Anthony DeLorenzo wrote:
"I have a vertical dropout frame I converted to singlespeed. I lucked
into a 40 x 18 combination that yields ideal chain tension, to the
point where I had to tweak the chainring bolts to eliminate those last
few binding sections.
"I want lower gearing for the winter. According to Sheldon, I could add
one link and go to a 36x18 or add two links and go to a 32x18 or maybe
a 36x22. http://sheldonbrown.com/singlespeed.html#vertical "
That's AWFULLY low gearing. How about 39/19, or even 38/20.
"My question: How exact is this formula (1 link = 4 teeth)?"
As others have pointed out, it isn't _perfectly_ accurate because it
doesn't take into account the changing angle of the upper/lower chain
run, but this is a pretty small effect. In any case, going to lower
gears would only make it slightly looser.
Peter Chisholm suggested:
"Why not get a chain tensioner...easy, quick and not expensive or make
one out of 1/2 of an old RDER..single speed...no problem and you can
use any combo you want."
I can't agree. It's true that pulley type tensioners work after a
fashion, but they're really mono-buttocked and kludgy. Also, it is
possible to have chain jump when using sprockets not intended for
derailer use, if you have a spring loaded tensioner.
Sheldon "Dunno Why Google Groups's Quoting Stopped Working" Brown
+----------------------------------------------------+
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