Rear Cassette

[Bazil Bush]

Morning All,
Bit of help if anyone can advise please.

I did a particularly lumpy sportive at the weekend and had a bit of a schoolboy error.

Bike I used was running a 11-25 11 speed rear cassette when I normally run a 12-28 on my other bike which I’ve used for that sportive in the past.

The 20% climbs were a bit brutal with the smaller cassette……

Question is, can I get away with the current chain and change out to a 11-28 cassette or is a new chain required too.

Bikes only got 700 miles on it so would prefer to get some more mileage out of current chain if possible.

Bike’s a Cervelo R3 running Ultegra.

Thanks

[outnumbered]

It depends how long the chain is, you might get away with it, you might not. Best thing would be to fit the new cassette and then see whether it will change safely into the big/big combination. If not, you'll need a chain as well.

In the old days you might also need to check that your rear mech can cope with a 28 tooth cassette, but modern mechs won't have an issue with it.

[WPA]

Until you try it your not going to know with chain length.

Also worth checking your rear mech will work with a 28t

[Bazil Bush]

Thanks for replies.

Guessed as much.

Will buy cassette and chain and have a bit of a tinker.

Bit of a shame that the current ones will have to be ditched as they’ve had limited dry weather use but could always keep them as a backup

[OutInTheShed]

The extra chain needed is only about 1.5 links. (1.5 rollers FTAOD)

With the existing kit, if you can change to the big front, biggest back gears, and still fold the chain in the lower run to effectively shorten it by a couple of links, then the chain is long enough.
You could use a chain hook or bit of bent stiff wire to shorten the lower run of chain while you assess how much movement the mech has left?

You shouldn't push this to the limit, the chain needs a bit extra to climb onto the sprockets and (I'm led to believe!), it will work better if there's at least say two rollers more than the bare minimum which would run around the sprockets. I think opinions differ how much spare there should be?

[addey]

Just switch the cassette over from your other bike and test it? Saves you from buying anything just yet. Other option is to change your inner chainring for something smaller and keep the same cassette/chain

[flight147z]

Id say if you're putting a new £50 cassette on the bike then you may as well pay the extra £20 for a new chain

Makes it easier to remember when to replace everything too - 3 cassettes per big chain ring, three chains per cassette

[BlackTails]

The first time I rode La Marmotte I used a 12-25 cassette, against the advice of my mates. They were right!

I think you’ll be ok with the existing chain and a 28 sprocket unless the chain on the 25 sprocket and big ring at the front is pulling the rear mech as far forward as it will go. Worst case: open the chain and add a quick link.

[thepritch]

I’d not get much more than 1750-2000km from a chain before they’d be replaced. But I love grinding up hills and ride through crappy winter conditions so they’d wear quite quickly. As I was going through5/6 a year, I’d never buy better than 105, and often try and get lesser chains. For training rides they were more than adequate.

Edited by thepritch on Monday 31st March 20:44

[Bazil Bush]

Thanks all, appreciate the comments