Gearing Debate...you decide!

In the past year my average cadence after warm up has slowly increased to where I'm now comfortable at 95-100 rpms.  Any idea what your cadence was? What about your co-rider's?  Cadence function on a cyclometer is invaluable when starting out on the bike.  For the longest time I was counting but when I got the tri-bike I made sure I had the function and it really has helped me.

Here, read these articles too, knowing pedal cadence, how to start the run, and also run cadence help tie it all together:

• BT - Cycling cadence
• Infamous Run
• BT - Run articles for stride rate

I think you said you were riding big gear in front to nearly biggest gear in back.  If I read that correctly, then you have cross chained your gears.  You might want to select a gear combo that keeps the chain straighter.  A straighter chain is a little more efficient pedaling and causes less chain wear.  Many of the gear combinations are nearly the same on a 2x10 bike.  Picking the one that is straighter from front to back is the better choice.

The other question is about cadence.  Let's have a brief physics lesson.  At a given speed the power to the bike is a constant.   The power is equal to product of torque on the pedal (force of your feet at the end of the crank) and cadence.  So if you pick a low cadence, your torque (force) has to go up.  In general, the higher the force the more fast twitch muscle fibers are engaged.  The fast twitch fibers fatique more quickly and are less efficient as well.  So the usual suggestion for the run of the mill masher is to up the cadence (pick a lower gear) and pedal faster at lower force. 

Of course, there is an upper limit on cadence.  The muscles have to switch on and off as you pedal.    When you pedal too fast, some fibers are still tense when they should let off.  Hence your muscles begin to work against themselves.   You can improve on your pedaling coordination so that you can increase the cadence at which this happens but the genetics of your nervous system eventually limits you.   Some of us are just not born to be sprinters.

The moral to the story is pay attention to your effort level.  Keep the cadence in the fast/comfortable range.  If you have a cadence meter, this is going to be in the 85-90 range for most people.   Try a couple of 20 mile rides with different gear combinations and see which is faster/more comfortable for you.  

TW

Gear ratio is normally expressed as the teeth in front chainring ÷ (not x) those in the rear cog. In your example, the 53-17 combination results in a gear ratio of 53÷17=3.12, which (I think) means for every revolution of the pedals you turn the rear wheel 3.12 times.

Gear ratio is seldom used in bicycling discussions, usually the diameter of the wheel is factored in to arrive at a measurement called gear inches, or in metric countries, meters development. Others factor in the crankarm length to calculate a gain ratio. Here's Sheldon Brown to explain it all:

http://sheldonbrown.com/gain.html

This is a bit of a generalization but in most cases it is the scenario .....

New riders = low cadence/too high of a gear

Experienced rdiers = higher cadence/lower gearing

I'm personally a spinner.  I've always had a high cadence.  In my race this past weekend I was always well over 100 rpms which makes it seem almost effortless to me.  When I start to fatigue I go down a gear.

As Bear mentioned it is also a matter of the gearing available.  I tend to run close ratio gearing (11-21 on my race wheels) so each shift is only a small adjustment.  If you are running a more spaced cassette (like an 11 - 25 or 27) then some shifts will jump two or three teeth in difference as opposed to the one tooth difference in the "tighter" cassette.  This will have a bigger effect on your ability to hold the higher cadence.

When I had a triple RB I rode mostly in the middle ring unless the speed went high enough.  On the Tri-bike I ride evenly between the small ring & big ring to prevent excessive chain crossover.

Daremo has a great point, know your gears!  Being I'm in FL (FL stands for FLat where I'm at) I ride a 12-23 10-spd cassette.  One gear change between the 12 & 19 tooth cogs for me is ~ 5-7 rpms.  Below is something I had in Excel when I was trying to figure out which cassette I should change to when I first had the triple RB with 8spd, it came with the 12-25 and I changed to a 12-21, having consecutive 12-17 really helped me out.

Having your chart might be a good opportunity to point out a couple things about shift patterns to the newbies out there.

• In the real world, nobody that I know of progresses through their gears in strict order according to their gear ratios. For instance, no one shifts from their 42-16 to their 52-19 (up one on the chainring and up two on the cassette) just because that's the next incremental gear. Most will be OK going to the 42-15 (up one on the cassette) as an easier more efficient shift. This eliminates the practicality of several gears in your range.
• As Don said, it's mechanically bad to cross-chain, or to have your chain on opposite extremes (example: have your chain on the small (30) chainring and the smaller (13 & 12) cogs in the back). Again, this eliminates the use of several gears.

What you end up with is a crossover system, where you stay on one chainring through a speed range, and shift to the next chainring (and a higher speed range) only when you reach the top of that initial range. Using Don's chart with his 12-21 cassette, I've eliminated the "impractical" gears so that you can see his 24-speed bike really only has 17 practical speeds:

I've also added (per Sheldon Brown) the speeds you will be travelling while pedalling 90rpm. So, generally speaking, on Don's bike he will remain on the middle chainring at speeds between 15.6 and 22.7 mph, which is where most of us spend the bulk of our training time, especially on relatively flat courses.

Not sure where Don got the term "gear drive" but it's actually "gear ratio," ot the number of teeth on the chainring divided by the number of teeth on the rear cog.

I made it up so I sound like I know what I'm talking about

If I turn the crank once, I drive the rear gear x.