Tiagra 11-34 cassette on 105 groupset

morgs2001

Hi,
I'm looking for some advice on changing a cassette to extend my gear range.
i will be doing a short but hilly tour in July and my current set up of 10 speed 105 with 11-28 cassette is not enough gears for me.
I am considering changing the rear cassette to a Tiagra 11-34 and putting on a long cage rear derailleur ,probably a Tiagra also to keep costs down.
Can anyone tell me will this work with my current set up of 105 10 speed shifters,chainsetand front derailleur .

Thanks

markhewitt1978

The cassette will work however the long cage Tiagra derailleur won't because it's been changed to be the same pull ratio as the 11 speed groupsets.

I can tell you that you can change your cassette to a 12-30 with your current setup which will work fine, not as low as 34T but it's cheap.

ugo.santalucia

Your 105 derailleur is not designed to clear a 34 tooth and as above the Tiagra has a different conversion ratio. Best option is to use a 9 (yes 9, NOT 10) speed MTBike rear derailleur, which has a conversion ratio identical to your 105 but it can clear big sprockets. Choose one with the barrel adjuster, otherwise you will need to add an inline barrel adjuster to index the gears

morgs2001

im glad i asked ,sounded so simple just switching out the rear derailleur and cassette .Never heard of conversion doodas!
Thanks folks.

ugo.santalucia

morgs2001 wrote:

im glad i asked ,sounded so simple just switching out the rear derailleur and cassette .Never heard of conversion doodas!
Thanks folks.

Compatibility is a minefield... it was all simple for Shimano up to road 10 / MTB 9 speed everything was compatible, then they began making all sorts of weird things with Tiagra 10, road 11 and MTB 10 and 11 speed nothing is cross compatible anymore

morgs2001

ugo.santxalucia wrote:

Your 105 derailleur is not designed to clear a 34 tooth and as above the Tiagra has a different conversion ratio. Best option is to use a 9 (yes 9, NOT 10) speed MTBike rear derailleur, which has a conversion ratio identical to your 105 but it can clear big sprockets. Choose one with the barrel adjuster, otherwise you will need to add an inline barrel adjuster to index the gears

So if I use ,say an Acera 9 speed derailleur matched with a 9 speed cassette that might work with my 105 shifters?

keef66

morgs2001 wrote:

ugo.santxalucia wrote:

Your 105 derailleur is not designed to clear a 34 tooth and as above the Tiagra has a different conversion ratio. Best option is to use a 9 (yes 9, NOT 10) speed MTBike rear derailleur, which has a conversion ratio identical to your 105 but it can clear big sprockets. Choose one with the barrel adjuster, otherwise you will need to add an inline barrel adjuster to index the gears

So if I use ,say an Acera 9 speed derailleur matched with a 9 speed cassette that might work with my 105 shifters?

No, a 9 speed MTB derailleur with a 10 speed cassette and shifters.

ugo.santalucia

as above 10 speed shifters, 10 speed cassette BUT 9 speed MTB derailleur

This is perfect

http://www.chainreactioncycles.com/shim ... -prod40543

tsarouxaz

morgs2001 wrote:

ugo.santxalucia wrote:

Your 105 derailleur is not designed to clear a 34 tooth and as above the Tiagra has a different conversion ratio. Best option is to use a 9 (yes 9, NOT 10) speed MTBike rear derailleur, which has a conversion ratio identical to your 105 but it can clear big sprockets. Choose one with the barrel adjuster, otherwise you will need to add an inline barrel adjuster to index the gears

So if I use ,say an Acera 9 speed derailleur matched with a 9 speed cassette that might work with my 105 shifters?

Nope, you don't need the 9sp cassete, why you mention that? up to 9sp mtb rear mech can be used on ANY 10sp road shifter EXCEPT tiagra 4700 shifters which is already designed for 34 large but have a diferent pull ratio than all other 10sp shifters for ROAD.

morgs2001

That's brilliant thanks everyone for your advice really helpful.