Old 05-10-21, 07:32 AM
  #7  
DaveSSS 
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Join Date: Sep 2008
Location: Loveland, CO
Posts: 6,440

Bikes: TWO Cinelli superstar disc with SRAM Force AXS

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Originally Posted by andrewclaus View Post
My 36/50 works fine for me. I live at the border of plains and mountains. I use them both. When I ride east, it's a big ring day. When I ride west, it's a small ring day. I spent a winter in Florida last year and never used the small ring. But it's low enough for me for the big climbs out here. (11-34 rear cassette)

The deciding factor will be your rear derailleur (RD). Try to find its chain wrap specs. Or do this test: Shift to small-small combination and the RD should be fully retracted, with the pulleys almost touching the chain. Then shift to large-large, and the RD cage (line between pulley axes) should be extended at a max 45 degree angle to the ground.

Every two teeth added on a gear will need one more inch of chain.
It takes 4T to use 1 inch of chain, but since 2T requires 1/2 inch and changes can only be made in 1 inch increments, that could still require another inch of chain. The chain length formula is relatively simple. Add the big/big and divide by 4. Multiply the chain stay length times 2 and add to the first amount. Then add 1 more inch for going through the RD. If the total ends in .5 or greater round up.

https://www.parktool.com/blog/repair...-length-sizing
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