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So this is something that i've made up opinions on, without really knowing what i'm talking about.

(first for clarifictation: when i say first cog, i mean the biggest cog in the back, when i say last cog, i mean smallest cog in the back)
My bike started out 3x9. When in the granny ring, i would only use the first few cogs in the back, and while in the big ring, i would only use the last few. When in the middle, i would use the entire cassette.

i then switched to 2x9. I did this just by switching out my big ring for a bash. so i thought my chain lines were the same as 3x9, so i should only really be concerned about crosschaining in my granny gear up front.

Then, I was riding with someone more knowledgeable than myself and i said something about being in big big (honestly, this is one of my most used combo's) and he said that you should never be in big big. He knew i was 2x9.

Give me your opinions on the matter.
 

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You aren't in "big big" because you took off your big chain ring. Your are in your middle chain ring which is fine. It would be better practice for you to start using the small ring up front instead of using the big cog in back, but whatever, you're fine.
 

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Many people ride 1x9s and use that middle ring/big cog combo all the time. As Mount Dora said, that isn't the same thing as most people mean when they say big/big.

Also, enter your chainring sizes and cassette type in this gear calculator page to see the different gear ratios you have and where they overlap. Assuming a 22/32 ring setup and an 11-34t cassette... "big/big" is almost the exact same gear as small ring/4th cog. This would technically be a better gear to use for wear and effeciency's sake. It would also let you shift further down in small increments unlike your "big/big" combo where you have to either shift the front for a huge sudden change in gearing or shift both the front and the rear to make an incremental change.
 

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No opinion here....

only facts. The fact is you removed half of your crosschaining worries when you removed your big ring and installed the bash guard. Unless you changed your bottom bracket or moved spacers, depending on the type of crankset you have, you didn't change your chainline one mm. So the crosschain rules only apply to your small ring up front now. You can still use any combination when in the middle ring as before.

As boomn noted, there are more efficient combinations and overlaps. Experiment a little and you'll find them. For example: you said your most used combination is the Middle ring and the big cog in the back. The next time you find yourself in that combination, shift the front down to the small ring and then shift the rear up two cogs to 3rd gear. I think you'll find that combination to be nearly identical to the middel/big combination you were in.

The bottom line is, Mr. More Knowledgable wasn't thinking correctly. Yes technically your middle ring has become your big ring. However it hasn't physically moved to the big ring position. So the crosschain rules for your "new" big ring aren't the same as for your "old" big ring. :thumbsup: They still apply to your small ring, but that's all.

Good Dirt
 

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On a tangent: As you have taken off the big ring you can also shorten your chain and your next rear derailleur could be a medium.

Google Sheldon Brown. Good reading.
 

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I have a 3x10 (11-36 cassette) and notice front derailer chain rub when in the middle ring up front and smallest ring in the back (11 teeth). Is this normal or is there an adjustment I can make to the fd?
 

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DTL said:
I have a 3x10 (11-36 cassette) and notice front derailer chain rub when in the middle ring up front and smallest ring in the back (11 teeth). Is this normal or is there an adjustment I can make to the fd?
You need a little more tension on the cable. Turn the barrel adjuster on the front shifter counter-clockwise a couple clicks and check it. You should be able to use the whole cassette when on the middle ring. If the der. is installed a little crooked or too high, it won't work great.

http://www.parktool.com/blog/repair-help/front-derailleur-adjustments

corrected after I reread it. glad you got it worked out.
 

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Hey thanks. This solved the problem. I can hit all gears in the cog while in middle chain ring with no rub. :thumbsup:
 

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dora's right. you may be putting a little extra stress on the chain but your not technicly cross chaining.
 
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