1x Drivetrain conversion – Dangerous?

Viewing 11 reply threads
  • Author
    • #192315

      I’ve been looking at the Specialized Stumpjumper FSR Comp Carbon 650B.

      It comes with two sprockets up front, and a 10 speed 11-36t Cassette.

      I do not want two sprockets up front, so my bike shop told me that they can accommodate a 1x drivetrain with a 30 tooth sprocket up front.

      Should I be cautious about this? Would I need a bigger cassette?

      Looking for other opinions before I commit.

      Here is the link of the bike I want:  https://www.specialized.com/us/en/bikes/mountain/trail/stumpjumper-fsr-comp-carbon-650b/106988

    • #192316

      I would say it depends on how often you find yourself using your really low end gears on a normal 2×10 set up.  I suspect your low end chain ring is like a 22 or 24, meaning you will loose like two to three of your low end gears for climbing since you would be going to a 30 on the front.  Your second chain ring on the 2 by set up is usually 34 to 38 meaning you will loose some high end gears as well, but those are less important since it is your low end you use for climbing. Hope that helps


    • #192317

      You should be fine,, My bike came with a 3×9 11-34    with the center ring 30t, I never used the small front ring, and very seldom used the big ring,, I am now running 1×9  12-36 cassette with a 32t front ring and doing fine.. If you tnink you need lower gearing you can just have them switch cassettes, there are 11-40 10 speed cassettes available. Little bigger jump between gears, but I think some of the gears are too close anyway.. I’m thinking about trying to build my own custom cassette 11-40 9 speed.

    • #192357

      I switched from a 3×9 to a 1×10 this past year. I went with a 30 up front with a 11-42 in the rear. The 30 is bit too small for my liking, as the 30-42 combo is more climbing gear than I need, and the 30-11 is not enough low end at certain times. I have found myself maxed on certain downhills wishing I had one more gear to drop. Doesn’t happen often and it really doesn’t impact my overall ride, but there have been times I hit the shifter and was maxed out.  I will probably switch out to a 32 front ring next time around.

      You will like the simplicity of a 1×10 system. Less moving parts and less weight. It makes for a smoother quieter ride as well. I have a lot less chain slap than I had before as well.

    • #192602

      How much weight do people shave by removing one chain ring and shifter with derailer? Probably about the same as chain guide, which helps in keeping that chain in place.

      The real question is what terrain you ride? If it’s flat to moderately steep then 1×10 is enough. When riding big steep stuff with 11-36 cassette you might find yourself walking uphill sometimes without that lil’ 22t chainring.


      • #193605

        @Stumpyfsr if you were using Shimano’s new XT group, here’s what you would save by going from 2x to 1x:

        Front derailleur – 121g

        Left shifter – 129g

        Ring – 80g

        Housing – 60g

        Cable – 30g

        TOTAL = 420g (or just under 1lb.)

        The new minimal chainguides are stupid light. The Hope guide that I tested recently weighed 82g, but there are others that are much lighter like the OneUp that comes in at 35g. So, long story short, even if you did add a chainguide back on – which isn’t absolutely necessary – you’re still saving a good chunk of weight.

        Hope Slick Chain Device Review

    • #193571

      I rode a 32 36 on my 26r and was fine but the rides after winter break were a challenge on occasion.

      I’m currently riding a 32 42 on a 650B which is a bit easier.

    • #193979

      I’m currently running a 1×10 with a 36 chainring and a 11-36 cassette. Some climbs are tough. That being said if you have a rear derailer with a clutch you will not need a chain guide. I ride all over from North Carolina to Georgia and haven’t found a need to put a guide on.

    • #194025

      Get yourself a narrow/wide ring along with a clutched derailleur and you’ll be fine. I also did a ghetto 2×10 conversion from my 3×9, I replaced the middle ring with a N/W 32t, pulled the front derailleur and left the small ring (24t?). I rarely used the small ring but I could reach down and drop it on the small ring if I knew I’d be making a long climb. Once you’re to the fun part just slap the chain back on the N/W ring and you’re good to go. Ghetto but works and you get to keep the granny low.


      At first I was running 1×9 with the x5 non-clutched derailleur and dropped the chain occasionally but never had an issue with the x9 clutched.  I’ve taken my hardtail down stuff no hardtail belongs on and the only issues I had were operator error shifting when I knew better.

    • #194122

      Thanks, Aaron, for info. A pound is actually a lot. Makes sense to simplify drivetrain a bit.

    • #194282

      I just switched to the 1x 10 setup myself, I bought my bike in January this year and so a lot of rocky riding and in turn ruined my 2nd sprocket in the front. , I went from a 2x 10 setup (36 & 22 tooth) to a 32 tooth, and left my 11-36 tooth setup the same. climbs are a little tougher, but  if you ride more than twice a week u will be fine!

    • #194745


      1x is awesome.  you’ll never regret it.  if you really want to put your mind at rest check out a gear ratio calculator.  this is my favorite:  http://www.bikecalc.com/gear_ratios   you can plug in various rings/cassettes to see which combo gets you close to whatever setup you currently like.  bear in mind, when you’re on the bike it’ll only take a few weeks to adapt to a new gear setup, and then you’ll forget all about whatever gears you think you were missing on paper.

    • #194752

      I have a stump jumper carbon comp 650b, just did a 1X11 conversion.

      narrow wide 32tooth chainring, 10 to 42 tooth cassette. (No chain guide)

      I used XTR shifter and clutch style derailleur, and a XT cassette.

      Not as much low gearing as the bike originally had, but pretty close.


Viewing 11 reply threads

You must be logged in to reply to this topic.