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6spd -> 9spd upgrade chainline issues? Advice needed

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6spd -> 9spd upgrade chainline issues? Advice needed

Old 03-16-12, 08:00 PM
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6spd -> 9spd upgrade chainline issues? Advice needed



So this is my 88-89 Bianchi Brava that I recently built up. It originally came with a FC-1050 105 crank, BB-1050 105 Italian bottom bracket (which should have 115mm spindle if velobase is correct), and 6 speed uniglide cassette.

I decided to upgrade to 9 speed. I switched the crank, FD, and RD to Shimano 600 Tri-Color, which was built for 7/8 speed and should have no trouble with 9 speed. However I was finding that a) shifting wasn't great going down onto the 11t cog when on the big chainring (53t) and b) it was a little rough when down there.

On closer inspection it appears that when on the 53t chain ring, and on the 11t cog, the chain rubs the 12t cog slightly due to the chainline being slightly off (crank pulls it in towards the frame by a mm or so).

The BB spindle length for the FC-6400 should also be 115mm for italian, but I'm thinking that spreading from 126 -> 130mm in the rear, and changing to 9speed, the crank needs to be out a little further.

What do you recommend? Trying to find a longer spindle? If so what size? Or should I just ride it as is and avoid the 11t cog?

Thanks
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Old 03-16-12, 08:20 PM
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Are you using a 9 speed chain? My advice would be to use a little bit of a spacer on the drive side of the bottom bracket and see if that solves the problem. That way your net width pedal to pedal (Q) would not change.

53-11 is a lot of gear unless you live where there are long downhills where you can really use it (realize that's beside the point, but the max I usually run is 53-13).
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Old 03-16-12, 08:54 PM
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An Italian BB shell? that sounds older than '87.

I am with Chrome Molly I think it mught just be your chain if you not using a 9spd. If you push the chainwheels further right to reduce the rubbing in the 11/53 you may cause more problems on the 14, 15, 16 /53 and those are gears you more likely to use.
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Old 03-16-12, 09:42 PM
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I am using a 9 speed chain. Sram PC-971.

I know some cranks use a very thin washer between one of the chain rings and the crank spider. Mine doesn't have these. Could this also possibly be an issue? Could also be a frame alignment issue? I didn't do the Sheldon Brown method for cold setting, and I currently just spread the frame to get the rear wheel in.

As for the year, it's been a topic of some debate, but we have discussed it a few times already. It's a Canadian market version, I'm judging date by decal style and part date codes. It could be off by a year or so, but it's not really relevant, but it was branded as made in italy, has formula two tubing, and has an italian BB shell.
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Old 03-16-12, 09:54 PM
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I like the build of your bike. I've never tried a spindle spacer, but as mentioned, it seems an economical fix. I recently converted an '83 bike to 9spd without any issues except slow upshifting up front. I think you are probably right, that the spread of the rear triangle has slightly changed the centerline. It's hard to tell from the photo, but I am also wondering if your using a 9spd chain. If so, then a slightly longer spindle length seems the way to go.
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Old 03-16-12, 10:24 PM
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For every 2MM you increase the dropout spacing, the cranks should move out 1MM.

That said, a 4MM DOS change shouldn't make that much difference unless your chain line was already insufficient.
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