hanson was avaialble there would be 3 sessions of track racing a week - one at Hanson, one at Edwardstwon and one at the Superdrome. There was no way everyone could race at each one and the few track riders there are in SA were spread thinner - with Hanson gone numbers have been consolidated at the other two tracks. Friday night at Edwardstown has been a definite beneficiary and I believe the Superdrome racing would have too if it wasn't so expensive!

On the other hand, Hanson is good for motorpacing training cos you can keep Joe Public out and you don't get wankers with dogs letting them run loose off the leash and others kicking footballs onto the track! Plus it has lighting so you can train in the evenings once daylight savings has ended.

It will be interesting to see what the final outcome eventually is.
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Pete Davis

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Post Wed Feb 20, 2008 1:55 pm

By the end of this they would have spent more money on all this testing and debating than it would have cost to just replacing the surface.
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Daimo

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Post Wed Feb 20, 2008 4:12 pm

I have encountered similar sort of stuff in other Engineering work..

Someone tries it on with technical testing that is a far cry from the true exposure that would be experienced in typical usage.

The trouble is, heading down the technical path will probably yield a dead-end uness someone is prepared to spend $$ and time on testing tha will disprove what has been done so far. This means more representative testing and that's hard to do, when there are so many factors at play that are more significant than rolling drag.

I have explained to Gemm why I think the SRM crank test was not useful but I wonder if there is an easy way out of this.

Suppose somebody with enough clout simply asserted that the track was unsafe for use due to its perculiar handling characteristics. One might say, for example, that the deflection under the bike in a 100% sprint was not characteristic of a normal track, and thus could cause an accident. Because I don't know the track, nor am I a track cyclist, I don't know this to be the case, but if it is, then all it takes is an 'expert oppinion' to over-rule the hardness test that does not fully describe the handling characteristics of the track.

Thoughts??
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Gemm

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Post Wed Feb 20, 2008 4:49 pm

We in the sport used a brand new SRM-equipped bike to prove to council that the track has buggered characteristics as that is the best measuring equipment we have available. The testing proved its worth in easily showing that for a steady state constant speed in still conditions it required shiteloads (that's a technical term) more power to maintain any given set speed at Hanson. I believe it was a valid test, all tests were done on the same day, using the same rider, same bike position and the same speeds over some significant distances (1000m minimum for each 5kmh speed increment, doing complete laps only). This data is available to anyone that wants to crunch it. Carlee Taylor on her road bike doing 25kmh on Hanson over 1200m required a considerably higher average power than 25kmh at Edwardstown over 1500m in the same wind conditions, same temperature, same riding position, same gear etc.... to simplify matters she has the same wind drag at 25kmh at Hanson as she does at Edwardstown and remember we are talking circles here! So the major variable between tracks only was the track itself!

Perhaps if you guys who are all happy to debate it online would care to meet me at Hanson one evening next week and ride the thing I think you'll see immediately what the problem with the surface is.... the softness of the surface affects both rolling resistance AND handling. It's not just a little bit spongey it's VERY spongey. Like what you were sitting on at the Outer Harbor Time trial playground course. Think of what it feels like to ride your roadie on lawn and you'll get the general idea.... so who's in for a test ride??
the ideal number of bikes is one more than you currently have
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aimeebear

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Post Wed Feb 20, 2008 5:03 pm

so who's in for a test ride??


I will bring my camera and popcorn :lol:
I like to ride my bicycle.
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