Hi there,

​​​​​I am a bicycle courier and have just run into a problem with my left crank arm. All shops are shut here in Spain at present with the lockdown so just want some advice on how to fix my bike with the tools I have. I first noticed a slight click on my pedal yesterday, which developed into a big wobble in the crank which quickly became unrideable. I came off the bike and realised that the crank arm was completely loose. I took the bike home and tightened the crank bolts with an Allen key (I don't have a torque wrench) and it did the job for the rest of the day. This morning the same problem has come back. I will probably be able to do the same quick fix, but I'm sure the problem will come back. Does anyone have any advice what the root cause of the problem would be? Would using a torque wrench be enough to fix it or do I need to buy some new components. Just to give a bit of background to the bike. I bought it last year in November and have done ALOT of cycling with it since then. I typically do around 2000km per month. I understand that it is hard to know exactly what the problem is without seeing the bike, but given that I have no experience with bike mechanics and all the shops are closed I just wondered if someone with more knowledge would perhaps know what could be going on? Many thanks for any help!