chain length

[citoyen]

Possibly a stupid question...

If I shorten the chain on my fixie by one whole link, how far forward will the wheel move in the dropouts? I'm guessing half a link, ie half an inch. Or thereabouts, accounting for the vertical difference between the top of the chainring and the sprocket. It seems like an obvious answer but I can't help wondering if there's some factor I'm overlooking.

I ask because I think the wheel is set further back than it needs to be and I'm wondering if I can get away with removing a couple of links but would rather have an idea before removing them if there's a danger of leaving the chain too short.

d.

[citoyen]

OK, just had a look at the fixie faqs...

This seems to answer my question, kind of:
http://fixiefaqs.netcipia.net/xwiki/bin/view/Main/#Q2.16

I assume adjusting the chain length has the same effect as changing the sprocket.

d.

[MSeries]

If you remove 1" from the chain, because it's doubled up, the rear wheel will have to move forward approximately^* 0.5". 

^*Greenbank will probably come along soon with a calculation telling us exactly how much it'll move depending on the size of your ring and sprocket.

[citoyen]

If you remove 1" from the chain, because it's doubled up, the rear wheel will have to move forward approximately^* 0.5".

 

That's what I thought. Great.

^*Greenbank will probably come along soon with a calculation telling us exactly how much it'll move depending on the size of your ring and sprocket.

36 * 14, if anyone's geeky enough to want to work it out.  

[edit: come to think of it, wouldn't you have to know the current chain length to be able to work it out?]

d.

[Hello, I am Bruce]

^*Greenbank will probably come along soon with a calculation telling us exactly how much it'll move depending on the size of your ring and sprocket.

Very very approximately^*

0.5" * (1 - D/(4*pi*L))

 where D is the difference in teeth between the chainring and sprocket, and L is the length of the chainstay in inches (measured centre of BB to centre of hub).


* 100% correct if your bike is infinitely long, or you have 1:1 gearing.