> What I've learned while I lived in Amsterdam is that you want to invest ~30% of the value of your bike to purchase a bike lock.

That advice predates the battery-powered angle grinder, which many bike thieves in Western Europe now use. Even the toughest, most expensive U-lock can be broken in about a minute with an angle grinder.

Having two locks can also be a good tactic, especially two locks in a different style e.g. a d-lock and a cable lock. The theory being that a thief would need to have two tools to steal your bike which means it's likely more hassle than other bikes that'll only have been secured with a single lock.

Founder of a bicycle insurer here and I can tell you that the only way to deter people is by parking in secure private or public spaces (never, ever semi-public) and by making your bike less attractive than the one next to it.

2 locks is indeed the standard in big cities. Also make sure they are sold secure gold rated or Art 3. Anything else is a waste of money. There are a few new lock types which are supposed to work better against angle grinders like Tex-lock or LitLok.

Because the average bike price is going up it also becomes interesting to steal parts. A decent handlebar + shifters are easy to sell individually. Companys like Hexlox or Pinheads are working on locks to tackle that.

Can you get GPS tracking systems that are reliable enough that insurance companies take note enough to discount if they are installed?

Where would you install them on the bike where they couldn't be removed easily? I've thought you could place one in the frame, but that would be difficult to do aftermarket and the GPS and WWAN antennas would need to exit it somewhere.

Shaft were the seat affixes, maybe use the frame as the antenna - dunno, was more interested in what is out there already in a way that is respected enough for insurance companies to make a difference. That's the true test of a security product - how much of a discount does your insurance get for having it ;).

If it's carbon frame then the antennas can be in the frame. Power source sounds more annoying though.

> Because the average bike price is going up it also becomes interesting to steal parts. A decent handlebar + shifters are easy to sell individually.

That's an interesting point. Doesn't that make a folding full-size bike the only real solution?

Something like Changebike DF-611MB:

https://www.changebike.com/df-611mb

> There are a few new lock types which are supposed to work better against angle grinders like Tex-lock or LitLok.

After a quick search...

Tex-lock cut in 32 seconds:

https://www.youtube.com/watch?v=ictBpMHKhK0&t=1m20s

LitLok cut in 16 seconds:

https://www.youtube.com/watch?v=D-On0DGcDlc&t=1m25s

An angle grinder will get through a cable lock in a few seconds. It buys you nothing over a U-lock against someone armed with one.

A cable lock can be cut with a dozen pocket-sized tools. They're not worth the money if you think theft is remotely an issue; D-locks are far more secure.

Neither of those are stopping an angle grinder for more than a few seconds

I saw a guy outside a grocery store taking one of those to a U-lock. He said it was his own bike. Wasn’t sure what to do after that.

Take a really good picture including his face. Send picture to the local police department in case someone reports that bike stolen.

Presumably if it's actually his bike, he'll be thankful.

I was under the impression recording people requires their consent in most of western europe?

How would a security camera work then?

In the UK this is not the case. Anyone can be photographed in a public place.

I challenged a guy I saw fiddling with one of the locks on a motorbike with its alarm sounding, by asking if he'd mind unlocking one of the other locks to show it was his bike. Which he promptly did - his alarmed disc brake lock had jammed.

Of course, my confidence to do so was buoyed by the fact there were two other bikers parking at the same time as me, it was in a busy public area, and I was wearing a bunch of leather and kevlar.

How much sound does it make though?

> you want to invest ~30% of the value of your bike to purchase a bike lock.

Or get two different ones. Bike thieves specialize on one or two specific locks and prefer easy targets.