Will a 12-28 cassette work with a 9 speed Tiagra rear mech?

Todd Sweeney

I currently have a 12-25 cassette on my Specialized Allez. This is used with a 9 speed Tiagra rear mech, and a compact 50-34 Hollowtech II crankset, and it has all served me well for a good few years. However, I'm taking part in the Etape Cymru in October, and additionally will hopefully be doing some more hilly rides in the next year or so (including the Alps), so I would like to obtain the lowest gear possible as a last ditch for the very steepest parts.

Shimano says that a 27 tooth cassette is the largest that is compatible with a 9-speed Tiagra rear mech, but I wondered whether it could stretch to a 28 tooth cassette. Does anyone have this set-up working?

Thanks in advance.

rickwiggans

Yes, I do , on my winter bike. It's fine.

Todd Sweeney

Excellent, thanks rickwiggans! Time to get a hold of a 12-28 cassette then.