I mostly ride in the Chicago area and it's exceedingly flat here. So much so that I'm looking at using a 12-25 cassette in my setup. Maybe something like 12-25 + 46/36 or 12-25 + 40T.
I'd like to switch to Di2 and also like the appeal of a 1x clutch derailleur to reduce chain slap. Unfortunately it seems that these two can't be combined since Shimano calls for a 11-40 or larger cassette with their 11sp mountain rear derailleurs. Gravel Cyclist had posted a video on YT with an XT/XTR rear derailleur and a road cassette and the shifting was sloppy even with Di2.
So this leaves me in a position of having to choose between Di2 and mechanical 1x clutch derailleur. Would appreciate your thoughts on the merits of both for gravel riding, if you could only have one. I don't race and mostly ride alone.
Narrow wide and tall short chainrings are pretty great at holding chains so you don't need a clutch.
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\nI've been running 1x campy chorus for like 2k miles and have never dropped a chain.
Thanks for your feedback. I haven't yet dropped a chain yet on my 2x Ultegra, but the chain slap is pretty bad in some of the areas I ride in, which is the main motivation. I've heard the 1x clutch makes the drivetrain much quieter due to the added chain tension.
An employee in a bike shop today mentioned that his Force 1 group shifts a bit firmer/clunkier due to the clutch drag/tension, more so than even standard Sram vs. Shimano. Not sure if this is the case with Force 1/ Rival 1 or down to the tuning of the drivetrain on his bike.
Oh, I never notice chain slap, but I also have a bunch of stuff on my bike that rattles so all the noise kind of blends together. You could wrap your chainstay or put a sleeve on it.
vinuneuro wrote:I mostly ride in the Chicago area and it's exceedingly flat here. So much so that I'm looking at using a 12-25 cassette in my setup. Maybe something like 12-25 + 46/36 or 12-25 + 40T.
I'd like to switch to Di2 and also like the appeal of a 1x clutch derailleur to reduce chain slap. Unfortunately it seems that these two can't be combined since Shimano calls for a 11-40 or larger cassette with their 11sp mountain rear derailleurs. Gravel Cyclist had posted a video on YT with an XT/XTR rear derailleur and a road cassette and the shifting was sloppy even with Di2.
So this leaves me in a position of having to choose between Di2 and mechanical 1x clutch derailleur. Would appreciate your thoughts on the merits of both for gravel riding, if you could only have one. I don't race and mostly ride alone.
If you asking my advice since you said you aren't a racer. I am still kind of the newbie to gravel riding. I am not 100% what chain slap is. When I ride my 2016 Raleigh Tamland 1 which I changed the gearing from 11 x 32 Shimano to 11 x 36 Sram with road link and stop pedaling real quick the chain jumps some. My LBS showed me that all bikes do that but my Tamland looks like it does it more. He said he could put a mountain derailleur on it to maybe stop it some. The bike was heavy so I decided to buy the Roker Comp which has 1x Sram Rival. Never had 1x before and it's a learning curve for sure. If I had it to do over again I probably would have bought the Roker Sport to stay with Shimano 2x just sayin. Not sure why you want Di2 if you aren't racing unless you want the bling or have some money to spend. Right now I don't think I will ever have Di2 but then they never say never. I still have a flip phone and no I phone and just bought a Garmin computer for my bike which for sure is a hard learning curve for me. Good luck in whatever you decide.
After trying clutch RDs I can't go back to "normal" ones now. One of the reasons I went with SRAM 1x is because the factory drop bar groupset has a clutch RD, you don't have to buy the derailleur separately and use adapters etc.
The quietness a clutch RD gives you is just so good. Now when I get on a bike with a non clutch RD and hear the chain slapping on the chainstay my first thought is that something is broken.
So IMO(!) clutch RDs are simply awesome and personally I would put them on everything (even road bikes, well actually I did that). When I choose a drivetrain the clutch RD is an important factor for me.
BTW a clutch doesn't put more tension on the chain, it's not a spring. It keeps the tension in the chain better over rough terrain. When you compare SRAM and Shimano road stuff SRAM has a much more positive and louder click as you shift, but the clutch is not so heavy that it's hard to push the lever. I have Shimano clutch RDs where you can turn the clutch on and off and you can adjust the tension. When you crank the tension up to a silly level you can feel it at the lever but at normal tension there is barely any difference.
1. Pad your chainstay (easy and effective). 2. Accept 11-40 1x gearing (which works for me everywhere in the Chicago area). 3. Give up on Di2 (which would be a shame).
I would add a couple notes here. When I first considered 1x gearing, I spent some time figuring out what gears I actually use in what situations, and did some graphing and analyzing. For my gravel bike I ended up with 42x11-40, using Shimano's 11-40 cassette, which has a (slightly) better progression of gears, compared to the SRAM equivalent.
What seems to be the case for me is that on the flats at speed is where you want smaller jumps to maximize cadence efficiency. Here, 17-15-13 are my cruising gears, with the 11 for tailwinds and drafting in fast groups. It's not 1-tooth jumps, but I really don't have a problem with it. On a typical wide-range road cassette, at those speeds with a 53t ring, you'd be up in the 2-tooth jumps anyway (though the 12-25 is probably an exception to that). The 42/11 is good for speeds up to about 30mph at a high but still comfortable cadence. I spin out on big paved descents, but we don't have many of those around here, do we? And what's wrong with coasting anyway?
When you hit the hills, especially the ones that transition quicker, which is more typically the case when it's not paved, you don't want those tight gear jumps. The 11-40 gives you 21-24-27-31-35-40. Nice solid jumps all the way down to almost 1:1. Low enough to get up almost anything.
If we lived in Colorado, we'd be having a different conversation. But in Chicagoland, 42x11-40 works really well for me, even though most of my riding is flat. And when I do get out on the hilly rides, it works really great there too.
I'm a big fan of 1x, ever since I started experimenting with it on my XC mountain bike back in the pre XX-1 days. I have it on 3 of my 4 active bikes. From where I sit, it's 2x that introduces unnecessary complications. Again, though, if we lived in Colorado (me and the original poster) that would be a different conversation.
Didn't mean to start advocating 1x here. My point, re the OP's conundrum, is that if he wants a gravel bike with Di2 (and I'm with him there—I love Di2) and a clutch (also valid), then he may want to reconsider embracing that 11-40 cassette, which, where he lives, wouldn't make much sense with double rings. I live in the same area and have solved the same problem for myself, doing it that way.
As an alternative, if he really wants that 12-25 (also valid), then if the issue boils down to chain slap, maybe padding the chain stay is the simple fix, allowing him to use road Di2 derailleurs, either one or two.
Sorry guys—I definitely didn’t mean to take this off in a 2x vs 1x direction. There are certainly no shortage of those out there!
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\nI may have misunderstood the OP. It seemed he was considering the merits of a 2x setup using Di2 vs. going 1x with a clutch RD. I only intended to add my take that 2x for his terrain and style sounded like a good choice and would remove RD complications from the equation. I did not fully appreciate chain slap was the main thing he’s looking to address.
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\nI should have fully read the other posts, too. Tim has some very good thoughts on 1x setups.
13-14-15-17... would be interesting, but in my case I think I'd need to go from a 42 in front all the way to a 50 to replace the 42-11 I use regularly in tailwinds situations. (I'm 64yo BTW, with an FTP around 200, if that helps anyone guage my remarks about speed, etc.)
The OP mentioned 12-25 x 46/36. 46x12 ends up being almost exactly the same as 42x11. At the other end, though, 36x25 doesn't come anywhere near 42x40. Perhaps a 46/32 or even 46/30 might be a nice pairing with the 12-25. Still not as low a low as a 42x40, but not bad. And, of course, the advantage of small jumps everywhere.
Tim, I hear what you're saying, but when over 30 miles a typical ride for me only has around 600ft of total elevation, I'm not sure if I can rationalize an 11-40? I'll have to play with the gear calcs more.
drwelby, that's a great idea, but unfortunately Shimano specs the min and max of the smallest cog at 11T. I'm not sure how much one would be able to get away with, maybe a 12T? Similarly would one be able to get away with a running an 11-36 when they call for a minimum 40T at the big end?
Someone had posted that the Shimano mechanical rear derailleurs can be taken apart and the tension spring reclocked to a different position to increase chain tension by 25(?)%, detailed in the first link below. And I believe Gevenalle sells a modified/beefed up rear mech with higher tension, second link. Is something similar possible with Di2 road derailleurs?
Is there any merit in running a 1x road setup? I think until this year (they've now switched to Force 1), Giant spec'd a 1x Ultegra Di2 groupset on their upper end TCX with a narrow/wide crankset and chain guide. With syncro-shift now available to completely handle front shifting, I guess there's no point losing the range if I won't be getting the clutch rear derailleur anyway?
"Dedicated" 1x groupsets don't use any black magic. Plenty of people just take off their FD and one of the chainrings of their 2x crankset. If you don't have a clutch RD I would definitely get a narrow wide ring for safety. You also need to watch the chainline.
Luckily there are options, Wolftooth makes narrow wide chainrings that are compatible with the asymetric Shimano 4 bolt standard, and they're even offset so your chainline is better with a 1x setup. So that's definitely an option.
vinuneuro wrote:/>drwelby, that's a great idea, but unfortunately Shimano specs the min and max of the smallest cog at 11T. I'm not sure how much one would be able to get away with, maybe a 12T? Similarly would one be able to get away with a running an 11-36 when they call for a minimum 40T at the big end?
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\nFWIW, I run Shimano XT long cage MTB rear derailleurs (M772) rated for 11T min/34T max on bikes with a 12-28 road cassette, 13-36 MTB cassette and one with a 12-36 MTB cassette with no issues. Adjusting the B screw can help accommodate the non-spec cassette teeth.
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\nPoint is, in my experience you can get away with cassette sizes a few teeth outside of the limits Shimano specifies.
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\nAnother variation on drwelby’s suggestion might be to consider using some larger cogs on the high end of the cassette in combination with a larger big ring on the front. For example, a 6800 11-32 cassette has 11-12-13-14-16-18...if you drop the 11-12 and swap in the 15 and 17 from your 12-25 cassette and go with a 52/36 ring combo, that gives you a nice straight block on the high gears at speed while maintaining a similar top gear to what you’d get with 46/11. On the low end, 36/32 seems like it would be plenty low for Chicagoland. What I’m wondering, ultimately, though is whether being in a larger ring/cog combo to achieve any particular gear on the high end (say 52-13 vs 46-11) raises your chain higher above the chain stay to mitigate your chain slap issues.
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\nAdmittedly a little unorthodox, but another idea.
OffB10Path wrote: FWIW, I run Shimano XT long cage MTB rear derailleurs (M772) rated for 11T min/34T max on bikes with a 12-28 road cassette, 13-36 MTB cassette and one with a 12-36 MTB cassette with no issues. Adjusting the B screw can help accommodate the non-spec cassette teeth.
Problem is, Shimano now specifies a minimum (!) largest cog as 40T on 11spd stuff. That's a big jump from 25T. Look at videos or pictures, when people use these RDs with tighter ratio road cassettes the B gap is absolutely huge, you can't back out the B screw enough. That's why shifting suffers. Also the B gap won't be as constant since the derailleurs are single pivot and designed for a completely different ratio cassette.
You’re correct. My point on the RD, though, was that a couple teeth outside spec on either end shouldn’t be a problem.
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\nWith respect to the suggestion of modifying an 11-32 cassette to use with a 52/36 ring combo, I was actually thinking you’d use a road mid-cage RD. I should have clarified that, sorry. My thought was that maybe the larger ring-cog combos would mitigate the chain slap so that you wouldn’t need the long RD specced for the 40T cog.
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Plenty of people just take off their FD and one of the chainrings of their 2x crankset. If you don't have a clutch RD I would definitely get a narrow wide ring for safety. You also need to watch the chainline.