Alternative gear ratio newbie question: Am I doing a mistake for this commuter?

Question

I have a commuter bike using a 3x9 MTB transmission:

• HG61 9 speed 11-32T: 11 / 12 / 14 / 16 / 18 / 21 / 24 / 28 / 32
• Deore XT crankset (104MM) 22 / 32 / 44.

I mostly use the 32-tooth middle chainring with either 12 / 14 / 16 / 18 sprockets. Fairly flat commute around London.

It's time to replace the parts and I would like to change the ratio so that I am not always on the low gears. I see two options:

1. Replacing the 32 chainring by a 32. I found one on amazon for 8 gbp and going for for a 11-28T cassette to add a low sprocket (11 / 12 / 13 / 14 / 16 ...)

2. Keeping a 11-32 cassette but going for higher chainring so my chain is well in the middle of the cassette in the future. Probably a 34T but I don't find them, mostly 36T but I'm worried this will be too much?

Appreciate any pointers so I don't guess this wrong re: gearing or chain length or anything else I don't know yet.

Answer 1

Even with your current setup, you could be spending more time in the middle of the cassette and dealing with less total drivetrain wear by using the 44 more. So part of the answer is going to deal with why exactly you aren't doing that - is it because you like having ready access to some or all of the lower (bigger cog) gear ratios in back without having to shift down to the middle in front? If that is the reason and it's a habit you don't foresee changing, the move becomes to use a gear calculator to see what those gear ratios are and then whether you'd still be able to get satisfactory access to them if you went to a 34 or 36 mid.

You can get good quality, economical matched sets of Shimano rings in 26/36/48 for 104/64 cranks, and if the setup is agreeable than that represents a sweet spot option for performance and price. The Shimano Deore and Alivio level 32, 34, and 36t rings in steel are the best there are for people hanging out in those gears a lot for on-road use, and they're cheap too.

Most 3x9 mountain/hybrid drivetrains can handle a 22t jump in front and 11-34 or 11-36 in back. The exceptions are mostly very old now. The other piece to look at is if you made both sets of changes (34t or 36t mid ring in front, 34 or 36t big cog in back), can the RD total capacity and max cog size handle that and if so, does it still give you access to the climbing gears you want in back while in the mid ring.

Answer 2

I would suggest keeping the 32t middle chainring (replacing if worn) and using an 11-28 9-speed cassette to get the result you seek.

The chainring should have ramps to work with the other 22 and 44 tooth chainrings to enhance shifting performance. Trying a different chainring size could result in a loss of shifting performance.

Swapping in a 11-28 cassette is a simple task and will provide an additional cog to choose from in your preferred gear range. A 9-speed 11-28 is possibly set up as 11-12-13-14-16-18-21-24-28, which adds a 13 tooth cog in exchange for your 32 you lose. Make sure you verify the tooth options suit you for the 11-28 cassette you would obtain, as there can be variations in the actual tooth options in cassettes of the same (11-28) range.

Answer 3

You seem to be relying heavily upon 32t.

Why not just keep 11-28 and go 1x with 36t?

I had this exact setup for a year in a flat city like yours, and was very comfortable with close ratios and simplicity of having 1x.

You just need to buy a 36t narrow wide chainring, and remove all three, replace with 1x. Even 28t at back was enough for me on short but pretty high grades like 7 percent - and I was 45 then, very unfit...