bluenote157
07-10-10, 06:36 PM
came across this and thought about putting it on my beater town cx/commuter. Whats the biggest cog I can go on this? 27t?
Bicycle Mechanics - max cog on a tiagra 9speed rear derailleur? rd-4400 short cage..
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HillRider
07-10-10, 06:44 PM
Shimano specifies a 27T large cog as the maximum for their road rd's but experience says that up to 30T is almost always doable. Your short cage rd will accept the same maximum cog as a long cage, it just won't wrap up as much chain so the total gearing range can't be as large.
bluenote157
07-10-10, 07:26 PM
gotcha! thanks hillrider.
operator
07-10-10, 11:09 PM
Shimano specifies a 27T large cog as the maximum for their road rd's but experience says that up to 30T is almost always doable. Your short cage rd will accept the same maximum cog as a long cage, it just won't wrap up as much chain so the total gearing range can't be as large.
27t is based on an assumed hanger length. Some bikes will not take even a 25 even if the r.d specifics 27t.
27t is based on an assumed hanger length. Some bikes will not take even a 25 even if the r.d specifics 27t.
HillRider
07-11-10, 04:05 PM
27t is based on an assumed hanger length. Some bikes will not take even a 25 even if the r.d specifics 27t.
Correct but the great majority of frames will clear the 27 and a bit more so one that won't is an exception, hopefully a rare exception.
Correct but the great majority of frames will clear the 27 and a bit more so one that won't is an exception, hopefully a rare exception.