I ride a fixie. What are the advantages or disadvantages of lower cog teeth or more teeth in a cog?

Thanks in advance

"Cog" generally refers to the gear on the rear wheel, and "chainring" refers to the one on the front. If you increase the size/number of the rear without changing the front it will be relatively easier to pedal (lower gearing) but you'll top out sooner, while if you reduce the size/number on the rear it will be harder to pedal (higher gearing) but you could theoretically reach a higher speed.

Some say larger cogs will last longer. Not sure but I think the closer the size between chain wheel and cog results in greater efficiency. Possibly the above is a difficult to measure pittance.

I'm assuming you are referring to keeping the ratio or gear inches the same with corresponding changes in chain wheel teeth regarding your question.

Simple math : Ratios ; count teeth _a 20 tooth hub cog turns a 40 tooth chain ring how many times?

I have more teeth than cogs, but as i age and my teeth decay, the bikes are catching up .....

First a question: When you say "fixie" that technically means you can't coast. Is that you? If you can coast you have a "single speed" that has a big impact on the precise answer.

As the first responder answered, more teeth make it easier to pedal and fewer teeth will allow you to go faster. IF YOU TRULY HAVE A FIXIE, too many teeth will force you to pedal uncomfortably fast downhills.

Read this:

The Gearing Primer

Half the answers on this thread have nothing to do with the OP's question.

More teeth = easier to pedal but lower speed.
Less teeth = harder to pedal and higher speed.

That's all.


-Tim-

So much simple math impairment these days, as this forum suggests, repeatedly..

On a fixed gear, more teeth on the rear cog make it easier to go down a hill, fewer teeth on the rear cog make it easier to go up a hill.

I've heard the same thing. I think it's based on the idea that you'll be spinning, not mashing, and therefore subjecting your drivetrain to less wear-and-tear.

Large ring/large cog combination is principally more efficient than small ring/small cog. This is because chain links work more efficiently when the link direction changes only slightly from one link to another. When links change abruptly direction part of the force on a subsequent link goes into deforming the cog without trying to propel the bicycle.