Keywords: all you need to know,assembly,installation,one+,u.p.

Calculating your single chainring (1x) gears

Gerard Vroomen - 18-Nov-2016
I often get questions about what gears to pick when going from 2x to 1x drivetrains. Here is my advice:

Basic approach
The easiest way would be to install a 1x drivetrain with the same gear range as your old 2x setup. To do that, you calculate your maximum gear ratio, your minimum gear ratio and then divide one by the other. Say you have a road bike (it works the same for MTB obviously) with a 53-39 crank and an 11-28 cassette. This means your biggest gear is 53/11=4.82 and your smallest gear is 39/28=1.39 and thus the range is 4.82/1.39=3.47. 

Since clearly all this range has to come from your cassette on a 1x drivetrain you need to find a cassette close to that range. Here are the ranges for the most common cassettes that you might want to consider for 1x setups:

11-36=3.27 range (Shimano or SRAM)

11-40=3.64 range (Shimano)

11-42=3.82 range (Shimano)

11-46=4.18 range (Shimano)

10-42=4.20 range (SRAM)

9-44= 4.89 range (e13)

10-50=5.00 (SRAM)

So in this example, the 11-40 is closest, a bit more range but probably the best choice (or if you think you can do with a bit less range, you could go with the 11-36). Within reason, you can mix these cassettes on drivetrains of another brand, as long as the range of the derailleur is OK. The exception is the SRAM 10-50 cassette which only works with SRAM Eagle. And the 11-46t cassette only works with Shinano XTR Di2. Note: you do also have to take into account that a Shimano MTB cassette uses a different cassette body on the wheel than their road cassette. Not a huge issue but something to keep in mind when picking the wheels.

So with the cassette picked, you then choose the chainring that gives you the same biggest and smallest gear, which in this case is the 53t ring.

A better way
The above way is the easy way, but I think there is a better way. The problem with the above method is that the steps between gears may be a bit bigger than you'd like. So instead of trying to copy your 2x range, I think it's worthwhile to first ask yourself: What gears do I really need? There are two sides to this:
  1. How often am I in my biggest gear (so 53/11 in the example) and even the second-biggest gear (53/12)? It's easy to figure out, just keep a close eye on it during your rides. There are many people who rarely use their biggest gear, so why hang on to it and "stretch" your 1x range at the expense of bigger gaps between the gears?

    Note that I am not suggesting to only lose the gear you NEVER use, but even a gear you use once in a blue moon, do you really need it? Can you not simply roll out instead of still pedalling on a 65kmh descent? Also realise that the answer to this question depends on the type of bike. Pedalling along at 65kmh may make more sense on a road bike on the road than on an U.P. on treacherous trails.

    And to those people who insist they need a 53/11 as their biggest gear, really? You need the same gear as Froome and Sagan? Unless you are a pro, it's unlikely you'll TT as fast, climb as fast or descend as fast. In fact, within 10% of them would already be very impressive, so that would be a 48/11 or 53/12 as biggest gear. And yes, I know the comparison doesn't fly 100% but I just want you to think about what you really, realistically need.

  2. Do I need my smallest gear (or alternatively, do I need something smaller than my smallest gear)? In particular when switching from a road bike to the U.P., you may need some extra small gears to ride the crazy terrain you're dreaming about. The easiest way to figure this out is to get a feel for "I would love to have one smaller gear, or two smaller gears". It's not an exact science, but an approximation.
Then look at the line of numbers below, pick the smallest and biggest cog of your current cassette, and then move up and down based on the cogs you decided at point #1 and #2 above that you don't need. Don't be concerned with the numbers in-between the biggest and smallest, the line below is not an approximation of your cassette, only the smallers and biggest cog matter:


So back to our original example, if your cassette was 11-28 on your 2x setup and you decide you rarely use the bottom two gears but need one extra at the top, then the 11 becomes a 13 and the 28 becomes a 32.

So now you have "virtual" 2x setup with 53/13=4.08 as the biggest and 39/32=1.22 as the smallest gear for a range of 4.08/1.22=3.34. Looking back at the cassettes, that means you have a choice: either go with the 11-36 and not quite get the biggest or smallest gear you wanted, or go with the 11-40 and get more than you really need.

The second approach works the best for people who have quite a big range on their 2x setup, so the above is not the best example.

Take for example a 50-34 compact crank with an 11-32 cassette, meaning 50/11=4.55 for the biggest and 34/32=1.06 for the smallest gear. If you don't need the two smallest cogs (biggest gear) but would like one extra small gear, then your 11-36 cassette becomes a virtual 13-36 cassette. Now your gears are 50/13=3.85 and 34/36=0.94 respectively, for a range of 3.85/0.94=4.10, so very close to the 11-46 and 10-42 cassettes (they are so close, you can really let personal preference for SRAM or Shimano decide). Say you choose SRAM's 10-42, then the biggest gear you wanted was 3.85, so the chainring you need to go with this is 10*3.85 so a 38.5t ring. Since with 1x, rings have to be even-numbered, the 38t makes sense.

For extra credit: If you want to go all out, you can now also do the math on both the chainring below and above the theoretical optimum, so the 38t and the 40t ring. You can calculate the biggest and smallest gear (in case that would be 38/10=3.80 and 38/42=0.90 with the smaller ring and 40/10=4.00 and 40/42=0.95 respectively) and see which of those options you like best? A bit more top end gear compared to what you first thought at the expense of a bit of your smallest gear end, or the reverse.

I hope this helps, please let me know if anything is unclear in this or if you have any other comments, questions, etc.

Comments & Questions

Thank for this. I have been thinking about going from 2x to 1x on my touring/railtrail/commuting bike
Post #1 of 91. Posted by Tom Moore on 18-Nov-2016 12:35:24 GMT in reply to blog [0<--1186]
ThankS for the information. Would you be OK with me sharing on my Instagram and facebook pages? @kbwheels
Post #2 of 91. Posted by CASEY FORD on 18-Nov-2016 12:50:11 GMT in reply to blog [0<--1187]
Of course.
Post #4 of 91. Posted by Gerard Vroomen on 18-Nov-2016 13:06:52 GMT in reply to post #2 [1187<--1189]
amazing, thanks, you must have read my mind!
Post #3 of 91. Posted by GT on 18-Nov-2016 12:57:35 GMT in reply to blog [0<--1188]
Great article, thanks!
I totally agree on your point about questioning how often the higher gears actually get used. I grew up with 52x14 or 13 top gear on a 5 or 6 speed cassette and even then didn't use them very much. I just don't understand the recent trend for adding to the number of ratios but just adding a smaller cog, these days most cassettes start with a 11t but I prefer a high cadence and rarely use anything higher than 50x14. So my road bikes have 50-34 x 11-28 or 32, a load of overlaps and three high gears I never or rarely use.
With treaded tyres, I'm going a bit slower on road and likely to encounter off-road climbs that are steeper and with less traction than I'll see on road.
When I built my Open UP, I went with a single 36t front and a 11-40 rear. I don't miss the top end, can still pedal at 50+ km/h, beyond that I'll coast. I haven't run out of gears at the bottom end yet and the gaps are fine. I'm really pleased with the setup, it's simple and it works for me. I'm thinking I might go 1x11 on one of my road bikes as a trial, I think 40x11-40 would be about right.
Post #5 of 91. Posted by Geraint on 18-Nov-2016 13:36:32 GMT in reply to blog [0<--1190]
Yep, your experience is pretty similar to me. I also often ride with an 11-40 cassette (and a 34t ring). And when it goes extreme, there is always the 9-44!
Post #19 of 91. Posted by Gerard Vroomen on 19-Nov-2016 06:57:40 GMT in reply to post #5 [1190<--1204]
Very helpful post Gerard.
Post #6 of 91. Posted by Pepe on 18-Nov-2016 13:41:10 GMT in reply to blog [0<--1191]
For a rider like myself who really values a more gradual ramp between gears, I've gone back and forth on the decision to go 1x. I'm leaning towards keeping a 2x with a very wide range for the following reasons:
- weight savings: is it really that substantial a difference?
- simplicity: OK, but I would not trade this for a smoother rate of development
- I'll ride at least 70% road on undulating terrain
- off road performance: I've heard chain slack is a problem, even with a clutch.

Interested to hear more thoughts on they 'why' one should switch vs. 'how'.
Post #7 of 91. Posted by Frank on 18-Nov-2016 14:03:50 GMT in reply to blog [0<--1192]
For sure it's not for everyone, the smallest gaps between gears (providing you don't mind double-shifting now and then) is with a 2x. 1x simply offers a lower weight, less complexity, an easier clean-up and fewer parts that can fail on long trips. As for chain suck, I don't think that happens more with 1x than with 2x presuming both are set up equally. Personally (but that's just an n=1 of course) I've never experienced it on my 1x and I have on my 2x, but of course over my life I have more miles on 2x too so that's not fair.
Post #20 of 91. Posted by Gerard Vroomen on 19-Nov-2016 06:59:59 GMT in reply to post #7 [1192<--1205]
I looked at it like this: riding 50-34 x 11-32 on road, going up through the gears I use 34 x 32, 28, 25, 22, then 50 x 28, 25, 22, 20, 18, 16, 14. There are half steps theoretically available through the mid range with this setup but I personally don't bother changing at the front once I'm past the point of overlap. My practical use of this setup therefore gives me 11 gears for a range (in gear inches) of 28.6 through to 96.2.

With 36 x 11-40 I get 11 useable gears from 24.2 to 88.2, this is 'one gear lower' through the range, which works well on a bike for mixed surfaces for the reasons stated above, and gives about the same size gaps as the 2x11.

For me, the 'why' was to get a simpler system and a lower bottom gear with road chainline and more flexibility than is available with road cassettes. I thought a road setup on this type of bike was too inflexible, the lowest I could go with Ultegra would be 34x32. The MTB rear mech will take a bigger cassette if I ever feel the need, and I can swap chainrings to increase ratios too.

I didn't care about weight savings particularly, and I haven't had any chainslap problems with the clutch rear mech.

My 2p, YMMV, etc etc.
Post #8 of 91. Posted by Geraint on 18-Nov-2016 15:05:54 GMT in reply to blog [0<--1193]
Thanks, those are all reasonable justifications and I'll continue to revisit the pros and cons. My intent was to do a 50/34 11-36 setup: From a bit of searching, I was able to understand that many have had success with this setup with shimano's long cage RD.
Post #9 of 91. Posted by frank on 18-Nov-2016 15:11:33 GMT in reply to post #8 [1193<--1194]
You're welcome. I forgot to mention that you can do 11-36 (and claimed 11-40) with Ultegra GS mech and a Wolf Tooth roadlink which moves the mech away from the cassette to give more clearance between the upper mech pulley and the largest cog(s). The SRAM 11-36 needs a 'road 11sp' disc hub though which may or may not be an issue for you, the Shimano XT/XTR 11-40 can be used with a MTB 10sp hub.
Post #11 of 91. Posted by Geraint on 18-Nov-2016 15:18:35 GMT in reply to post #9 [1194<--1196]
There seems to be several reports of successful setups with 11-36/GS without the Wolf Tooth... but now, I'm really reconsidering a one by!
Post #12 of 91. Posted by frank on 18-Nov-2016 15:27:03 GMT in reply to post #11 [1196<--1197]
You certainly can use an 11-40 cassette with a long-cage Ultegra GS, and a Wolf Road Link! I've done many happy kilometres like this as my set up (albeit with a 50-34 front).
Given the intended purpose of the U.P., I'm actually a bit surprised that the supplied mech hanger isn't longer, so that it can replicate the function of the road link 'out of the box'?? ... maybe this is something that OPEN are considering for the UP2 ...???
Post #13 of 91. Posted by Stuart on 18-Nov-2016 16:01:19 GMT in reply to post #12 [1197<--1198]
hear hear..
The longer hanger is a must. Go anywhere, for that I need a 11-40 with a 33 - 50 in front. (33?? yes it exists.. and trust me on sustained dolimes roads over 20% that is really nice to have) 1x = nuts.. I'd really love a triple with a narrow q ratio.
Could not care less about the weight penalty. Never walking is the adagio..
Post #14 of 91. Posted by Youp on 18-Nov-2016 16:23:45 GMT in reply to post #13 [1198<--1199]
Not quite sure why 1x is nuts just because you have 20% grades. Your smallest gear is 33x40, mine is 34x40 on my 700c wheels and 34x44 on my 650b, so 6% smaller than yours?

For sure 1X isn't for everyone but it's not because you can't get a small enough gear.
Post #27 of 91. Posted by Gerard Vroomen on 20-Nov-2016 04:58:46 GMT in reply to post #14 [1199<--1213]
Sheldon Brown has extensive thoughts and done research on this very subject.
also have to be very mindful of crank length and wheel size. 40 crankset with a 10-42 cassette seems to be the popular 1x system, people seem to gravitate and praise this range. It fails however in that you never know what tires and cranks they run with this set up. Ratios wise it ends up being for every increase or decrease of 7.5 mm of crank length, you will need a 2 tooth increase or decrease on your crank. A 162.5 crank length with a 38 tooth crankset will feel the same as a 170 crank and 40 tooth. Its also pretty close for every 3mm increase in tire size, it will pretty close feel like and extra 2 teeth on your crankset.
Post #10 of 91. Posted by SEAN M on 18-Nov-2016 15:13:47 GMT in reply to blog [0<--1195]
I don't know that a 40t chainring with a 10-42 cassette is popular, I see almost everything out there, especially for the chainring. Why would the 40t be good for many people? If I'm 10% worse than you, I should ride a 36t if you're on a 40t. For the cassettes I also see a lot of variation, and actually a lot of 11-40's for people who like smaller steps and don't care too much about their biggest gear (since it's often combined with a smaller front ring) and then I see a lot of 9-44 lately for people who want "everything".

As for crank length, it does not affect the gear ratios. It affects what Sheldon Brown calls the gain ratio but it is debatable whether that helps you here or not. For sure with the bigger arm on the crank you can push a bigger gear and the gain ratio takes this into account, but if you're already at a minimal rpm in your smallest gear, say 40rpm clawing up a hill, can you really afford to go at 38rpm? Maybe you can develop to force for it, but you may be stuck in the dead zone of your crank rotation for too long to keep that going, and crank length won't help you with that. So that's something to keep in mind.

As for tire size, the effect is much smaller than you indicate. Not sure if you mean 3mm in extra width or extra diameter but roughly every mm extra in tire width creates 1.5mm extra in tire diameter or about 0.2% extra diameter. That also means there is 0.2% extra rollout of that tire. If we take the whole range from a 21mm to a 40mm 700c tire, the rollout increases by 3.8% or "1.5 teeth" on a 40 tooth ring. So for the whole range from skinny road tire to bulky knobby gravel tire, the effect is less than 2 teeth.
Post #21 of 91. Posted by Gerard Vroomen on 19-Nov-2016 07:15:28 GMT in reply to post #10 [1195<--1206]
I have a 40t chainring with a 10-42 cassette and find is perfect for the riding I do, I go up some pretty steep off road climbs, only one of them needs the 42t sprocket!
Post #38 of 91. Posted by Robin on 24-Nov-2016 17:40:11 GMT in reply to post #10 [1195<--1236]
anyone have thoughts / suggestions on chain line?
Post #15 of 91. Posted by GT on 18-Nov-2016 19:23:41 GMT in reply to blog [0<--1200]
I have many thoughts, but what specifically do you want to know?
Post #22 of 91. Posted by Gerard Vroomen on 19-Nov-2016 07:16:00 GMT in reply to post #15 [1200<--1207]
Must have read my mind Gerad.
I love my "MTB"-U.P. With 32x10-42 (SRAM XX) on 2.1 tires. But now I want to be able to switch to the other extreme, the "Road"-U.P. on 28 mm tires. My initial thought was your first approach wich resulted in a theoretical 42x10-42. Unfortunately there is no information out there on a extreme Road setup in regards to gears and ride quality. Have you ever build and riden a road U.P. and could give some insight?
The intention is to switch between MTB and Road setup fairly quickly by changing wheels, chairing and chain. Intention for the road setup is to have a road bike for the Alps, especially with bad weather conditions.
BTW did I mention I love my MTB U.P.?
Post #16 of 91. Posted by Daniel on 19-Nov-2016 01:22:02 GMT in reply to blog [0<--1201]
Good question. I'll ponder this a bit and put it in a new blog.
Post #23 of 91. Posted by Gerard Vroomen on 19-Nov-2016 07:17:12 GMT in reply to post #16 [1201<--1208]
Thank you.
Post #28 of 91. Posted by Dan on 20-Nov-2016 10:52:44 GMT in reply to post #23 [1208<--1214]
I build my UP to be great on both tarmac, gravel AND mtb single-track. And therefore chose 2x, which actually works as a "double 1x": In the woods I almost only use the 34t chainring, and on the road almost only the 46t chainring.
It's a reasonably priced and "dirty" mix: Shimano road gear/hydraulic brake levers, Ultegra front derailleur, BB/cranks (Q factor!) and 46/34 chainrings, XT 11sp rear derailleur (the clutch!) and SRAM XX1 (low weight!) 10-42 cassette. To improve compatibility; WolfTooth Tanpan and GoatLink.
And yes, I have both 650B and 700 wheelsets, in order to take full advantage of the UP design.
Post #33 of 91. Posted by Bengan on 22-Nov-2016 15:53:33 GMT in reply to post #28 [1214<--1229]
The concept of double 1x sounds interresting in theory but what i love about 1x is the clean simple look and functioning. So to have one ring and a deraileur that i will not need on every single ride is in stark contrast to this. I rather switch the chainring/ wheels before going road/MTB and stay with the clean look. It seems more road build specific UPs are showing up in the Showcase...
Post #36 of 91. Posted by Dan on 24-Nov-2016 16:05:01 GMT in reply to post #33 [1229<--1234]
contemplating a Bokeh (sorry Gerard) build with Shimano hydro Di2 STI's & Easton crank with cinch system & Deore XT rear derailleur & a couple of missing link chains & a couple of wheelsets & the E-tube app, that should do imho, the trick? fast changing of chainring, wheels+cassette and super-easy adjusting of your gearing.
Post #40 of 91. Posted by hans on 01-Dec-2016 17:58:05 GMT in reply to post #16 [1201<--1243]
Yes, or if you pick the rings and cassettes cleverly, you may even get away with one chain length.
Post #44 of 91. Posted by Gerard Vroomen on 04-Dec-2016 16:09:20 GMT in reply to post #40 [1243<--1248]
I rode both the Bokeh and the UP same day. Had a great chat with Dom Mason that day as well. Both have pluses and minuses but I went for the UP. Mason pluses for me were better rear clearance, flat mount discs which makes it more future proof, and I really loved the parallax fork. Dom has put a huge amount of thought into the smallest details. But the feel of the alloy bike just wasn't the same and it didn't feel as fast as the UP. On the OPEN I preferred the speed, the feel, the weight, and the agility, it's more flickable and felt better in turns. I have ultegra Di2 on my open, novatec CXD tubeless rims, and zipp bars and finishing kit. Having ridden the UP now for two months I'm very happy with my choice, but slightly unimpressed by the durability of the paint finish, already got a few chips on it, and black carbon shows up a lot through the orange. Looking at having it repainted this summer in matt black but keeping the orange on inside of chainstays and fork. Might have a chat with Dom about a parallax fork for it, or possibly a lauf. Both are awesome bikes, and both developed at same time, so interesting to see how similar they turned out. Bokeh Ti looks truly stunning, a bike for life. One thing I did notice is if you look around the south east coast of the UK you can actually get a fully built UP with ultegra Di2 for cheaper than a built bokeh with Di2, which I did find surprising.
Post #47 of 91. Posted by Pancho on 27-Dec-2016 12:00:17 GMT in reply to post #40 [1243<--1279]
Hi Pancho, thanks for the feedback. The paint is something that has our constant attention, but after 20 years in the bike industry across many companies, my experience is that it's something that keeps popping up at the most unexpected of times.

I can definitely recommend the Lauf, there is also a custom version with matching orange color available. Don't know the parallax fork. As for the timing of the two frames, the UP pre-dates it by about 2 years on the market, and the development started 2 years before that. But we're happy to see others follow the trend, it's the future!
Post #48 of 91. Posted by Gerard Vroomen on 28-Dec-2016 06:04:49 GMT in reply to post #47 [1279<--1280]
Thank you
Post #17 of 91. Posted by Zuky on 19-Nov-2016 01:53:17 GMT in reply to blog [0<--1202]
Great post very useful for understanding the real combo of gear ratio...
Post #18 of 91. Posted by Stefano Fabrizi on 19-Nov-2016 06:24:01 GMT in reply to blog [0<--1203]
I use right now 12-27 9 speed cassette with 22-32-44 ring in my 26” mtb. I want to switch to sram eagle and 29”. I think the sheldom brown gear calculator is a much easier way to calculate equivalent gears, comparing distance made per pedal walk. In the Sheldon Brown calculator you can even select tires size into the equation. With a pen and paper, it’s just a mater of comparing the numbers, and choosing the correct front ring. I will go for a 34 I think. Only problem will be the huge steps in gears, compared to my awesome 9 speed dura ace titanium cassete, and the fact that current cassettes last as much as a pair of tires, and a new eagle cassette is 300€… Hohohoho… Capitalism is bigger than ever!
Post #24 of 91. Posted by Weed farmer on 19-Nov-2016 10:07:27 GMT in reply to blog [0<--1209]
Of course a calculator is easier, but the reason to do it by hand and the reason for the post is to create understanding. It's like the difference between studying for knowledge and studying for the test. Both can be fine, although I hope my doctor studied for knowledge.

And of course a calculator doesn't tell you how to think about the gears you have vs the ones you need, etc, but if the calculator works for you, great. To each their own.
Post #25 of 91. Posted by Gerard Vroomen on 19-Nov-2016 10:57:42 GMT in reply to post #24 [1209<--1210]
BTW, I will assume you're also switching to a different wheel size, otherwise that 34t ring is giving you nowhere near the same gear inches as you have now?
Post #26 of 91. Posted by Gerard Vroomen on 19-Nov-2016 11:00:44 GMT in reply to post #24 [1209<--1211]
Yes, I am cahnging wheel size and tire width, and the sheldon brown calculator will tell me exactly the equivalent gears I look for in x1, for any wheel size and tize size.

Yes, knowledge is fine, but after 20 years of riding and tinkering, I control that knowledge, I want a calculator to tell me preciselly the differences, cold as numbers.

BTW, I know 1x is a shit decision, 300€ per cassette every 5000 kilometers is a joke, but for rich customers who buy open cyles, or for people who is rich but don't ride their bikes, will be no problem. I´m looking forward to join that group of people who are rich, and have a center of gravity much closer to the rear wheel, the dentists group!!
Post #29 of 91. Posted by Weed farmer on 20-Nov-2016 12:39:30 GMT in reply to post #26 [1211<--1215]
Sorry, you decided you want to switch to Eagle even though you know it's a shit decision? Yes, sounds like you're in control of the knowledge. And you clearly have no knowledge about our customers. Anyway, whatever works for you, enjoy the rides.
Post #30 of 91. Posted by Gerard Vroomen on 21-Nov-2016 09:54:51 GMT in reply to post #29 [1215<--1225]
I´m a 1x user and I´m very happy with it !
I use it with my CX bike, my TT bike, my Gravel Bike and also wity my road bike. Now I have a project of a road disc bike and the problem I find is that most of the "road disc hubs" are using a MTB hub O.L.D dimmensions and they are not the same... That would not be a problem for a bike like the OPEN UP because of the 420mm chainstays, but for a 405mm road disc bike chainstays it is a problem in chainline.
For "on-road" I don´t like to use my biggest and not even the my second-biggest cog for efficiency issues, so I have a big chainring to do not cross the chain very much. If I´m going to ride in a epic rout with a lot of long and step climbs I change the chainring. But If I´m riding flat I like my 1x setup with 54t chainring :)
Post #31 of 91. Posted by Andres Diaz on 21-Nov-2016 13:27:47 GMT in reply to blog [0<--1226]
Actually the problem is not that big. If you use a true road crank, just use a 2x crank and put a FLAT (not an offset) single chainring (for example Wolf Tooth) on the OUTER ring position. Then you have your MTB chainline. And the newer 1x cranks like the new Force 1 basically line up with a MTB cassette position right out of the box with a 45.5mm chainline instead of the regular road chainline of 43.5mm.
Post #32 of 91. Posted by Gerard Vroomen on 22-Nov-2016 03:48:37 GMT in reply to post #31 [1226<--1227]
Hello Gerard.
i wanna ask you, i currently using 1x11 ;10-42 with 34t chainring.
and thinking to go back to 1x10 ; 10-38 with 32t chainring. what's the range difference between these two?
Post #34 of 91. Posted by Danpyo on 22-Nov-2016 20:20:53 GMT in reply to blog [0<--1231]
Well, the range is 3.8 vs 4.2, but of course where the gears lie is also different. These sorts of questions are easily checked with sheldon brown's calculator, the only area where that's not so handy is if you have the ratios and want to calculate which rings and cassette to achieve them with. Or you can just do it approximate and see that 2t less on a 32/34t ring is around 6% (2 of 33 equals 6 of 100). so all your gears at 6% smaller. But then your biggest cog is around 10% smaller so your smallest gear is around 10% bigger. And that works out to about 4% bigger in aggregate.
Post #35 of 91. Posted by Gerard Vroomen on 24-Nov-2016 05:07:58 GMT in reply to post #34 [1231<--1232]
Lots of talks, lots of useless math, since there is an easy way: http://ritzelre...
Post #37 of 91. Posted by Klettermax on 24-Nov-2016 17:11:08 GMT in reply to blog [0<--1235]
Yeah, math is useless. Takes 20 seconds to calculate your gears and understand what you're doing. The calculators all take longer because you need to use trial and error. Ride on!
Post #39 of 91. Posted by Gerard Vroomen on 26-Nov-2016 16:22:24 GMT in reply to post #37 [1235<--1238]
Thank you for the blog. I found it informative. My 2x setup is 5.15 which works really good for me, but I'm thinking about a 1x changeover.
One thing I couldn't pass up. 39 ÷ 28 = 1.39 So instead of a 3.60 number, it's a 3.47 It's a small thing, but it does change things. ??????
Post #41 of 91. Posted by giantkiller on 03-Dec-2016 19:00:31 GMT in reply to blog [0<--1244]
The question marks were supposed to be smiley faces.
Post #42 of 91. Posted by giantkiller on 03-Dec-2016 19:01:52 GMT in reply to post #41 [1244<--1245]
Noted! :-)
Post #45 of 91. Posted by Gerard Vroomen on 04-Dec-2016 16:09:44 GMT in reply to post #42 [1245<--1249]
You're absolutely right. I fixed it.
Post #43 of 91. Posted by Gerard Vroomen on 04-Dec-2016 16:08:10 GMT in reply to post #41 [1244<--1247]
I'm running 2x at front so possibly not best place to post this. But will the UP take a rotor inpower 3D MAS crankset? I'm missing my cadence sensor due to clearance so the inpower looks a suitable alternative. Also thinking of custom painting my UP after winter, do you supply decals and what do I do about the serial number sticker??
Appreciate your time to answer both questions and happy new year.
Post #46 of 91. Posted by Pancho on 27-Dec-2016 11:50:48 GMT in reply to post #43 [1247<--1278]
In general power cranks where nothing sticks out on the inside of the crank, and which are designed for BB385EVO, works. Rotor has such a powermeter, just make sure you get the right BB version.
Post #49 of 91. Posted by Gerard Vroomen on 28-Dec-2016 06:06:13 GMT in reply to post #46 [1278<--1281]
Could you expand on 'the right BB version'. I was looking at 30mm BB386EVO, not BBRight. Also the decals and serial number question regarding respray?
Post #50 of 91. Posted by Pancho on 28-Dec-2016 11:56:01 GMT in reply to post #49 [1281<--1285]
I have a Rotor Inpower 3D+ crankset on my UP and it works perfectly. It has a standard 5-arm spider not the MAS, and a single ring. BB is a Chris King PF30.
There are pics of my bike in the gallery.
I'm not sure there are different BB versions of the Rotor Inpower cranksets, as far as I know they all use a 30mm axle. There is a preload adjuster/spacer on the axle which allows some adjustment for small variations in BB width.
I had my UP painted 'BoB' and got the painter to mask off the serial number decal.
Post #51 of 91. Posted by Geraint on 11-Jan-2017 14:48:38 GMT in reply to post #50 [1285<--1337]
Hi I think I saw on tour site that the CX Gravel bike can fit some SRAM gears and cranks that are MTB specific just wondered if you can fit XX1 11 speed and alternatively Eagle 1x12
Post #52 of 91. Posted by Jon Birkett on 16-Jan-2017 11:26:24 GMT in reply to blog [0<--1352]
Hi Jon, you can fit the SRAM 10-42 XX1 cassette in combination with a SRAM Force 1 (or similar) long cage rear derailleur and road shifters. For the cranks, I would recommend staying with the road cranks because of the narrower Q factor, it just rides much better. Eagle 1x12 does not work with any road set-up.
Post #53 of 91. Posted by Gerard Vroomen on 17-Jan-2017 14:57:09 GMT in reply to post #52 [1352<--1362]
Hi Gerad,

same thoughts also from me. Currently I have a 2x10 setup (34/50 + 11/28). This is my first road bike/setup. After some years I know what could be better, but also what must be the same:
- one additional climbing gear (I have a high cadence)
- same gears between 25-35km/h at 90+ cadence

Best setup for me is ... 1x12!

have done 1x11 calculations for hours, but every calculation hurt my gears between 25-30 km/h or doesn't add a climbing gear.

Hope that SRAM isn't that slow to bring 1x12 to road bikes! And hopefully it's possible to test 3T Exploro in south of Germany (near Augsburg) sometimes. This bike feels like it's "my" bike, but want to test drive like every car buyer also do.
Post #54 of 91. Posted by Helmut on 13-Feb-2017 16:31:35 GMT in reply to blog [0<--1465]

I have recently upgraded from xx1 10-42 with a 32t front blade which was magic to the eagle Xx1 with a 34t front blade - reason for upgrade was that I needed a additional bigger blade - would have liked a 44 - all being said - I have the eagle and am attempting to get the same ratios as my 11spd just with the additional 50 blade - I find the 34t ratio to in between and was wondering if the 36t front blade would be the better option ... can you help?
Post #55 of 91. Posted by Garth Briggs on 18-Mar-2017 11:49:32 GMT in reply to blog [0<--2606]
If you want the same as before with just the addition of the 50t, why don't you stick with the 32t front ring? Then you still have 32x10 as the biggest gear, you have all the same eleven cogs from your XX1 10-42 and then you have the extra 50t smallest gear? Or maybe I misunderstand what you are trying to do?
Post #56 of 91. Posted by Gerard Vroomen on 18-Mar-2017 14:01:41 GMT in reply to post #55 [2606<--2608]

I am in Chicago, and Trek of Highland Park has UPPERs with the right fit for me. But this will be both a cross and gravel/adventure bike for me, so must cover a lot of terrain. My current cross bike is SRAM Red with a 46/36 front and 11/26 cassette. What would give me the same range in SRAM Force 1X?
Post #57 of 91. Posted by Cal Brown on 01-May-2017 22:52:17 GMT in reply to blog [0<--3829]
For example a 46t front ring and an 11-32 cassette is almost the same (an 11-33 cassette would be even closer but those can be hard to find :-). Of course if you would rather have a slightly bigger range you could go with an 11-36 cassette too. Then you could also go with a slightly bigger ring to have some more top-end than you have currently. If the top end isn't that important you could also stick to the 11-32 cassette and go with a 44t ring. Hope that helps.
Post #58 of 91. Posted by Gerard Vroomen on 03-May-2017 12:23:15 GMT in reply to post #57 [3829<--3834]
Hi Gerard,

just see your 1x only 3T Strada and hopefully, 12 speed is coming soon. It would be then an instant buy. I'm more into tarmac with very very light gravel.

Just want to correct my ideal 12 speed settings after climbing some hills in tuscany with 11-36 / 34-50:
Post #59 of 91. Posted by Helmut on 06-Jul-2017 08:39:43 GMT in reply to blog [0<--5918]
Hi Helmut, quite difficult (to put it mildly) to shift that combo with a 2x road group. That's the funny thing with 1x, if you want the most range, 1x offers you more than 2x, even more than 500% with the e13 9-46 cassette.
Post #60 of 91. Posted by Gerard Vroomen on 09-Jul-2017 08:02:32 GMT in reply to post #59 [5918<--5922]
Hi Gerard,

thank you, never looked at MTB cassettes. With 11 speed I really miss one gear, I calculate for hours and also observe me how I cycle.

Hopefully SRAM release 12 speed for road bikes soon and hopefully 3T Strada is available in that black/grey color painting like Exploro. You finally made "my" road bike.
Post #61 of 91. Posted by Helmut on 11-Jul-2017 16:58:35 GMT in reply to post #60 [5922<--5924]
Hi Gerard,
Not great with all the maths tbh & I'm planning on building my first 1x11 gravel bike shortly.
It's gonna be used primarily off road with the road sections mainly getting me too & from the trails.
Therefore I'm not interested in flying along at 25mph on the road, I'd prefer easier climbing gears.
I would however like to spin along at 15-18mph on the road home.
I'm also thinking of 650b wheels.
Could you advise on a suitable crank/rear mech/cassette ratio please?
Should I go with a road crank & MTB mech/casstette for the best chain line ?
Thank you
Post #62 of 91. Posted by David on 09-Aug-2017 16:40:01 GMT in reply to post #61 [5924<--6971]
Hi David, personally I think the SRAM 10-42 cassette is great. Of course it depends on how strong you are, but say you combine that with a 34t ring. That is much smaller than most people use, but 34x10 is really big enough to ride 15-18mph. I rode 34x11 as my biggest gear at Almanzo 100 last year, didn't miss any top gear really. And when you get tired, having 34x42 is a blessing. The few seconds you may lose at the top end are nothing in comparison with minutes, hours and you lose (not to mention the frustration) if you end up walking up the super-steep stuff when you're tired.

I'm a fan of the 650b so I would agree with that. For the cranks, anything goes really. You can simply go with a full SRAM drivetrain, including the 1x crank, that works fine. You can also use a different (2x or 1x) crank and get a ring from Wolf Tooth or similar companies to complete the set-up, if you want something special (like THM super light or Easton, etc). Don't worry about the ring offset too much.
Post #63 of 91. Posted by Gerard Vroomen on 09-Aug-2017 19:17:41 GMT in reply to post #62 [6971<--6972]
I'm running a 46/30 double chainring, with 11-36 cassette. I've found this a really nice combo for on and off road rides. It would be good to see more of these super-compact chainsets available. Mine's a sugino xd601, rated for 10 speed but works perfectly with shimano 105 11 speed. I've used a road link from wolf tooth to drop the rear derailleur hanger so I can use the 105 mech with a 36 force cassette. Took a bit of tinkering, but I'm really happy with the results.
Post #64 of 91. Posted by Rob on 08-Sep-2017 13:34:59 GMT in reply to blog [0<--7045]
Hi Gerard,

Meant to say the super compact setup I described above isn't on an Open UP. Would the UP allow a 30 tooth inner chainring, or would it cause clearance problems with the dropped chain-stay? Thanks Rob.
Post #65 of 91. Posted by Rob on 08-Sep-2017 14:05:41 GMT in reply to post #64 [7045<--7046]
30t is indeed pretty tight with the chain stay. It depends a bit on the RD and chain length as well on how low the chain drops, etc, so there is no absolute answer, but I can imagine it will be hard to make that happen.
Post #66 of 91. Posted by Gerard Vroomen on 11-Sep-2017 13:53:27 GMT in reply to post #65 [7046<--7052]
Gerald, I was also considering an UP build with the new FSA SL-K modular 30/46 cranks. Seems like super compacts give the best of both world. Sounds like that might not work on an UP? Would love to know definitively from the master ;)
Also, debating XT 8050 Di2 vs Ultegra 8070 Di2. Would like the clutch on the XT rear, but will there be problems shifting up front with XT giving different drops and BB widths?
Post #68 of 91. Posted by John on 10-Dec-2017 15:00:28 GMT in reply to post #66 [7052<--8299]
The 46/30 definitely works, maybe I was a bit unclear there, but smaller than 30 gets tight.

As for XT(R) vs Ultegra/DuraAce, it's actually very simple due to the restrictions Shimano has put on what can talk to what in the Di2 system:

- Front and rear derailleur have to be of the same family, so both road or both MTB.
- That means that if you run 2x, you need to run road derailleurs as a front MTB derailleur won't work and a road front with a MTB rear won't talk to your shifters
- If you run 1x, you have to run an MTB rear derailleur because without a clutch, your chain retention on 1x won't be that great.

Now, this may all change with new product developments, who knows, but that is the situation as of today. One more note of caution, while road shift levers work with the MTB Di2 rear derailleurs, Shimano likes to play around with the software and its restrictions. Sometimes you need to connect them to a road derailleur to initialise and then swap out to the MTB derailleur, and who knows what software modification they think of tomorrow. So buyer beware.
Post #69 of 91. Posted by Gerard Vroomen on 10-Dec-2017 15:12:22 GMT in reply to post #68 [8299<--8300]
Thanks Gerard for clarifying... Super helpful!
Post #70 of 91. Posted by John on 10-Dec-2017 21:16:26 GMT in reply to post #69 [8300<--8302]
Hi Gerard

when you swap the RD, from UL 6870 Di2 to XT Di2, don't you need to start Etube in MTB setting?
(never tried XT rear, but i am about to give it a try)
I think i was told from a user, that you connect to MTB setting directly?
Do you mean you start the system in road setting with (ex) 6870 Di2 and then swap to the XT Di2?
But then again, don't you need to re-set Etube to MTB to install the XT RD and download firmware?
Post #71 of 91. Posted by Rhys on 18-Dec-2017 13:37:48 GMT in reply to post #69 [8300<--8332]
From time to time Shimano changes the software but as far as I know, you either connect the MTB derailleur immediately (used to be like that) or you initialise with a road derailleur and then swap (more recent).
Post #72 of 91. Posted by Gerard Vroomen on 23-Dec-2017 00:17:41 GMT in reply to post #71 [8332<--8353]
Useful info re mixing and matching there Gerard
Post #76 of 91. Posted by imajez on 28-Apr-2018 16:04:57 GMT in reply to post #69 [8300<--11725]
Brilliant article, easy to follow and figure out. Thank you.
Post #67 of 91. Posted by Stephen Carroll on 29-Sep-2017 06:57:48 GMT in reply to blog [0<--7107]
Hi Gerard,

I suggest using this website:
Post #73 of 91. Posted by Jeroen Brouwer ('t Kopje) on 10-Apr-2018 15:43:01 GMT in reply to blog [0<--10649]
I hope Gerard or anyone here on this tread can answer my questions,Im using a force 22 crankset 2x BB30a and I wanna convert it to 1x set up 40t,so my questions are can I use the xsynch diret chainring without using the existing spider? And waht offset do I need if I use 40t ring,any other modifications that I need to do for BB,spacers etc? I just wanna copy the set up on this tread page photo,, my first open bike btw..Thanks everyone..Ed
Post #74 of 91. Posted by Ed on 18-Apr-2018 12:00:45 GMT in reply to post #73 [10649<--11679]
"And to those people who insist they need a 53/11 as their biggest gear, really? You need the same gear as Froome and Sagan?"
Ahem, hills. ;) I would like a taller gear than my current 50/34-11/32, not because I'm as fit as those guys but because there are some seriously long steep hills in these parts.
Plus when going really fast I prefer to turn pedals at a slower cadence, because it's a lot more stable than twiddling pedals furiously. So I certainly find I run out of gears at top end. With MTB's with 1x setups I find I can run out of gears on the flat. :/

Also rather than tediously faffing with maths, use this cleverly designed gear selection tool to quickly and visually see exactly what gear ratios/inches any combination has.
This is the closest 1x combination to my current setup. Though I would need a custom 12 speed block to do so, mainly to reduce big gear jumps. I use all the cogs to find correct cadence. Less of an issue off road where terrain is far more variable. But my gravel/cx bike does loads of road miles too inbetween the off road stuff, so I prefer the smaller jumps. A 1x with a custom 15 block would be perfect. :D
Post #75 of 91. Posted by imajez on 28-Apr-2018 16:02:57 GMT in reply to blog [0<--11724]
This absolutely brilliant bike is fast, super stable with the enve ar 4.5 and schwalbe pro replacement for the road bike (it is faster than any bike I have ever been on in real world conditions). With the biturbo rs and g one 40mm this is an amazing all road bike it flies over gravel. The best way to build this bike if you live and ride high my missed terrain with steep long climbs is to build it as a 2 times 1x.
Rotor 46/30 and SRAM 10-42. So on road I ride on the big ring and for almost every climb it suffices. Off road and for really long climbs like the grossglockner or the zoncolan I switch to the small ring. The brilliant bike has only one design mistake and that is the exit hole of the rear derailleur cable. This makes it impossible to mount an mtb derailleur which shift much better than road and have clutch. In September shimano Rx will be available then the open will be the almost perfect bike (etap wifli clutch and re engineered front der would make it perfect) (and no 1x makes most sense ever, unless you do the same loop every time and you know exactly what to expect. Walking a bike up a hill because you ran out of gears to save 30 gram looks really really stupid)
Post #77 of 91. Posted by Youpmelone on 01-May-2018 04:21:25 GMT in reply to blog [0<--11729]
Gerard, I'm pushing the boundaries here it seems with a 9-46 E13 cassette, and 40t oval chainring. I would have like to go above 40t for a truly all around bike (yes, I want to crank hard even above 35mph), but it's geometrically impossible it seems to go to 42 or above, this would not shift into the 9t. Do you know what this limitation is called? I can't find anyone else doing this kind of range. I have an UPPER.
Post #78 of 91. Posted by Ilya Cantor on 19-Jul-2018 03:49:08 GMT in reply to blog [0<--13909]
Great article, I'm planning on converting my roubaix to 1x11. i currently ride with a 50/34 and 11-28 t and fine this gearing really versatile, although i generally only use the easier gears for steeper hills but stay mainly on the larger chainring (but do want to keep the 1st 3/4 easier gears as have a few mountain races) can you help suggest a decent front chain ring and rear cassette which would replicate these gears for me please? also in terms of rear derailleur im thinking the new ultegra rx800 with the clutch.

Also do you find you need the chain guide on the front ring to keep the chain on? ive read mixed feelings about this and not sure to what extent the chain might unseat form the front chainring?

Thanks in advance for your advice / help.
Post #79 of 91. Posted by Gino on 29-Aug-2018 09:17:51 GMT in reply to blog [0<--13963]
Hi Gino, the closest you can get to that would be a 46 ring in the front and a SRAM 10-42 Cassette in the back. Your smallest/biggest gears are now 1.33/4.98. With the new 1x setup it would be 1.2/5.04. I have no experience with the RX800 but Force 1 RD or XT/XTR DI2 RD keep the chain well in place.
Post #80 of 91. Posted by Andy Kessler on 29-Aug-2018 11:45:34 GMT in reply to post #79 [13963<--13968]
Thanks for the quick reply. Thats very useful information.

If i wanted to replicate a 50/34 and and 11-32t rear cassette am i right in thinking i could use a 44 up front and a 10-40 rear? or similar?
Post #81 of 91. Posted by Gino on 30-Aug-2018 08:37:06 GMT in reply to post #80 [13968<--13971]
Hi Gino, sorry it took me a while. Here is the link to a good website to calculate gear ratios
Post #82 of 91. Posted by Andy Kessler on 11-Sep-2018 10:27:44 GMT in reply to post #81 [13971<--13995]
Hi Gerard
This post and thread is the best explanation of 1x setup selection I have come across by far. I am currently running a compact 50/34 x 11-32 on my roadbike as its hilly round here, and following your advice it seems 44 x 11-40 would be best for my new winter bike, which comes with sram apex. Would this specific casette be compatible with the sram drivetrain? Shimano CS-M7000 SLX 11 ?
Post #83 of 91. Posted by Mark W on 13-Sep-2018 03:22:17 GMT in reply to blog [0<--14990]
Hi and thank you for your research. I’m new to the IM distance, kind of a strong rider, and fascinated from the 1x system. I’m not the kind of guy, although capable, that will change cassettes depending on the IM course. I would like to have 1x system that adressss flat courses and hilly ones like Lake Placid. What would you suggest? Thank you!
Post #84 of 91. Posted by Vasilis Chatzigiannis on 12-Oct-2018 01:49:13 GMT in reply to blog [0<--16035]
Hi there,
Riding Rebeccas Private Idaho, and some other gravel stuff in 19 and thinking about going to 1x on my upper. Was thinking about doing the new 3T Torno with a Shimano RX805 rear. Do you have any thoughts or insight into this setup, my understanding is there maybe a slight giveaway in ranging?
Post #85 of 91. Posted by Matt on 21-Dec-2018 13:54:21 GMT in reply to blog [0<--17173]
Hi there,
Riding Rebeccas Private Idaho, and some other gravel stuff in 19 and thinking about going to 1x on my upper. Was thinking about doing the new 3T Torno with a Shimano RX805 rear. Do you have any thoughts or insight into this setup, my understanding is there maybe a slight giveaway in ranging?
Post #86 of 91. Posted by Matt on 21-Dec-2018 13:54:24 GMT in reply to blog [0<--17174]
Hi Matt, not sure what the rest of the setup is on your bike. But if it is Ultegra or Durace DI2 then I would rather go for a XTR DI2 rear derailleur because then you could even use a 11-46 cassette in the back that gives you a nice range.
Post #87 of 91. Posted by Andy Kessler on 04-Jan-2019 02:42:41 GMT in reply to post #86 [17174<--18182]
Thanks for the información
I have a 1x Bike now with the 11-42 Sram as Cassette and a 40t chainring. I’m going to buy another chainring to gain some speed, What would you recomiend? A 44t in orden not to change the chain or 46t to be closer to the ratios of a 2x 50-34 making even longer the chain? Thanks. Borja
Post #88 of 91. Posted by Borja on 30-Jan-2019 17:55:11 GMT in reply to blog [0<--18211]
Will a 46T elliptical chainring fit on the new open upper in a 1x set up?
Post #89 of 91. Posted by Mike on 09-Apr-2019 13:13:29 GMT in reply to blog [0<--18347]
I'm completely agree with You ! The essential useful gearing are not more than 8 or 9. I did my choise two yweas ago for 1x11 Sram (32 oval x 10/42) and I feel great on my mtb 29er. I rarely use the smallest cog, while I don't hammer very often 32 x 11 . Even the lacks of cadence smoothness is not a problem as this fact help muscles to work out in a different way for the benefits of blood circulation and heart ! I thinks that 1X have great benefits on brain work out too.
Post #90 of 91. Posted by Ste Fabrizi on 10-Apr-2019 10:26:58 GMT in reply to blog [0<--18348]
Okay, I'm rubbish at maths and this is all very confusing, but I really want to go 1x. Would you cut out the brain ache and recommend the correct 1x gearing please? I need the equivalent (or nearly) of a 50x13 biggest gear and 34x32 smallest (I'd take extra, say 34x34 if I could). I'm not too bothered about the jumps between gears. Is there a cassette and front ring that has this scope? Thank you.
Post #91 of 91. Posted by darren halford on 20-Jun-2019 06:52:30 GMT in reply to blog [0<--19616]