Changing cassette gearing

[cabbieman]

Hi. Can I swap a shimano Sora 13-25 cassette for an 11-30/32? Do I need a new chain? It's a secondhand bike purchase for my niece and I don't think she could cope with the hills on a 25. Any suggestions ?

 

[Sharky]

The old chain/cassette is bound to be a bit worn, so probably prudent to fit a new chain as well.

What's on the front?

 

[cabbieman]

I'm asking, just awaiting a reply. Is the rear derailleur designed to just take up the slack when changing gears? I'm never sure about changing cassette sizes

 

[vickster]

I'm asking, just awaiting a reply. Is the rear derailleur designed to just take up the slack when changing gears? I'm never sure about changing cassette sizes

You may need a different rear mech for the new cassette and a longer chain. Need to know what's there currently

 

[Cycleops]

You'll need a new chain but mech will be able to cope up to 34T. It is designed to take up extra chain length .
Formula for chain is big cog front to big cog rear omitting the Derailleur plus two links.

 

[si_c]

You'll need a new chain but mech will be able to cope up to 34T. It is designed to take up extra chain length .
Formula for chain is big cog front to big cog rear omitting the Derailleur plus two links.

Not necessarily, could be a short cage derailleur.

 

[cabbieman]

This is the bike in question
https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.co.uk/ulk/itm/173849426936

 

[si_c]

Looks like a short cage with a 50/34 up front, so you should be ok with a 32.

 

[Cycleops]

Not necessarily, could be a short cage derailleur.

Shimano Sora R3000 9 Speed.

Sora R3000 9 Speed rear deailleur from shimano. Sora rear derailleur feautre a light action shifting with a wide link design give incresed rigidty for better shifting. The 11 tooth pulley wheels help to increase chain life and reduce chain noise. Available in Black compatible with 9 speed drive trains only.

Use Road
Mount Direct Mount
Max Sprocket Size 34 tooth

 

[cabbieman]

Thank you for your efforts in helping me out.

 

[si_c]

View attachment 460091
Shimano Sora R3000 9 Speed.

Sora R3000 9 Speed rear deailleur from shimano. Sora rear derailleur feautre a light action shifting with a wide link design give incresed rigidty for better shifting. The 11 tooth pulley wheels help to increase chain life and reduce chain noise. Available in Black compatible with 9 speed drive trains only.

Use Road
Mount Direct Mount
Max Sprocket Size 34 tooth

There are two variants for the RD-R3000, the GS (long cage with Max 34t) and the SS (max 32t), all of which is irrelevant because the OP is running Sora 3500 and both the SS and GS variants have a max 32t sprocket, the difference between the two is the total capacity - meaning the GS version can be used with a triple at the front and the SS can't.

 

[cabbieman]

So I can just change the cassette for an 11-32 no problem? Maybe the chain as well if it measures a bit worn

 

[TheDoctor]

You're very likely to need a longer chain with the bigger cassette.

 

[vickster]

So I can just change the cassette for an 11-32 no problem? Maybe the chain as well if it measures a bit worn

I’d always add a new chain to a new cassette (and indeed vice versa). 9 speed chains are inexpensive

 

[Cycleops]

Yes straight swap and you will need a new longer chain.