[Closed] Silly Gear Ratio Question

you may get marginally more friction with a 40:20 and less chain security with a 24:12 but they'll pretty much pedal the same on the same size wheel.

wwaswas - Member

you may get marginally more friction with a 40:20 and less chain security with a 24:12 but they'll pretty much pedal the same on the same size wheel.

That what I though - well I think I did! 😆

Thank you 8)

With larger chainrings and sprockets there is less friction in the chain due to the smaller angle through which each chain link has to turn as it conforms to the sprocket. This makes using larger sprockets more efficient. I’ve no idea how much more efficient though, I’d bet you’d not be able to notice. Larger sprockets will last longer though, so that’s a good enough reason to use them.

crogthomas - Member
Larger sprockets will last longer though, so that’s a good enough reason to use them.

Why is that?

Load and therefore wear is spread over a greater number of teeth. Ever noticed that it is the smaller sprockets on a cassette that seem to wear out first?

crogthomas - Member

Load and therefore wear is spread over a greater number of teeth. Ever noticed that it is the smaller sprockets on a cassette that seem to wear out first?

Thought this was solely down to usage 😳

Smaller sprockets are definitely not as good.

I used a 22t chainring for Iditarod in 2009 and wore it out in 350 miles. I used a 28t front and a bigger rear this time and it was still in decent shape after 100 miles.

my lbs was on about top dead centre the other day, not the faintest idea what that is but bigger is better according to him.

Bigger cogs need a longer chain (assuming singlespeed), making more weight, making it tougher when climbing.

Otherwise I'd say it's down to wear (more on smaller cogs).

Oh, the other point is that if it's on a bike with suspension, the cog size will change the chainline and potentially affect the linkage, giving a reduction in efficiency.