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I purchased a gravel bike with drop handlebars, mostly for commuting and maybe for some weekend bike camping trips. I've only ever ridden mountain bikes with flat bars in the past, but I figured I'd get used to the drop bars. After a month I'm realizing that drop bars are just not for me. So I want to take my Jones Loop off of my MTB and put it on the new gravel bike.

The gravel bike had Micro Shift MTB bar end shifters so I picked up the matching flat bar adaptors for $40 and that will be a real easy 10 minute switch. Now I just need brake levers but I can't seem to find definitive answers online about which ones will be compatible with my brakes.

I've never bled a brake line before but I'm confident that I could do it and its only another $20 for the line bleeding kit. More than one blog says that there are not many compatibility issues with hydraulic levers when switching from drop bar to flat, but I can't find anything that says if I can just use any random hydraulic levers with these brakes.

The brakes on the bike are TRP Hylex hydraulic disc brakes. From what I can tell, TRP only makes one flat bar hydraulic disc brake set and they don't seem to sell replacement levers.

I don't need top of the line parts, but I don't want to buy something that is going to break easily. I found a store selling what look like very basic levers, Shimano BL-MT200, at $15 for the set. I also found a list of other Shimano levers at varying price points, BL-M6000, BL-M7100, and BL-M8000.

My questions are:

  • Can I just swap out the TRP Hylex drop bar levers for these cheap Shimano levers?
  • Could I hypothetically use just about any random hydraulic levers? SRAM / Tektro / Shimano
  • Does it make good sense (would I notice a difference) to buy a more expensive lever like the BL-M8000?
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  • TRP is the high end brand of Tektro. I'd don't see why both would not be compatible. Tektro flat bar MTB levers are cheap and reasonably easy to source because Tektro is a popular OEM choice.
    – Klaster_1
    May 1 '20 at 15:03
  • @Klaster_1 thank you, I had not realized that Tektro was the same parent company
    – Thomas
    May 1 '20 at 18:56
  • @VladimirF I had seen that post, however, I see plenty of Shimano parts but not many TRP parts and I was mostly wondering about using the two brands (or another brand's levers) interchangeably
    – Thomas
    May 1 '20 at 18:57
  • Regarding drop bars: Are you sure you have them adjusted correctly? Riding on the hoods should be very comfortable. I’ve seen beginners riding on the drops all the time because they don’t realize you can even ride on the hoods.
    – Michael
    May 2 '20 at 7:11
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An important reason why you can't randomly mix and match hydraulic brake parts is because different manufacturers use different hydraulic fluids. SRAM uses DOT 5.1 brake fluid. Shimano uses mineral oil. Campagnolo uses mineral oil. Using the wrong kind of fluid can damage the seals.

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    Campy’s brakes are made by Magura, and Magura and Shimano both think the other brand’s mineral oil will damage their own brakes. So you may not even be able to interchange different mineral oils. Shimano + Tektro may be interchangeable, but one should check first.
    – Weiwen Ng
    May 1 '20 at 16:11
  • That's a useful clarification, thanks @WeiwenNg.
    – Adam Rice
    May 1 '20 at 16:38
  • Thank you all for that clarification about the fluids, I had seen that in a few blogs and youTube videos and I think I had used it to eliminate a few models / brands at first but then I got lost in other things like levers with built in shifters and prices so I put the fluid issue aside. I will definitely keep that in mind at all times as I move forward!
    – Thomas
    May 1 '20 at 19:02
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    Aftermarket fluids eg Cyclo brand are sold either as DOT or mineral. Cyclo suggests suitable for shimano, tektro, magura....just FYI
    – JoeK
    Oct 17 '20 at 19:41
  • @WeiwenNg Meanwhile, Hope say that their mineral oil brake calipers are compatible with Campagnolo and Shimano levers.
    – sdgfsdh
    Apr 14 at 21:39
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Can I just swap out the TRP Hylex drop bar levers for these cheap Shimano levers?

Unlikely to work, not recomended

Could I hypothetically use just about any random hydraulic levers? SRAM / Tektro /

Technically, no. The issue is that the lever and caliper together need to provide the correct leverage ratio between the fingers on the lever and the pad on the rotor. That's set by the relative cross-section areas of the pistons. If you have a mismatch you either get too much force but not enough pad movement, or too much pad movement and too little force. You cannot guarantee that different manufacturers have so happen to have chosen compatible piston areas.

There is no documented general compatibility between road calipers and MTB levers. Shimano's compatibility documents show no compatibility between their road and MTB brake components, and neither do SRAM's.

Your best course of action would be to replace the levers and calipers, so you know you will have brakes that work properly.

Shimano makes hydro brakes in their lower-tier Acera (where the BT-M200 sits) and Alivio lines which would probably be fine for your purpose. You could also use equivalent Tektro flat bar brakes.

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    I downvoted the answer because of "no general compatibility" statement, which I disagree with. All Shimano hydro calipers and levers are compatible, road and MTB. The same is very likely true for SRAM, but I have data on this. What works in real life and what manufacturers declare are two distinct things.
    – Klaster_1
    May 1 '20 at 15:04
  • Can whomever downvoted explain why they think this answer is incorrect? May 1 '20 at 15:05
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    @Klaster_1 note I said that Shimano and SRAM do not document compatibility between road and MTB. Also see bicycles.stackexchange.com/a/45053/24228, bicycles.stackexchange.com/a/45219/24228 May 1 '20 at 17:53
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    @WeiwenNg leverage ratios are definitly a thing. The cross-section area of the pistons acts in the same way as the lever length May 1 '20 at 17:56
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    @ArgentiApparatus my main gripe is about "general compatibility" part, I also find the answer too lopsided towards the safe side, citing official sources only. The answer would benefit from an additional viewpoint of mix and match, you can at least Google and resume experience of people with Tektro levers/Shimano calipers (there are MTBR threads), the potential downsides of such setup are already listed. The OP can decide what to choose if all pros/cons are clearly listed. I'm too lazy today to answer myself, but as a regular contributor, you might benefit from constructive feedback.
    – Klaster_1
    May 1 '20 at 18:07
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all other considerations aside, the Hylex is a well thought of system and should have a decent resale value complete. This adds to your budget for replacements.

while a shimano lever-only might work, you will get the best performance from system-matched parts. plus it's usually possible to install new pre-bled brakes without having to bleed them even when reducing hose length, which saves time.

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