You may recall that I busted my front derailleur the other day and now have a 1X Bianchi whether I like it or not. Well, I like it because I’ve been thinking about having one for years, but a 50-tooth chainring with 11/27 cassette is not going to get me up many hills around here without blowing out a kneecap.
So I’ve been forced to do a little math. Luckily I was drinking a beer at the same time or it could have ended badly. As I write these words, I think I understand what I need to do. Don’t test me tomorrow.
Firstly, I determined my current ‘range’. My biggest gear ratio is 50/11, which comes out to 4.54. My smallest is 34/27, so that’s 1.26. The first number over the second gives me my ‘range’: 3.6.
This is what I would be looking for in top and bottom gears if I needed to replicate my 2X set-up. With me?
But really, how often do I use my 50/11 or even the 50/12? Not much is the answer. I do, however, find myself in the 27 plenty of times so I’m keeping that. Therefore, I can effectively shorten my range by deciding that I don’t need the two biggest gears.
So, now we are left with a virtual set-up of 50/13 (3.85) and 34/27 (still 1.26). The range I could live with is now 3.05.
There’s a whole section of the article I’ve just used that I haven’t told you about, but it involves cassettes and their ‘ranges’. An 11-34 cassette just happens to have a range of 3.09, which is pretty close to what I need…so there you go.
Now that I know what cassette I need on the back of my future 1X, I have to determine the size of the chainring on the front. For that I need to know the biggest gear that I want, which was 50/13, or 3.85, multiplied by 11, the smallest ring on the cassette. 3.85 x 11 is 42.
So, if my poor mathematics skills haven’t failed me totally, what I might be looking for is a 42 chainring with 11-34 on the back and Bob’s your uncle.
It goes without saying that I’ve got no clue how to accomplish this, but I’ve got friends with technical smarts and the internet is never far away. If nothing else, it’ll be a nice confinement project.