Thanks to Haribo Joe for this excellent description.
Last week the rear axle of my bike broke half way into a 30 mile ride, luckily the wife was happy to rescue us.
I'm still unsure about what to do about my bike so I borrowed my brother in law's bike today so that I could do some exercise.
It is a mountain bike with fat, spongy tyres and full suspension, so every time I pushed down on the pedals the bike bounced up and down, losing loads of energy.
So not only was it really hard work, I felt sea sick.
When Joe saw me I was bouncing around so much he thought I was Psy doing his dance.
It's probably a good mountain bike, but a terrible road/hybrid bike.
When choosing your bike, make saw you know the type of riding you'll be doing and get advice.
It will save you a lot of time, energy and money.