My MTB has currently a Deore FC-617 2x crankset. I am looking what components I need to convert to 1x. Do I need to change the crankset, or simply getting a new chainring for my existing crankset will work fine ?

  • I will most likely get a clutch derailer, 'Shimano XT M786 Shadow+ 10 Speed Rear Mech' seems a good choice. Currently have SLX Shadow 10spd, so at least I can keep the shifter.
    – Giannis
    Jul 1, 2016 at 21:02

1 Answer 1


The problem going x1 from x2 is the chain line can end up being wrong. Its easier with an x3, you just use the middle position and can often get away with using the standard chain ring. With a 2x conversion you use spacers to get the chain ring into the correct position Refer Here, which usually required longer chain ring bolts than standard on a 2x.

The M786 has a derailleur is less than ideal for going to 1x unless you plan to stick to an 11-36 cassette. Although many run it with 40 or 42 tooth cassettes, its max tooth size specification is 36 teeth. You can use third party adapters to increase its useful maximum tooth size at a cost. If you already need a new cassette and derailleur to go 1x, the extra cost of a shifter and chain means going 11 speed will give a much better system for only a little extra cost.

  • I haven't managed to find the spec from shimano, but all sellers say M786 is fine with 42 -11 cassette. For 11speed, I assumed I would also need changes on the wheels / hun, which would drive the cost up significantly. Thanks for the chainline info!
    – Giannis
    Jul 2, 2016 at 8:59
  • The specs are hard to find, I cannot find the ones I referenced when I was looking at going down that path. You can do it, and "it works" but you don't get the same chain wrap as you really should, shifting is not as good as it should be etc. In come cases you have to shag around with the B screw. Works fine when everything is new and shiny, but people have various degrees of luck later on in the components lifespan, that said, plenty of people are doing it and the third parties (e.g. oneup's rad cage and Wolftooth goat link.) give options if your setup is not quite 'there'.
    – mattnz
    Jul 2, 2016 at 21:50
  • I have now found that it's best to go with the 11spd mech, and that works great! Thanks for all the info.
    – Giannis
    Jul 2, 2016 at 21:51

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