Shimano Cassette - Derailleur Compatibility

bianchibob

In a recent posting I was considering changing my Specialized Allez from a Compact to a Triple to assist hill climbing.
Have now after looking at replies decided to replace rear cassette.

Present cassette is a 9 speed 11-28 and I want to fit a 11- 30.

Has anyone else done this, and if so will the standard Sora rear derailleur cope with the extra two teeth ?

I have noted that Sora Derailleurs come in two cage lengths, how do I know which one I have ?

Thanks

arlowood

If you are already running a compact then your rear derailleur will be the standard size. The other size is the long cage which is only required when you have a triple crankset to cope with the extra chain length/tension for the small 30 tooth inner ring on the triple.

You should have no problem moving from an 11-28 to an 11-30. I went from an 11-28 Ultegra to a 12-30 Tiagra cassette without having to make any changes.

I would suggest that if your current cassette has done a few miles then it would always be advisable to buy a new chain at the same time as you buy the cassette. KMC 9 speed would be my suggestion.

Pretty cheap from Merlin:-

http://www.merlincycles.com/bike-shop/m ... tAodL0cAGA

Just use the following link to calculate the optimum chain length:-

http://www.epicidiot.com/sports/chain_l ... ulator.htm

tommo7567

You most likely have a short rear derrailleur with your compact which will allow a maximum front tooth difference of 16 teeth (50-34). If switching to a triple the maximum difference will be 20 teeth (50-30) so will need a long cage or GS rear derailleur.