9/10 speed rear derailleur compatibility

by Peowpeowpeowlasers   May 21, 2014  

My Tiagra 4500 9-speed rear dérailleur has so much play now that if I select the lowest gear, the cage hits the spokes. Obviously this is a bad thing and I want to replace it immediately. The trouble is, they're like hen's teeth. There are plenty of 10-speed dérailleurs out there, but before I order anything, I want to confirm that 10-speed is compatible with 9-speed.

I've found conflicting claims on the internet, related to pull ratios. Can anyone put my mind at rest and let me order a new 10-speed dérailleur? I'd rather not upgrade the entire drivetrain as I'll be buying a whole new bike later this year.

12 user comments

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Chain Reaction have Sora 9 speed for £18, if you're replacing the bike this year that should see you through.

glynr36's picture

posted by glynr36 [405 posts]
21st May 2014 - 10:14

3 Likes

ran a 10 speed ss mech on my 9 speed tiagra sti's for ages without any problems

still on the 3rd switch-back of Bwlch !

posted by therevokid [714 posts]
21st May 2014 - 10:33

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I tried to use a 10-speed shifter with a 9-speed derailleur (105 shifter and Deore rear derailleur on my touring bike) and the pull-ratios meant that it just would not work - the total amount of cable pulled was not enough to move the derailleur from top to bottom. The opposite will probably be true of trying apply a 9-speed shift to a 10-speed derailleur - the cable-pull per index stop will be larger than the derailleur is meant to handle.

adamthekiwi's picture

posted by adamthekiwi [49 posts]
21st May 2014 - 16:18

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adamthekiwi's picture

posted by adamthekiwi [49 posts]
21st May 2014 - 16:22

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This is the problem, see - 50% say one thing, 50% the other.

I wonder if Shimano produce a compatibility table.

posted by Peowpeowpeowlasers [77 posts]
21st May 2014 - 16:48

1 Like

glynr36 wrote:
Chain Reaction have Sora 9 speed for £18, if you're replacing the bike this year that should see you through.

I'm not sure if I'll keep the bike or not (probably not) but this is a good suggestion, thanks.

posted by Peowpeowpeowlasers [77 posts]
21st May 2014 - 16:48

3 Likes

The CRC description for a 105 5701 rear mech says it'll work with 8, 9 and 10 speed systems, so I'm going to buy one of those. If it doesn't work then I can just return it.

Thanks all for the replies, I will post back with results.

posted by Peowpeowpeowlasers [77 posts]
21st May 2014 - 16:57

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Are you sure it is play in the mech, rather than a bent gear hanger?

I have never known that much play is a rear mech, in fact I wouldn't have thought it possible unless it was literally falling to pieces.

posted by Chris James [188 posts]
21st May 2014 - 17:01

1 Like

You could try a Deore 9 speed mtb derailleur. I have got one on my Tiagra specked Croix de Fer

posted by carytb [20 posts]
21st May 2014 - 19:32

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I have a 105 ten speed derailleur on one of my bikes with tiagra 9 speed shifters
just use the limit screws to stop it going to far. never had a problem with it

arch684

archie gordon's picture

posted by archie gordon [7 posts]
21st May 2014 - 21:27

1 Like

ST4500 shifters are showing as being compatible with the following rear derailleurs:
RD-7800
RD-6600G
RD-6600
RD-5600
RD-5600L

E of the bay dot com showing RD-4500 at under £30 (free p+p)
http://www.ebay.co.uk/itm/Shimano-Tiagra-Rear-Derailleur-RD-4500-SS-9-Sp...

If that's any help....

The_Kaner
FREEEEEEEEDOM!

The _Kaner's picture

posted by The _Kaner [438 posts]
22nd May 2014 - 14:08

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Just to let people know, I replaced the old, worn out Tiagra 4500 dérailleur with a 105 5701 10-speed. It shifts perfectly, there are no issues. It's totally compatible.

As an aside, shifting is now hugely improved. Mind you, the old dérailleur really is a floppy knackered old thing with play in every direction. I'll take the (almost new) jockey wheels out of it and retire it to the recycle bin.

Thanks for all the help.

posted by Peowpeowpeowlasers [77 posts]
29th May 2014 - 18:54

3 Likes