What is on those TdF bikes?

[MSeries]

Peter wrote:
> MSeries wrote:
>
>> rosco" <reverse-the-following"ocsor_g wrote:
>>
>>
>>> They could supply RFID tags for all the team's bicycles including
>>> the backup ones. The new tag should still register when it crosses
>>> the
>>> finish line. After the fact, they must have some manual process to
>>> associate the new tag with a particular rider. It would be easier
>>> if
>>> the riders could just wear the tag like runners do.
>>
>>
>> The feedback loop on the road is 1.2m past the finish line, the
>> transponder it 1.2m behind the front of the front wheel.
>
> ? I presume you mean the sensor on the road is 1.2 m before the
> finish
> line so that the transponder on the bike would be over it just when
> the front wheel reaches the line.
>
yes

 

[MSeries]

Tim McNamara wrote:
> "MSeries" <[email protected]> writes:
>
>> rosco" <reverse-the-following"ocsor_g wrote:
>>
>>>
>>> They could supply RFID tags for all the team's bicycles including
>>> the backup ones. The new tag should still register when it crosses
>>> the finish line. After the fact, they must have some manual process
>>> to associate the new tag with a particular rider. It would be
>>> easier if the riders could just wear the tag like runners do.
>>
>> The feedback loop on the road is 1.2m past the finish line, the
>> transponder it 1.2m behind the front of the front wheel. Attaching
>> the transponder to the rider would be less accurate since the
>> placings and timings are taken on the bike not the rider
>
> Yes, but the leading edge of the front wheel, not some spot on the
> rear triangle.

The sensor is 1.2m before the finish line (not after like I said yesterday)
and the transponder is 1.2m behind the front of the front wheel so when the
transponder triggers the senser, the front wheel is crossing the line.

 

[Blue Gator]

"Edward Dike, III" <edd(2+1)[email protected]> wrote in message
news:daTGc.8$%[email protected]...
>
> "Mark Hickey" <[email protected]> wrote in message
> news:[email protected]...
> | "Edward Dike, III" <edd(2+1)[email protected]> wrote:
> |
> | >
> | >"LAN Support" <[email protected]> wrote in message
> | >news:[email protected]...
> | >| The tags aren't used for determining finishing order, as their time
> | >| resolution isn't good enough. They just record which riders finished
in
> | >| which bunch. Photofinish camera are still used to determine placings.
> |
> | >Chip timing resolution is .01 second for running/ skating races;
probably
> | >greater if needed.
> |
> | At 40mph / 65 km/h .01 seconds is only good down to a resolution of
> | 0.18m (or a little over 6"). There can be several bikes squeezed into
> | that space. They'll be keeping the cameras for a while it appears.
> |
> | Mark Hickey
> | Habanero Cycles
> | http://www.habcycles.com
> | Home of the $695 ti frame
>
> Given the unparalleled stakes of the TdF, and reliability issues with chip
> timing in general- occasional missed scans at starts/ finishes, that's a
> good thing.
>
> Whoa to the poor soul who trips on the extension cord and unplugs it at
the
> wrong moment.
>
> I suspect the resolution is mostly a function of the spreadsheets used to
> record data. I have no idea what it takes to overwhelm a chip timing
> system, but high speed film allows for the input of human judgments, and
> verification by almost anyone viewing the results, which certainly adds to
> the credibility of the results.
>
> ED3
>
>

IIRC, something was said on OLN during the prolog that while times were
being shown in hundredths of a second, they were actually recorded out to
eight decimals.

This is the same technology used to time Indy car races. If they can
accurately track cars that travel well over 200 mph then they should be able
to do the same with a bicycle.

Arlie C.

 

[Ryan Cousineau]

In article <xo_Gc.25272$JR4.792@attbi_s54>,
"Blue Gator" <[email protected]> wrote:

> IIRC, something was said on OLN during the prolog that while times were
> being shown in hundredths of a second, they were actually recorded out to
> eight decimals.

Don't believe the hype. If they're really getting data with any accuracy
to the nearest hundred-millionth of a second, I'll eat my hat. The nice,
pink Campagnolo cycling cap I just got.

I would believe that they were getting moderately credible data to the
nearest thou or even ten-thou, but the rest is probably down to
statistical fuzz.

At 50 km/h, the cyclists are travelling at tetch over 45 feet/s, or just
under 14 m/s. The quantities aren't important except as general,
plausible values.

so, in one one hundred-millionth of a second, a bicycle at 14 m/s
travels 0.00000014 m. 1.4x10^-8 m. 14 nanometres.

I'm a pedant, so I went searching for things that big. I found one on
the web!

http://www.umass.edu/newsoffice/archive/2000/121400nano.html

They're building "nanowires" that thick, touted as 10,000 times thinner
than a human hair. There is no way the transponder is positioned with
nanometre accuracy (I suspect the organizers would be happy with
millimeter accuracy), so right there goes most of your decimal places,
and that makes the rash assumption that everything else in the system is
nanometre-accurate.

> This is the same technology used to time Indy car races. If they can
> accurately track cars that travel well over 200 mph then they should be able
> to do the same with a bicycle.

It's not that hard to track a fast-moving object. Compared to radio
waves, they're really slow . Thousandths of a second are within reach
of this technology. For measuring nanoseconds, you need slightly higher
technology.

I'm actually not very impressed with fretting over greater accuracy than
we have. I think it's okay to look at really close results and just
declare that no meaningful performance difference has been measured, and
that it's a tie.

--
Ryan Cousineau, [email protected] http://www.wiredcola.com
President, Fabrizio Mazzoleni Fan Club

 

[David Reuteler]

MSeries <[email protected]> wrote:
> The sensor is 1.2m before the finish line (not after like I said yesterday)
> and the transponder is 1.2m behind the front of the front wheel so when the
> transponder triggers the senser, the front wheel is crossing the line.

nope, can't see the cheat there. anyway wouldn't you have to place it within
a nanometer?
--
david reuteler
[email protected]