1X or 2X Drivetrain

80 replies · 16,909 views

scottNU
7 posts
#1Jul 18, 2017, 4:39 PM
Hi folks,
I’m looking for some advice on a drivetrain for a gravel bike. I am leaning towards a 2x setup, but I know people also like a 1x for a gravel bike. When I ride my 1x mountain bike on the roads (with the kids or just tooling around), I can definitely tell that I am limited on the top end. The small chain ring means I have to spin like a mad man to keep a brisk pace (>18 mph).
So, if I want my gravel bike to be quick on the roads, tough on the gravel and able to chew up 50 mile+ days, a 2x system seems like the plan. One of my buddies showed me the mess of his bike after the Almanzo and said keeping as “simple” a set-up as possible would be great and a 1x offered that big advantage. But a 2x setup still feels like it is going to give me more of what I am looking for in a gravel bike.
Am I missing something? Can anyone convince me I’m wrong (it happens a lot….).
Thanks!
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ronij
14 posts
#2Jul 18, 2017, 6:38 PM
My gravel bike is now 1x and I'm pretty confident that I won't go back to 2x.

I run a 42t chain ring and an 11-36 cassette. I can ride pretty comfortably at about 25-28mph (assuming there is a downhill, of course) but can manage up long climbs just fine (I'm in the PNW where 5-10 mile climbs at 7-12% aren't so uncommon). I used this gearing setup for the DK200 this year and was very happy with it - I never felt limited by my gearing choice. I also find that with the 11-36 cassette, the jumps between gears aren't too large that I find myself wanting for more options. I imagine that if I went with an 11-40 or 11-42 cassette, this could be an issue.

Since switching to 1x, I haven't had any issues with dropped chains - which was a problem with my previous Ultegra (36/46 with 11-32) setup. A dropped chain on its own isn't so bad, but when it gets jammed between the crankset and the frame, it can be pretty frustrating - especially during a race.

I'm now using an XT di2 rear derailleur with Easton EC90 cranks and the corresponding chain ring. For a while, I stuck with my mechanical shifters and used a mechanical XT derailleur with a Wolftooth Tanpan - this worked really well but the di2 is fantastic.
1
PoolBoyMatt
49 posts
#3Jul 18, 2017, 9:13 PM
I will agree with ronij 100%.

I am running Rival 1, with the 11-36 cassette it is great. I am not limitied by speed. When I ran the 10-42 the jumps between gears were pretty serious sometimes. Especially the jump from 10-12 is steep - its 20% difference. That is a big one.

If you can run 11-36, I would say 1x ALLLLLL DAY. If you need the 42, look at running at 2x.
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cmcalpin
107 posts
#4Jul 19, 2017, 7:22 AM
1x here as well on southern Iowa hills. I alternate between a 38 and 42 front ring. Even with the 38 I can comfortably hit 25-28 mph. I seldom see that on the gravel here but it can be done. On the rear I am running a Sunrace MX3 11-42 cassette. If you are running a 10 speed and want more range you should check derailleur compatibility and try one out. They shift nice and give me that extra low I sometimes need around here.
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bobknh
794 posts
#5Jul 19, 2017, 7:23 AM
My $.02: Of course, this is another instance of personal preference. I personally prefer the versatility of 2x, to the simplicity and trouble free operation of 1x. There are also varieties of both 2x and 1x gear sets. In my case, I use a CX oriented crank - 46/36 with a wide spaced rear der. 11-36 for hilly NH dirt and gravel. The 46/36 is a standard crank offered by most manufacturers. I like having a lot overlap between my chain rings. This means that I have to make fewer front der. shifts during my ride. It's sort of like riding two 1x set ups - one for moderate rolling to flat, the other for more challenging ups and downs. Frankly, I regret that the major manufacturers have virtually abandoned triples in favor of "compact" 110 cranks. I love the 3x9 gear set on my old Canondale R1000 tandem.

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shoota
91 posts
#6Jul 19, 2017, 9:13 AM
I'm with Bob on this one. I like my 2x. I fail to see how the "simplicity" of a 1x is worth sacrificing either low end, high end, or jumps between cogs. I guess I just don't find changing between chainrings all that cumbersome.
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dangle
465 posts
#7Jul 19, 2017, 11:10 AM
scottNU wrote: I am leaning towards a 2x setup, but I know people also like a 1x for a gravel bike. appens a lot….).

Nobody is right or wrong. If you are leaning towards a 2x, do it. There's a good chance you'll always wish you had gone 2x if you have a 1x setup.

Specific to your points:

What's your mt bike chainring? A 32? A 32 x 11 is a somewhat low combo. It's not really an apples to apples comparison. 32 x 11 on my mt bike feels limited (to me) riding to the trails.

Low end gearing
I'm a fan of trying to get a 1:1 ratio (I like gear inches better, but this is simple to
explain) on the low end if you're going for some of those adventure rides with regular double digit inclines on gravel or dirt where standing to pedal isn't an option. Even with a 2x, that's still putting an 11-36 (or soon to be released 11-34) cassette on the back. An 11-32 gets you close enough with a 34 up front and is what I did most of last year. I'm on 42 x 11-40 since last fall and that's working great for the loose, steep climbs in the driftless region.

High end gearing.
A true gravel bike doesn't need anything bigger/faster than a 38 or 40 up front. I used my cx bike with road tires for some spirited group rides and even with 'only' a 42 up front I was fine. 90 rpm is putting you at 27mph in the 42x11. Anything quicker really doesn't last terribly long. I can't say there's many times I'm pedaling on unpaved roads much above 25mph.

A 40 front with 11x40 rear is all the range a gravel bike needs. 46 x 11 is a little overkill on the top end unless you prefer to pedal downhill instead of tuck in. If it's going to do a lot of road duty, then it's hard to not do 2x. Of 5 bikes, my only 2x is a dedicated road bike. I would go 2x again on the tt bike if I race something long and hilly.

I'm with PoolBoyMatt on the SRAM 10-42 cassette. That 10-12 jump drives me bonkers and I can't say I have ever noticed 'gaps' in a cassette other than that. The 11-40 cassette is about perfect for me in a gravel application.
2
El Train
19 posts
#8Jul 19, 2017, 11:50 AM
WHere do you live? That is question one.
If its flat, I think 1x is viable. The range of speeds are a lot smaller on flat terrain.
If you have hills or mountains, the range of speeds on a ride are pretty wide.
I live in the Northern Rockies and run 3X! Need lower than 1:1 for the steepness, this lets me run a 26/30 low gear and have a nice close spaced cassette.
1
ronij
14 posts
#9Jul 19, 2017, 12:24 PM▲ Top
A big factor that people always seem to gloss over when discussing 1x vs. 2x is fitness. If you're a super strong climber and you can climb 10%+ gradients at 7 or 8mph, then you don't need to have a 1:1 ratio and you may do just fine running 1x. On the other hand, if you're going to be climbing at 3mph, maybe you're going to need a larger gear range.

Similarly, your preferred cadence will have a large effect on your decision. For example, if you are fine pedaling at a cadence of 60rpm, you won't need as low a gear as the person who prefers to pedal at a cadence of 90rpm.

In other words, the decision of 1x vs 2x (vs 3x!) is not the same decision for every rider and needs to be made based on your own strengths and weaknesses.
4
scottNU
7 posts
#10Jul 19, 2017, 10:04 PM
Wow! Thanks for all the great input. Very helpful.

Thank you!
0
Smithhammer
103 posts
#11Jul 19, 2017, 11:56 PM
ronij wrote:
In other words, the decision of 1x vs 2x (vs 3x!) is not the same decision for every rider and needs to be made based on your own strengths and weaknesses.

This, in a nutshell.
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kklasman
18 posts
#12Jul 20, 2017, 6:13 AM
I'm with bobknh, in that I use my 44x30 and 11-40 11-spd as a 2 x 1x system. The wide range cassette means I don't shift the front very often and while I stay in the bigger ring most of the time, I've got super low gears available when I want/need them.
2
bobknh
794 posts
#13Jul 20, 2017, 6:52 AM
dangle wrote:

Nobody is right or wrong. If you are leaning towards a 2x, do it. There's a good chance you'll always wish you had gone 2x if you have a 1x setup.

Specific to your points:

What's your mt bike chainring? A 32? A 32 x 11 is a somewhat low combo. It's not really an apples to apples comparison. 32 x 11 on my mt bike feels limited (to me) riding to the trails.

Low end gearing
I'm a fan of trying to get a 1:1 ratio (I like gear inches better, but this is simple to
explain) on the low end if you're going for some of those adventure rides with regular double digit inclines on gravel or dirt where standing to pedal isn't an option. Even with a 2x, that's still putting an 11-36 (or soon to be released 11-34) cassette on the back. An 11-32 gets you close enough with a 34 up front and is what I did most of last year. I'm on 42 x 11-40 since last fall and that's working great for the loose, steep climbs in the driftless region.

High end gearing.
A true gravel bike doesn't need anything bigger/faster than a 38 or 40 up front. I used my cx bike with road tires for some spirited group rides and even with 'only' a 42 up front I was fine. 90 rpm is putting you at 27mph in the 42x11. Anything quicker really doesn't last terribly long. I can't say there's many times I'm pedaling on unpaved roads much above 25mph.

A 40 front with 11x40 rear is all the range a gravel bike needs. 46 x 11 is a little overkill on the top end unless you prefer to pedal downhill instead of tuck in. If it's going to do a lot of road duty, then it's hard to not do 2x. Of 5 bikes, my only 2x is a dedicated road bike. I would go 2x again on the tt bike if I race something long and hilly.

I'm with PoolBoyMatt on the SRAM 10-42 cassette. That 10-12 jump drives me bonkers and I can't say I have ever noticed 'gaps' in a cassette other than that. The 11-40 cassette is about perfect for me in a gravel application.

+1 on most of your gearing comments - especially high end. I use my gravel bike in the warmer months in rural NH. I can more or less run my 36 all day without ever shifting up to my 46. OTOH, when I'm doing high speed group rides on pavement in the winter in SC low country -- the 46 x 11 is more than adequate- even in sprints. Good comments and observations. If I were ever to go 1x on gravel, I think that a 36 would be more than adequate -- at least on the choppy hills of southern NH.

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bobknh
794 posts
#14Jul 20, 2017, 7:06 AM
shoota wrote:I'm with Bob on this one. I like my 2x. I fail to see how the "simplicity" of a 1x is worth sacrificing either low end, high end, or jumps between cogs. I guess I just don't find changing between chainrings all that cumbersome.

I agree about front shifting not being cumbersome. But that speaks to other factors like the the tooth differential between the chain rings, the quality of the front der. and it's installation, and rider skills and habits. I'm running a eTap front der. with my 46/36. Once the eTap is setup up, you can more or less forget about missing a shift, dropping a chain, or chain suck. I also habitually avoid cross chaining, and shifting under high chain tension. It's just a habit that comes from years of racing. It's about paying attention to the road, and anticipating the need to shift early. I started riding with 2x5 10 speed bikes with down tube unindexed Campi shifters! I've never been a fan of the "compact crank" with a 50/34 set up. This gear set was an invitation to cross chain, and dropped chains. Notice that many new road bikes now come with built in chain watchers to prevent disasters. IMHO a 16 tooth drop is too big for practical riding.
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dangle
465 posts
#15Jul 20, 2017, 10:00 AM
ronij wrote:A big factor that people always seem to gloss over when discussing 1x vs. 2x is fitness. If you're a super strong climber and you can climb 10%+ gradients at 7 or 8mph, then you don't need to have a 1:1 ratio and you may do just fine running 1x. On the other hand, if you're going to be climbing at 3mph, maybe you're going to need a larger gear range.

Similarly, your preferred cadence will have a large effect on your decision. For example, if you are fine pedaling at a cadence of 60rpm, you won't need as low a gear as the person who prefers to pedal at a cadence of 90rpm.

In other words, the decision of 1x vs 2x (vs 3x!) is not the same decision for every rider and needs to be made based on your own strengths and weaknesses.

I'm not saying 1x is the solution for everybody. Fitness is also a good consideration. I think your example is a little misleading though. 3mph is a pretty extreme number. I don't think it's very easy to keep a bike balanced in the low 4mph range, let alone 3. 3mph and you would be safer walking....at a similar speed. People that confident in their bike handling to grind up a hill at 3mph probably already have their minds made up entirely as to what drivetrain they want. A 1x specific 38 x 40 at 60 rpm will get you in that wobbly low 4mph range too.

The other thing is how do you get that low in your gearing going 2x unless you're getting creative with combining long cage mt bike derailleurs with road shifters? Yes, it's totally possible (and easier with SRAM). I have seen several X5 or X7 SRAM rear derailleurs paired to SRAM road shifters. However, sticking to road parts, the smallest gear I can think of in the 11 speed world (staying somewhat close to the recommended specs of any road group) would be a hard to find 46/30 crank with the currently available 11-32 cassettes. If you tried throwing a SRAM 11-36 cassette on, you would have to run your chain too short and a big/big cross chain (which you shouldn't do anyways) would rip the rear derailleur off. Shimano GS and SRAM WiFli are both supposed to max out at 37 tooth chain wrap capacity. That means with a 46/30 crank (16 tooth difference) you have 21 teeth to work with for the cassette. That gives you an 11-32. I'm assuming the yet to be released Shimano 11-34 11 speed cassette could still work since chain wrap capacities are slightly conservative, but I KNOW from trying than an 11-36 either leaves the chain slack in the small/small configuration or won't shift into the largest cogs when in the big ring (you shouldn't do that either). So you have a Shimano or SRAM approved 30 front with a 32 rear as your lowest 'road' combo.

For example, say you're rolling on 700 x 38mm tires with 175mm cranks. That puts you at 25.6 gear inches. Take that same setup with a 1x and a 36 front and 40 rear. That's a full gear inch lower at 24.6. Increasing the front ring to a 38 gives you 26.0 gear inches which is pretty darn close to that 25.6. Selling 2x as the best way to get needed low end doesn't make a lot of sense. The person that needs to be that low for climbing doesn't likely need to be geared higher than a 38 x 11. Also known as 25+ mph at 90 rpm with that same setup.

I suppose a mt bike 2x crank with a clamp on front derailleur (to get it lower enough vs a braze on) is an option too. Then you're getting to the point where your top is limited to a 36 or 38 anyhow. I suppose it gives you less 'jumps' in gears.

Have they made road shifters in a 3x configuration in the last 10 years? I kept a comfy Giant road bike until this year with a 6703 set on it. Even with a 'long' cage derailleur, the lowest I got was 1:1 with a 30 front and 12-30 rear. I have no problem with 3x. Everything shifted perfectly. Lots of redundancy and I almost always shifted by 2 or 3 gears at a time though.

I guess this just supports the idea that there is no one perfect solution for everybody. I'm just trying to point out that 1x is not as limited as some on this forum would lead you to believe. I know very few people that actually tried 1x that had any real issues with it. I'm going to ride my 2x road bike Saturday and love it.
dangle
465 posts
#16Jul 20, 2017, 10:01 AM
kklasman wrote:I'm with bobknh, in that I use my 44x30 and 11-40 11-spd as a 2 x 1x system. The wide range cassette means I don't shift the front very often and while I stay in the bigger ring most of the time, I've got super low gears available when I want/need them.

Impressive. What rear derailleur are you using?
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ronij
14 posts
#17Jul 20, 2017, 11:15 AM
dangle wrote:

I'm not saying 1x is the solution for everybody. Fitness is also a good consideration. I think your example is a little misleading though. 3mph is a pretty extreme number. I don't think it's very easy to keep a bike balanced in the low 4mph range, let alone 3. 3mph and you would be safer walking....at a similar speed. People that confident in their bike handling to grind up a hill at 3mph probably already have their minds made up entirely as to what drivetrain they want. A 1x specific 38 x 40 at 60 rpm will get you in that wobbly low 4mph range too.

[...]

I don't disagree with you. To be clear, I run a 1x setup and have no plans on going back. My point was that with better fitness, you can run a tighter rear cluster as you won't be going as slowly and that this is a good consideration for some people.

As for my speed estimates, I should have paid closer attention to my math - I was converting from km/h to mph since I assume most people here are American. I find that I'm typically climbing on my gravel bike around 14km/h (9ish mph) and often chat to people going much slower, probably around 4-5mph and while that may seem pretty slow to many, it's not uncommon on climbs that average 8-10%+ for 10 miles which are pretty common in the PNW when gravel racing/riding.
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bnystrom
459 posts
#18Jul 21, 2017, 8:59 AMedited
As someone who's primarily a roadie and a former racer, I really dislike big gearing jumps on my bikes. All it takes to get an adequate range for gravel and small gearing jumps on a 2x is a bit of creativity. My original 'cross/gravel bike has a 39x24 crank, which was originally a triple, but now has a chainguard/bashguard from BBG in place of the big ring. The cassette is an 11-25, which gives me a lower than 1:1 at the bottom end and a high end that's adequate for my off-road needs (dirt & gravel in the NH and VT hills), with nice, small jumps between gears. If I ever felt the need to go lower, there are plenty of cassette options.

My new rig - a Niner BSB 5-star build - has a 46/36 with an 11-32 in the rear. For me, the low end isn't low enough, the high end is simply ridiculous (way too high even for road use) and the gearing gaps are barely tolerable. I'll shortly be replacing the crank with a 44/30, which fixes the low-end problem, but the high end is still more than I need and the gaps don't change. Unfortunately, nobody makes a 12-32, 11-speed cassette, which would be great.

I would like to use a MTB crank and a tighter cassette, but there are two issues preventing that:
1. The frame has a 135mm rear end, but it's designed for the chainline of a road crank.
2. The bike has Di2, so changing to an MTB front derailleur to work with the smaller chainrings would require changing to an MTB rear derailleur too, due to designed-in restrictions in the Di2 firmware (Shimano, you suck!). I really don't want to spend the extra money for a rear derailleur that I don't need.
Regarding Di2, I found that the closely-spaced buttons make it way too easy to miss-shift when you're getting bounced around on a rough surface, but there's a pretty simple workaround. I've reprogrammed the system to use Synchro Shift with both buttons on the left set to downshift and both buttons on the right set to upshift. The point here is that no matter how badly I get rattled around, all I need to do is find either button on the appropriate side to make a shift. It will work perfectly with winter gloves on, or even mittens, for that matter. So far, I like it and haven't found any issues with it. Shifting can't get any simpler.
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drwelby
531 posts
#19Jul 21, 2017, 7:17 PMedited
bnystrom wrote:Unfortunately, nobody makes a 12-32, 11-speed cassette, which would be great.

I think there's a combo where you can use the bottom 8 cogs from the 12-28 with the top 3 cog carrier from an 11-32.

If you want really tight gears and don't need top end you might be able to bosh something together with the 14-28 junior freewheel, which has 1 tooth jumps from 14 to 21 teeth, though you'd want to drop the 20 and find a 23 to stick after the 21.

bnystrom wrote:The frame has a 135mm rear end, but it's designed for the chainline of a road crank.

Can you elaborate on this?

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ronij
14 posts
#20Jul 21, 2017, 7:29 PM
Couldn't you take an 11-32 11sp cassette and swap the bottom 4 or 5 cogs from an x-12 11sp cassette?
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