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Tech: Deep dive on 1x10 narrow/wide conversion gearing

34K views 48 replies 43 participants last post by  marty2  
#1 · (Edited by Moderator)
Editors Note: 'Science Behind the Magic' delves into the inner workings of your two-wheeled steed. Art's Cyclery web content editor Brett Murphy uses his mechanical engineering background to explain the latest industry advances and breakdown the inner workings of common components. The original article can be found here.

I recently wrote reviews of the e*thirteen Extended Cog and GuideRing M after converting my own bike to a 1Ă—10. I had great things to say, and have received some requests to further discuss 1Ă—10 gear ratios, including extended cog range setups. I thought it would be useful to compare some stock setups with the 1Ă—10 extended range possibilities. Comparing the gear ratios and the cost differences should help you make an informed decision about where to spend your money.

This recent survey on Mtbr shows the popularity of 1x10 Narrow/Wide conversion drivetrains.

This recent survey on Mtbr shows the popularity of 1x10 narrow/wide conversion drivetrains (click to enlarge).​

The growing popularity of extended cogs is a result of 11-speed 1x drivetrains by SRAM and Shimano. There are mechanical and weight advantages to ditching the front derailleur in favor of a wider range cassette that can do the job of a double or triple chainring system. The manufacturers have decided however that these wide range cassettes should come with a hefty price tag and the requirement for a new shifter, derailleur, and potentially a new freehub body or hub. E*thirteen, Hope, and others all have extended cogs that increase the range of your current 10-speed system by adding a 40 or 42-tooth cog to the freehub body; making room by removing the 15T or 17T cog on the existing cassette.

Ratios

The following graphical representation shows a comparison of gearing between four setups. The X-Axis is arbitrary and represents the number of gears available. A 3x system has 30 gears to choose from, however most of them overlap and are redundant. The Y-Axis shows the number of centimeters of forward movement per crank revolution. Rolling centimeters are calculated by multiplying the circumference of a 29-inch tire by the gain ratios of the gearing.

Gearing Chart

The jumps in rolling distance observed in the 3x (blue plot) and 2x (red plot) show the change from one chainring to the next. While 3x does offer a slightly better range of gearing, the amount of redundancy in gear ratios is extreme. Comparing the 24T ring of the triple to the 32T ring, you can see that the first 8 high gears overlap in rolling distance to gearing in the 24T ring. Only the last two shifts offer a new ratio. The same is true of the 42T ring. Of the 30 gearing choices on a triple 10-speed setup, only 14 combinations offer unique gearing, the rest are redundant. The same is true of a double but to a lesser degree. Of the 20 gearing combinations on a double, 14 are unique ratios. Doubles offer an almost identical range of a triple with one less ring.

The typical 1Ă—10 conversion drivetrain involves removing the 15 or 17 tooth cog and adding in the 42 tooth after the 36. The front chainrings and derailleur are removed in favor a 32 tooth Narrow/Wide front chainring.

The typical 1Ă—10 conversion drivetrain involves removing the 15 or 17 tooth cog and adding in the 42 tooth after the 36. The front chainrings and derailleur are removed in favor a 32t narrow/wide front chainring.​

The major concern for most people when moving to a 1x system is that they will be losing gears, making it harder to climb. I set up the gearing in the chart so that all combinations would have approximately the same gearing for climbing. All setups have roughly 150 centimeters of forward movement per pedal stroke in the lowest gear. So let's set that concern aside, it will be just as easy to climb with your new extended range (42t) 1Ă—10 as any other factory setup. Now on the high end of the gear range there is a bit of a different story to be told. The 3Ă—10 setup wins the highest gear award with the ability to move 878cm per pedal stroke and the 1Ă—10 comes in last at 627cm. This explains some of the reasoning behind SRAM's XD freehub body that allows for a 10-tooth cog, which increases high-end ratios.

Now before dismissing the 1x setup on account of a lack of high gearing, ask yourself if you really think you've ever used this range before. Looking again at the chart, we can see that the same ratio of a 1Ă—10 extended setup (30T ring in the 11T cog) is available with a 3Ă—10 setup using the 42T ring with the 15T cog. So take your current 3Ă—10 bike out for a ride, and when you are descending the trails or riding back to the car on the flats, see if those last two gears (the 13 and 11-tooth cogs) make a difference to you. From personal experience, I find I don't have an issue spinning out on my bicycle. At 90RPM this last gear would have you traveling at 30mph. While I do have loads of fun ripping trails at 30mph, I don't find myself pedaling in these situations and also don't spend time on the road spinning at this speed.

Depending on your bicycle and riding style, perhaps higher RPMs and speeds are more important to you. Check out some of the pro XC setups around today. For the most part they are running an XX1 10-42 cassette with either a 36T or even a 38T chainring. So perhaps if you are building a XC rig, you look at a bigger front ring paired with that 10-speed extended cassette. Below we can see the results of the new 1Ă—10 11-42T cassette with a 36T chainring stacked against the original triple and 30T 1Ă—10 setups. Shifting the line upwards in favor of higher speeds and less climbing.

1x10 36T

Continue to page 2 for calculations and the bottom line »

Calculations

Looking at some of the bicycles currently in the Art's inventory, I've found some general gearing trends for today's mountain rides: 3Ă—10 setups are on the budget conscious bikes, 2Ă—10 on mid-range bicycles, and 1Ă—11 on the top-end models. The 3x bikes usually have a 24/32/42 chainring setup, while 2Ă—10's sport a 24/38-tooth setup. Regardless of the number of front chainrings, an 11-36T 10-speed cassette seems to be the norm in the rear. The 11-speed setups tend to include either a 30 or 32T front cog with a 10-42T in the back. These are not hard-and-fast rules, just some general trends used to evaluate drivetrains for the purposes of this article.

When comparing, the first thing to do is divide the number of teeth up front by the number in the rear of the currently selected cog. This gives you the gain ratio of the system and tells how many times the wheel will rotate per revolution of the crank. The data below shows the gain ratios of 3Ă—10, 2Ă—10, 1Ă—10, and 1Ă—11 systems.

Gain Ratios

One thing this data doesn't take into account is the size of the wheel. I'm sure there are plenty of you out there that are still rocking 26-inch wheels, while your friends run 27.5 wheels or 29ers. By multiplying the gain ratio by the circumference of the tire, we can calculate the distance the bicycle will travel for every pedal stroke. Because 26-inch wheels have a smaller circumference, we can step up the gearing so that it will roll the same distance in all gears. The math is there for you to double check, but a general rule of thumb is to step down 2 teeth in a chainring for every wheel size. So while I'm happy with the 34-tooth ring on my 26in bike, I would probably switch to a 32-tooth on a 27.5 bike with the same cassette, or a 30-tooth on a 29er. The below tables show the centimeters of forward movement for every pedal stroke on a 29er tire with a 30T ring compared to a 27.5 tire and 32-tooth ring.

1x10 Distance Traveled per Pedal Stroke

Bottom Line

Now that we've done a bit of analysis on gear ratios, you might be almost convinced to make the switch, but lets look at things from a monetary angle. The costs involved in a new extended range 1Ă—10 drivetrain really depend on your current equipment. A rear derailleur with a clutch is a requirement, along with either a narrow wide chainring or a chain guide. Without a front derailleur, the clutch derailleur and tall chainring tooth profile are necessary to keep the chain in place. If you already have these items, you might get away with just buying the extended cog. Because everyone's situation will be different, the table below list prices and weights on every component (you might not need every component) and then compares to an entry level X1 11-speed system.

Price and Weight Breakdown for 10 and 11-speed

10-Speed Price10-Speed Weight11-Speed Price11-Speed Weight
DerailleurShimano XT M781 $69.99237 gramsSRAM X-1 Type 2.1 $230.99257 grams
Cassettee*thirteen Extended Cog $65.99367 grams (w/ XT Cassette)SRAM X1 XG-1180 $245.00312 grams
ShifterShimano Zee M640 $34.99142 gramsSRAM X1 Trigger Shifter $69.99123 grams
Chainringe*thirteen GuideRing M $43.9943 gramse*thirteen GuideRing M $43.9943 grams
Totals$214.96789 grams$589.97735 grams

The end result is an additional $375 for an X1 drivetrain over a custom 1Ă—10 setup, saving a total of 54 grams. I leave the decision to you my friend, but I will personally be waiting for 11-speed drivetrains to trickle their way down into less expensive component groups. [Editor's Note: SRAM may well have answered this call with its new, more affordable GX drivetrain, which debuted after this article was written.]

https://reviews.mtbr.com/first-look-sram-gx-drivetrain

 

Attachments

#2 ·
One by setups were a no brainer for me. I dropped the large sprocket on my 3x10 some years ago because I did not use it in favor of a bash guard. With the invention of the 40t+ range expanders and the adoption of narrow wide chain rings, specifically the race face 104 bcd 30t, dropping the granny, front derailleur mech and front shifter was a no braining. With a 30:40 ratio setup the only trail that kicked by butt was Slick Rock in Moab. There really is not quite enough ratio to climb super steep pitches seated, which is what you have to do on a full squish bike. I'll be running a crank with a direct mount 28t sprocket up front and will be fitting a 42t range expander this year. This should get me enough ratio for a true granny gear, and still 11:28 on the high end will allow me to cruise the flats at 17 mph with a nice cadence.
 
#4 ·
The 11sp gives you about 1 more gear than 1x10, and very close to the range of 2x10. It seems a bit lacking to not include the 3x9, as that was standard for so long and many people are now retiring their 9sp drivetrains.

1x11 and 2x10 gives up about a gear off the 3x9.

11sp requires different hub, which is the major limiter to trickle down right now. Even if you have a convertible hub, the conversion kit costs $80-100 to switch from 8/9/10 to 11. But you get that sweet 10-42 cassette!

The other issue with 1x10 is several of the companies have weight limits on the 42T cogs. Having a single 40 or 42T is much weaker for the weight than building all the large sprockets together. Big guys may bend /break the extended range cogs.
 
#5 ·
Pick your gear ratios to accomplish what you like. If getting up that super steep climb is what's important the go with a double (22-36 chainrings) and 11-36 at the back. If you're young and strong and top end speed is what's important to you the 1x setups are ideal. For the average rider it's tough to have both climbing power and top end speed. With my 22 chainring and my 36 at the back I was able to ride up all those hills at Moab on my Trek Remedy. I'll be 60 this summer.
 
#6 ·
As Pat said you forgot to mention the hub cost and also many people cassettes may nit have removable 15t or 17t cogs so they may need to factor in more money for a cassette. That being said I have been running 1x10 for a little over a year and will never go back. I am tempted by srams new GX stuff but I was planning a new wheel set anyway. Great article thanks for the info.
 
#8 ·
Here are the problems I have with 2x, 1x, vs 3x gearing systems.

- 2x systems very close range (more than usable) but forces you to be in the granny gear too much. I prefer to be in a more efficient, slower wearing bigger front ring for 95% of my riding. Being in a 22 or 24 tooth front ring will wear the ring and chain faster, and they are slightly less efficient. Granny gears also typically interact with suspension more on most bike designs. So to me, since you have a front derailleur anyways, why not 3 instead of 2? Plus, with bottom brackets getting lower, I much prefer to have a bashring, and for most of my riding, 32 front ring is enough and you can simply replace the big ring with a bash to protect your gears for cheap, and slap on the big ring for a situation where you may need it. From what I've seen, most true 2x systems don't allow for use of a bashguard. A frame mounted bash may be an option, but really only if you have the correct mounts on the frame, which not all frames have. Plus I prefer the bash mounted to the crank, not the frame.

1x - 1x10 has obvious gear step issues and ieven if you replace the 15 with a 16, the gaps are still not the best. Plus the durability issues mentioned above are definitely true, and a friend of mine absolutely destroyed an allow 42 tooth ring and while a strong rider he's only about 160 lbs. 1x11 seems OK, but you are limited to the gearing range of a 3x with a bashring. Again, it looks that SRAM/Shimano 1x11 cranks aren't really designed w/bashgaurd and 32 tooth middle ring. Plus to get the same low range/high range as a 32/24, you need to go to a 28 tooth ring, which is approaching Granny status for efficiency/wear. Not to mention the expense. Although GX is approaching more reasonable cost, it is still about 2x more than XT/SLX, and the rear cassette is a pig and I'd prefer to have weight around the BB area than the rear axle.

I don't really understand the whole 'redundant gear' argument. The way you should use a 3x system is to adjust the front derailleur to the terrain (granny for steeper uphill, middle for rolling, big ring for flat, downhill) and then fine tune with the rear derailleur for the smaller variations in those 3 categories. You get smaller steps in gears and then can essentially choose the high/low appropriate to the category of the terrain. I have never found the front derailleur so big of a problem that I would sacrifice any range of gears. There's nothing worse than having to walk, or spinning out, in my opinion, and you ride a wide range of terrain this is going to happen with a 1x system. Now, this is from the perspective of an intermediate rider, that does mostly trail riding and the occasional XC race. For someone focusing more on downhill or is good at low cadence climbing in taller gears (high strength to weight ratio), I can see the appeal, but for the person with average strength to weight ratio that has a single bike they would use for multiple riding situations, I just don't get the hype of removing front chain rings. Seems like a net loss, not a gain.
 
#9 ·
This chart and article ignore one of the main reasons I prefer a 2x10 setup over 1x11, smaller spacing between gear ratios. You can see it in your charts. Yes, there is a lot of overlap between the different rings, but not necessarily at the same spot. Sometimes on that long climb, you want that perfect gear ratio, you loose that fine grained choice with a 1x11 and especially with a 1x10.
 
#10 ·
The 1x10 set up looks like it has good climbing gears, okay downhill ratios, but very few options in the middle ranges. There's a huge gap between 350 and 450cm on the chart. On a flatish or undulating trail, the most important range is non-existent. For toodling along this seems fine, but for having fun or going fast this seems like a big negative.

And what's the "up side"? I lose several ounces off my bike to make me faster up a hill? What does a front shifter, derailleur, and small ring weigh? Okay maybe it's a pound off my bike. So I can get up a really long climb 20 seconds faster, but I'm slower on the flats and downhills? Is that really a tradeoff that I want to make?

I have no issues with people running 1x10 - I run a singlespeed pretty often - however, I don't see why it needs to be justified through math that's not there. The upside is 1x10 might make you learn to pedal differently due to a lack of gear choices. The downside is that there will be times where you wish you had more gears.

I like my singlespeed, but on trails where the goes downhill at a 2-3% slope, it's not much fun. I can't drift as fast as I want to go, but I'm going to fast to pedal. I avoid trails like this when I singlespeed. With a 1x10 there would also be some trails that are less fun.
 
#11 ·
Much as everyone hates on the ol' front mech, here are two more real world scenarios:

I have XX1 on my trail bike, 2x10 on my XC, there are times that I've set on the XC bike that I can't get anywhere near on the XX1 bike because you run out of gears.... the XC is a 26" Giant Anthem by the way. Typically these are flatter trails, where you can keep getting more and more gears as you build speed. XX1 runs out, I run a 32T up front.

Second is riding in mud. I did a race with XX1, 75km endurance race that was very muddy. Spent a lot of time in the 42T because anything more would cause the rear wheel to spin. Sufffice to say I walked up a lot of hills and wished I had the 2x10 for more usable gears in the range I wanted...
 
#12 ·
Some great comments here. That 19 tooth on the 1x10 is ridiculous! Should be an 18 and the gap would be spread out more evenly.
One setup that wasn't mentioned because not many of us using it is the 3x7. Personally, I like having a stiff, light SS wheel. For me, stiffness and much better chain line is more important than gear range. All I loose is the very top end which I didn't use anyway. It goes without saying that I am in a very small group of riders.
 
#13 ·
Don't forget, everyone rides different trails and everyone has different skills. For me, riding around St Louis, even my fat out of shape butt can ride an antique 1x9 drivetrain. I couldn't ride that setup in the mountains, to each his own.

Don't forget that lots of folks ride 1x1 and are perfectly happy. I am too fat out of shape (previously mentioned) to ride 1x1.
 
#16 ·
I run a 26er right now and a 29er. For climbing steep long climbs my 1x10 26er is barely passable at 26/42. I can do it but sometimes need one more gear to just grind it up in the saddle.
On the 29er I have a 24/32/42 with a 11-36 cassette. It needs more gear as it is in my estimation 2 gears off on climbs compared to the 26er. When I was younger these would have been considered ridiculous gears. To the very fit gearing is a theoretical discussion. To those of us who are just grinding trying to get fit and enjoy the mountains we need lower gears.
On my new 29er I plan on getting the new XTR di2 and going back to 2x or even 3X and using the syncro shift with a 10-42 SRAM cassette (since Shimano blew it by only going to 40T) to get max range.
On the 1X I do spin out way to easily on the flats.
 
#18 ·
2x and 3x always work better in the real world. People who got sold on 1x really just bought into a fad. These are the guys who drive their mountain bikes to the trailhead, hike a bike up the steepest climbs and generally like to be seen with the latest gear cause it's oh so popular with the bros.
 
#19 ·
I agree. I tried 1x. No good. It was awful actually. So then I tried 2x. Much much better than 1x. I sacrificed top end speed on flats. But I find it acceptable. Shifting is far superior on 2x than it was with 1x. With 1x, if I set it up to handle inchworm climbing on tight / tech / singletrack, then it was absolutely awful on the high end. 'Smooth shifting' is key for 'me' relative to 'fun' riding. If the bike's gear shifting isn't smooth, but notchy, then I'm not happy. 1x simply cannot be set up to be at once 'smooth' and all-inclusively 'high / low' range. Trail results are a heck of alot different than the what the results tell you 'on paper'. Screw 1x. Anyone who tackles the full gamut of riding from flats to tight technical steeps....would quickly find themselves missing what they NEED. ...I had to find this out the hard way by wasting $$$. 2x is usable and offers the necessity's.
 
#23 ·
1x10 for over a year on both mtn bikes and one Cx bike. Never had any shifting issues using XT on Mtn bike while using 30 tooth with 36 cassette. Riding Pisgah and other WNC trails perfect set up. Don't need any more gears for downhills or gravel roads. Cx bike is set up for racing with 40 tooth and road rear derailleur no drops. Simple
 
#24 ·
I ride a 2x on my Full suspension on steep grades and like it because I can relax and enjoy the ride. I ride a 1x11 for XC racing and will never go back to the 2x for this kind of riding because it is lite, quick and without mechanical issues. For Cyclocross I ride a 1x10 and absolutely love it for the same reason as the 1x11. To say it is a fad is someone that is close minded and probably still rides a 26er because 29ers are just a passing fad...NOT!