Disgruntled Goat
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User259iroloboy said:Depending on the terrain you ride in generally, a 13 29 is for BIG hills/Alpine climbs, run with a triple or compact chainset. 12 26 should get you up most hills comfortably in 39 52, or go for a 34 50 compact , if you have lots of steep climbs in your neck of the woods.
ghitchen said:If you are talking Campag then I can confirm that you can run a short-cage mech with both a 12-25 and a 13-29 cassette. I run these with a 34-48 Compact chainset which with a 14 tooth difference would mean you could also use a 39-53 chainset no problem. If a short-cage can cope with this then a medium or long would have no problem either.
spandex said:you can run any cage as long as its the right speed.
long = some off road ? but mainly road mtb
short = off road mtb
short = road/ racing
User259iroloboy said:
Its not about indexing correctly its about the cage plates ability to accommodate the tooth difference. The 'indexing' wont be affected in any way.User259iroloboy said:When I enquired at one of my LBS about this dilemma, I currently run a short cage 11t-25t in conjunction with a compact 34t 50t chainset ( New UT centaur) I was told if I wanted to change to a 13t-29t I would have to swap my current RD for the long cage in order for it to index correctly, and this was after consulting the Campag website, as the guy in the shop wasn't sure himself, and neither was the chap who was with him. As I didn't have £171 on me to purchase a new long cage RD and a 13t-29t rear cog, I decided (on advice of the LBS guy) to try a bit harder on my climbing, I did and (it worked).
That's how I understand it too, but surely the larger and therefore the more teeth that the largest rear cog has, the longer the RD cage has to be, in order to accommodate the slack of the chain as it moves across the gears, therefore a short cage will hit the bottom of the largest cog, that's my understanding of why a 29t rear cog will need a long cage, or am I wrong?mickle said:Its not about indexing correctly its about the cage plates ability to accommodate the tooth difference. The 'indexing' wont be affected in any way.
The rear derailleur does two jobs, it moves the chain between sprockets in response to instructions given to it via the shifters and it accommodates chain slack when changing between different sized sprockets.
The toe-rags in your LBS do not know what they are talking about.
I refer the right honourable member to the answer I gave in the post before the one quoted.User259iroloboy said:That's how I understand it too, but surely the larger and therefore the more teeth that the largest rear cog has, the longer the RD cage has to be, in order to accommodate the slack of the chain as it moves across the gears, therefore a short cage will hit the bottom of the largest cog, that's my understanding of why a 29t rear cog will need a long cage, or am I wrong?
The Toe Rag is a kiwi, if that makes a difference? LOL!!!