SS Crank Length v. Cog Size



D

David M. Grey

Guest
Been reading a lot about single speed for mountain bikes. Some say to
use a longer crank arm to increase leverage. For example, if you
normally use 175 than move up to 180 to get more leverage for hill
climbs. Question: Can't you achieve the same result by increasing cog
size from say 16 to a 17 or maybe an 18.

/Dave
 
David M. Grey wrote:

> Been reading a lot about single speed for mountain bikes. Some say to
> use a longer crank arm to increase leverage. For example, if you
> normally use 175 than move up to 180 to get more leverage for hill
> climbs. Question: Can't you achieve the same result by increasing cog
> size from say 16 to a 17 or maybe an 18.


Exactly. There's a lot of nonsense written about the supposed
advantages of long cranks.

See: http://sheldonbrown.com/cranks

Sheldon "165-170" Brown
+----------------------------------------+
| Millions of people say I exaggerate. |
| --Marty Gasman |
| http://www.tiac.net/users/mgasman/ |
+----------------------------------------+
Harris Cyclery, West Newton, Massachusetts
Phone 617-244-9772 FAX 617-244-1041
http://harriscyclery.com
Hard-to-find parts shipped Worldwide
http://captainbike.com http://sheldonbrown.com
 
David M. Grey wrote:

> Been reading a lot about single speed for mountain bikes. Some say to
> use a longer crank arm to increase leverage. For example, if you
> normally use 175 than move up to 180 to get more leverage for hill
> climbs. Question: Can't you achieve the same result by increasing cog
> size from say 16 to a 17 or maybe an 18.


Yes, and you may find it easier to spin on the flats or down hills with the
shorter cranks. I think it's best to first choose the crank length you
like, and then choose your gear ratio to suit.

The larger cog wheel should also theoretically result in less tension on
the chain and slower cog wear; whether this will be significant in this
case I don't know.

--
Benjamin Lewis

"Love is a snowmobile racing across the tundra and then suddenly it flips
over, pinning you underneath. At night, the ice weasels come."
--Matt Groening
 
David M. Grey wrote:

> Been reading a lot about single speed for mountain bikes. Some say to
> use a longer crank arm to increase leverage. For example, if you
> normally use 175 than move up to 180 to get more leverage for hill
> climbs. Question: Can't you achieve the same result by increasing cog
> size from say 16 to a 17 or maybe an 18.


Indeed you can. Long cranks are for people with long legs (or people
with short legs who like long cranks for some reason).