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Do I need a different rear derailleur?

Old 11-20-19, 03:51 PM
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ddeand 
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Do I need a different rear derailleur?

I have a CX bike from around 2005 that came with a Shimano 105 long cage rear derailleur and 105 9-speed brifters - it worked pretty well for me. The front derailleur is also a 105, and the crankset is a a Campy Centaur 46/34 setup. I recently stumbled across a free pair of Shimano Ultegra 10-speed brifters (6600 series) in much better condition than the 105s, so I swapped them in and started to dial in the shifting. I also swapped a 10-speed Shimano cassette (13-30t) onto the bike. The 9-speed cassette was also a 13-30t. I'm finding the bike difficult to get set - it's close, but not perfect. While I never would ride it like this, I can't get the shifting to cross-chain on the two different extremes (large chainring/large cog or small chainring/small cog). I can get all the other combos, though. I guess my question is if this is normal or should I get an Ultegra 10-speed rear derailleur? Also, if I do get a 10-speed Derailleur, do I need a long cage if I stay with 30t cog? After reading the thread about rear derailleur design and function, I'm wondering if a different RD might be best. And is the Centaur crankset a decent math for this setup? If not, what would be a good crankset that will still allow for 46/34 chainrings? Thanks for any advice and opinions.
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Old 11-20-19, 04:23 PM
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Bill Kapaun
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10 speed shifters don't pull the same amount of cable as 9 speed shifters.
Match a 10 speed cassette to 10 speed shifters, or 9 speed cassette to 9 speed shifters.
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Old 11-20-19, 04:32 PM
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Originally Posted by ddeand View Post
While I never would ride it like this, I can't get the shifting to cross-chain on the two different extremes (large chainring/large cog or small chainring/small cog). I can get all the other combos, though.
Never Fix A Running Piece. Why waste your time and effort trying to get the cross-chained combinations to work? Just don't use those combinations, that you say you would never use anyway. If the other combinations work just go and ride.
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Old 11-20-19, 04:42 PM
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Originally Posted by Bill Kapaun View Post
10 speed shifters don't pull the same amount of cable as 9 speed shifters.
Match a 10 speed cassette to 10 speed shifters, or 9 speed cassette to 9 speed shifters.
Yeah, thatís what I did - 10-speed cassette to 10-speed shifters (and 10-speed chain). It seems the 9-speed derailleur would cover the same range on both the 9-speed and 10-speed cassettes, but I could be mistaken on that.
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Old 11-20-19, 04:50 PM
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1. Shimano

6, 7, 8 and 9 speeds

Rear shift ratio is 1.7, that is for 1 mm of cable pull/release, RD is moved left/right by 1.7 mm. Shimano calls this 2:1 ratio for marketing reasons.

All these RDs are compatible and any 6 to 9 speed RD will work perfectly with either 6, 7, 8 or 9 speed shifter. Regardless whether it’s a MTB, or road shifter, or RD. They are also compatible with Shimano 10 speed road shifters, except the Tiagra 4700 series.

Shimano Dura Ace from 1984 to 1996 period (6 to 8 speeds)

Rear shift ratio is 1.9. They are compatible only with Shimano Dura Ace shifters from the same period (that is for 6, 7 and 8 speeds).

10 speed ROAD RD

Rear shift ratio is 1.7, so it’s compatible with all the 6 to 9 speed shifters, as well as road 10 speed shifters. Same rear shift ratio. MTB 10 (and 11 speed) shifters won’t work well.

Exception is Shimano Tiagra 4700 10 speed road RD – it has the same shift ratio as Shimano road 11 speed RDs, so it will work only with Tiagra 4700 shifters and Shimano 11 speed road shifters.

Another exception is the new “gravel” group (with hydraulic brakes): Shimano GRX. Caple pull wise it’s the same as Tiagra 4700.
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Old 11-20-19, 05:29 PM
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So F1 x R1 and F2 x R10 work fine, but F1 x R10 and F2 x R1 do not work?

Did you also switch to a 10 speed chain or are you still using a 9 speed chain? I wonder if using the wider 9 speed chain causes too much gap that it prevents the chain from riding the ramps when shifting at the extreme cross angles. Maybe try using a 10 speed chain.

You made sure to check the L and H limit screws, B-screw, and that you can physically press the RD with your hand to be centered to the largest cog on the inside, and that when on the smallest cog, the RD is about 1mm offset to the outside of the center of the cog?

The cable housing is clean?

https://bike.bikegremlin.com/1220/1-...compatibility/
https://bike.bikegremlin.com/1232/bi...compatibility/
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Old 11-20-19, 07:17 PM
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Folks, he said he's using 10 speed cassette, chain and brifters.... OP, if your 9 speed 105 RD clears the 30T cog, in theory it should work with your 10 speed stuff. However, they were only rated for 27T. If you decide to try a 10 speed RD, look for one of the later ones rated for your 30T. Early ones were 28T, IIRC.
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