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Discussion Starter · #1 ·
I have Dura Ace 10 with FSA K-Force cranks and an 11/23 cassette and for the most part my setup works perfectly. It shifts smoothly into and out of every gear and the ride feels smooth and efficient at just about every cadence and power output. The only problem is when I am going up a steep hill, greater than about 12% or so and I start really pushing it in the 39/23 to power up the hill I hear (and feel) a bit of a grinding in the back. I have looked at the wheel while it was doing this and the derailleur was not rubbing the spokes or anything so I am unsure what the problem is. I don't think there is a problem with frame/drivetrain handling the power because I have no trouble when sprinting in the big ring. Moreover, the problem is very hard to diagnose because it only happens in the situation described so it can't really be replicated on a stand.

Has anyone else had a similar problem or ideas/suggestions?

Thanks.
 

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similiar

I have a simliar thing, it looks to me like the pulley cogs on the rear der. are bumping into the chain from the bottom, when it is in the 25. It is kinda rough feeling. I could see it when I sit next to the bike and pedal backwards. I haven't found a fix for it.
Can the rear der be adjusted down?
 

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several things to check, VERY carfully check to ensure that the L limit screw is adjusted properly, best done on a stand take your time and be sure that the jockey pully near the cassette is alined with the largest cog (your 23) make very small adjustments till its there and make many "downshifts" to that cog on the stand (be sure to shift very quickly) and make sure that the chain dose not try to "overshift". Next be sure that your FD cage is about .020" from the chain (1/2mm) with tention AT IT'S close'st point (many times when applying power the FD cage just rubs lightly) this may be why you can't dup the noise on the stand.

Next and mainly for b987654, adjusting the "B" tention screw goes like this, first be sure your chain lenth is correct (for shimano dubble, put chain on your 53/smallest rear and ensure that the RD cage is very close to vertical) nest with the bike on the stand advance the "B"screw till there is no rubbing on largest cassette cog when in your 39.

Would reccomend doing the adjustments in the listed order. Wish you guys luck. -- Bill
 

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B screw...

As others noted, it's probably the B screw needing adjustment to move th eupper derailleur pulley further from the largest cog. Could also be the large cog limit screw needs adjusting and/or simple shift cable tension adjustment. Hopefully it's not the obvious front derailleur chain rub, easily cured by backing out the left limt screw about 1/4 turn.

About chain length. Eyeballing the cage being vertical in the 53/11 is a pretty crude (but often recommended) way to adjust chain length. What you really want is just enough length to maintain some tension on the chain in the 39/12. One inch longer and the chain will either have no tension or rub on the upper pulley chain guide tab in this combo. If you're absolutely sure that you'll never use a 12-25 or 12-27, you could make the chain one inch shorter than this length.
 

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Discussion Starter · #5 ·
Thanks guys, it is probably the b-screw for me. I have it out pretty far so hopefully tightening it up will do the trick. I will experiment with it tomorrow. After my 2 hour, 20 degree ride with 30+ mph wind gusts yesterday, I think a day off in today's 25 degree weather is in order.
 
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