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I did a quick search for this info but came up empty, so I'm hoping that somebody more knowledgable than me can help out.

I currently have a 9-speed triple setup, but can't get satisfactory results from the big ring, it seems to like to rub the front der. cage more than my liking. Front crank is Bonty with a Shimano 105 der.

So, I did something impulsive :blush2: and bought a Bontrager 50/36 compact crank on eBay, which I notice is listed as a 10 speed crank.

Question 1: is this going to work with the rest of my 9-speed drivetrain? I don't want to make that switch at this time.

Question 2: I'm running the Truvativ GPX bottom bracket. Do I need a different BB with the compact crank than the triple crank? Both cranks are GPX cranks, but I'm wondering about the difference between double and triple.

If this sounds like it is going to work, then I'll go ahead and get the double compatible front der. Planning to leave the rear long cage Ultegra der because I have a 26 tooth chainring in the rear.

If this isn't going to work then I'll be unloading the compact crank and I guess I'll stay in the 42 middle ring all of the time.

thanks!
 

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You couldn't adjust the front derailleur to eliminate the rubbing? It sounds like it just needed to be raised a bit.

The 10sp crank should work fine with a 9sp chain.

With external bearing cranks the "bottom bracket" axle is connected to the crank, not really part of the BB. So the regular BB cups work for both double and single.

A 26t rear cog doesn't need a long cage deraileur, but it'll work just fine.
 
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