Chain locks are made up of a series of hardened steel links (usually inside a protective nylon sleeve) and lock. The lock can be integrated into the chain or it can be a separate padlock. There are 3 great things about chain locks:
Relative length and flexibility
Be carried relatively easily wrapped
Relative length and flexibility introduce.
First of all, their relative length and flexibility means you can secure your bike to a wide range of objects.
Be carried relatively easily wrapped introduce.
Secondly, they can be carried relatively easily wrapped around your seat post, so you don’t have to deal with any of those annoying u-lock frame mounts!
More resistant introduce.
And finally they are more resistant to some of the common methods of attack used on other bike locks. For example they can’t be bottled jacked or leveraged open. And they’re more difficult to cut with power tools.
If you choose a chain lock for portability and safety, I suggest that you wrap the chain tightly on the upper tube to secure the bicycle. This will keep it away from the ground and make it difficult (if not impossible) for a thief to cut a decent portable chain lock. You have to use different ways to protect your wheels, but there are many options, at least your bike is safe! But please check the weight carefully before buying. Even the shortest portable chain lock can be heavy. If weight is a big issue, it is better to use a U-lock.