Help Me Understand My Bicycle's Gears I've recently started commuting with a bicycle (Giant hybrid bicycle).  I've been trying to learn a little about bicycling to make my commute easier and my time on the bicycle more enjoyable.  Please forgive me for using the wrong terminology.

I've read that I should keep my pedalling speed mostly consistent and use my bicycles gears to adjust my speed.  The problem I'm having is understanding the 'how'.

My bicycle has 3 gears on the front of the chain and 8 gears on the back.  

Low gear == easy to pedal
High gear == harder to pedal

What I've found is that the gears don't follow a very logical (to me anyway) progression and because of that - I don't know how I should be shifting.  Currently, I've been keeping my front gear in the middle and using the back shifter to change between gears 3-7 or so.  I'm only use about four gears on my '21 speed' bicycle!

I'm also pretty sure the salesman said it was a 21 speed bicycle - but by my count there are 24 combinations.  I know (now) that I'm not supposed to have the front gear in the lowest position and the back gear in the highest (and vice-versa) but that seems to leave 22 gears.

How should I be shifting?  Should I really use all 21 or 22 gears?  I haven't done the math but it really feels like there is a big amount of overlap between the gears.  I hope this ascii art will make sense to someone.  This is just how it 'feels' to me.

----1----2----3----4----5----6----7----8----
------------1----2----3----4----5----6----7----8----
--------------------1----2----3----4----5----6----7----8----


Does that make sense?  Is it right?

It feels like there is overlap between the three front gears and that to shift the most 'smoothly' I'd need to constantly change both gears.  But this seems really complicated to me.

I've ridden bicycles with only three gears and I found myself thinking 'More would be nice' - but now I'm overwhelmed.  I'm also questioning if anyone really benefits from so many gears?!
Don't overthink it. Since you've got a triple, you're probably right to be in your middle ring most of the time That's normal.


In the middle ring you should have access to the whole cassette/freewheel in the back, though you might get a little extra noise as you approach the extreme gears in either direction.
You'll use the big chainring when you're going downhill or your on flat ground and in a hurry. Stay out of the biggest couple of cogs in the back when you're in the big ring up front. This causes extra strain and extra wear on the drivetrain which can result in premature failure.
Your little ring up front is your climbing ring. Use this for hills, or as your bail-out ring when you're totally out of energy. Just like big-big is a no-no, so is small-small, so stay out of the smallest cogs in the back when you're in the smallest ring in the front.


Regarding your hunch that you've got a lot of overlap between gears, you're absolutely right. Think of each ring as a gear range (climbing for small, normal use for middle, ass-hauling for big). If there were no overlap between the chainrings you would either A) have far fewer gears in the back or B) have a range of gears in the big and small rings which were far too small or far too big to be usable.Think about how big the jumps between gears would be if there was no overlap at all! Trust me, it's not what you want. Typically, you'll find yourself Shifting the front in one direction and immediately afterwards shifting the back in the opposite direction so that it feels like you've only skipped about a single gear in either direction. In time, you'll come to appreciate the overlap between gears in the different chainrings.
Finally, if you really want to see how much overlap you have, you can divide the front rings by each of the back rings to get a ratio for every gear combination. There are fancier ways of doing this, but for your purposes this is the easiest and most straightforward.
EDIT: Here's a pretty good article on Wikipedia about bicycle gearing if you'd like to get more in depth.