Changing gearing affecting singlespeed chain tension

[Anthony DeLorenzo]

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

 

[Kinky Cowboy]

On 21 Sep 2006 11:27:19 -0700, "Anthony DeLorenzo"
<[email protected]> 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
>
>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

 

[[email protected]]

Kinky Cowboy wrote:
> On 21 Sep 2006 11:27:19 -0700, "Anthony DeLorenzo"
> <[email protected]> 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
> >
> >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.

 

[Qui si parla Campagnolo]

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
>
> 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.

 

[Booker C. Bense]

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In article <[email protected]>,
Anthony DeLorenzo <[email protected]> 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
>
>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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