Bike lock Dragons Den Invention idea.

[PurpleFrog]

the locking mechanism would be its weakest link. Freezer spray is used on D-locks so they shatter

Urban myth.

But I think there is a lock like the one in the OP and that it doesn't work very well. Sorry.

 

[Easy_Rider]

They also use mohair for fabric roofs.
Porsche 968 used it.

 

[FluffyChicken]

Kevlar is fire resistant and will not burn so you're safe there, think somewhere are 500C it'll break down <?> not too sure.

It is reasonable easy to cut in it raw loose form (I have some at school for demonstrations.) Much harder in a tight multidirectional layering setup.

You would need to composite it to do anything useful I would have though, a car roof could be kevlar possibly coated in a 'rubbery' material (quick search picks up this http://www.freepatentsonline.com/EP1149720.html and mentions a kevlar or fine mesh layer). You would gain the kevlar resistance (like they use in gloves etc) but it's not impossible to slice it. Go have a go Take a rechargeable dremel to it.

I think the dremel is the tool you will have most problems against with this idea. It's quick and light and can alter the cutting tool.
Though never tested how good it is.

You should either go out and buy some kevlar weave or buy some kevlar gloves (remember they only claim resistance to cutting and abrasion) and test out on them) or maybe some kevlar rope or wire.


EDIT nice link here to have a read http://www2.dupont.com/Kevlar/en_US/index.html

EDIT 2
Specialised made a kevlar covered metal chain it seems, though that's not the idea here.

 

[PurpleFrog]

Kevlar's abrasion resistance is actually quite poor. I really don't see it surviving against a carbide coated saw blade. And if it can be cut by scissors then a rescue hook - made for cutting car seat belts - will laugh at it.

 

[gibbleking]

or a chav with an empty can of wife beater the day before dole cheque day

 

[barry2017]

I still quite like it.
It will be extremely lightweight. Think of it not as an alternative to a D lock, but as an alternative to no lock.
Just the thing for stopping to buy a cup of coffee on a long ride.

 

[jez-4-bikes-max]

Ok - cheers for the responses guys - really helpful constructive stuff.

Ok - maybe kevlar composite may have its flaws (difficult to tell without setting up a test rig concept)

However - ther emust be some other materials that offer this kind of strength and flexibility without the weight gain...I still think the concept holds water, just the material needs to be discovered.

 

[PurpleFrog]

Ok - cheers for the responses guys - really helpful constructive stuff.

Ok - maybe kevlar composite may have its flaws (difficult to tell without setting up a test rig concept)

However - ther emust be some other materials that offer this kind of strength and flexibility without the weight gain...I still think the concept holds water, just the material needs to be discovered.

To be honest, this is such an obvious idea (I did wonder something similar myself) that if a suitable material was available then it would probably already have been done - unless there was eg a problem with engineering that material that took a clever solution. It's hard to escape the need for density in objects that have to resist angle grinders, saws, and similar devices. An alternative lock would also have to be blow torch proof and immune to the trick of setting fibres in epoxy and then shattering/sawing them when they're rigid. (Even if the epoxy takes time to dry the thief can use the trick of jamming the lock and coming back at night - but a fast set epoxy will probably do the job in half an hour.)

 

[REKIBorter]

... I still think the concept holds water ...

Fill it with smart water or a permanent dye so when it is cut the thieving toe rag gets covered in the stuff.

 

[REKIBorter]

Jez sprints down to the patent office ...