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From: Jeff Liebermann <jeffl@cruzio.com>
Newsgroups: rec.bicycles.tech
Subject: Re: Jamming Shimano Di2
Date: Sun, 18 Aug 2024 10:45:53 -0700
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On Sun, 18 Aug 2024 09:52:58 -0500, AMuzi <am@yellowjersey.org> wrote:

>On 8/17/2024 7:02 PM, Frank Krygowski wrote:
>> On 8/17/2024 4:40 PM, AMuzi wrote:
>>>
>>> I'm not qualified to comment on specific technical methods 
>>> but I see the question as, 'Who would want to win a 
>>> bicycle race by cheating?'.
>> 
>> This is only vaguely related, but what's the current status 
>> of the "hidden motor" racing scandal from a few years ago?

>Infrared cameras.  End of story.
>https://cdn.road.cc/sites/default/files/styles/main_width/public/motor-hidden-bike-frame-stade-2-video-image-april-2016.jpg

Detecting the heat produced by the motor only works immediately after
a race or after a test ride.  If the bicycle, motor and the rider have
had time to cool off, an IR camera see much.  I don't know how soon
the bicycle needs to be inspected.  IR inspection is practical if the
officials only inspect the winners, but that leaves the possibility of
non-winning finishers to bypass finish line inspections.  

However, finish line inspections fail miserably if the offending rider
changes bicycles near the end of a stage or race.  The could ride with
almost the entire stage or race with motor assist, change bicycles,
and pass any possible finish line inspection.  It might be possible to
inspect ALL the bicycles involved in a race, including those that have
been replaced, but the logistics of doing that are probably
impractical.

Since most racing bicycles have carbon fiber frames and the brushless
DC motors that are being used require powerful rare earth permanent
magnets, it should be possible to detect the magnetic field.   Even a
MuMetal shielded magnet through a few mm of carbon fiber tubing with a
compass, nail finder or magnetometer can be detected where no magnetic
field belongs.  

I just tried it with a small brushless electric drill and the MEMS
magnetomter in my smartphone.
<https://play.google.com/store/apps/details?id=com.keuwl.magneticfieldcounter&hl=en_US>
It indicated roughly 80 uT (micro Teslas) or 0.40 gauss from my Dewalt
DCD777 hand drill though an aluminum tool box.  The earth's magnetic
field is about 40 uT and the motor is shielded.  By moving next to the
drill motor, it peaked at over 400 uT.  If you're going to try
repeating my crude test, be sure to set the app to |B| which is the
absolute value of the vector sum of the magnetic field in all 3 axes.

Soon, all pro bicycle computers will include a magnetometer to allow
riders to test if their hidden downtube motor can be detected.

Has anyone tried a giant rubber band down the seat tube?  Wind up the
seat post and saddle for an extra boost of power.


-- 
Jeff Liebermann                 jeffl@cruzio.com
PO Box 272      http://www.LearnByDestroying.com
Ben Lomond CA 95005-0272
Skype: JeffLiebermann      AE6KS    831-336-2558