Chain Length Help

[Gasman1440]

I have a road bike with a 48/35 crank and a 10-28 12 speed cassette. I’d like to use the brand new chain I have for this and change the cassette to a 10-33 or 10-36. I have gotten much advice on how to size a chain when you have it but is there a way to know if the existing chain (which again is brand new) will work with the larger cassette?

 

[Smokin Joe]

http://www.machinehead-software.co.uk/bike/chain_length/chainlengthcalc.html

Works every time.

 

[T4tomo]

if the chain has been shortened to work nicely with a 10-28, then it should be too short to work with 10-33 and defo too short for 10-36.

best way is to have a new chain on stand-by (order it with the cassette as you will use it at some point and having a spare is good) and then carefully test how it goes with the new cassette as you fit it (not riding it).

I think you will find you are straightening the RD before you get to the largest 1or2 sprockets on the big ring. In which case change the chain to the longer one as accidently selecting this ratio could damage the Rear mech and bend your mech hanger.

 

[iluvmybike]

The chain will need to be a bit longer given that increase in the size of the largest sprocket. Do check that yuor rear derailleur has the capacity to accommodate that size though.

 

[T4tomo]

The chain will need to be a bit longer given that increase in the size of the largest sprocket. Do check that yuor rear derailleur has the capacity to accommodate that size though.

I assume its SRAms new ish 12 spd system, in which case the RD is good for that range - its aimed at gravel bikes hence the wide range and covers 1X and 2x front set up.

 

[livpoksoc]

I made a mistake 2 weeks ago, putting a larger cassette onto my smart trainer. Only when I couldn't engage the larger sprockets did I realise what I had done.

New chain fitted using a GCN video and problem solved. (I had to also put the same size cassette on my rear wheel to match).

Not sure about rear mech/hanger spacing though.

 

[Ajax Bay]

I have a road bike with a 48/35 crank and a 10-28 12 speed cassette. I’d like to use the brand new chain I have for this and change the cassette to a 10-33 or 10-36. I have gotten much advice on how to size a chain when you have it but is there a way to know if the existing chain (which again is brand new) will work with the larger cassette?

If you fit the new cassette (10-33t) on the current chain will not be long enough. This assumes the existing chain is the right length and not a link (1") too long. Think about how many teeth the rear half of the 33t sprocket has, compared with the same semi-circle of the 28t.

 

[Lovacott]

http://www.machinehead-software.co.uk/bike/chain_length/chainlengthcalc.html

Works every time.

For chainstay length, do you take the measurement from the bottom bracket centre to the dropout centre?

 

[Smokin Joe]

For chainstay length, do you take the measurement from the bottom bracket centre to the dropout centre?

You do.