What would cause this?

[HovR]

I use a £7 Clarks chain bought from Amazon! I'm impressed with it, and it's resisted surface rust really well (unlike the chains that come on all new bikes I've ever bought).

The chain is manufactured by YBN, and at this low price I'll be happy replacing it at anything over 1500 miles. Sure, it's not as light as these modern chains with hollow pins and side plates, but these can cost over £60!

Having some sections of your old chain will be better than nothing in the event of an emergency, but preferably you should have some new chain as Gary E has explained above.

 

[Aiden_23]

Just read up on how to fit a new chain and will pop a few links into my tub just incase. To be honest I would just change the entire chain if anythig was wrong with it the couple of links would just be fitted to get me home.
Thanks again for the tips, something that I can check off my list of bike maintenance "on the go training"

 

[HLaB]

I had a KMC chain break similarly after a fall on ice, amazingly it lasted the 50miles home and it was only when I was cleaning the bike I notice quarter of the link was missing all kudos to KMC but that chain got binned straight away.