Swapping Cassette on a new bike

sketchley

I'm going to be ordering a Genesis Equilibrium 20 soon, it comes with a 105 12-25t cassette. If I buy a 11-28t 105 cassette is this a straight swap out or do I need a longer chain?

nferrar

It depends on how short your current chain has been cut, if it only just managed big/big combo on a 25 then you'll need a link or two more to cope with a 28 (not that you should use big/big but just in case you do accidentally you don't want things snapping). If it currently does big/big fine then I'd just try the new cassette and see if big/big still works OK after. Ofc if the cassette is worn then the chain would be to so you'll need to change it anyway otherwise it will skip on the new cassette.

rolf_f

It's a new bike so the cassette hopefully won't be worn!!

I think I added two full link pairs (ie four links in total) when I changed a 25 for a 29 on one of my bikes. It did cope with the original chain length but it was a bit tight really. If you know you don't want to use the 12-25, could you try asking Genesis to put an overlong chain on it. If you do intend to use the 12-25 at times, just get another chain. You can never have too many chains.

cush123

It also depends on which model of the rear deraileur you have. If it's a 105, there are three or four model and only one says it can cope with a 28 tooth large sprocket.

rolf_f

Cush123 wrote:

It also depends on which model of the rear deraileur you have. If it's a 105, there are three or four model and only one says it can cope with a 28 tooth large sprocket.

Just because the instructions say it can't cope with 28 doesn't necessarily mean it can't

Paul E

I have a 105 triple on mine and long cage rear mech and it's had a new 11-28 5700 105 cassette on it and a new ultegra chain, the mech seems to cope fine but it's only had to cope with going up one tooth from the original cassette.

Only thing I can't say is if the new chain is longer as my local (up in scotland) lbs did it as it was in for it's major service before a big trip

keyser__soze

I read on the parktools website it's a bad idea to try to lengthen existing chains, is this really the case? I have a lightly used 11-25 cassette/chain and am thinking of getting a spare 11-27 or 28 for my Dolomites trip and a potential Fred Whitton next year, but my chain is quite tight as it is. Do people use powerlinks/similar to extend or do they have spare chain lengths?

IanTrcp

Who are you buying it from? If you ask nicely they might supply and fit your preferred cassette for free, or at least credit you for the 25t and take it back into their stock. Just a thought!

rolf_f

Keyser__Soze wrote:

I read on the parktools website it's a bad idea to try to lengthen existing chains, is this really the case? I have a lightly used 11-25 cassette/chain and am thinking of getting a spare 11-27 or 28 for my Dolomites trip and a potential Fred Whitton next year, but my chain is quite tight as it is. Do people use powerlinks/similar to extend or do they have spare chain lengths?

It's hard to see the point. Unless you are imminently about to retire from riding, you'll need another chain soon anyway. For the Fred Whitton, I just bought one of the bargain CRC chains though last I looked they were discontinued. I use that one with my 13-29 cassette (which wasn't enough for Hardknott after 100 miles!!).