anti theft camera bag for your M?

[erl]

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If you live in fear, don't travel, much less carry a camera.

 

Just go and enjoy. You may avoid a catastrophe at home!

[stunsworth]

But a pillion passenger and driver are braced ready for the pull, which makes a massive difference to the outcome, and in their favour. That is the dynamic of the situation, all the elements should be taken into consideration. Think of it like two tug of war teams, one standing upright , and one braced and leaning in the opposite direction, which will win?

 

The problem (ok it's not really a problem) is that, assuming the pillion rider has his arm around the waist of the person steering the moped, the main thing that will keep them on the bike is the grip that the person steering has on the handlebars. In this situation, where the seat is relatively slippy, I doubt that bracing will make much impact. Imagine being on wet ice and bracing yourself as something heavy moves towards you. No matter how well you brace yourself you're likely to slide backwards as there's not much friction between your shoes and the ice.

 

I've tried a few sums - apologies to any physicists reading this.

 

If we imagine that the strap doesn't break, that means that the person carrying the bag and themselves can be seen as one unit. Let's assume, to make the sums easier, that the person weighs 50 kilos. Lets also assume that the moped is travelling at 20kph.

 

Under these circumstances grabbing the bag will attempt to accelerate the person (and the bag of course) to 20kph in a short period of time - let's say a quarter of a second.

 

Now the maths, which revolves around that old favourite of Newton 'F=MA'.

 

The M part of this is pretty easy, it's the 50 kilos mentioned earlier. We can calculate the A because 20 kph is roughly 5 metres per second (it's higher, but the sums are easier if we say it's 5). So if we try to accelerate from 0 to 5 metres per second in a quarter of a second, that gives an acceleration of 20 metres/second/second.

 

Multiply this by the mass and we get 50 x 20 i.e. 1000 Newtons (the 'F' part). This is the equivalent of a weight of 100 kilos in Earth's gravity.

 

That's a lot to hold onto with one arm (the passenger) or two hands (the cyclist). Which is why I think the cyclists would be dragged off their bike.

 

At this point my physics teacher would have pointed out all the flaws in my reasoning, but in my defence I'm remembering that from 40 years ago.

[pico]

I'd not bet against the momentum of the moped thief and I am 6'3" and solidly built.

 

Point taken, Big Guy. You can carry my camera bag any day.

 

There is no emoticon for that one.

[250swb]

. Lets also assume that the moped is travelling at 20kph.

why I think the cyclists would be dragged off their bike.

 

Any sensible pair of thieves won't be travelling at 20kph when they hit, it would make them circus performers in terms of accuracy, dexterity, and success rate. They will be accelerating away from a much lower speed, which would not only be more accurate, but less likely to pull the pillion passengers arm out of his socket. I think even scumbags on a moped would have some common sense even if only acquired after trial and error.

 

Steve

[pop]

Unless the victim is pyramidal in shape, he will not be accelerated in the general direction of the moped's cruise but simply toppled over. That's where Bill might be at a disadvantage, offering a longer lever than us groundhuggers.

[jdsheepdog]

Some small errors in Steve's post. 50 kG is a pretty low number for the average Western tourist with the kind of diet that goes with buying Leicas. Taking his weight (mass x G) up to a more realistic 80 kG changes things.

 

Acceleration also comes from Newtons laws of motion, and depending on assumption, either the rider, or the victim can win, especially if assumptions vary as to the speed of the motorcycle.

 

Finally, the victim, if his reaction is to brace, can be considered for leverage as an encastered cantilevered column, while the motorcycle is a pin ended column supported by the angular momentum of the wheels, actually significantly weaker, except for the force required to decelerate it.

 

The angular momentum depends on the radius of gyration and mass of the wheels.

 

There are reasonable assumptions that give the advantage to the victim, and equally reasonable assumptions that give the advantage to the perpetrator.

 

Bottom line, too many variables for a consistent conclusion across all cases. Quit fighting guys, you are both right, depending on how, what, when, and who.

Edited August 3, 2013 by jdsheepdog

[elgenper]

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.... 50 kG is a pretty low number for the average Western tourist with the kind of diet that goes with buying Leicas.....

 

:D

 

At last, the correct explanation for my 100+ kg! Not too many steaks; too many Leicas....

 

Either way: don´t tell my wife!

[Mr_Jones]

I've heard of a few cases of moped bag snatching in London, one ended with a pedestrian karate kicking the moped passengers to the floor which resulted in a returned bag and arrests for the thieves.

 

There is a device available that you can place in your luggage which tracks your bag. You could trace it for a while at least.

 

Trakdot | Luggage Tracker

[erl]

I like the karate kick option better!

[StephenPatterson]

I often travel by train in China, and these trips are usually 8-12 hours and many are overnight journeys. On Chinese trains in 1st or 2nd class compartments you are always with strangers (4 beds in 1st class and 6 beds in 2nd class) and while violent crime is very rare in this country petty theft is not, so keeping my camera gear secure is a must. For this reason I always put all my camera gear in a Think Tank International roller case. I use the Think Tank case for two important reasons. First, the case has very secure locks to keep little hands out in the evening while I am sleeping. Second, the case has a cable lock so I can secure it to the luggage rack and know that it will not roll away while I'm in the washroom.

 

As for my shoulder bag/backpack my rule is that I just never have it out of hand, until I'm back at the hotel or my apartment.

[Leicafanatics]

don't they have a GPS device for personal belongings, if it's away from you certain distance, it would alert you?

[erl]

Sounds a bit like shutting the gate after the horse has bolted!

[Knightspirit]

I think many here may have misunderstood the intent of the original poster. Most  responses were flippant or centered on theft - but I think the point was to have an alert should the bag be mistakenly left behind. Don’t laugh - I did this once in Mexico. I left a whole bag full of Leica gear in a cab! I just forgot to grab it as I was exiting the taxi - and I realized it just as he was driving away. I immediately contacted the cab company and by some miracle had it back in my hands within minutes. I gave the cab driver all the money I had with me in thanks. 
 

A friend of mine in Los Angeles was on his way to play a gig at Disneyland and saw a ladder on the freeway entrance so he pulled over to pick it up. It wouldn’t fit in his car the way it was packed, so he pulled his instrument out (a trombone) to get the ladder in. It wasn’t until he got to Disney that he realized he had forgotten to put the trombone back into the car! He never got it back.

 

As people we sometimes do dumb things. I am constantly worried I’m going to leave my bag somewhere after having already done it once, so a proximity alert in the bag seems like a great idea. I want one!

[Derbyshire Man]

Apple tag in the back. It notifies you when you wander off. 

[jdlaing]

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[Herr Barnack]

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