Kent Eriksen machined alloy crankset spider to convert 1x mountain bike cranksets to run road double chainrings

At first glance, we just thought this was a fancy aftermarket spider. Then we noticed it was on a mountain bike crankset, which was being shown elsewhere on cyclocross and gravel bikes. Curiosity piqued.

As Kent Eriksen explains it, neither Shimano nor SRAM have updated their road cranksets’ chainline as bikes have started migrating to 135mm rear spacing for disc brakes. So, not only does that affect chainline, but, as cyclocross and gravel tires get bigger, you start running the risk of chain/tire clearance issues.

But, mountain bike cranks were already designed around wider rear axle spacing, but their spiders weren’t set up to handle double chainrings with road-oriented tooth counts. Hmmm

Kent Eriksen machined alloy crankset spider to convert 1x mountain bike cranksets to run road double chainrings

Designed by in-house builder Brad Bingham, their new aftermarket spider for SRAM direct mount cranks solves this issue by moving the chainline out ~4mm. So, it’s pushing the chain a bit wider than a road crankset, but not quite as wide as a standard MTB crankset. It then let’s you run a road double on a crankset originally designed for singles. And if you’re running electronic shifting (Di2, EPS, eTAP), it also lets you quickly switch between single and double chainring setups since all you really have to do is unplug and remove the front derailleur. Just use a chain with a quick link (don’t worry, we won’t tell anyone you’re reusing that – we do it, too).

Kent Eriksen machined alloy crankset spider to convert 1x mountain bike cranksets to run road double chainrings

Another benefit is you can you run larger chainrings and still clear the chainstay, good for a bike whose chainstays are wider to clear bigger tires.

Kent Eriksen machined alloy crankset spider to convert 1x mountain bike cranksets to run road double chainrings

Kent said it’s only a matter of time until SRAM or Shimano addresses this on their own. Until then, they plan on selling them and recommend them with Praxis chainrings. The upcharge for it on a complete bike will be $400 with rings, but aftermarket price is TBD.

Stay tuned for full coverage of his bikes, two of which won awards this year!

KentEriksen.com

30 comments

  1. MMinSC (@MMinSC) on

    Eriksen makes beautiful stuff, but this just isn’t needed.
    I’ve been running 7800 D/A cranks on my 135mm Salsa Las Cruces for 10 years. NEVER an issue.
    I’ve run everything from road tires (23c) up to 40c meat.
    It’s a solution looking for a question.

    Reply
    • Champs on

      Even if you limit the timeframe to road/CX disc I don’t think necessity has been a barrier to even more useless things.

      With that chainline you get better shifting and can build a road disc frame with shorter stays. You can’t complain about the former, and if the latter is niche it is less so than oversized spindles and asymmetric rings for power transfer.

      Reply
    • thesteve4761 on

      Going out on a limb, I think the average Eriksen customer might have a higher expectation of performance than the average Salsa customer. “Good enough” might work for you, but clearly not for the customers Kent has in mind.

      Reply
      • Tyler Durden on

        To the contrary, gravel is much more similar to road than mountain in terms of position and time spent in the saddle. To think that widening your Q-factor is a good idea from a “performance” perspective is just ignorant. However, from a bro perspective, which I assume is important for a large amount of custom Ti bikes’ customer base nowadays, I totally see it.

        Reply
        • greg on

          You’d be surprised how many people would actually benefit from a wider stance, and how many people’s performance would be completely unaffected.
          “Q factor is a red herring” -can’t remember who is credited with that quote, but they’re right.

          Reply
        • greg on

          SRAM and FSA make road cranks with wider chainlines to support 135/142 rear ends on road bikes. One thing they don’t do (or at least haven’t seen) is widen the arm stance on those cranks to clear chainstays with more tire clearance. So in that sense, this could be nice to have.

          Reply
        • Duster13 on

          I’d love to see a double blind test conducted where all these guys feel these “massive” differences of a few mm of Q factor. Reminds me of the stereophonic hobby guys, who consistent.ly claim they can hear all these differences among speakers, but those funny little double blind test keep saying almost all of them have nothing but vivid imaginations. 🙂

          Reply
    • Derek on

      Your Salsa likely has longer chainstays than what is currently popular. Shorter chainstays make the chainline a bigger issue and also reduce tire and chainstay clearance to the rings.

      Reply
  2. Rob on

    “To think that widening your Q-factor is a good idea from a “performance” perspective is just ignorant.”

    .. apparently the Q in Q-factor stands for ‘Quack’.

    Reply
  3. Thor29 on

    Can anyone really tell the difference? I must be missing something – shouldn’t the difference in chainline be only 2.5mm since the hub is centered in the frame? (Extra width is split between drive and rotor sides, 135 – 130 = 5, 5/2 = 2.5). It should result in a slight bias towards the lower gears but nothing that would be noticeable.

    Also, what about the Q factor? If you are so sensitive that you notice such a tiny variation in chainline than I imagine you’d go nuts feeling that extra width.

    Reply
    • rodegeek on

      This spider will not change the Q factor of the crank. Of course, the typical MTB crank has a wider Q factor than a similar road crank. Noticing the chainline being slightly off is about chain angle and possibly chain clearance with the tire. This can be pretty easily observed. Q factor is more about biomechanics (or ergonomics if you prefer that term). If you have short legs you might notice a small change in Q factor; tall riders probably wouldn’t notice.

      Reply
      • rodegeek on

        Oh, I should add that 4mm is the correct change in chainline because the spider is designed for frames with 142mm dropout spacing, which is what all the trendy ‘cross bikes are using these days. 142mm thru axles hubs aren’t really needed for these bikes, but they do result in less wheel dish and allow use of a large selection of MTB hubs.

        Reply
  4. Veganpotter on

    SRAM has a pretty narrow Q at 156 with the right model. I don’t get why he didn’t just do this with SRAM road cranks with removable spiders. The q factor would be narrower and just as easy/hard to produce

    Reply
    • thesteve4761 on

      Just a guess, the road crank arm won’t clear the big ring with the chainline pushed out that way. Or maybe, just maybe, they wanted the Q factor from the MTB crank, but the ability to run 110/130 rings with proper chainline and no pedal spacers? Regardless, I’ll bet that Brad and Kent thought this one through way more than us armchair dorks here…..

      Reply
    • Ford on

      The big ring would probably be fine but I think the issue would be the FD cage. I set up an eTap group with a quarq yesterday and the inside of the crank barely clears the outer cage.

      Reply
  5. Ol gimpy can no longer put english on the pedals whimpy on

    Please do a 94bcd double with super compact gearing options ie 46/28 or 46/30 ect ect

    Reply
    • Champs on

      I hate to be the one who keeps bringing up French rando bikes—really, I do—but Compass Bicycles does have a crank for that. If you don’t mind the pricetag and goofy design decisions like a three arm spider and 6mm length increments, you can get as low as 42/24. Those bottom brackets last forever too.

      Reply
    • Meshkat on

      White Industries also gives you that option with their Variable Bolt Circle cranks from 165-180mm. Sugino also has the OX601 that has a dual 110/74 BCD similar to the current Campagnolo cranks.

      Reply
  6. Ford on

    I understand wanting to have greater chainstay/tire clearance but I’m confused about the chainline argument. On my 11 speed, 130mm OLD hub the center of the cassette is 39.5mm from the centerline. Road double chainrings sit at 41mm and 45mm from the centerline. Seems to me that having a wider hub would fix more chainline issues than it creates. What am I missing here?

    Reply
    • anonymous on

      Chainrings are more like 40mm and 47mm, and the small ring tends to be more sensitive to chainline issues because there’s the problem of the chain rubbing against the big ring in small small. Cassette width isn’t cassette chainline. Cassette chainline tends to be around 43.5mm.

      Reply
  7. Burton on

    The concept of “Q” was invented by Grant Petersen, so it’s suspect (along with his other 9,999 idiosyncracies). Everyone has been blindly believing that narrow Q is worth striving for. Maybe it is, maybe it isn’t — I don’t know. But it’s worth debating.

    Reply
    • Veganpotter on

      Not everyone reacts the same way but I get ankle pain from wider cranks. If I ride too long (with the same fit as my narrow cranked bikes), I get a lot of hip pain and I’m over 6′ tall. Typically the taller you are, the less it should matter

      Reply
    • Necromancer on

      It does have a legitimate basis in kinesiology though, relating to the angle your hip and femur make, for running and walking having a large q-angle often leads to injury

      Reply
  8. Birdman on

    Would this really work for electronic shifting with the 2.5mm wider chainline? Especially with road intended front derailleur mount. I know my EPS won’t handle too wide of chainline.

    Reply
    • bradti on

      @Birdman, if you look at the complete build (on the other BR posting) the front der mount is a SRAM “wide spacing” mount. This solves the wider position of the rings vs. der. There are other solutions out there as well, but the SRAM mount is super clean.

      Reply

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