New chain length
08-15-15 | 03:14 PM
#1
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Bikes: Habanero Titanium Team Nuevo
New chain length
Ok I have a standard double 53-39 with a 12-25 rear. I am going to go to an 11-28, realizing this is not the way to size a chain, but what is guess to how much the new chain will be longer? I am thinking just one more full link will be ok. Now I am going to measure and do it right but there must be some formula.
08-15-15 | 03:25 PM
#2
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From: St Peters, Missouri
Bikes: Catrike 559 I own some others but they don't get ridden very much.
There is a mathematical formula but I don't know what it is and everybody that I know uses the analog approach:
Run your new chain around the biggest chain ring and biggest rear cog bypassing your rear derailleur. Figure out the shortest place that you could rejoin the chain. Now add 1 inch of chain (2 links), including your master link, to that. That's the shortest chain that you can safely use with that gear combination.
Run your new chain around the biggest chain ring and biggest rear cog bypassing your rear derailleur. Figure out the shortest place that you could rejoin the chain. Now add 1 inch of chain (2 links), including your master link, to that. That's the shortest chain that you can safely use with that gear combination.
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08-15-15 | 03:29 PM
#3
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From: Lincoln, Nebraska
Bikes: Roadie: Seven Axiom Race Ti w/Chorus 11s. CX/Adventure: Carver Gravel Grinder w/ Di2
There is a mathematical formula but I don't know what it is and everybody that I know uses the analog approach:
Run your new chain around the biggest chain ring and biggest rear cog bypassing your rear derailleur. Figure out the shortest place that you could rejoin the chain. Now add 1 inch of chain (2 links), including your master link, to that. That's the shortest chain that you can safely use with that gear combination.
Run your new chain around the biggest chain ring and biggest rear cog bypassing your rear derailleur. Figure out the shortest place that you could rejoin the chain. Now add 1 inch of chain (2 links), including your master link, to that. That's the shortest chain that you can safely use with that gear combination.
Park explains it here at the bottom:
Park Tool Co. » ParkTool Blog » Chain Length Sizing
And someone made a javascript calculator webpage here:
Javascript Bicycle Chain Length Calculator
Instead of using Big/Big, use Small/Small such that you chain clears the pulleys by ~1cm (IIRC the Campag manual says 8 to 15mm). The difference is that instead of sizing your chain for the shortest chain length, you size for the largest sprocket size your derailleur can handle. Now, using an 11-28 odds are you'll never use a larger cassette, but you never know.
Last edited by Marcus_Ti; 08-15-15 at 03:32 PM.
