Going from 12-25 to 12-27 cassette on my P2C. Will I need a new chain?

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2008-09-05 2:18 PM

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Subject: Going from 12-25 to 12-27 cassette on my P2C. Will I need a new chain?

I plan on getting a 12-27 cassette to go with my PowerTap.  My P2C has a 12-25 on it right now.  Will this change cassette require a new chain?

 Thanks!

2008-09-05 2:35 PM
in reply to: #1653382

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Subject: RE: Going from 12-25 to 12-27 cassette on my P2C. Will I need a new chain?
 I went from a 11-23 to a 12-27. I used the same chain and have had no problems yet. Make sure that you can go from small chainring to the 12 and big chain ring to 27. Do this on the workstand and try it pedaling slow and under no load. You won't ever ride in these configurations, but if you inadvertantly shift into one of these configs another poster said he wrecked his rear derraileur doing so. http://beginnertriathlete.com/discussion/forums/thread-view.asp?tid=115458&posts=38&highlight=12-27&highlightmode=1#M1475525

Edited by mdg2003 2008-09-05 2:39 PM
2008-09-05 3:09 PM
in reply to: #1653382

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Subject: RE: Going from 12-25 to 12-27 cassette on my P2C. Will I need a new chain?
How old is your chain and how many miles?  That is the determining factor, not the change in cassette by 2 teeth.
2008-09-05 4:41 PM
in reply to: #1653382

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Subject: RE: Going from 12-25 to 12-27 cassette on my P2C. Will I need a new chain?
It is about 2 months old.  Probably about 400-500 miles on the chain.  I have two bikes that I ride.  I purchased a dura ace chain anyway.  Could not hurt to have an extra chain around.
2008-09-05 6:40 PM
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Subject: RE: Going from 12-25 to 12-27 cassette on my P2C. Will I need a new chain?
You can certainly use it then with no problems.
2008-09-05 7:19 PM
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Subject: RE: Going from 12-25 to 12-27 cassette on my P2C. Will I need a new chain?

No issues. Std shimano chains are 12-27 length, no worries. If you get a bigger cassette, yes, it gets silly. But anything between 11-21 and 12-27 works with no problems.

And the shifting wasn't that poster's issue. There was something else going on to wreck his rear derailleur. You can't kill a derailleur with a stock shimano chain on 12-27 unless something else is up.



2008-09-06 12:39 PM
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Subject: RE: Going from 12-25 to 12-27 cassette on my P2C. Will I need a new chain?
 Rick, what do you think might have gone wrong in avjetdale's case? I've never heard of anyone wrecking a rear derrailleur before. Typically when troubleshooting anything mechanical, I look to recent changes made to the "machine" after looking for an obvious mechanical failure such as a bearing seizure or structural failure. I'm curious because I'm currently messing around with my gearing set up on my bike. I'm looking into possibly putting on Qrings and have already installed a hill friendly cassette. I guess worse case scenario I lunch my rear shifter and can upgrade to 10 speed but, I really want to avoid that! Laughing Thanks for any advice you can throw my way.
2008-09-06 7:04 PM
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Subject: RE: Going from 12-25 to 12-27 cassette on my P2C. Will I need a new chain?

I know you are asking the other Rick but .......

If someone lunched their rear. der. after changing their cassette out it could be any number of things.  First, they may have put in the spacers slightly wrong (more of a concern about any that might need to go behind the cassette) which threw off the set screw and cable tension adjustments so if they shifted into the largest in the rear it may have gotten thrown into the spokes.  Or if their der. hanger was bent then the der. does not align correctly and the extreme of the inside cog mixed with changing it out to something bigger may have also launched it into the spokes, or allowed the chain to come off and wedge into the area between the cassette and spokes.

Without knowing the reference to avjetdale's exact problem I couldn't really give you any more ideas on it .......

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