11t-40t/42t cassette on 3x9 system I need your help about gear ratio.
I am currently riding 3x9 drivetrain, Deore m592 rear (SGS-Shadow), Deore XT m770 front.
My gear ratio is:
11t-32t (rear) and
22t-34t-44t (front).
My local hills and trails consist of hard uphill and some small downhill tracks. The hard uphills are the reason why i want to make a change in my cassette ratio.
I am planning to upgrade to a bigger, 11t-40/42t cassette, but I'm confused if this is possible with a 3x system or not.
I've read that the max cog (rear) for some derailleurs (including my SGS Deore) is 36t, but a lot of people say that 11t-40/42 or even 46t is possible. Are these cassettes too large for a 3x9 drivetrain? Do I need to convert to a 2x in front as well?
Will a hanger extender + the b-link somehow make it possible to get the cassette size i want?
Any help would be appreciated.
Thanks in advance :)
It's not clear why you would want to use an 11-42 cassette in a 3x drivetrain. 11-42 cassettes are typically used with 1x or 2x systems. With a 22 tooth chainring and 34 tooth sprocket you already have a pretty low gear ratio (0.65) - lower than a typical 1x drivetrain with a 30 tooth chainring and 11-42 cassette (0.71), and only a little higher than a 2x 36 tooth small chainring and 11-42 cassette (0.62).
Just to give you a definitive answer on compatibility: the two derailleur specs you need to know about are the max cassette sprocket size and the total capacity. Max sprocket sizes is obvious, total capacity is the ability of the derailleur to take up slack chain and needs to be greater than or equal to (difference in largest/smallest sprocket size) + (difference in largest/smallest chainring size). Your current setup requires capacity of (34-11)+(44-22) = 45.
You can find Shimano specs here: https://productinfo.shimano.com/#/, in the archive PDF spec sheets. The M592 SGS has max sprocket of 36, total capacity of 45 - which obviously precludes a larger range cassette.
If you used a Alivio 2x9 crank with 36-22 rings and a 11-42 cassette the capacity requirement would be (42-11)+(36-22) = 45, but your derailleur still can't handle a max cassette sprocket over 36 teeth. (Although, I've heard of people successfully using a derailleur hanger extension to accommodate a large range cassette.)