Can you hear it? It's spring time!
Ok, maybe you don't know what I mean by this kkrkkrkkrkkr sound, but I'm quite sure it's familiar. It's the cyclist in front of you. The one who thinks that cycling in the winter is not possible and parked his bike for a few months either inside or outside (sometimes you can even make that out by the volume of the kkrkkrkkrkkr).
It's the chain, of course. The chain that is a bit rusty now, but has neither been cleaned nor greased after reviving the bike with love, ehm air.
Please guys and girls, I'm begging you. Look after your chains. I hate that kkrkkrkkrkkr sound. I don't mind if you don't want to cycle in the winter. I'm happy for each and everyone that cycles (ok, in secret I already think about how I can convince you to cycle on in fall, and then winter too).
But: Look after your chain. Clean it and oil it and your life will be much easier (also talking about the power you need for pedaling). And quieter.
And: Look after your chain. Cleaning and oiling is not enough. I had to learn that the hard way when my chain was torn apart while cycling. It happened in fall, hence it wasn't a "start cycling in spring" thing. But it was one year after I had checked my chain the last time. You know, chains stretch continuously. If they are too long, they do a lot of harm to your (relatively expensive) sprockets.
There is a gauging tool to check whether the chain has lengthened too much, but you can easily do it yourself without that. I found this how-to and an even more useful video about chain wear on BicycleTutor.com (highly recommended). Read all about chain maintenance on Sheldon Brown's homepage if you want to become omniscient. And since we are just at it, here's a chain length calculator in case you need to replace your chain. By the way, well-looked-after chains may last for 5000km or even more. And also new chains are a steal (starting at 10€).
If you don't want to do all this yourself, it's worth to pay a mechanic to check your bike. I dislike kkrkkrkkrkkr people, thus better not be among them. Look after your chain and you can be my bike buddy :-).