Moving from 2×10 to 1×12: is it right for me?

Should I go from a 2x to a 1x drivetrain?

I’m a numbers guy, and a like a clean cockpit on a bicycle. Let’s see if upgrading makes sense for me, without penalizing my top speed or climbing ability when moving from 2×10 to 1×12.

Disclaimer: this is just to explore the ranges and I have ignored all the intricacies of swopping to a NW chainring and the need or not for a new XD driver body and whether it fits etc. First I want to see if the range make sense. Then we deal with the practical implementation.

My current MTB specs with the 2x drivetrain

I currently have a slightly sentimental 2015 Specialized EPIC comp MTB with a SRAM 2×10 drivetrain that it came with. Standard it was 24/36 up front and 11-36t at the back, but I have since changed the bog ring from a 36T to a 38T and didn’t even notice the difference while climbing. My favourite go-to gear on this years’ ABSA Cape EPIC was the 38T up front and the 3rd ring from the top at the back – great momentum and just enough pull.

Behind-the-scenes and the way I ride

I’m over 100kgs and very comfortable turning slower heavier gears as opposed to spinning, so the top end speed is important. At the same time, I love the current 2x solution where if you get around a corner and find yourself having to bail into a lower gear straight into a steep climb then it is available at the flick of a single lever as the front derailleur moves seamlessly from the bigger to the smaller chainring.

OUT WITH THE OLD: Current range with the 2×10 drivetrain

I’m really interested in only 2 numbers:

  • How fast can I go and
  • How easy can I climb.

How fast can I go now?

The former is found by taking the biggest chainring upfront (38T) and dividing into it the smallest gear on the cassette at the back (11t) – so 36/11 gives you a gear ratio of 3.45.

PS, using the gear ratio calculator you can instantly see a whole matrix that shows each and every gear ratio for your drivetrain setup. Give it a go and see all the details. There are other alternatives as well, and some with more detail, ie and Sheldon Brown’s Derailer Gear/Internal-Gear Calculator, but I prefer the simplicity from the first mentioned bikecalc.

How easy can I climb now?

The latter is found by taking the smallest chainring upfront (24T) and dividing into it the biggest gear on the cassette at the back (36t) – so 24/36 gives you a gear ratio of 0.67.

And here comes the disclaimer: Please note the lower isn’t always better here because you get to a point (especially in my case) where you don’t have enough momentum to go over the rocky climbs or lose your balance because you are going too slow. I like climbing the very steep sections slightly quicker and then taking a few pedal strokes as a breather after the summit.

Here are the gear ratios on the current 2x10 setup with 24/38T chainrings up front and a 11-36t cassette at the back
Here are the gear ratios on the current 2×10 setup with 24/38T chainrings up front and a 11-36t cassette at the back

IN WITH THE NEW: New range when moving to a 1×12 drivetrain

When I found a 1x upgrade kit promotional email from EVOBIKES in my inbox this morning I thought this is a great opportunity for this blog post. And let me make one thing very clear: I have no issues with the 2x setup and love the way it works but I do know that spares are becoming harder to come by) certainly none at a race like the EPIC) and I do like the cleaner cockpit of a 1x system. Just no batteries for the moment please 😊

The Sram NX Eagle Upgrade Kit (1×12) upgrade kit advertised is for a chain and shifter and derailleur only, so assuming I keep my 38T chainring (and I will be comparing it to the previous 36T as well to see the difference). The cassette is a 12-speed SRAM SX Eagle PG-1210 with a range of 11-50t. Now let’s compare and see if upgrading from 2×10 to 1×12 would make sense for me.

And here are the 1x12 details showing what the gear ratios would be with either a 36T or the current 38T chainring up front, mated to a 10-50t cassette at the back
And here are the 1×12 details showing what the gear ratios would be with either a 36T or the current 38T chainring up front, mated to a 10-50t cassette at the back

How fast would I be able to go?

With only a single chainring upfront, the calculation becomes even easier. The top speed would be the 38T upfront over the smallest ring on the cassette at the back of 10t to give a ratio of 3.8. Which exceeds the 3.45 from the current 2x drivetrain by about 10%, which means my top speed will increase by 10% and I like that! PS even with a 36T chainring my top end would increase from a ratio of 3.45 to 3.6 (marginally, by about 4%).

How easy would I be able to climb?

Now this is the kicker. And fortunately, I do not use my granny gear that much. But I must admit, on a smoother gravel surface, when the gradient is steep and the going is tough, it is a really nice-to-have, if only for knowing that it is there. But I must admit at the current 0.67 gear ratio there is very little power and it becomes a bit of a balancing act on the bike.

With the new 1x the easiest gear ratio moves to 38T upfront divided by the largest cog on the cassette of 50t at the back for a new gear ratio of 0.76. now that is a substantial difference, almost 12%. And even with the smaller 36T chainring it will still be a harder climbing gear by about 7%…

Will it be too much? Let’s see! On my current SRAM PG-1030 10SPD 11-36 cassette the gears are 11-13-15-17-19-22-25-28-32-36. And now for the good news: my favourite steep climbing gears on the current setup are the 28 and 32, ie the 2nd and 3rd from the top. Assuming I use the 2nd from the top as my new max, the gear ratio would be 24T over 32t which is 0.75 – and that is almost an exact match for the 38T over the 50t at 0.76.


For me then, upgrading on the next round is a now-brainer 😊

PS, what about my rear wheel?

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