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Replacing a rear Tiagra derrailure

1964johnr1964johnr Posts: 172
edited November 2015 in Road beginners
I need to replace my rear Tigra derrailure which runs on a 9 speed Shimano cassette. I seem to be looking at a lot of 10 speed Tiagra derrailures, but can't seem to find a 9 speed one. My Giant SCR 2 is 8 years old now. Can I replace the Tiagra with a 10 speed, even though my Shimano cassette is a 9 speed? I ave a triple chain set. I also see that derrailures seem to be short or medium. Not sure which one I need. Any help would be appreciated.

Posts

  • navrig2navrig2 Posts: 1,704
    This would be better than a 10sp Tiagra IMHO:

    http://www.ribblecycles.co.uk/sp/road-track-bike/derailleurs-rear-shimano-sora-3500-9-speed-rear-derailleur/shimgrrr211

    The number of "speeds" determines how much the derailleur moves with each index (click) of the shifter. Fitting a 10spd derailleur to a 9 speed shifter means that the spacing will be out of line and you MAY struggle to get a smooth movement of the chain through the jockey wheels.
  • wongataawongataa Posts: 967
    The number of "speeds" determines how much the derailleur moves with each index (click) of the shifter. Fitting a 10spd derailleur to a 9 speed shifter means that the spacing will be out of line and you MAY struggle to get a smooth movement of the chain through the jockey wheels.
    It's the shifter that determines how much the derailleur moves during each shift, not the derailleur. As long as the derailleur geometry is the same then the number of 'speeds' is irrelevant.
  • mikpemmikpem Posts: 139
    The number of "speeds" determines how much the derailleur moves with each index (click) of the shifter. Fitting a 10spd derailleur to a 9 speed shifter means that the spacing will be out of line and you MAY struggle to get a smooth movement of the chain through the jockey wheels.
    It's the shifter that determines how much the derailleur moves during each shift, not the derailleur. As long as the derailleur geometry is the same then the number of 'speeds' is irrelevant.

    Agreed, I have a '9 speed' sora derailleur mixed with 10 speed 105 shifters and a 10 speed tiagra cassette. As long as the shifters and cassette match you can use 9/10/11 speed derailleur.
    I would go with medium, it gives you more flexibility on the cassette.
  • keef66keef66 Posts: 13,123
    The number of "speeds" determines how much the derailleur moves with each index (click) of the shifter. Fitting a 10spd derailleur to a 9 speed shifter means that the spacing will be out of line and you MAY struggle to get a smooth movement of the chain through the jockey wheels.
    It's the shifter that determines how much the derailleur moves during each shift, not the derailleur. As long as the derailleur geometry is the same then the number of 'speeds' is irrelevant.

    Agreed, I have a '9 speed' sora derailleur mixed with 10 speed 105 shifters and a 10 speed tiagra cassette. As long as the shifters and cassette match you can use 9/10/11 speed derailleur.
    I would go with medium, it gives you more flexibility on the cassette.

    Not so fast with lumping 11 speed in with the others. Shimano changed the geometry of the rear mech with the move to 11 speed, so you'd have problems using an 11 speed mech with 10 speed shifters, or the reverse.
    8, 9 and 10 speed Shimano mechs will work with 8, 9 and 10 speed shifters etc. In terms of speeds, the shifters, chain and cassette need to be the same.

    To the OP, I'd go for the 10 speed Tiagra mech. Since you have a triple you should go for the longer cage version (medium)
  • navrig2navrig2 Posts: 1,704
    Sorry guys. Had a stupid moment when I typed my answer. Too much to do and too little time at the moment.
  • AnonymousAnonymous Posts: 79,667
    The number of "speeds" determines how much the derailleur moves with each index (click) of the shifter. Fitting a 10spd derailleur to a 9 speed shifter means that the spacing will be out of line and you MAY struggle to get a smooth movement of the chain through the jockey wheels.
    It's the shifter that determines how much the derailleur moves during each shift, not the derailleur. As long as the derailleur geometry is the same then the number of 'speeds' is irrelevant.

    Agreed, I have a '9 speed' sora derailleur mixed with 10 speed 105 shifters and a 10 speed tiagra cassette. As long as the shifters and cassette match you can use 9/10/11 speed derailleur.
    I would go with medium, it gives you more flexibility on the cassette.

    Not so fast with lumping 11 speed in with the others. Shimano changed the geometry of the rear mech with the move to 11 speed, so you'd have problems using an 11 speed mech with 10 speed shifters, or the reverse.
    8, 9 and 10 speed Shimano mechs will work with 8, 9 and 10 speed shifters etc. In terms of speeds, the shifters, chain and cassette need to be the same.

    To the OP, I'd go for the 10 speed Tiagra mech. Since you have a triple you should go for the longer cage version (medium)

    I would agree with this. All a deraiileur is , is a big spring with a couple of jockeys on it really. Its the shifters that dictate how it moves. The only real difference in say a Tiagra RD and a Dura Ace is weight and materials. They all work exactly the same way (less Di2 Obviously) So long as the spring has the same range of movement as that of the cassette width it will work fine.
  • Thanks for the replies, I now know what to purchase and will go for a 10 speed medium cage Tiagra rear mech.
  • 10 speed cassettes need 10 speed chains. Different speeds use different thicknesses of chains which is why you need the correct speed chain with a particular speed cassette. So why doesnt the rear derailleur matter in this context? The chain travels along the jockey wheels which surely are designed with a certain sized chain in mind.
  • AnonymousAnonymous Posts: 79,667
    10 speed cassettes need 10 speed chains. Different speeds use different thicknesses of chains which is why you need the correct speed chain with a particular speed cassette. So why doesnt the rear derailleur matter in this context? The chain travels along the jockey wheels which surely are designed with a certain sized chain in mind.

    Jockey wheels can be changed you know. Thet are only bits of plastic on bearings.
  • 10 speed cassettes need 10 speed chains. Different speeds use different thicknesses of chains which is why you need the correct speed chain with a particular speed cassette. So why doesnt the rear derailleur matter in this context? The chain travels along the jockey wheels which surely are designed with a certain sized chain in mind.

    Jockey wheels can be changed you know. Thet are only bits of plastic on bearings.

    Yeah I know. What I dont know is whether different sized jockies would work in a derailleur made for a different number of gears. I was also curious as to whether there is greater tolerance in the jockies with regards to chain size.
  • Now I am confused again. Does this mean that if my current chain is a 9 speed, it will not work with a Tiagra rear mech which is 10 speed ?
  • AnonymousAnonymous Posts: 79,667
    Now I am confused again. Does this mean that if my current chain is a 9 speed, it will not work with a Tiagra rear mech which is 10 speed ?

    A 10sp Tiagra derailleur would most probably work with a 9 Sp cassette and shifter.

    The cage width would restrict any wider chains going through but a 10 sp would work ok.

    I have a 10sp Tiagra groupset less crank I just removed from my VN7 that I ugraded to 105 for less than £100 (front, rear derailleur shifters + cables) for sale if anyone wants it!

    If you have the cash its well worth ipgrading the lot. The step from Tiagra to 105 is bug and you get the cleaner cockpit with better shifter cable running
  • keef66keef66 Posts: 13,123
    Now I am confused again. Does this mean that if my current chain is a 9 speed, it will not work with a Tiagra rear mech which is 10 speed ?

    It will be fine.
  • Agreed. It will be fine. For years, I ran my 2008 Giant SCR2 with Tiagra 9sp shifters, cassette, and chain, but with a 10sp 105 5600 rear derailleur. I never once had a problem. In fact, I'm bringing it out of retirement and rebuilding it up in to a winter bike.
    Shimano, for some reason stopped calling long cage mechs 'long cage', now it's medium. Maybe long cage sounds uncool???
    Giant TCR Advanced II - Reviewed on my homepage
    Giant TCR Alliance Zero
    BMC teammachineSLR03
    The Departed
    Giant SCR2
    Canyon Roadlite
    Specialized Allez
    Some other junk...
  • rolf_frolf_f Posts: 16,015
    The number of "speeds" determines how much the derailleur moves with each index (click) of the shifter. Fitting a 10spd derailleur to a 9 speed shifter means that the spacing will be out of line and you MAY struggle to get a smooth movement of the chain through the jockey wheels.
    It's the shifter that determines how much the derailleur moves during each shift, not the derailleur. As long as the derailleur geometry is the same then the number of 'speeds' is irrelevant.

    Agreed, I have a '9 speed' sora derailleur mixed with 10 speed 105 shifters and a 10 speed tiagra cassette. As long as the shifters and cassette match you can use 9/10/11 speed derailleur.
    I would go with medium, it gives you more flexibility on the cassette.

    Not so fast with lumping 11 speed in with the others. Shimano changed the geometry of the rear mech with the move to 11 speed, so you'd have problems using an 11 speed mech with 10 speed shifters, or the reverse.
    8, 9 and 10 speed Shimano mechs will work with 8, 9 and 10 speed shifters etc. In terms of speeds, the shifters, chain and cassette need to be the same.

    To the OP, I'd go for the 10 speed Tiagra mech. Since you have a triple you should go for the longer cage version (medium)

    I would agree with this. All a deraiileur is , is a big spring with a couple of jockeys on it really. Its the shifters that dictate how it moves. The only real difference in say a Tiagra RD and a Dura Ace is weight and materials. They all work exactly the same way (less Di2 Obviously) So long as the spring has the same range of movement as that of the cassette width it will work fine.

    No, no, no! It's not just about the range of movement. You are quoting keef, agreeing with him and then contradicting him! A derailleur is more than a big spring with a couple of jockey wheels on it. It is a big spring with a couple of jockey wheels on it and a lever. The lever is important but fortunately a constant for the OPs options. Of course, probably the only real reason for the lever to vary whatever the number of speeds is to sell more mechs but that's another cynical story.........
    Faster than a tent.......
  • AnonymousAnonymous Posts: 79,667
    The number of "speeds" determines how much the derailleur moves with each index (click) of the shifter. Fitting a 10spd derailleur to a 9 speed shifter means that the spacing will be out of line and you MAY struggle to get a smooth movement of the chain through the jockey wheels.
    It's the shifter that determines how much the derailleur moves during each shift, not the derailleur. As long as the derailleur geometry is the same then the number of 'speeds' is irrelevant.

    Agreed, I have a '9 speed' sora derailleur mixed with 10 speed 105 shifters and a 10 speed tiagra cassette. As long as the shifters and cassette match you can use 9/10/11 speed derailleur.
    I would go with medium, it gives you more flexibility on the cassette.

    Not so fast with lumping 11 speed in with the others. Shimano changed the geometry of the rear mech with the move to 11 speed, so you'd have problems using an 11 speed mech with 10 speed shifters, or the reverse.
    8, 9 and 10 speed Shimano mechs will work with 8, 9 and 10 speed shifters etc. In terms of speeds, the shifters, chain and cassette need to be the same.

    To the OP, I'd go for the 10 speed Tiagra mech. Since you have a triple you should go for the longer cage version (medium)

    I would agree with this. All a deraiileur is , is a big spring with a couple of jockeys on it really. Its the shifters that dictate how it moves. The only real difference in say a Tiagra RD and a Dura Ace is weight and materials. They all work exactly the same way (less Di2 Obviously) So long as the spring has the same range of movement as that of the cassette width it will work fine.

    No, no, no! It's not just about the range of movement. You are quoting keef, agreeing with him and then contradicting him! A derailleur is more than a big spring with a couple of jockey wheels on it. It is a big spring with a couple of jockey wheels on it and a lever. The lever is important but fortunately a constant for the OPs options. Of course, probably the only real reason for the lever to vary whatever the number of speeds is to sell more mechs but that's another cynical story.........

    So. NO, NO, NO....Actually yes you are right just I elaborate a bit more on what you said by adding in a little more detail. Point for the OP is what he is asking will work. Thats all that matters in the end.
  • richkrichk Posts: 564
    Whilst it's the other way round, I'm running a 9sp rear derailleur with 10 speed cassette etc with no problems.
    There is no secret ingredient...
  • Thanks guys. I've learnt a lot and will now purchase a 10 speed Shimano Tiagra medium cage rear mech and put it on myself after watching a couple of you tube videos. It doesn't seem that difficult although I am sure I will be back posting when I hit a problem. Although my Giant SCR 2 is eight years old I find it a great winter bike. It actually gives me a smoother ride than my Summer bike which is a Ribble Gran Fondo carbon frame. Not sure why, but the cheap Vittorio tyres seem to be soft and comfortable rather than quick. I tested my 30 mile Saturday ride on both bikes. The Ribble is faster, but the giant more comfortable with less vibration.
  • rolf_frolf_f Posts: 16,015
    So. NO, NO, NO....Actually yes you are right just I elaborate a bit more on what you said by adding in a little more detail. Point for the OP is what he is asking will work. Thats all that matters in the end.

    Absolutely! I was more making the point to avoid confusion for the next person who comes along wanting to swap is 11 speed mech for a 10!
    Faster than a tent.......
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