Going 1x – derailleur qn

Been a while since I’ve done the maths on this, so would appreciate any real-world experience!

I’m finally switching my Cotic to 1×11 (from 3×9) gearing. I’ll probably just keep the middle chainring to start, so 32T at the front, 11-46 rear, at least to start. Most of the parts are pretty cheap, which helps; but the cheap XT rear mechs are GS (medium cage) – which normally I fan of, but amn’t sure it’ll work.

The XT GS 11spd mech apparently has a capacity of 39T, and a max front difference of 10T; but max rear sprocket of 46T.

– Am I right that max front difference is redundant as it’s only a single chainring?

– 39T capacity should be good for 11-50 cassette in theory, but does the max sprocket size (46T) trump that?

– my gut feeling is that 32/46 should be fine at the low end, but will I be wanting 32/50, realistically? If I’ve done the maths right, I’ve lost 2 ratios off the bottom of my 3×9 setup

Cheers

When talking 11 speed, GS mech works fine for the 11-46 ratio.

Note – Shimano 11-46 casette has an awful big gap at the top to the big sprocket, other options are much better.

The sram GX 10-45 gets you a bigger, and smoother spread of gears (and you can drop a chainring size), or the higher end sunrace 11-46 has a much, much nicer spread of ratios and is a really nice casette.

My old setup of this:https://sunrace.com/product/csmx8-eaz/

Plus M9000 XTR shifter and Mech is my favorite ever setup, and I sometimes wish I’d never upgraded to 12 speed!

NB for 29inch wheels then 32-46 is quite big, I’d suggest you want 30-46 or 28-46 if you can for anything hilly.

Fortunately I’m still on 26″ wheels!

I’m using an older hub, so the SRAM 10T sprocket may not fit(?), but thanks for the headsup on the Sunrace. Is it a decent cassette? (I’d be looking at Shimano SLX, for comparison)

Aiui the capacity is how much chain slack it can take up, the max sprocket is to do with actually being able to shift.

I know some of the older long cage Shimano mechs can happily handle the chain slack but struggle to change up on a big cassette. I’d think all 11 speed mechs should be ok as that was when 1x took over

i had no issues with my medium cage xt mech getting over a 51t sunrace cassette

If you want to go 50t, would probably be wise to get the Deore mech made for that… it works well.

Also, change the chainring when switching the cassette and chain, very much a false economy not to.

@nicko74 yes, the sunrace MX range casette linked is easily equivalent to Shimano XT in quality/weight but has the much better ratio spread. I’ve had tonnes of 11 speed stuff and this was my favourite Shimano HG fitment casette. Don’t mistake it for the budget sunrace option.

(forget the Sram if your on older wheels as you state).

32 t will be fine on 26″ wheels but you’ll want a narrow wide chainring to get the benefit, it’ll be dropping otherwise.

Deore 11 speed cassette and derailleur works a treat. You can use a 12 speed XT derailleur if you want.
I’d recommend a 34 chain ring as well on a 26er.

@kelvin

Also, change the chainring when switching the cassette and chain, very much a false economy not to.

Why is that?

The original chainring won’t be a N/W and it may be worn anyways.

Yeah, was looking it over yesterday and it’s looking a bit hooked. Plus it probably has ramps etc optimised for shifting, which I guess is the opposite of what one wants for 1x…

I’d recommend a 34 chain ring as well on a 26er.

Yeah? You’re thinking more about top end gears rather than bottom end, I guess?

With 32x 11-46, I reckon I’m losing the bottom 3 ratios from my current 3×9, which is fine as I never use them. And obviously the entire top 9 ratios, of which maybe 5-6 are not covered by the 32T chainring?

This is just from my experience, when I went from 3×9 to 1×10, even with a 11-40 cassette, 32 was too low.
I would whole heartedly recommend the Deore 11-51 for 11 speed. It lasts forever and is dirt cheap. The derailleur is also cheap and you can swap the jockey wheels for XT, which have bearings instead of bushings.
Oh, and XTR shifters are worth it if you can find one.

I think Shimano Cues has a 11-50T cassette option and the matched derailleur has the same capacity as your GS XT choice (39T) so presumably you’ll have no issues?