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Advice on 3x9 to 1x9 conversion

desmo's picture

By desmo - Posted on 05 October 2014

NB: Originally posted elsewhere on the Global Riders Network and appears via syndication.

Need some advice on a budget 3x9 to 1x9 conversion.
Due to a new frame (warranty replacement) on my old bike, my old BB and Deore 9sp crank triple won’t fit.
Rather than buy a new 9sp triple crank, I want to convert it to a 1x9 with a 30t ring, using the existing 9sp Shimano XT rear mech and cassette.
Therefore I need to buy:

  • New 104 BCD crank that is capable of running a single 30t 10sp chainring
  • 30t 10sp narrow wide chainring

Below are the options I have found, but my main concern is whether the 30t ring will fit onto the crank and still allow enough chain clearance.

Crank: Deore M590 (9sp triple) or Deore M610 (10sp triple) - from this I would remove the 3 chainrings and fit a new 30t as the middle ring.

30t chainring:

Any advice on the compatibility appreciated, or even suggestions on a better approach.

Andrew's picture

I'm not sure about your frame. However I just put a 36 tooth Blackspire Mono Veloce Narrow Wide Chainring on my Redline Monocog flight. It is running as a 1x9.

I highly recommend a non-ramped Narrow Wide chainring to avoid the chain bouncing off when it gets rough.

TheOneRing's picture

If you have a look at the photos on CRC, the black raceface ring is a 30T. You can see that there are raised blocks around the bolt holes to move the ring away from the spider and provide clearance. (if you do a quick google search of 30T raceface narrow wide, look at the images and you can see how it works - the chain sits comfortably behind the spider.)

Looking at the other sizes, no blocks are needed as there is enough clearance.

You shouldn't have a problem. I use the same Deore cranks on my hardtail, running 1x9.

all74's picture

Wolftooth use the same built in spacers on their 30t

fairy1's picture

I'd imagine you would have a long cage mech and that will make it much more likely for you to drop a chain compared to a short cage rear mech.

I'm running a 36T(26er) front and with a Short cage Zee rear mech it will drop a chain with the clutch off when the trail gets a bit silly. I am however riding a hardtail so I imagine that would make keeping a chain on slightly more difficult.

desmo's picture

@Andrew - Yes, the chainring is a narrow wide, so hopefully no drops.

@TheOneRing - Thanks for the tip. Looks like it will fit fine.

@fairy1 - It's a 9sp XT rear mech, no clutch. The riding on this bike will be mostly on mild terrain, so I am hoping the narrow wide ring will be enough to keep the chain on.

Discodan's picture

don't forget you will need single ring chainring bolts, they are shorter than the triple ring ones you will have

all74's picture

Factor in a 10 speed chain, generally the narrow wide chain ring manufacturers recommend a 10 speed chain even with a 9 speed system, for best retention.

desmo's picture

Have decided on the M615 Deore Double crank. I hope to mount the single 30T where the large ring would normally go. Hope the built in spacers provide enough offset for a decent chainline.

Am planning on a 10sp chain - thanks all74.

fairy1's picture

Eight and Nine speed chains are fine on Blackspire NW rings, not sure if they recommend it but it worked fine. With the clutch on the only time I have ever dropped a chain was from back pedaling for some odd reason.

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