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Old 01-18-14, 11:43 AM   #1
loimpact
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Adjusting FD to not rub in middle cog on a 3/8 specifically 2/7 gear.....

Forgive my ignorance if the title doesn't make sense, I'll reiterate....

Triple w/ 8 speed cassette in back. Altus front/Alivio rear. (Cannondale Quick4)

As mentioned before I have 2 identical bikes. Bike 1 rubs in middle crank cog & 2nd smallest rear cog. (2/7) All the rest are good down to 2/1 which maybe rubs a tad, but I'd change cogs before going there anyway as I try to stay out of 1 or 8 in any cog.

FD barrel adjuster is as loose as it'll go. (counter-clockwise) If I tighten it (clockwise) I can get it to rub from 2/8 down to 2/5, if I tighten all the way. So I think I need to actually pull the FD cable a little tighter, no??

All else appears ok. FD height/alignment appears good (like bike 2) and I think that's set by Cannondale anyway so I really wouldn't want to tweak that unless somebody thinks it really needs it.

Any suggestions much appreciated!!! (Will post pics if anybody wants)
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Old 01-18-14, 12:14 PM   #2
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First, thread the barrel adjuster all the way in and then back it out a full turn. Then shift to the smallest chainring position, loosen the cable fixing bolt, pull the slack out of the cable and tighten the bolt. Also, be sure the cable is run over the top of the little tab on the back side of the derailleur's operating arm before going to the fixing bolt.
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Old 01-18-14, 12:17 PM   #3
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You might look to see if the FDER runs parallel to the chain line.
Sometimes just rotating it on the seat post a tiny bit can make a difference.
It might make it better or worse.
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Old 01-18-14, 12:28 PM   #4
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raise the FD to clear the middle chainring, (have you chosen a smaller outer chainring ?)
or get a smaller middle chainring ..

Or double type FD with a shallower back plate to not interfere .

or by 'cog' do you mean the rear gear cluster, 'cassette'?



<Better answer, if I could see it on the shop stand in front of Me. >
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Old 01-18-14, 01:43 PM   #5
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Quote:
Originally Posted by HillRider View Post
First, thread the barrel adjuster all the way in and then back it out a full turn. Then shift to the smallest chainring position, loosen the cable fixing bolt, pull the slack out of the cable and tighten the bolt. Also, be sure the cable is run over the top of the little tab on the back side of the derailleur's operating arm before going to the fixing bolt.
Will do right now. Here's a pic of the cable route. Definitely over the top and expectedly so. Both bikes recently setup by the LBS & very respected.

If I can note any differences since I've got both bikes side by side, I'd say that with both bikes in 2/3 (2nd chainring, 3rd gear out back) bike 2's chain is definitely closer to the inside of the FD cage than bike 1's. I'd say bike 2's is more appropriately set as 2 chainring/3 cassette should probably be a little inside whereas bike 1's is about perfectly centered which I'd reserve more for 2 chainring/4 cassette.....(in an 8 speed setup, of course)

That all make sense??
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Old 01-18-14, 02:25 PM   #6
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Hill,

Perfect!! Done exactly as you described and was able to barrel-adjust right out of it. I further went down to 2/2, gave about a half turn the other way and now have no FD cage rub in any gear from 2/2 up to 2/7. A little in 2/1 and 2/8 but that's some gnarly cross-chaining that I just don't engage in doing so that's perfectly fine with me!

90% of my riding is done on the 2nd chainring and I've grown to like it very much on bike 2 as I used to swap cogs 2 & 3 once I got going fast enough but I'd rathr focus on just that rear derailer & now I can!!

Thanks again very much!!!!

P.S. FWIW, I'd say I probably pulled between 1/8 to 3/16 of cable slack out & couldn't get any more without being forceful so left it at that, & tightened her down.
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Old 01-18-14, 05:29 PM   #7
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Good. It sounded like your shifter wasn't able to pull enough cable as there was too much slack. Glad it's working now.
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