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Discussion Starter · #1 ·
This is a LONG Post. But I hope it helps someone with the detail provided.
Just finished fixing up my wifes old 2006 (I think?) 26er hardtail for my daughter, by upgrading it to a modern 1x11 wide range M5100 Deore drivetrain.

It used to have a Shimano 3x9 system with FC-M443 non-series crank and RD-M681 Deore LX rear derailleur. Both shifters were not working , the chain and everything else was worn.

The reasons for this option was:
  • Cheaper than equivalent new kids bike. About $300 AUD for parts versus $600+ for new bike
  • Compatibility with old parts. I re-used the crank and rear wheel including the 9-speed HG freehub.
  • Plenty of range for my daughter to get up hills.

What I had to buy:
  • RD-M5100 Deore rear derailleur
  • SL-M5100 Deore 11 speed shifter
  • CS-M5100 11-51t 11 speed Cassette
  • CN-HG601 SLX 11 speed Chain
  • a 34t narrow wide chainring with 104 BCD off ebay
  • a crank-puller tool to remove the octa-link crank from the bottom bracket (To get the old chainrings off)
What I re-used:
  • Old Shimano MT15 rear wheel with 135mm QR axle and 9 speed freehub (Works with 11 speed cassette)
  • The FC-M443 crank (I removed the 3 chainrings)
  • Hanger - had to straighten it
  • Old Deore hydro brakes
What I got rid of:
  • Both front and rear 9 speed shifters and derailleurs
  • old 9 speed cassette
  • old front 3 chainrings
While it was first time for me, it was a very straight forward process really. Well... except for removing the octa-link crank which was annoying because my old square-taper crank puller didn't work.
  1. Break chain, remove chain, old cassette, rear derailleur, front derailleur
  2. Straighten hanger
  3. Remove drive-side crank from BB (I had to buy an octa-link crank puller tool), remove 3 x chainrings.
  4. Clean and re-grease freehub and Octa-link spine on BB and cranks
  5. install 11speed cassette on 9speed freehub
  6. install 34t narrow wide chainring on middle position of 3x crank
  7. install derailleur - set low and upper limit screws
  8. Install chain - using Shimano's recommended method (chain-wrap + 4-5 links) in their documentation.
  9. Clamp derailleur cable and set b screw limit, using 51tooth guide mark on rear derailleur
  10. Tune the shifting using the barrel adjuster on the derailleur
If anyone is considering a similar process. Here's some tips:
  • Be patient when working - yes... old parts are greasy, dirty, often stuck, rusted and likely more worn than you were expecting. If something is not loosening or tightening as expected, take a moment and keep your cool. Maybe the thread is the other way? maybe you need a stronger tool?. I had to borrow a friends breaker bar just to get the rusty old cassette lock ring undone!!
  • Gearing - use an online gearing calculator to identify how the 1x system will compare to your old 2x/3x system. This will help you identify what chainring you should have, to give you desired mix of crawler vs top end gearing. I used this one https://ritzelrechner.de/ as it gives me a visual.
  • Chain length - 11 speed Shimano chains come in 116 or 126 link sizes. Consider whether you might buy the bigger size? This old bike had 430mm chain stays, 34t chainring and 51t cassette. My 116 link chain only had 2 links spare when I sized it. If my chain stay was longer or I ran a bigger chainring, I would have needed the 126 link chain.
  • Chainring clearance - check that your frame has enough clearance to run your desired chainring size. Some old frames might not have space for a 34t or 36t
  • Chainline for Crank - if you are re-using your old 2x or 3x crank. Make sure the chain line is ok. Some 2x cranks in particular might need a shim/washers between the crank and 1x chainring to get the correct chainline. Just plug your crank ID into si.shimano.com for more details on chainline.
  • Chainline for Tyre Clearance - old 142mm non-boost and 135mm QR hubs (like mine) mean the chain runs close to the tyre sidewall and tread, particularly in the dinner plate 51t gear. You will probably not be able to fit a tyre bigger than a 2.25 or a 2.3?
  • Documentation and instructions - I used the si.shimano.com site for Dealer Manual instructions on how to install the chain, derailleur. I also used Youtube and found this video very useful (Yes it's 12 speed video but its identical process)
If you made it this far, here are some photos of old and new 馃槂.
Bicycle Tire Bicycles--Equipment and supplies Wheel Crankset
Bicycle Bicycles--Equipment and supplies Tire Crankset Wheel
 

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I did a similar conversion a couple of months ago. I felt the 50mm chainline wasn't working well with the big cogs. I got some chainring spacers and got it down to 46mm, where it seems to be working quite well.
 

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Good post mate
Im about to converting my trance 2x11 to a 1x11, i will replace the cassete and put 1 chainring on front.
In your case you used the middle position for the chainring, do you have any ideia if in my case i will need some spacers to put the chainring more centered with the cassete?
thanks in advance
 

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Discussion Starter · #4 · (Edited)
Good post mate
Im about to converting my trance 2x11 to a 1x11, i will replace the cassete and put 1 chainring on front.
In your case you used the middle position for the chainring, do you have any ideia if in my case i will need some spacers to put the chainring more centered with the cassete?
thanks in advance
I haven't done a conversion from a 2x crank but...
Before I answer your question - a few things
  • Good 1x chainline for newer boost hubs (148mm through axle) = 52mm
  • Good 1x chainline for old non-boost hubs (135mm QR or 142mm through-axle) = 49mm
A bit of stuff on the internet:
  • I'm going to assume that you are converting your Shimano M8000 XT 2x11 crank to 1x
  • There seems to be discussion on the internet that the 2x M7000/M8000/M9000 11 speed cranks do take a shimano 1x chainring but the resulting chainline is several mm too wide
  • One up seems to be aware of this problem and recommend using a spacer if you use one of their 1x chainrings Understanding Chainline for Optimal 1X Conversions (Boost and Non-Boos
  • Shimano's page on their 11 speed cranks (note there are both boost and non-boost cranks) don't really provide helpful information on chainline e.g. FC-M8000-2
Summary (TL;DR)
If you convert a 2x crank to 1x, it may work, or you may need to experiment with spacing the chainring inward towards the BB. Maybe buy some cheap washers and play around until it is right, doesn't grind and chain doesn't drop off the cassette when back pedalling.
 
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