I’ve finally updated my gear rations spread sheet (almost 8 years later) to include 1x drivetrains. I also built it out for 2x drivetrains, but as 1x has become the defacto standard in the mountain bike industry, I’m going to skip the 2x’s for now. If anyone really wants to see the 2x spreadsheet, I’ll be happy to share it. Also, for the sake of brevity, I am focusing on 1×12 drivetrains only. If you want to see 1×11 or 1×10, I can share that as well.
Obviously the 1x spreadsheet is far simpler to view than the 3x. That said, lets jump in.
Columns A & B are inputs and their descriptors. A describes the data required, and B is the input field. Inputs are; tooth count of all 12 cassette cogs, chainring tooth count, crank arm length in mm, and wheel diameter (with tire, under load).
Columns D – I are the same as the 3x drivetrain sheet. Quickly, they are;
- Column D: Simple Gear Ratio
- Front chainring size (in teeth), divided by rear cassette cog size (in teeth).
- Column E: Gear Inches
- How a particular ratio equates to an old style high wheeler (penny-farthing) which were measured by the height of their front wheel.
- Column F: Inches of Development
- How far (in inches) you will travel along the ground in a given gear.
- Column G: Feet of Development
- How far (in feet) you will travel along the ground in a given gear.
- Column H: Sheldon Brown Method
- Sheldon Brown’s “radius ratio”
- Column I: Sequence
- Sequential order of gears. This is a hold over from my 3x sheet.
As you can see by comparing the two sheets, there is no way to get the same range from even a 1×12 as a 3×10, or even a 3×9. Your only adjustment is the change your chainring size and by doing so you will either sacrifice low end (climbing) or top end speed. That said, the tallest ratio on a 3×10 is really pretty theoretical. There are very few instances where you’re able to push a 4:1 ratio, unless you’re a pro athlete or on a long steep decent. And with the weight advantages of a 1x system (I shaved over a pound by converting one of my older bikes) I think the positives far outweigh the negatives.
- As I’ve already stated, there is a pretty significant weight savings by swapping over to a 1x system.
- By moving from a 3×9 to a 1×10, I saved 1.1lbs on my old Bullit. This includes removing 2 chainrings and bolts, front derailleur, shifter pod and cable and housing. This also includes the increase of 1 rear cog and, obviously, a thinner chain. This weight savings is NOT inclusive of changing crank arms to a 1x specific set and the removal of the bolt bosses.
- Better Chainline
- All gears are usable, you’re not carrying anything you won’t or can’t use. Therefore the chainline is better set to work across the entire rear cog set.
- Without having to deal with the front mech, you are less likely to have a missed shift, dropped chain, chain suck and can more than likely, get to the gear you want quicker and more accurately.
- No more dropped chains
- I mentioned this above, but it bears further mention. By losing additional chainrings, we are now able to run Narrow/Wide chainrings which substantially reduce dropped chains.
The only real negative that I can think of (after being on 1×10 and 1×11 systems for over 3 years now), is really more of a perception, which is the reduced range of gears available. With the correct chainring for your riding style and terrain, you end up with 11 or 12 very usable gears. With a 1×11 on my Nomad, I can climb nearly anything here in the Santa Monica Mountains, and I can still hit the high 30s and (very) low 40s if I really try. And thats running out of leg, not gear.