# Chainlinks to teeth changes



## bonefamily (May 17, 2011)

Is there a formula to use to know how many links need to be removed or added when changing chainrings and freewheel sizes?

My new single speed has a 46 x 18 gear. I live in a quite hilly area and my previous conversion bike has a 42 x 18 which I much prefer. I just spin on the flats and have a great gear for climbing. For the new ride, I'm either wanting to change the front ring from the 46 to a 42, or the rear from the 18 to a 19. The former will give me the easier gear, but I think I would also be ok with the latter.

If I choose the 46 x 19, will I need to add a link or two or can I just ride with the rear wheel a bit more forward into the frame? If I choose the 42 x 18, approx. how many links will I need to remove to keep the rear wheel in about the same area? Right now the rear wheel is centered in the dropouts. Thanks.


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## Dave Hickey (Jan 27, 2002)

bonefamily said:


> Is there a formula to use to know how many links need to be removed or added when changing chainrings and freewheel sizes?
> 
> My new single speed has a 46 x 18 gear. I live in a quite hilly area and my previous conversion bike has a 42 x 18 which I much prefer. I just spin on the flats and have a great gear for climbing. For the new ride, I'm either wanting to change the front ring from the 46 to a 42, or the rear from the 18 to a 19. The former will give me the easier gear, but I think I would also be ok with the latter.
> 
> If I choose the 46 x 19, will I need to add a link or two or can I just ride with the rear wheel a bit more forward into the frame? If I choose the 42 x 18, approx. how many links will I need to remove to keep the rear wheel in about the same area? Right now the rear wheel is centered in the dropouts. Thanks.


Removing a link will move the axle approx 1/2".... A change in teeth will move the axle approx 1/8"...Based on this info, your axle will stay in approx the same position if you remove one link and change the ring from 46t to 42t


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## bonefamily (May 17, 2011)

Thanks for the info, Dave - much appreciated.

So, if I choose to go with the 18t FW to the 19t FW change, the axle will move forward by 1/8"? Would I feel a change or response in the ride with the rear wheel moved forward by this 1/8"? I guess I am leaning for toward the next size up freewheel as the current stock one that came with the Schwinn Madison is not that good I fear. I am thinking about replacing it with an ACS Crossfire 19t....


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## jammincakes (Apr 5, 2012)

bonefamily said:


> Thanks for the info, Dave - much appreciated.
> 
> So, if I choose to go with the 18t FW to the 19t FW change, the axle will move forward by 1/8"? Would I feel a change or response in the ride with the rear wheel moved forward by this 1/8"? I guess I am leaning for toward the next size up freewheel as the current stock one that came with the Schwinn Madison is not that good I fear. I am thinking about replacing it with an ACS Crossfire 19t....


1. Yes.
2. No, not really, as long as the tension is the same. (Not for me, anyway. But I wouldn't worry about gearing much at all. You'll get bigger muscles!)
3. Do what you want to do. It's never a bad idea for upgrade.


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## Sheepo (Nov 8, 2011)

4 teeth rule---

4 teeth = 1 link
2 teeth = 1/2 link

Each tooth change will move the axle 1/8 inch


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## Sheepo (Nov 8, 2011)

I cant tell 1/8 inch changes in chainstay length on a mountain bike. So dont sweat it on your road steed!


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## bonefamily (May 17, 2011)

Cool - thanks guys.


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## bonefamily (May 17, 2011)

One more question guys - does the 1/8" axle / per tooth move apply to both front and rear teeth? i.e., will the axle stay the same if I go one tooth higher in the back and one tooth smaller in the front? Thanks!


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## tihsepa (Nov 27, 2008)

One tooth is one tooth. Front or rear. The effect ratios differently but not chain length.


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## bonefamily (May 17, 2011)

tihsepa said:


> One tooth is one tooth. Front or rear. The effect ratios differently but not chain length.


Cool, thanks. Then it would be a wash...


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## tihsepa (Nov 27, 2008)

bonefamily said:


> Cool, thanks. Then it would be a wash...


Remember though, one tooth on a cog or chainring is only a half-link on a chain.


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## bonefamily (May 17, 2011)

tihsepa said:


> Remember though, one tooth on a cog or chainring is only a half-link on a chain.


Yes - but what I am wanting to do is go from my current gear, a 46/18, to a 45/19. One tooth up and one tooth down. By doing this I can still get the same axle postion without adding or taking away a link, correct?


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## OldZaskar (Jul 1, 2009)

tihsepa said:


> Remember though, one tooth on a cog or chainring is only a half-link on a chain.


You mean 2 teeth on a cog or chainring = a 1/2 link on a chain...

4 teeth rule---

4 teeth = 1 link
2 teeth = 1/2 link

I just went from 52/18 to 52/16 - the axle stayed put and I swapped a link FOR a half link. Worked out great.


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## tihsepa (Nov 27, 2008)

OldZaskar said:


> You mean 2 teeth on a cog or chainring = a 1/2 link on a chain...
> 
> 4 teeth rule---
> 
> ...


My brain hurts


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## OldZaskar (Jul 1, 2009)

^ oops ^ 

Typo. I originally typed "I swapped a link of half link" meant to type "I swapped a link FOR a half link"

I could see how that'd make your brain hurt ;-)


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