Bicycle Mechanics - Moving from 12-27 to 11-23. How many chain links do I remove?

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carleton
10-15-10, 03:19 PM
I'm switching from the stock 12-27 cassette to an 11-23. This freed up a lot of chain. Is there some rule of thumb to determine how many links to remove?
Thanks.
C
Lightingguy
10-15-10, 03:37 PM
The rule of thumb I follow is to put the chain on the big ring and the largest cassette. The R derailer should then have a forward angle of about 45 degrees and not be pulling the derailer any further forward.
Then do a small ring, smallest cog and make sure the chain is clearing the upper jockey pulley as the derailer is almost level.
Then remove/add clinks as required.
SB
carleton
10-15-10, 03:40 PM
Thanks!
dstrong
10-15-10, 05:24 PM
Ohhhhhhh....I suppose just because I have a different way to do it I've just got to say something! :)
I use the big-big combo as lightingguy suggests but not threaded through the RD. Pull the chain tight, see where the ends match up, then add two links to that length and break the chain so it mates up correctly. As with most things where it's tough to undo a mistake, round up a link if in doubt.
My guess is that this way works also because when you add the two links, it's adds the necessary length to get that angle in the RD lightingguy was referring to.
carleton
10-15-10, 05:30 PM
Thanks, dstrong.
lightingguy's method worked. But I was a bit ambitious and lopped of 2 links at once. I probably should have done just 1 being that I was planning to use the stock cassette on a trainer wheel with a trainer tire. Doh!
I guess I'll just have to get an 11-23 for that wheel, too.
Retro Grouch
10-15-10, 07:48 PM
Then do a small ring, smallest cog and make sure the chain is clearing the upper jockey pulley as the derailer is almost level.
If you just do that - use the little/little chain sizing method that's recommended by Campy, you'll probably find that you don't have to remove any links. You're only changing the smallest cog by one tooth. Assuming your derailleur had enough slack take up before chances are it will probably still be adequate. The advantage of using this method is that, if you decide to revert to the 12/27 cassette again, you'll be good to go without having to mess with your chain.
JiveTurkey
10-15-10, 08:52 PM
All of them. I replace the chain when the cassette is replaced, unless the cassette has barely been on there any time.
carleton
10-15-10, 10:55 PM
Word. The bike is new (less than 200 miles).
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