Coolwhip-GA

I am sure this has been answered on here a million times, but I am not sure of the right vocabulary to use to find it with the search. So if you don't want to answer the question go read a different thread, don't be a ****** with to much time on your hands and tell me to search for it.

I was wondering what is the difference between running a small chaingear and cog vs a big chaingear and cog(assuming about the same ratio/GI)

elTwitcho

bigger looks cooler and wears out slower. Other than that, not much

Scratcher33

smaller weighs a little less

MuddyPaws

Perhaps Sheldon spoke of this, yep....
https://sheldonbrown.com/fixed.html
Big or Small?

nce you have decided on your gear ratio, then there's the question of which of several different equivalent sprocket/chainring combinations to use.
For instance, 36/12, 39/13, 42/14 45/15 48/16 all give the same 3:1 ratio. Which to choose?

Bigger Smaller
Good:
Slightly less friction
Longer chain/sprocket life
less chain tension
Slightly lighter
More log-jumping clearance
More chainstay clearance
Bad:
Slightly heavier
Chainstay clearance may be a problem on some frames
Rapid chain/sprocket wear
Greater chain tension (increased liklihood of the axle slipping in the frame)
These differences are mostly pretty minor. Most riders will be best served by a chainring somehere in the 30s for technical off-road use, 40s for road or bike path use, low 50s for track use.
Since 42 tooth rings are very commonly available on road cranksets, this size is particularly popular for conversions.

If you use a flip/flop hub, running smaller sizes gives you a bigger gearing difference for each tooth difference on the flip flop.

operator

51/19 has 19 skid patches vs 3 for the other combo. The former also takes more wear and weighs more. The former is also not available in dura ace cogs if you so cared.

brooklyn_bike

search for it

brooklyn_bike

i'm kidding. i run larger rings and cogs as it takes wear and tear better and it also runs slightly smoother. 51 is pretty large. 45s, 47s and 49s are pretty good...

larsalan

Did 53/19 for the longest on a new ride and loved it. Also, the more skid patches, always go for the odd rear

iwegian

i guess i'm used to riding bmx, but i would have to say the contrary