Converting Specialized Stmpjmpr (‘16) to 1x11: What Cranks? Hub change?

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Converting Specialized Stmpjmpr (‘16) to 1x11: What Cranks? Hub change?
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Posted: Jan 19, 2020 at 20:56 Quote
I have a 2016 Specialized Stumpjumper FSR comp 27.5 I bought in 2016. It came 2x10 w/ sram S-1250 cranks w/ PF30 BB and x9 derailleurs. I had since converted to 1x10 by removing front shifting/derail and small chainring.

Now I am upgrading to 1x11. I have a Sram GX 11sp rear derail and Sram X1 rear shifter. I will be getting GX or X1 11sp cassette next. (EDIT: Sunrace 11-42T HG driver 11sp cassette! actually!)

I am looking at cranks now. Can I just buy Sram X1 1400 cranks and just pop them on? Or, is there a specific spindle length I need and any spacer adjustments in BB to make chainline better for 1x11?

Also, do I need to adjust rear hub for 1x11?

Posted: Jan 19, 2020 at 20:57 Quote
I found a Sram X1 1400 crank 175mm w/ 30t chainring that is listed for sale with the following specs (see below). Would this work?


X1 1400
X-Sync Narrow-Wide 30t chainring - 0mm offset
11 speed
175mm crank arm length
BB30/PF30 spindle
This is the longer/101mm spindle
spindle spacer not included

Posted: Jan 20, 2020 at 3:56 Quote
There is no functional difference between the cranks. Measure the bcd and buy the new NW chainring to match. Woolftooth has a handy guide on those measurements and what bcd they translate to.
As for your first post, you will need an XD driver to run the gx11 cassette. My guess would be you will probably need a new rear hub altogether. Roval is notoriously difficult brand to get 3rd party parts from. You can much more easily source a Sram nx11 speed or sunrace 11 speed that will mate nicely with your hg driver.
The crank you are looking at should work. It's hard to say if the 0mm offset chainring will be the one you need. Your chain line will determine that.

Posted: Jan 20, 2020 at 11:57 Quote
gotohe11carolina wrote:
There is no functional difference between the cranks. Measure the bcd and buy the new NW chainring to match. Woolftooth has a handy guide on those measurements and what bcd they translate to.
As for your first post, you will need an XD driver to run the gx11 cassette. My guess would be you will probably need a new rear hub altogether. Roval is notoriously difficult brand to get 3rd party parts from. You can much more easily source a Sram nx11 speed or sunrace 11 speed that will mate nicely with your hg driver.
The crank you are looking at should work. It's hard to say if the 0mm offset chainring will be the one you need. Your chain line will determine that.

Thank you. Very helpful!

Regarding Cranks: Sounds like I can use my existing spindle and BB and just put on the new crank arms then. Maybe the included chainring will work, but perhaps I will need a different chainring with a different offset measurement, depending on my chain line. How do I figure this out?

Regarding hub: I didn't realize my current hub won't work with 1x11 cassette. I'll pursue Sram NX11 or Sunrace 11sp HG driver cassettes to use until I upgrade wheels. Thank you for tip!

Posted: Jan 21, 2020 at 7:05 Quote
Both the sunrace and the nx cassettes are fine for 1x11 setups. The only difference between zero and hg is the ability to use SRAMs 1 piece cassette that has a 10 tooth cog. This means a slightly wider gear range given the same size chainring Your current crankset would work fine, change nothing but the appropriate chainring. You cannot swap the spindle on either of those cranks. They are part of the crank itself.

Posted: Jan 21, 2020 at 7:09 Quote
The chain line issue is kind of up to you. I would err toward compensating for the larger chainrings. This will help prevent the chain from moving down the cassette when back pedaling. A 0 offset ring set on the inside is generally ok. Look at woolftooths explanation of chain line for a little more in depth explanation.
https://www.wolftoothcomponents.com/pages/boost-chainline-and-chainrings

Posted: Jan 22, 2020 at 16:11 Quote
gotohe11carolina wrote:
Both the sunrace and the nx cassettes are fine for 1x11 setups. The only difference between zero and hg is the ability to use SRAMs 1 piece cassette that has a 10 tooth cog. This means a slightly wider gear range given the same size chainring Your current crankset would work fine, change nothing but the appropriate chainring. You cannot swap the spindle on either of those cranks. They are part of the crank itself.

Thank you. This is helpful. Would a spindle of 101mm work on my bike?

Posted: Jan 22, 2020 at 17:42 Quote
Could not say for certain. Sounds a little wide for a pf bb setup. Measure your current one and shoot for something in that range.

Why are you insisting on changing the crank?

If you have been running a narrow wide chainring running on your 1x10 setup it is exactly the same as any other 1x11 chainring and the only change on 1x12 for sram is a slightly different tooth profile (x sync 2). You can buy x sync 2 chainrings in any bolt pattern that Sram makes. All of them are 1x 10,11,12 etc. compatible.

Posted: Jan 23, 2020 at 9:18 Quote
gotohe11carolina wrote:
Could not say for certain. Sounds a little wide for a pf bb setup. Measure your current one and shoot for something in that range.

Why are you insisting on changing the crank?

If you have been running a narrow wide chainring running on your 1x10 setup it is exactly the same as any other 1x11 chainring and the only change on 1x12 for sram is a slightly different tooth profile (x sync 2). You can buy x sync 2 chainrings in any bolt pattern that Sram makes. All of them are 1x 10,11,12 etc. compatible.

I guess I should have clarified why I am intent on new cranks... the non-drive side crank arm is slightly bent so there is a slight wobbling (is this a word?) that I would like to correct.

Anyways, I did find some cranks afterall. Sram/Truvativ XO carbon non-boost PF30 (used in EX condition for good price). I also ordered the Sunrace 11sp 11-42T cassette that fits my current rear hub driver. This was a great tip.

Now it's time for the chainring. I am going with 30T and have to figure out offset for correct chainline. Will dig into that wolftooth link shared above. From first glance, it appears that 6mm chainring offset is standard for non-boost bikes such as mine...

Posted: Jan 25, 2020 at 18:29 Quote
The easiest way to determine is to see where the crank sits. Pull a string line to figure out which one gives you a better chain line. If you live somewhere you spend a lot of time climbing you might want to bias toward the big cogs to reduce the wear and tear. If you spend more time in the middle try and get neutral. If you spend all your time in the smallest cogs buy a bigger chainring 8p. Remember there are no wron answers we used to run three chainrings across 10 gears not so very long ago.

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