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I will be putting road drop bars on one of my mtb's for this coming winter as a project that has Shimano 10 speed 1x Deore. My goal is to "simply"🙈😆 have road shift levers and hydraulic brakes with good shifting and braking performance. Here is my setup can some tech cyclist help me figure out my cheapest options? All the different leverage ratios for 10 speed across mountain and road (and now GRX) gets quite confusing. I would like to stay 10sp. Thanks !!! Here is the bike and I have 5 other (1 road, 2 gravel, 2 other fs mtb's currently built up with too many frames to count) so this is going to be my only e-bike: https://www.marinbikes.com/bikes/20-nail-trail-e1

Current Setup:

  • SHIFT LEVER: Shimano Deore 10sp
  • DERAILLEUR REAR: Shimano Deore Shadow Plus 10-Speed
  • CASSETTE: SunRace 10-Speed, 11-46T (I would like to be able to have that large of a cassette still)
  • BRAKES: Shimano BR-MT201 Hydraulic Disc, 203mm Rotor
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    That's not easy and going to be expensive. Have you considered buying a gravel bike with extra wide tyre clearance? – gschenk Sep 5 at 8:27
  • Thanks, I actually have one of those already. This is a fairly expensive mtb that I just want to convert for winter months until the snow clears. – Jim Sep 5 at 20:38
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    Why would any one be willing to sacrifice a £3000 ebike for a project and look for the cheapest options converting it to something it was never designed to be ? Just spend half the original value and buy a gravel / cx bike. – Dan K Sep 6 at 5:30
  • As mentioned it will be a winter project for riding it on the road and as also mentioned, I already have 2 mechanical gravel bikes built. Not sacrificing anything I will put back the mtb set when the snow clears. Here in the Colorado Rockies trails here are mostly covered. May not have been designed to do it but e-mtb's used for gravel work just fine. I suppose I could spend more and buy an e-gravel bike. 😆 – Jim Sep 6 at 7:27
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    @Jim Plugging Shimano road hydro levers into mountain calipers usually is fine so there's no need to give up the big rotors. However, there's no non-shifting left lever for those, and if that RD can be made to clear a 46, it will be at the expense of good shifting. It's intended only for 36. – Nathan Knutson Sep 6 at 14:47
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The only road shifter compatible with a Shimano 10 mountain RD is the Microshift BS-M10.

If you went BS-M10 you could use TRP Hylex brakes to stay hydro.

A number of bikes have been released with those exact components with Shimano 1x10 or 2x10 mountain drivetrains. It works fine if you're amenable to bar ends.

Other than the above, to get 1x10 with brifters and hydro and re-use your RD, all the options are seriously contrived, like buying the 1x11 hydro GRX STIs only to also buy a Jtek for them. Apex 1ing the bike will be cheaper.

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    +1 On the proposed setup of BS-10 bar-end shifter and Deore 10-speed rear derailleur. I've been using it for 2 years with no issues. I run mechanical disc levers though, so no comments on TRP Hylex brakes; they seem like the only hydraulic single speed road option available though. – Grigory Rechistov Sep 5 at 16:51
  • Thanks, more great info ! I had read about BS-10 shifters in a previous post but thought not an option because they weren't hydraulic. Have the TRP's on my old carbon 29 ht frame I converted to Di2 gravel ultegra gravel bike pre GRX (drilled out the cable stops). They don't have the stopping power for this bike though more than the cable pull hydraulics can provide. Wow, I have not used a Jtek in many years. I hated my old Ultegra or Dura Ace levers always breaking so I went to Campy's that I would just replace the gspring every couple of years. I need to research Apex I don't know what it is. – Jim Sep 5 at 21:03
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    @Jim Apex is SRAM’s 1x gravel groupset. – MaplePanda Sep 5 at 23:41
  • Thanks I will check it out ! – Jim Sep 6 at 0:06
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Hydraulic brake levers and brake calipers are in general not interchangable.

Shimano MTB 10 speed rear derailleurs do not work with road levers.

You already encountered GRX. It has a 2x10 option, RX400. The rear derailleur is not designed for 1x, however, it has a clutch (Shadow+) and is rated to 46t. I expect it will work well enough in a 1x set up.

Also check chain line. The MTB has the chainring mounted further to the right. For the low gears (many teeth) the chain might have to angle far to the left.

Check brake caliper compatibility with your frame. GRX calipers are attached with the flat mount standard. Adapters for flat mount brakes to mount on IS ir post mount frames have been designed already. The adapters may be hard to find and pricey though.

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  • Thanks great help I will definitely look more into GRX RX400 10sp option. I had been thinking it might be easiest. I have no idea which mount standard this new bike is I will need to do the research. I would have hoped when road hydraulic levers came along they would have gone with mtb standard. Obviously not though. What makes this more complicated would be the 203mm rotors I would like to keep and not have to switch them out also. – Jim Sep 5 at 20:51
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    Caliper mount standard question: bicycles.stackexchange.com/q/44161/30402 – gschenk Sep 5 at 21:31
  • Thanks I was just brain dead, it is standard post mount so I would use a flat mount adapter for GRX calipers but I will bet they only go up to 160mm. So my 203 and even a 180 rotor for that heavy bike are toast. singletrackworld.com/forum/topic/… – Jim Sep 6 at 0:33
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    The constraint "it should remain 10 speed" makes it difficult to find a solution that fits your brake requirements. 11 speed drivetrains offer more options because as there are post mount calipers. For instance in SRAM 1x groups – gschenk Sep 6 at 8:40
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Thanks to everyone's great help here is the solution that seems like it would work out for me, yrmv (remember this is just a theoretical setup.) Want to stay with as much as OE as I can since just winter setup, 10sp 4700 tiagra levers (same shim 11 sp road cable pull ratios including grx so can't just use any rear derailleur even though is 10sp that gets complicated see # in references and other threads.), splice in xt calipers to the levers (same cost as going with flat mount to post mount adapters which are freakin 40 bucks each.) Use a GRX RD-RX812 11 sp max 42t rear d. Will handle =~ 46t in many setups' and as scene* seems to shift fine as a 10sp d. Why Shim does not make things compatible across mtb and road anymore since 9 or 10 speed I forget when they were. If Shim hydraulic 11 speed road levers worked with mtb stuff, why have GRX$ ? Same reason gravel frames slowly are getting more clearance. They are mountain bikes hardtail frames are mostly with drop bars that Tomac use to race in the 90s (we started doing it in the 80s). https://roadbikeaction.com/the-origins-of-fat-tires-drop-bars/ That is pretty much it. All of the documentation and references are in the comments from all the help and research above. *

More supporting references: https://bikepacking.com/bikes/corvid-cycles-map/

https://www.facebook.com/watch/?v=727469104375415&extid=DtFEHaupmPoJLo43

http://blog.artscyclery.com/science-behind-the-magic/science-behind-the-magic-drivetrain-compatibility/

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There are two problems in your plan.

Firstly, it's almost impossible to find road drop levers for hydraulic brakes without shifters. Thus you're stuck with levers that have integrated shifters.

Secondly, in their infinite wisdom, Shimano has made road levers incompatible with the cable pull ratio needed by MTB rear derailleurs. Thus, if you select a lever with shifter, it's not going to be compatible.

Normally, in situations like this I would recommend bar-end shifters and brake levers without shifters. The bar-end shifters are compatible with practically anything, especially in the front (also in the rear too if you stick with friction shifting). However, I doubt there is a bar-end shifter compatible with 10 speed MTB rear derailleur cable pull ratio -- they are usually made for road ratios. Also, finding hydraulic road drop levers without shifters is going to be a challenge.

In theory, some bar-end shifters allow friction shifting in the rear after turning a switch. However, in practice, you probably won't want to be shifting all the time this way.

It unfortunately seems the DIY market is not well catered for in today's environment, and you would need to change so many parts of your bike that the conversion is not going to be cheap.

The situation was entirely different when I converted a 3x8 speed hybrid bike to a 2x8 speed drop bar bike. It had V brakes (fortunately road drop levers are available for the V brake cable pull ratio), and the 8 speed Ultegra bar-end shifters worked perfectly, as 8-speed road and 8-speed MTB cable pull ratio is the same (with the exception of some old Dura-Ace parts).

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  • Hello, and welcome to 2020. There is a market for third party adapters for solving problems exactly like this. One example: jtekengineering.com/shiftmate/… – ojs Sep 5 at 9:31
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    @ojs Oh but no, these products cost more than a reasonably priced rear derailleur! Why would one purchase such a product instead of merely replacing the rear derailleur? – juhist Sep 5 at 9:35
  • The reasons I would buy one are are for building combinations that manufacturer doesn't support (like the OP is asking about) and using an existing irreasonably priced rear derailleur. It also costs less than a single GP5000 and you don't seem to have a problem putting the money into consumables that have a very marginal benefit. – ojs Sep 5 at 9:38
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    @gschenk Tiagra 4700 is hydraulic as well. – MaplePanda Sep 5 at 19:01
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    ...and the Tiagra 4700 derailleur is cheaper than the GRX derailleur (the Tiagra 4700 derailleur is the derailleur I consider "reasonably priced"). But however, its cable pull ratio is the same as for 11 speeds so you cannot combine a random 10-speed derailleur with the Tiagra levers. – juhist Sep 5 at 19:23

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