Single speed gear ratio

[FC&P2C]

Help please.

My kids and I race bmx and our gear ratio is expressed by: chainring / Rear sprocket x diameter rear wheel inflated.

Thus for instance I am running 39/17 with rear wheel diameter 23.8125 inch = 54.63"

 

Does it matter how you get to your final ratio? For instance mathematically a 55" ratio is a 55" ratio doesnt matter if its made up by 39/17 or a 37/16 or even a 35/15 for arguement sake.

Some of my Track rider friends swear by making up with as small as posible front chain ring is better cause you get your leg speed up fsster! Then heard an arguement at the bmx crowd that its better to have a bigger front chain ring as it gives you more power of the start?!

I am a believer of my calculator saying that it doesnt matter small or big and that 12 equals a dozen!

Any insight into this matter shall be hugely appreciated.

[Melch]

I remember reading about this topic applied to track cycling years ago, might of been in the cyclists training bible. What the author said was that track sprinters like to run small front chain ring / small rear sprocket as it feels more responsive while the track time trial specialists tended to run larger front chain rings and rear sprockets. The argument for the larger front chain ring/ rear sprocket combination was that it was more efficient as the chain links did not have to bend as far as they moved around the chain ring and sprockets. Not sure if you will find any real information to back this up though.

[droo]

The only difference that I could see is chain tension, which is dependant on the size of the rear cog. So the bigger you go on both cogs, the less tension (and therefore wear) there would be on the chain.

 

And of course, smaller = lighter if you're counting grams.