Rear Mech

[john7]

On my Specialized Allez road bike I've changed the standard 8 speed cassette from a 12/25 to a 11/28 with no issues. At the weekend, after trying to climb a 'big' hill (for me), I've now realised that a higher gear is needed. I think changing to a 11/30 or 11/32 cassette will require a change from the standard mech, Shimano 2300, to probably a Claris 2400 mech.......am I correct in this assumption or will my current mech be suitable?

[Bobley]

I think you're dead right.

According to this your 2300 rear mech is already out of spec as it's designed for 26T sprocket max

http://si.shimano.com/pdfs/si/SI-5XA0A-001-ENG.pdf

but the Claris RD 2400 SS will go up to 32 but it also says -13T so you may struggle for top end speed? The total capacity front and rear is 37 teeth.

http://cycle.shimano-eu.com/content/seh-bike/en/ho...

The RD 2400 GS has 41 tooth capacity so that might be your answer?

Edited by Bobley on Tuesday 6th June 23:19

[The Rookie]

Presumably you mean a lower gear.....

Shimano stated sizes are pretty conservative, I'm running a 9 speed XTR rear mech (nominal max size is a 34T) on a 40T wide range cassette on my MTB, try it and see is my advice.

[john7]

Cheers, thanks for your inputs and you are quite correct - lower gear.