changing from 105 cassette to tiagra

k3vinjam3s

My dad wants to change his 105 12-27 cassette to a more hill friendly tiagra 12-30 cassette. The bikes a Scott cr-1 team and how do I know if this cassette is compatible. Also will they be much of a difference for him when climbing as this seems the more cost effective than changing to a compact on the front.

freezing77

Why not get a SRAM 11-32 to give a wider range of gears. May need a longer rear derailleur, but probably not.

http://www.ribblecycles.co.uk/sp/road-track-bike/sram-sram-cassettes-sram-10-spd-pg-1050-cassette/sramcass260

The cassette is 100% compatible with 105 shifters.

lc1981

k3vinjam3s wrote:

Also will they be much of a difference for him when climbing as this seems the more cost effective than changing to a compact on the front.

You can work this out by dividing the number of teeth on the chainring by the number on a cassette sprocket, to give the gear ratio. The lower the number, the easier it will be on the hills.

plumpy

There are 2 types of 105 rear derailleurs, short cage (SS) and medium cage (GS). If his bike has an SS it won't handle 12-30 or 11-32. A GS will handle either.

You might also find that fitting both a larger rear cog and a longer cage derailleur (if applicable) results in the chain being too tight in some combinations. He'll notice because the shifting will get cr*p! But wait and see before lashing out on a new chain.

If he's got a standard chainset (as I think you're suggesting) then I'd agree with the SRAM cassette idea. 39/32 will feel MUCH easier than 39/27.

k3vinjam3s

plumpy wrote:

There are 2 types of 105 rear derailleurs, short cage (SS) and medium cage (GS). If his bike has an SS it won't handle 12-30 or 11-32. A GS will handle either.

So how do I find out which is on the bike? Is it labelled in some way?

keef66

Easier to look at pics of both and compare with what's on the bike? Shimano techdocs should have illustrations you can use. Eg this is for the 5600 series

http://techdocs.shimano.com/media/techd ... 646682.pdf

zx6man

Those docs also tell you the max teeth allowed for the rear mech 5600 state 27 I think

jomoj

medium cage looks like this

short cage like this


the medium cage mechs still only go up to 28T in theory, 30 would probably be ok , 32 possibly a couple of teeth too far. You might also need to add some links to the chain if it's too short for the 52/30 combo - shift into that by accident and it'll be a big mess..

zx6man

5700 105 does go to 28T, and I think thats whats on the 2012 and 2013 models.

sungod

go to http://techdocs.shimano.com

look at the SI-* document for the exact model of 105 rear mech (i.e. 5500, 5600, 5700, 5700-a), check the specification

there are two numbers that matter

i) the maximum sprocket size
ii) the maximum capacity, capacity is the sum of the differences between largest-smallest on front and rear, so for 53-39 and 12-30, the capacity will be 14+18 == 32

for short cage 5700-a for instance, the figures are 30 and 34 respectively, so you'd be ok

if the results are within specification, follow the set-up instructions for the rear mech in the SI-* document, including for chain length

if the results are not within specification, but only slightly over, you may be able to get away with it, but there may be problems with chainslap on smaller sprockets, and if you went on largest-largest there's potential for something much nastier to happen

btw i'm sure the wheel hub will be a 9/10 speed compatible type, on this hub the tiagra 10-speed cassettes do not need a spacer on the hub, whereas other shimano 10-speed cassettes do need a spacer, sram 10-speed cassettes do not need a spacer

zx6man

I dont get why they claim 28 to be the highest then. bit weird

sungod

zx6man wrote:

I dont get why they claim 28 to be the highest then. bit weird

even with a range, like 105, depending on vintage/context there can be significant variations in what is 'correct', so going to the exact model specification is the only way to be sure

the cynic in me suspects that the marketing people prefer to keep things opaque!

zx6man

The 5700 does say 28 T though spec wise :-)

zx6man

I only have 2300..... so like to be involved with upper class gear :-)

sungod

zx6man wrote:

The 5700 does say 28 T though spec wise :-)

ah, but i said 5700-a, which is 30T :-)

http://techdocs.shimano.com/media/techd ... 746860.pdf

zx6man

It does indeed, just nipping to specsavers...

mr_poll

I am having a similar issue - I currently have 105 5600 Compact running 12-28.

According to Shimano tech specs the compatibility chart essentially says I have to stay with 5600 or upgrade.

http://www.shimano.com/publish/content/global_cycle/en/us/index/tech_support/tech_tips.download.-Par50lparsys-0025-downloadFile.html/01)%20Drivetrain%20Compatability%20Chart.pdf

Essentially I want to downgrade - I have just ordered a summer bike so I want some hardwearing cheap parts as my drive train is currently at the end of its tether, probably to tiagra or even sora. Main issue is the Cassette, Chain and large chainring. Unlike the OP I am not after a hill solution just inexpensive and compatible. Any ideas?

Monty Dog

You'll be fine running a Tiagra cassette on 105 - any suitable 10 speed chain will be OK and you'll get away with a 9 speed chainring

arlowood

Fully agree with Monty Dog

Too many people getting hung up on mech sizes and capacities. If he's already running 11-28 then I'm sure he'll be fine swapping over to the 12-30 Tiagra cassette. Just go ahead and try it - the 12-30 only costs about £20. Might have to lengthen his chain but I doubt it.

This thread summarises my experience about 9 months ago. I had no problems whatsoever.

viewtopic.php?f=40004&t=12850935&p=17597505#p17597505

mr_poll

Thanks for the advice Monty Dog - just seen this at a crazy price, as much as i said i was wanting to drop down it is all down to price. As I have a compact i believe i need a 110mm - can I use this http://www.chainreactioncycles.com/Models.aspx?ModelID=35788