Rear derailleur limitations with rear cassette

[robbiecollison]

Hey guys,
I would like to know if my Shimano Sora RD-3500 SS rear derailleur would be compatible with a 32-11 Shimano HG50 9 speed cassette? I currently have the 'standard' 9 speed 12-27 Sora rear cassette but find living around the south downs I need a bit more range when going up and down hill. I've looked on the Shimano website/looked on a few forums but I've found some contradicting information/opinions about whether I would be able to do this or not.

FYI my Chainset is the Shimano Sora Compact (50-34).

Cheers Robbie

 

[KneesUp]

Model Number RD-3500-SS
Series SORA
Cassette Compatibility 9
Maximum Sprocket 32T / 14T
Minimum Sprocket 25T / 11T
Maximum Front Difference 16T
Total Capacity 37T


16 teeth range at the front is right at capacity for your rear to take up the slack.

The total capacity is 37. Total capacity = difference in the front + difference in the back.

Diff front = 16. Proposed diff at back is 21 give required capacity of 16+21 = 37.

I'm not sure though why there are two values for min and max sprockets. I suspect you can only use a 32 at the back if the smallest at the back is 14 - but perhaps others can advise.

 

[evo456]

Short answer is - no , you'll need GS version for 11-32

 

[robbiecollison]

Ok I thought so, thanks for the help.

Do you know what cassette I could have? i.e 30-12 or 30-11.

 

[PpPete]

I'd say suck it and see.
Based on the numbers provided by KneesUp (which TBH I couldnt find in the Shimano TechDocs) the SS might well cope if the chain is the right length.
All the mechs will go a good few teeth beyond their spec (I've run a whopping 46T total difference off an old GS mech that was supposed to be for 37T total)
Don't forget you might need a new chain to cope with the bigger cassette, even if the old one you've had on the 12-27 isn't worn.

 

[KneesUp]

Specs are from here: http://cycle.shimano-eu.com/publish.../product.-code-RD-3500-SS.-type-.rd_road.html

 

[robbiecollison]

Thanks for the specs KneesUp. It looks like the derailleur will be able to cope with a 32-11 rear cassette.

Max Sprocket = 32T
Min Sprocket = 11T
Max front difference = 16T (50-34 on my compact)
Total capacity = 37T ([50-34] + [32-11] = 37)

So I will be able to run this cassette, however it's right on the limit of my derailleur.

 

[KneesUp]

It actually says

Maximum Sprocket 32T / 14T
Minimum Sprocket 25T / 11T

I am assuming that means that you can have a 32 if the smallest is 14, but only a 25 if the smallest is 11.