# Correctly sized chain with impossible too loose B-screw adjustment?

I have recently changed my cassette from a 11-32 to a 11-25 (11 speed). To make the change possible, I have reduced my chain size to 106 links (53 inches) by the largest cog, largest chain ring method. For further information, my crankset is a 52-36 teeth.

When I installed my RD-6800 (SS), I noticed that even by removing the B-screw, the derailleur is never too close to the largest sprocket (largest sprocket, smallest chain ring configuration). How is that possible?

I thought that maybe I screwed up the chain sizing, but I have just recalculated using the equation and the recommended chain length is 53 inches:

``````L = 2*(16.125) + (52.0/4 + 25.0/4 + 1) = 52.5"
``````

Is it maybe due to the bike or hanger design?

• At the LBS I was told that shortening is not necessary in this case. 11-25 is inside the range of 11-32 and the derailleur takes up the tension. On the other hand, with a chain length adjusted for 11-25 it will be to short for an 11-32 cassette. Aug 8, 2017 at 20:09
• @Carel I wouldn't be shocked if without resizing the derailleur was too far away from the largest sprocket. But with the correct one, it is indeed bizarre. Aug 8, 2017 at 21:02
• On your 11-32 cassette the 25 is the third sprocket. On the 11-25 it's the last. The RD will logically be in the same position if your chain runs on any of both 25s independently of the cassette. I have three rear wheels with 11-25, 11-28 and 11-32 that I use on an Ultegra GS-cage RD. The front is normally 52-36 but sometimes 50-34. All of those combinations run on a chain-length for 52/36 and 11-32 without trouble. With an SS-RD however 11-32 was over the limit of 11-28 and the chain was too long anyway for 11-25. In that regard a GS is more versatile. Aug 10, 2017 at 7:20