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  1. #1
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    Drop Bars and 4-Pot Brakes

    Hey collective, so I'm trying to make a sick drop bar mountain bike and I want to run 4-pot brakes with drop bars. Can I straight up do this with Shimano GRX brifters and Deore 4-pots? What are my other options?

    No SRAM please, I'm trying to stay out of the insane asylum.

  2. #2
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    I had My grx lever hooked up to a 2 pot xt caliper woth no problem. Hoses are the same size, or close enough that they worked. Not sure if the 4 pots have thicker hoses but if not it should work.


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  3. #3
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    Drop bar mtb is so 1990. Btdt. Do yourself a favor and just get some Jones H-bars


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  4. #4
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    All GRX Brifters:
    -ST-RX815 (11s Di2)
    -ST-RX810 (11 speed mechanical shift, hydraulic brake, Ultegra level)
    -ST-RX600 (11 speed mechanical shift, hydraulic brake, 105 level)
    -ST-RX400 (10 speed mechanical shift, hydraulic brake)
    all these use the same hose, the SM-BH90 which is the highest level hose used all the 4 pot mountain brakes.

    The combination of GRX drifters and 4 pots are not on the official Shimano compatibility charts.
    BUT as an example the chart shows is:
    XTR MTB levers will work with with Dura Ace 2 pot road, or XTR MTB 2 pot or XTR MTB 4 pot.
    So my conclusion is the same lever pushes the same fluid to a 2 pot and to a 4 pot, so your GRX will work with 4 pot.

  5. #5
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    Quote Originally Posted by Dee Hubbs View Post
    All GRX Brifters:
    -ST-RX815 (11s Di2)
    -ST-RX810 (11 speed mechanical shift, hydraulic brake, Ultegra level)
    -ST-RX600 (11 speed mechanical shift, hydraulic brake, 105 level)
    -ST-RX400 (10 speed mechanical shift, hydraulic brake)
    all these use the same hose, the SM-BH90 which is the highest level hose used all the 4 pot mountain brakes.

    The combination of GRX drifters and 4 pots are not on the official Shimano compatibility charts.
    BUT as an example the chart shows is:
    XTR MTB levers will work with with Dura Ace 2 pot road, or XTR MTB 2 pot or XTR MTB 4 pot.
    So my conclusion is the same lever pushes the same fluid to a 2 pot and to a 4 pot, so your GRX will work with 4 pot.
    Thank you for the datapoints. Sounds like I should just try it out. At the very least it will work from a hook up point of view, perhaps I won't get the amount of force I am looking for though.

  6. #6
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    Second question, currently the bike has a Deore 10-speed RD and 10-speed 11-42 cassette. I know that the 10-speed Deore RD is not compatible with any of the drop-bar pull ratios.

    My question is - what are my options to keep this 10-speed RD and 11-42 cassette? This is going on an e-bike so I would prefer to keep the 10-speed cassette. Obviously the easiest option would just be to go all 11-speed GRX but I feel that I'll probably wear everything out much faster.

  7. #7
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    1x10 or 2x10?
    If you have it set up 1x10 I'd buy a GRX RD-RX400. ($60) Its officially capable of handling a 11-36 cassette. You can maximize the B-screw and it should shift into the 42. Maximised B-Tension might compromise the sifting on the 11t and 12t end of the cassette, but it will just be a little sloppy/slow.
    Depending on your frame and hanger size/shape you might need a Wolftooth Roadlink.

  8. #8
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    Quote Originally Posted by Dee Hubbs View Post
    1x10 or 2x10?
    If you have it set up 1x10 I'd buy a GRX RD-RX400. ($60) Its officially capable of handling a 11-36 cassette. You can maximize the B-screw and it should shift into the 42. Maximised B-Tension might compromise the sifting on the 11t and 12t end of the cassette, but it will just be a little sloppy/slow.
    Depending on your frame and hanger size/shape you might need a Wolftooth Roadlink.
    1x10. That's what I was thinking of doing. I am running 11-40 using an Ultegra RX derailleur on a gravel bike now 2x11 and I get that sloppy shifting at the small cog end which is less than ideal but it is what it is.

  9. #9
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    If you are willing to consider an aftermarket option, check out the Hope RX4 calipers. Just installed them on my gravel bike and they have great stopping power.

  10. #10
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    ^ I saw those but pricier than the Deore bits lol

  11. #11
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    https://www.wolftoothcomponents.com/...roducts/tanpan

    Converts road ratio to mnt ratio. I used on skibee's (Mrs mntlion) touring bike for 5000+km. works great


  12. #12
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    I think ALL shimano brakes use the same fluid ratio, so seem to all be cross compatibly.

    2 vs 4 piston

    road vs mnt

    old vs current.


  13. #13
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    Quote Originally Posted by mntlion View Post
    I think ALL shimano brakes use the same fluid ratio, so seem to all be cross compatibly.

    2 vs 4 piston

    road vs mnt

    old vs current.
    Well that is a shocker. Tell someone at Shimano they better get right on changing that!

  14. #14
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    What is the intended use for a drop bars e-mountain bike?
    Quote Originally Posted by Downbound Train View Post
    And there will come a day when our ancestors look back...........

  15. #15
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    Quote Originally Posted by PNWbrit View Post
    What is the intended use for a drop bars e-mountain bike?
    Commuting. This thing will barely see dirt unless you count the bottom of potholes.

  16. #16
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    The why the fuck would you put 4 pots on it, you commute over a 2,000' hill? And why drop bars?
    Burn it, and then delete this thread.
    No longer stuck.

    Quote Originally Posted by stuckathuntermtn View Post
    Just an uneducated guess.

  17. #17
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    Quote Originally Posted by stuckathuntermtn View Post
    The why the fuck would you put 4 pots on it, you commute over a 2,000' hill? And why drop bars?
    Burn it, and then delete this thread.
    I'm betting he already has the 4-pots...and, it's his bike. WTF do you care?
    Florence Nightingale's Stormtrooper

  18. #18
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