Changing rear cassette query

Danville

I am presently using Shimano 52-36 with 11-28 cassette.
Can I change the rear cassette to a 12-34 with a simple swap or will it be necessary to change the chain length?
Thanks in advance.

paddydriver

Think longer chain may be needed and you'll likely need to change the cage on rear derailleur or new derailleur - have a look at below link and might help:

https://guides.wiggle.co.uk/rear-derailleurs-buying-guide#:~:text=The%20distance%20between%20the%20upper,move%20to%20the%20smaller%20rings.

Cee-Jay-Cee

Danville wrote: »

I am presently using Shimano 52-36 with 11-28 cassette.
Can I change the rear cassette to a 12-34 with a simple swap or will it be necessary to change the chain length?
Thanks in advance.

You’ll need add two links to your current chain or buy a new one and split it two links longer than current chain.

Carawaystick

Will he not need it 6 links longer to go from 28 - 34 on the back?

Also check the deraileur, if the cage isnt long enough to allow the extra range

magicbastarder

Carawaystick wrote: »

Will he not need it 6 links longer to go from 28 - 34 on the back?

the chain only wraps halfway around the cassette, rather than all six extra teeth being used by the chain.

Danville

paddydriver wrote: »

Think longer chain may be needed and you'll likely need to change the cage on rear derailleur or new derailleur - have a look at below link and might help:

https://guides.wiggle.co.uk/rear-derailleurs-buying-guide#:~:text=The%20distance%20between%20the%20upper,move%20to%20the%20smaller%20rings.

Thanks for this, very informative.
I see that with a Medium Cage the state’s;
Max Cassette is 34 and
Max Capacity is 37

My capacity as per formula given is 38.
Q. Would I ‘get away with’ being out by one?

Cee-Jay-Cee

Shimano generally understate the max capacity. I have used a 32T cassette with a short cage 6800 RD and had no problems, I didn’t even need to screw in the B screw.

If you already have a medium cage RD then you’ll be fine with a 34T cassette so long as you lengthen your chain by 2 links.

martyc5674

Danville wrote: »

Thanks for this, very informative.
I see that with a Medium Cage the state’s;
Max Cassette is 34 and
Max Capacity is 37

My capacity as per formula given is 38.
Q. Would I ‘get away with’ being out by one?

You’ll be fine- that capacity figure also assumes you’ll be cross chaining which I assume you don’t.

Wishbone Ash

martyc5674 wrote: »

You’ll be fine- that capacity figure also assumes you’ll be cross chaining which I assume you don’t.

Even if a rider doesn't typically cross chain, it can happen. I'd rather allow for it even if it never happens rather than be stranded in the middle of nowhere with a broken chain.

Type 17

...broken chain if you’re lucky - I’ve seen a carbon frame with a shattered chainstay because the chain was too short, the rider shifted to big/big whilst pushing hard on a hill :eek: