Best guide for any budding mechanic that I have found is Park Tool's, Park Tool Big Blue Book of Bicycle Repair.
Clear and concise and is not half as much of a Park Tool advert as you might expect. It is full of color pictures and it is all done in step by step guides, pretty much everything about replacement and repair is in there. http://www.amazon.co.uk/Park-Tool-Blue-Bicycle-Repair/dp/B001B6NAW2
Best guide for any budding mechanic that I have found is Park Tool's, Park Tool Big Blue Book of Bicycle Repair.
Clear and concise and is not half as much of a Park Tool advert as you might expect. It is full of color pictures and it is all done in step by step guides, pretty much everything about replacement and repair is in there.
http://www.amazon.co.uk/Park-Tool-Blue-Bicycle-Repair/dp/B001B6NAW2