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Drivetrain advice


RDL101
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Posted (edited)
1 hour ago, TheoG said:

Sorry not true.  Put a 11sp and 12 sp cassette on a flat table and compare the height, it is the same, hence you need "smaller" shifts for 12sp.

If the cog spacing differs then there's no way the pull ratio between 11 and 12 speed is the same. 

Edit: You're contradicting yourself. You just said that your comment was clearly a joke - so given the same pull ratio, sram 11/12 speed rear derailleurs is not shifter dependent. Now you're saying that "you need "smaller" shifts for 12sp."

Okay dankie baai.

Edited by M L
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58 minutes ago, TheoG said:

Yes if you use it with a 12sp cassette.  12sp shifter with a 11sp cassette will NOT work properly over the full range.  You might be able to get the majority of the gears to work OKish, but it would never shift as its supposed to.

Correct 

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21 hours ago, RDL101 said:

Good afternoon. Wanted to know if one can use a 12speed sram shifter in a 11 speed sram derailleur and cassette. 11 speed shifters seems difficult to source at the moment and I already have the 11 speed derailleur. 
Thank you in advance

nope not possible unless you change the internal mechanism. Easier to convert a SRAM 11speed shifter to 12speed with aftermarket kits from these guys:

https://www.singletracks.com/mtb-gear/take-a-sram-11-speed-to-12-with-a-kit-from-ethirteen/

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18 hours ago, ChrisF said:

 

And yet many users have stated that this mixing works 100% ....

 

somehow either one of these statements are correct and the other one not ......

 

Would love to know the CORRECT facts and options .....

It is only true for Shimano 12 speed and SRAM Eagle.

9, 10, and 11 speed units are not compatible between Shimano and SRAM

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why i'm considering building a bar end friction shifter into my next project....you can use them with any and all rear mechs, even the latest and greatest mechanical 12 speed things. 

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39 minutes ago, M L said:

If the cog spacing differs then there's no way the pull ratio between 11 and 12 speed is the same. 

Pull ratio is how much the derailleur moves relative to how much the cable is pulled and has nothing to do with cog spacing. They can definitely be the same even if cog spacing is different because the differing spacing is handled by how much cable the shifter actually pulls per shift.

What is important is that the shifter and derailleur are designed for the same pull ratio otherwise you will get too much or too little movement per shift.

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Posted (edited)
8 minutes ago, Jehosefat said:

Pull ratio is how much the derailleur moves relative to how much the cable is pulled and has nothing to do with cog spacing. They can definitely be the same even if cog spacing is different because the differing spacing is handled by how much cable the shifter actually pulls per shift.

What is important is that the shifter and derailleur are designed for the same pull ratio otherwise you will get too much or too little movement per shift.

Shimano  allows 'moderm wide range' 11 speed setups running the new 5100 11-51 casettes, using the 12 speed derailleurs with the 11 speed shifters from the previous gen setups. Their m7000/8000 11 speed derailleurs cant go higher than 46T in the rear, so you use the 6100/7100/8100/9100 ones.

Edit, not to mention (i'm sure it already has been) the 9100 stuff can be set up either 11 or 12 speed right out the box. the pull ration of the shifter is the most important. Like i mentioned above, also why you can use any and all mechs with friction shifters still. When there is no indexing....it's still just a cable pulling on a spring that moves a parallelogram that pushes the chain to the next ring.    

Edited by MORNE
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Posted (edited)

the reason you cant mix and match road and mtb suff always for instance is because the derailleurs are physically made to move up the cassette differently. look at how a mtb cassette ramps up vs a road cassette. The one is alot more 'parabolic' than the other. The derailleur that demonstrates this the best is the Shimano Saint rear mech. It comes with a little plate that can be added or removed depending on what type of cassette you want to run on your DH rig - close or wide ratio (road or mtb). Adding or removing the plate changes the way the mech is positioned over the gears as it goes up the cassette. if you use it in mtb cassette mode with a road casette....the B-Screw gap gets bigger and bigger as you move up the cassette...and shifting eventually gets crap. the other way around and it will hit the casette around the 5 th or 7th gear as the B-gap gets smaller. I've tried it myself to see.

Edited by MORNE
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1 hour ago, M L said:

If the cog spacing differs then there's no way the pull ratio between 11 and 12 speed is the same. 

Edit: You're contradicting yourself. You just said that your comment was clearly a joke - so given the same pull ratio, sram 11/12 speed rear derailleurs is not shifter dependent. Now you're saying that "you need "smaller" shifts for 12sp."

Okay dankie baai.

I'm not contradicting myself, please read properly.

Lets rephrase:

1.) If the shifter & cassette match each other (11-11 or 12-12, you can possibly make the derailleur (10/11/12) work regardless.

2.) If the shifter & cassette do not match, no way it will work properly.

And that is what I was saying all the time with the exception of my joke/sarcastic post.

 

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Posted (edited)

For what it is worth - 

Deraileur shift or actuation ratio is the amount the deraileur moves per the amount of cable movement. e.g. older shimano deraileurs are 1.7x - the deraileur moves 1.7x as far as the cable does.

So if you have 2 deraileurs with the same shift ratio they are then interchangeable. the 11s shifter used with the deraileur will give you 11s gears and the 12s shifter will give you 12s. (I haven't checked that the shift ratios are the same here, that was someone else's claim).

Back in the mists of the past when we had 10s and 11s groupsets the cog pitch was the same for both arrangements, the 11s cassette was just 1 cog taller (but the shift ratio was different). In this case you could install a 10s groupset (shifter + deraileur) to give you access to the first 10 cogs on an 11s cassette (or vice versa). 

Edited by 100Tours
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On 5/27/2021 at 2:38 PM, RDL101 said:

Good afternoon. Wanted to know if one can use a 12speed sram shifter in a 11 speed sram derailleur and cassette. 11 speed shifters seems difficult to source at the moment and I already have the 11 speed derailleur. 
Thank you in advance

To get back to your original Q. In your particular case some of the gears will be 1/12 out at some point .I only know of Shimano shifters that can be altered between gear ratios 

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46 minutes ago, eala said:

To get back to your original Q. In your particular case some of the gears will be 1/12 out at some point .I only know of Shimano shifters that can be altered between gear ratios 

Yip, as far as I know its only the Shimano XTR 12sp shifter that can toggle between 11 and 12 speed.

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36 minutes ago, BaGearA said:

Only heard of this working on 12 speed systems , NOT 11spd 

 

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5 minutes ago, BaGearA said:

cool thought we were discussing sram and shimano 

Cool, you posted directly after my post without quoting anyone so I assumed you were commenting on my post ... 🙈

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