12 sp SRAM NX / SLX M7100 & Chainset limitations

[RecumbentRide]

I have a question regarding chainring sizes as I'm hoping to make the change to a 12sp setup soon.

My current gear range in inches is 18-81 (using a 9 speed cassette and triple front combined with 24in wheels). If anything I'd want to lose something at the bottom end of the range so that I can get as close to 90in. Also I'm aiming more towards a touring setup than speed.

To get something like a gear range of 20-90in I was hoping to be able to use a 45 tooth chainring but notice with SRAM this is not possible with the 12 sp groupset, or even the 11sp groupset. Actually the single chainring setup with both Shimano and SRAM seem to top out at 34! Why on earth so they not have more options. I don't want to have to use a front derailleur and want to stick with solely a rear derailleur setup.

I'm posting this as I may be missing something so any input from those wiser than me would be appreciated.

[Brucey]

that chainset is meant to be used on a 29er type MTB (probably with a daft 10T sprocket), not on a 24" wheeled road machine, so large chainrings are not usually required.

You may be able to buy an aftermarket chainring in a different size though.

However you won't be able to buy a 45T chainring in 'narrow-wide' format; it is even tooth counts only.

FWIW I would guess that it might be a lot easier to get the gears exactly how you want by revising the 9s setup. A 1x12 setup might suit some folk but on a recumbent (moreso than on an upright) you are liable to be using very low gears when climbing or high gears when descending. This is OK but it means that you get to spend more time running cross-chained; probably not an issue if you have a long chain run. The other thing that you can't so easily escape from is that if you have top gear of 90" then when cruising (at about 70"?) then you will still be using a tiny drive sprocket at the back. This will be inherently less efficient than it needs to be and will also wear more quickly than it would if it was larger.

cheers

[RecumbentRide]

Food for thought indeed thank you. But I'm relieved to know I'm not tied to the SRAM setup up front. I'm still determined to go for the single chainring 12sp setup though and it's simplicity. I've heard good reports from those who have tried it.

After doing further research I've also been led to believe that I can use a 12spd chain on a 11 spd single up front as the internal diameter is the same on the chain for the 11s & 12s and if this is true it would give me more options. I'm after the NX 12spd cassette, chain & derailleur. I'd just get the chainset from somewhere else I think.

BUT I'm now wondering if I did get the Sram NX 12spd single chainset could I remove the chainring and replace it with a ring from another manfacturer to give me the 44 or 46 I want up front.

[NickJP]

I recently setup a bike for my wife using a Sunrace 11-50 12-speed cassette and GX Eagle cranks with a 36t chainring. With the 650B wheels, that gives a gear range from 19" to 88". SRAM make a 36t chainring - I bought the cranks without chainring and purchased the 36t chainring separately. The shifter, RD, and chain are all SRAM 12-speed. The Sunrace cassette fits on a normal 10-speed Shimano cassette body.

I also have another bike setup with 1x12 where the cranks were originally Deore XT 2x10 - I just fitted an aftermarket narrow-wide 36t chainring and that works fine with the rest of the components.

[djnotts]

It all sounds very complicated to me. On my rather nice, cheap, 531 atb style tourer dirt cheap 3 x 7 with lovely xt thumbies gives 20 to 100" range on 26 x 1.5 tyres. And it all just works!

[zenitb]

It all sounds very complicated to me. On my rather nice, cheap, 531 atb style tourer dirt cheap 3 x 7 with lovely xt thumbies gives 20 to 100" range on 26 x 1.5 tyres. And it all just works!

Sounds lovely...would love a photo DJ !!

Regarding the OP's query the SLX clutch mech SHOULD keep the chain on the single chainring...although a chain guide is an option if the chain starts falling off..

[djnotts]

It all sounds very complicated to me. On my rather nice, cheap, 531 atb style tourer dirt cheap 3 x 7 with lovely xt thumbies gives 20 to 100" range on 26 x 1.5 tyres. And it all just works!

Sounds lovely...would love a photo DJ !!

viewtopic.php?f=15&t=3832&p=1405940#p1405940

Towards the bottom of the page!

[Brucey]

unless you are absolutely scrupulous about changing your chain regularly (and not even then, sometimes) cassettes wear out faster than almost any other bicycle part. This goes double for an arrangement where you are having to use a small sprocket most of the time on the flat, because you only have a stupid small chainring.

So the idea of using 1x12 doesn't in the slightest bit appeal to me for the simple reason that when the cassette is worn (which I think will happen sooner rather than later), it will cost about a hundred quid for another one. There would have to be a compelling advantage of some kind to make me even consider it.

Please don't try and tell me 'it is so much simpler'; it clearly isn't...

cheers

[zenitb]

It all sounds very complicated to me. On my rather nice, cheap, 531 atb style tourer dirt cheap 3 x 7 with lovely xt thumbies gives 20 to 100" range on 26 x 1.5 tyres. And it all just works!

Sounds lovely...would love a photo DJ !!

viewtopic.php?f=15&t=3832&p=1405940#p1405940

Towards the bottom of the page!

OT I know but I read your posts on it and it looks like a unique touring bike well ahead of its time. 531 MTB tubing...!!!! ..I'd buy that for cycle camping/touring now if I could Going back to your original point I agree 3x7 is still as good a solution as it ever was (and I still use Deore 7spd thumbies )

[RecumbentRide]

unless you are absolutely scrupulous about changing your chain regularly (and not even then, sometimes) cassettes wear out faster than almost any other bicycle part. This goes double for an arrangement where you are having to use a small sprocket most of the time on the flat, because you only have a stupid small chainring.

So the idea of using 1x12 doesn't in the slightest bit appeal to me for the simple reason that when the cassette is worn (which I think will happen sooner rather than later), it will cost about a hundred quid for another one. There would have to be a compelling advantage of some kind to make me even consider it.

Please don't try and tell me 'it is so much simpler'; it clearly isn't...

cheers

YES your absolutely right! What was I thinking

[swscotland bentrider]

David at Laid-back has a 1 x 12 setup on his utility Fuego. He has run that system for a good few months and says it works well. But, of course on a 26" rear wheel.

I have just finished building a Nazca Gaucho. Like RecumbentRide I am a tourer. I liked the idea of 1x12 but decided it couldn't work for me. Big gaps between gears and a barely adequate top gear. The wear issues also concerned me.

On my Fuego (3 x 9) I tried blanking off the big ring leaving only the 30/39 available just to see how it felt. It was OK but I was in the top three gears most of the time and span out on any downhill slope.

So my Gaucho has a Tiagra 10 speed double (34/48) with 165 cranks. Cassette 11 - 36. So far so good. From my experiment with the Fuego I reasoned that I would spend nearly all my time on the 48 ring and only rarely would need to change to the 34. And all the components were relatively inexpensive!

[RecumbentRide]

It all sounds very complicated to me. On my rather nice, cheap, 531 atb style tourer dirt cheap 3 x 7 with lovely xt thumbies gives 20 to 100" range on 26 x 1.5 tyres. And it all just works!

Nothing wrong with your setup at all if it does what you need. I love seeing the 531 tubing when I come across it.

For me my current setup didn't endear me when I was touring last year and I yearned for a straightforward evenly spaced spread of gears instead of messing about with front and rear derailleurs. I've cycled most of my life and it's never been a problem before. But it is now!

Some people settle for Rohloff hubs some people are fine with a 3 speed setup (Heinz Stücke, globetrotter).

What can I say?

[Brucey]

http://ritzelrechner.de/?GR=DERS&KB=44&RZ=11,13,15,17,19,21,24,28,32,36,42,50&UF=1910&TF=90&SL=2.5&UN=MPH&DV=gearInches&GR2=DERS&KB2=34,50&RZ2=36,13,15,17,19,21,24,28,32&UF2=1910

compares 1x12, 11-50T cassette, 44T chainring with 50-34 x9 using a 13-36T cassette. Honestly, I'd prefer the 2x9 setup for most of the riding I'd do.

cheers

[RecumbentRide]

http://ritzelrechner.de/?GR=DERS&KB=44&RZ=11,13,15,17,19,21,24,28,32,36,42,50&UF=1910&TF=90&SL=2.5&UN=MPH&DV=gearInches&GR2=DERS&KB2=34,50&RZ2=36,13,15,17,19,21,24,28,32&UF2=1910

compares 1x12, 11-50T cassette, 44T chainring with 50-34 x9 using a 13-36T cassette. Honestly, I'd prefer the 2x9 setup for most of the riding I'd do.

cheers

Thank you for the link I will have a look at it.

What's on paper isn't going to necessarily describe the feeling of actually riding the proposed setup. One has got to try these things out and I'm happy to make the commitment and if it doesn't work then I'll try something else. But I hope to come back and provide feedback once I've given it a trial.