Changing gearing affecting singlespeed chain tension

Anthony DeLorenzo said:

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

My question: How exact is this formula (1 link = 4 teeth)? Because my
chain is optimally tight, I can't have it get any tighter at all, and
of course I'd rather it not get much looser. I don't have any of those
gears available to test it out, and I don't want to purchase new
chainrings only to find out that it won't work.

Reducing the included angle between the chain runs makes the chain
looser, so your 36/18, 32/18 or 36/22 will all be fine but, for
example, 44/18 next summer might be too tight if you're already as
tight as you wanna be.

If you scroll to the bottom of
http://www.parktool.com/repair/readhowto.asp?id=26
you can find the relevant formula. Where it says divergent chain angle
makes the (required) chain longer, the corollary is that for a fixed
length of chain the chainstay would have to become shorter, which is
obviously not an option with VDO

Kinky Cowboy*

*Batteries not included
May contain traces of nuts
Your milage may vary

Kinky Cowboy said:

Anthony DeLorenzo said:

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

My question: How exact is this formula (1 link = 4 teeth)? Because my
chain is optimally tight, I can't have it get any tighter at all, and
of course I'd rather it not get much looser. I don't have any of those
gears available to test it out, and I don't want to purchase new
chainrings only to find out that it won't work.

Reducing the included angle between the chain runs makes the chain
looser, so your 36/18, 32/18 or 36/22 will all be fine but, for
example, 44/18 next summer might be too tight if you're already as
tight as you wanna be.

If you scroll to the bottom of
http://www.parktool.com/repair/readhowto.asp?id=26
you can find the relevant formula. Where it says divergent chain angle
makes the (required) chain longer, the corollary is that for a fixed
length of chain the chainstay would have to become shorter, which is
obviously not an option with VDO

Kinky Cowboy*

*Batteries not included
May contain traces of nuts
Your milage may vary Change your gearing when you wish for what ever reason. Just use a new chain sized to your rig.

Anthony DeLorenzo said:

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

My question: How exact is this formula (1 link = 4 teeth)? Because my
chain is optimally tight, I can't have it get any tighter at all, and
of course I'd rather it not get much looser. I don't have any of those
gears available to test it out, and I don't want to purchase new
chainrings only to find out that it won't work.

Regards,
Anthony

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.

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In article <[email hidden]>,

Anthony DeLorenzo said:

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

My question: How exact is this formula (1 link = 4 teeth)? Because my
chain is optimally tight, I can't have it get any tighter at all, and
of course I'd rather it not get much looser. I don't have any of those
gears available to test it out, and I don't want to purchase new
chainrings only to find out that it won't work.

If you know what already works, you can get a pretty good idea of
what else might work at

http://eehouse.org/fixin/

Although it says fixed gear, the math is just the same for a
freewheel of the same cog size.

_ Booker C. Bense

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