[Closed] 12 speed and chainring size?

Same wheel size as the old bike on the new build?

http://www.gear-calculator.com/?GR=DERS&KB=24

Put your numbers into the compare function on this and it will tell you the difference between your current and new setups.

50x34 will give you a significantly easier bottom gear than 42x32, all other things being equal, I would have thought.

I have a feeling 34t will be too high but 30t too low? Am I best to stick to a 32t?

Build it and ride it, the new setup will have a lower easy gear and a harder top end so more range either side of your current setup.

Going from 27.5 to a gnarpoon 29er.

Top end was fine on 42x32, sometimes span out. Will give it  go on 34t then. £70 for a chainring!

Blimey, I had a look at that calculator gearing link on a moby and well f me that is tricky to use and tge display is simply aweful.

I at the same time too am unfamiliar. It looked as though I’ll have 458% gear ratio running a 34T ring with 11-50T on a 29er.

but unsure tbh and well I think I know what to expect but feel too that I should be on a 32T for the 29er.

but yeah don’t feel the need to stomach £50 on a new ring

Full suspension? It might be that the linkage is optimised around a particular ring size, or that you can tune to your preference slightly by tweaking ring size.

but yeah don’t feel the need to stomach £50 on a new ring

Any 11sp ring will be fine

On a 1x system you'll get the same gear range for any given cassette no matter what size chainring you are using.

Are you running out of gears at either end of your current setup? If you need more at the bottom end then stick with 32T, if at both ends then 34T. 30T will give you lots more at the bottom end but lose you some range at the top end - roughly making the new top equivalent to the 11T cog on your current cassette.

Any 11sp ring will be fine

Yeah shoulda said circa £50 on another Renthal.

or a cheapy SS tatt that wouldn’t suffice on my build muwhahaha

Just took a look and that's pretty much the standard gear calc although someone seems to have hacked the drop downs a bit since I last saw it.  It turns up with many different names in different places.  I just hope the guy that originally front it is happy with this!

Anyhoo.  Plugging a 32T 10-42 in and comparing to a 34T 10-50, the 10-50 has more bottom (20 gear inches vs around 22)  and more top too.  If you already found 10-42 hard work then maybe moving down for a bigger bailout would make sense but as it is, you'll not be losing out at all.  Frame pending, you could probably just about squeeze a 36T in there without climbing getting any harder than 11sp SRAM.

So going up to a 34t with 10-50 I’d be less likely to spin out on the top end and have a bit more lower down.

Sounds better all round then. Thanks everyone, I’ll give the 34t a go then.

Have you entered both configurations in the gear calc? It's the only way to eliminate guess work, it's a great tool.

Myself and one of my pretty fit cycling pals have both swapped from 32 tooth front rings to 30 with a 10-50 casette on the back , both on 29ers . I managed with the 32 but felt like I was in the 50 more often than I wanted to be . The 30 oval feels much better to me and I don't find myself spinning out either . I live in the Isle of Man and it's pretty hilly .

I don't really get on with gear inches and personally prefer basic maffs

32:10 - 1 turn of the front ring turns back wheel 3.2 times

32:42 - 1 turn of front ring turns back wheel 0.76 times

34:10 -  1 turn of the front ring turns back wheel 3.4 times (ie a bit faster)

34:50  - 1 turn of front ring turns back wheel 0.68 times (ie a fair bit lower / easier)

personally i use 32 on a 29'er and works fine, never spin out and a nice bail out gear