Some reassurance needed before switching cassettes

Nomadski

I Like Bikes
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LBS, Usually
I have a 2012 Cannondale Synapse with original official spec parts. My rear derailleur is a Shimano 105 5700, and my current cassette is a Tiagra 10 Speed 12-28.

Ive been looking at switching to a Tiagra 10 Speed 12-30 as I understand I lose out a little on the approach to the largest cog, but the upshot is that final one is bigger, which I sometimes need when I hit the bigger hills near me.

I've been looking at Wiggles site and a few questions have popped up about sizing and they get mixed responses. Some saying cannot work with the short cage RD, some say will work, others say may have issues.

Can anyone say comprehensively one way or the other if its a none starter, or I will be ok, and will it just be the usual tweaks needed (adjusting B Screw and re calibrating gear barrel?)
 

Smokin Joe

Legendary Member
Shimano short cage mechs will work with a 30t sprocket. Just check if your existing chain is long enough -

http://www.epicidiot.com/sports/chain_length_calculator.htm
 
OP
Nomadski

Nomadski

I Like Bikes
Location
LBS, Usually
I've just fitted a brand new KMC chain to the bike and cut it down to the same size as the previous one. (It was while doing this, and cleaning the cassette it dawned on me how easy the process was and maybe I should get a secondary cassette).

Should have asked this before I did the chain replacement!
 

slowmotion

Quite dreadful
Location
lost somewhere
I've just fitted a brand new KMC chain to the bike and cut it down to the same size as the previous one. (It was while doing this, and cleaning the cassette it dawned on me how easy the process was and maybe I should get a secondary cassette).

Should have asked this before I did the chain replacement!
Use the chain calculator that was posted above. If you have cut it too short, just use a KMC missing link to spice another bit on.
 
OP
Nomadski

Nomadski

I Like Bikes
Location
LBS, Usually
Use the chain calculator that was posted above. If you have cut it too short, just use a KMC missing link to spice another bit on.
Ive already got the chain connected via a missing link. Would need to fit an internal part of the chain, no?

Still got the old chain so will lay that down and measure it tomorrow. I need 134.62cm or 53 links, to fit apparently.
 

slowmotion

Quite dreadful
Location
lost somewhere
Ive already got the chain connected via a missing link. Would need to fit an internal part of the chain, no?

Still got the old chain so will lay that down and measure it tomorrow. I need 134.62cm or 53 links, to fit apparently.
You can use more than one Missing link on the chain. In order to spice the length that you chopped off, use a missing link at each end. I hope you can see what I'm getting at...I'm not explaining it very well!

Edit: cross post with Joe ^^^^^^^^^^^^^^^^^^
 
OP
Nomadski

Nomadski

I Like Bikes
Location
LBS, Usually
Not 100% @slowmotion really, lol. :smile:

Its strange. The calculator told me I would need a 134.62cm chain. I've just laid out the old chain that came off the bike on some cardboard and measure it, and that chain is about 136cm anyway? Not sure how the calculator works out the chain should be shorter than current, I double checked the Chainstay Length for the calculation.

Unless the original chain put on by Pauls Cycles to the Cannondale (which I've never altered) was a tad too long?

Going to order that 12-30T. Too intrigued now and its cheap anyway so.

Thanks for the advice, everyone. :smile:
 

Cold

Guest
I just bought and fitted a Shimano RD-5701 105 short cage and it is fine with with myTiagra 12/30 cassette.
 

slowmotion

Quite dreadful
Location
lost somewhere
If you give me this info, I'll have a stab at working out how to make the chain if you would like.

*How big is your biggest chain ring?

*What is the chainstay length?

* What is the length of your new cut chain in terms of number of inner links and number of outer links? What type are the links at each end of the chain, inner or outer?

*What does the short cut-off remnant comprise of?
 
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