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Dropbar to flatbar hydraulic brake levers

Old 08-12-21, 08:34 PM
  #1  
sdimattia
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Dropbar to flatbar hydraulic brake levers

I'm currently running dropbars, 2x10 Tiagra (Shimano) with a hydraulic disc brake in the front and a v brake in the rear. I have the Tiagra ST-4720 Hydro brifter paired to a Deore BR-M6100 Hydro disc caliper. I want to switch the whole setup to a flatbar.

I have a Deore BL-M6100 Hydro brake lever; my question is can I simply unscrew the hydraulic brake line from the Tiagra hydro brifter (on the brifter end) and screw it into the Deore hydro brake lever (again on the lever end)? Do I need to adjust the amount of fluid in the brake line?

I'm comfortable re-indexing the brifters to shifters and changing over the rear brake. However, i usually leave all things disc brake related to my LBS as I don't have the necessary tools or skills to play around with hydro disc brakes. Will this conversion be "plug and play" or will I have to bring the bike to my LBS to bleed the whole thing again?

Thanks in advance.
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Old 08-12-21, 09:29 PM
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cobba
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With the correct hardware you could connect it, the old fitting would need to be cut off to attach the new fittings and the brakes would need bleeding afterwards.

Road an mountain levers use different flare nuts with a different thread one is M8, the other is M9.

Look at parts #1 in these 2 exploded diagrams.
https://si.shimano.com/api/publish/s...6100-4661B.pdf
https://si.shimano.com/api/publish/s...4770-4610B.pdf

Road flare nut: https://www.sjscycles.co.uk/brakes/s...70-y8rd98010/?
Mountain flare nut: https://www.sjscycles.co.uk/brakes/s...it-y8ja98010/?

Would the old hose be long enough?
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Old 08-13-21, 08:51 AM
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sdimattia
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Originally Posted by cobba View Post
With the correct hardware you could connect it, the old fitting would need to be cut off to attach the new fittings and the brakes would need bleeding afterwards.

Road an mountain levers use different flare nuts with a different thread one is M8, the other is M9.

Look at parts #1 in these 2 exploded diagrams.
https://si.shimano.com/api/publish/s...6100-4661B.pdf
https://si.shimano.com/api/publish/s...4770-4610B.pdf

Road flare nut: https://www.sjscycles.co.uk/brakes/s...70-y8rd98010/?
Mountain flare nut: https://www.sjscycles.co.uk/brakes/s...it-y8ja98010/?

Would the old hose be long enough?
Much appreciated for the detailed response. The old hose will definitely be long enough, might even be too long by a couple of inches.

This may be a stupid question but I am not familiar with disc brake hardware . . . Can I not just slide the olive and flare nut off the hose and slide the correct flare nut back on? Or is cutting it the only way? I do have extra hose length to cut if need be.
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Old 08-13-21, 11:27 AM
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cobba
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Originally Posted by sdimattia View Post
Can I not just slide the olive and flare nut off the hose and slide the correct flare nut back on? Or is cutting it the only way?
They need to be cut off and replaced, when the flare nut is tightened into the brake lever, it deforms the olive and crushes it onto the hose to make a seal.

https://si.shimano.com/pdfs/si/SI-8KH0A-001-ENG.pdf
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Old 08-13-21, 12:23 PM
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sdimattia
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Originally Posted by cobba View Post
They need to be cut off and replaced, when the flare nut is tightened into the brake lever, it deforms the olive and crushes it onto the hose to make a seal.

https://si.shimano.com/pdfs/si/SI-8KH0A-001-ENG.pdf
That makes sense. Well, thank you again for your help!
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