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What do these Campy Derailleur specs mean?(6 posts)

What do these Campy Derailleur specs mean?Inhighgear
Dec 3, 2002 7:49 PM
This is from the campy site for their new 2003 Chorus triple derailleur. One has a medium cage and one's has a long cage. They both will allow a rear 29 cog but what does the difference in Cap. 36 vs 39 mean?

min. sprocket 12 - max. sprocket 29 - cap. 36 - max. front diff. 23 -lightened upper body.

min. sprocket 13 - max. sprocket 29 – cap. 39 – max. front diff. 23 – lightened upper body
Cap 39 will take 39 tooth difference..Spunout
Dec 4, 2002 4:32 AM
so that you can use the 13-29 and a 30 tooth granny. The medium cage should be used with a cogset no larger than the 26 with triple. I have a medium cage to use with 13-29 and a double chainring.

Capacity: Refers to the chain wrap from the small-small combo to the large-large. So, with a 52+29=81 large and 30+12=42 small (not that we'd really use those combos because of the chain-line) we would require (81-42)=39 capacity rear mech.

Cool or what!
Cap 39 will take 39 tooth difference..Inhighgear
Dec 4, 2002 4:58 AM
Very cool...Thanks very nice explanation.
cool but not quite correct...C-40
Dec 4, 2002 8:16 AM
Total capacity is calculated by adding the difference between the chainrings and the difference between the cogs.

In the case of a 52/42/30 triple and a 13-29 cassette the needed capacity is (52-30)+ (29-13) = 38.
And I'm not quite wrong...Spunout
Dec 4, 2002 9:37 AM
(52+29)-(30+13)=38

While you wrote:
(52-30)+(29-13)=38
same answer...C-40
Dec 4, 2002 11:50 AM
You're right, you get the same answer either way. Just seems like an unusual method to derive the answer.

My method seems easier to do in your head. A 22T difference up front and a 16T difference in back adds up to 38.