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record short cage r.der with 29t sproket?....(8 posts)

record short cage r.der with 29t sproket?....karlooz
Jul 28, 2002 4:18 PM
....can it be done with a 39t chainring? i know campy recommends the medium cage but are they just being conservative? whats another 3 teeth anyway (26t max sproket for the short cage).
re: record short cage r.der with 29t sproket?....Rusty Coggs
Jul 28, 2002 4:35 PM
Front chainring does not matter.It's whats in the rear that counts.
YES, it will workJohnG
Jul 28, 2002 9:01 PM
I tried it and it does work OK, albeit the chain is a bit tight in the 53-29 position.

Make sure you set up the chain length so that the measured distance (as shown in the manual) is no more than 1cm.

JohnG
thx, dude! nmkarlooz
Jul 28, 2002 9:31 PM
Isn't your chain bound to be set too slack this way?ColnagoFE
Jul 29, 2002 9:14 AM
I mean without the med cage der.
nope.......... It will work just fineJohnG
Jul 30, 2002 6:53 AM
"Little-little" combo should be setup with NO MORE than 1cm.

With this chainring length the der will work just fine on BOTH the little-little AND the big-big combo.

The "right way" ..... LOL. Been doing this for so long I get a real hoot out of that.

Note: IF you do use the medium cage der you MUST set up the chain length short!!!! Set it for 2 1/2 - 3cm per the manual. If you use less than this you will have interference problems between the roller and the 29 cog.

JohnG
just don't EVER shift into Big/Big combination (nm)ColnagoFE
Jul 29, 2002 9:13 AM
If it was my bike, I'd do it right the first time.Spoke Wrench
Jul 29, 2002 1:40 PM
With the combination you mentioned, you are going to be fudging on both design capacities of your rear derailleur.

The issue with the maximum size cog is how close the top pulley comes to the biggest cog. Sometimes you can get it to shift, but it's noisy and rough. Doesn't meet my performance standards. Derailleurs that are rated for larger cogs space the top pulley farther from the cassette.

Slack take up is the other factor. With a Campy short cage derailleur you only have 27 teeth of wrap up and you need about 32 with a 29 tooth big cog. If you make your chain fit the big/big, it will go slack in the smallest 2 or 3 cogs in the small chainring. If you make your chain fit the little/little, you risk serious damage if you shift into one of the biggest cogs while in the big chainring.