Join Date: Jun 2006
Bikes: 03 Raleigh Professional (steel)
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You're addressing two different things in this thread. First is maximum rear cog size, the second is the amount of slack that can be handled by the RD - usually called "capacity".
For cog size, Shimano generally specs 27T as the max for its road RDs, but experience has shown that they can usually handle 30T. That's why you see the two different numbers. As per urbanknight, you may want to assume that 28T is the max. The 7400 group is an odd duck and may behave differently than the "norm" for Shimano.
For capacity, it's the difference between the biggest cog pair (front+rear) and the smallest, in tooth count. I don't know what the 7400 spec is, but you shouldn't have a problem with those two cranksets.
Stupidity got us into this mess - why can't it get us out?
- Will Rogers
Last edited by DMF; 02-14-08 at 03:04 PM.