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-   -   Big crank or small crank, technique? (http://www.bikeforums.net/general-cycling-discussion/550310-big-crank-small-crank-technique.html)

FrenchFit 06-09-09 08:51 PM

Big crank or small crank, technique?
 
When blasting around the city, not road racing, what's the advantage of being in the smaller chainring then the large chainring - assuming you are using the appropriate cog on the rear so you keep the gear ratio the same? Any? Seems to me using the smaller ring up front provides better leverage and acceleration, but that could be pure imagination. Again, assume the gear ratio between the two compares exactly.

Retro Grouch 06-10-09 07:05 AM

Quote:

Originally Posted by FrenchFit (Post 9073792)
what's the advantage of being in the smaller chainring then the large chainring - assuming you are using the appropriate cog on the rear so you keep the gear ratio the same?

1. One of those combinations is likely to give you a straighter chainline. Straighter is more efficient and will also prolong chainlife.

2. The leverage factors using the bigger/bigger combination will result in less tension on the chain. Less tension is better.

3. Using the bigger/bigger combination will result in more teeth being engaged on both the cassette and chainring. Spreading that load should result in longer component life.

I wouldn't expect any of those factors to make enough difference to affect my lifestyle. For me, component replacements intervals are affected by season of the year as much as wear. I tend to replace stuff when I'm overhauling my bike. A tiny amount of wear difference, one way or the other, probably wouldn't affect my decision.

jack002 06-10-09 10:05 AM

When tooling around town I keep it in the small ring for the most part. The only reason is that you ARE gonna have to stop what with lights, signs and traffic, so you have less work getting in a low gear from there than if it was in the large ring. Aside from a chainline like what was said above, theres no reason at all I can think of why it matters. 'Go to the big ring when you run out of gears' is the rule for me.

FrenchFit 06-10-09 03:49 PM

Very thoughfully answers, thanks. And I did notice the improved chainline visually, the line of the small to cog is a better line than big to its appropriate cog. Perhaps that's what I'm feeling, a little more like my single speed.


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