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Campy 10 speed gear calculation tables(7 posts)

Campy 10 speed gear calculation tablesaltidude
Nov 18, 2002 6:51 PM
I'm trying to decide between 12/25, 13/26 and 53/39 vs 53/42 for a new Campy Chorus 10 speed drivetrain. Where can I go to see what the gear inch calcs are for all the gears involved to avoid duplication of gear inches.
re: Campy 10 speed gear calculation tablesthe Phantom
Nov 18, 2002 7:19 PM
Check out the Charles River Wheelmen web site, Search for the gear calculator link, it is quite good with the ability to display a nice gear progression graph in color. The macro was written by an M.I.T. gearnut type who knows his poop.
BTW, get the 53/39 and 13/26 combo. Better yet get a record triple group with a 53/39/30 and a 13/26.
re: Campy 10 speed gear calculation tablesthe Phantom
Nov 18, 2002 7:28 PM
Sorry, the correct site is .
re: Campy 10 speed gear calculation tablesroadcyclist
Nov 19, 2002 3:22 PM
Or go to Sheldon Brown's site. I agree with the 53/39, 13-26
because that's what I have. on the Campag site NMSpunout
Nov 19, 2002 5:07 AM
Can you multiply and divide?Kerry
Nov 19, 2002 6:30 PM
Gear inches = chainring teeth/cog teeth times wheel diameter (26.35 inches for a 700x23 tire). Development is chainring/cog*82.5 (inches) or times 3.25 (meters). You'll not avoid duplication with either set, but that's OK. The real question you should ask is whether you actually need the 12. By the time you spin it out on a downhill, you'll go just as fast in a tight tuck. Go with the 13/26 unless you're a super sprinter. The fact that you ask the question suggests that you're not, and you'll be better served with the 13/26.
not avoiding duplication...C-40
Nov 20, 2002 3:36 PM
The idea of choosing between the cog and chainring combinations that you've listed is not to avoid duplication - it's unavoidable.

One difference between a 53/42 and a 53/39 is in the number of cog shifts that must be made after a shift is made from one chain ring to the other. A 53/42 usually requires a 1-cog shift and 53/39 requires a 2-cog shift to continue through a uniform progression. 53/42 was most popular before the days of indexed shifting.

The 53/42 also reduces the total gear range, requiring an extra cog at the big end to achieve a comparable lowest gear ratio.

Unless you really hate making the 2-cog shift after shifting between chainrings, there is no good reason to use a 53/42.

What you really need to know, is the lowest and highest gear ratios that will permit you to efficiently perform over the terrain that you expect to ride. For most of us amateurs, it's either a 12-25 or a 13-26, unless you really ride the flatlands and don't need the the low gears.