10 gears to singlespeed My second hand Hercules bicycle came with 10 gears. Two gears in the front and five in the back. The gearshift does not work well and since I cycle in the same gear all the time anyway, I consider turning it into a single-speed bicycle. Can I just remove the derailleur in the back and adjust the length of the chain? Any reason why I shouldn't do this besides the obvious fact that I will have less gears? Anything I would have to take care of?
I've got a 2nd hand Hercules too and I've done this exact thing. Get a quality chain tool and look up some videos on Youtube about how to remove and re-link a bike chain. I pretty much winged it as I had no clue what I was doing. It took a bit of work and a lot of frustration to get the chain length right. I probably did it wrong, but it works. 

EDIT: Argenti Apparatus mentioned the dropouts.. One thing i did to get the chain tight was loosen the rear wheel from the frame, and pull it back as far as i could pull it.