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Gearing Question/Riding Technique(5 posts)

Gearing Question/Riding TechniqueGiles
Aug 26, 2002 10:52 AM
The question on a triple vs. a double had me wondering about something. Lots of the gears on a standard double (53/39) relatively overlap (gear inches) or are similar. Small chain ring in front small cogs in back or vice versa for the big chain ring. Is it better to ride in the big ring or the small ring when your cadence will be roughly the same? I generally ride in the big one, but wonder if I am unecessarily tiring myself out.
I also noticed that it feels faster in the 52 chainring, eventz
Aug 26, 2002 11:08 AM
though gear ratios and loads are about same as with 42 chainring. Theoretically, only gear inches should matter.
Any comments on this?
In a frictionless world...brider
Aug 26, 2002 2:20 PM
you'd be right. But there are frictions in the system. The larger chainring/cog combo causes less friction due to the movement of the chain links (very small, but it IS there). Also, the velocity of the chain is smaller with the big chainring/cog combo. But the bigger difference will be chainline. The straighter chainline will be the more efficient. So the answer really depends on what combination you're using.
In a frictionless world...Fredrico
Aug 26, 2002 3:46 PM
Recalling a study Moser made on TTing with large gears vs. small gears, he settled on large rings for his speed record attempt, claiming they were easier to "lever" in circles, being pulled furthur out on the crank arms. He concluded larger gears front and back turned easier than smaller gears for the same ratios. For example, 53-17 is easier to crank than 39-14, although they have the same roll-out.

This is in addition to your argument that larger gears provide less friction than smaller ones. They distribute cranking power over more of the chain links and cog teeth, reducing friction and wear.
I try to keep cadence up.fracisco
Aug 26, 2002 1:41 PM
I try to keep my cadence up, so if I'm just rolling around and want to light pedal and spin, I'll often be in the small chainring. I think using cadence as a benchmark is useful when riding alone or with just a couple of others.

In a group ride I don't have time to think about which chainring I'm in/cadence I'm spinning. I'm usually in the big chain ring and going up and down the cassette, unless it's climbing time, or warmup/recovery time.