today I was installing brand new GRX brakes into new frame. It was not my first time, I've already build 10+ bikes, I messed up through. I inserted rear brake hose without any issues, I had my guide, it was OK. I wanted to add Jagwire Internal Housing Damper, but it didn't go well so I had to take brake house out and then back again.

Second time it got caught by internal part of cage holder (not removable), so I had to take a little bit more time but I got it outside with little more force.

But then I noticed, that hose feels weird in hand. So I took a deep look and found out, that the whole part which was going inside frame was scratched a lot.

If this was for mechanical brake, I won't be concerned at all, because I know there is metal cover inside. But what about this hydraulic hoses? Should I be concerned? Deepest one is on pictures no. 2 and 5. I'll have to shorten hose, but this part will be about 5-10 cm outside the shifter.

I have spare hose but I think this is only esthetic problem and it's gravel bike, so it'll get many more scratches during few rides. Thanks for other opinions.

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  • It's probably fine, but you've possibly created some vulnerable sections of hose (2nd and 5th photos). Since this is GRX, I'm going to assume this will see some rough and tumble use, possibly some single track, possibly some trips (accidental or otherwise) through the brambles. It's a new bike. My opinion is that you might as well replace the hose and start it off right.
    – Paul H
    Feb 14, 2023 at 20:11
  • Welcome to SE . picallow.com says "images are temporary and will be deleted soon" so I'm ediing the images into this question directly.
    – Criggie
    Feb 14, 2023 at 21:15
  • As long as you can't see the underlying white layer, I think you should be fine. Not legal advice though.
    – MaplePanda
    Feb 14, 2023 at 22:26
  • Is the blue housing in the picture theJagwire Internal Housing Damper?
    – David D
    Feb 15, 2023 at 14:14
  • No, it's Shimano brake hose under white light. Feb 17, 2023 at 11:24

1 Answer 1


Your assessment it is cosmetic is correct. Hydraulic hoses are similar in many ways to the outer of mechanical brakes with layers providing specific function. They have an inner liner (to keep the fluid in) a mid-layer of Kevlar to hold the pressure and an outer layer for protection.

Unless the cuts are so deep they have damaged the Kevlar, the hose is mechanically fine and only reason to replace it would be cosmetics and pride.

(This is Jagwire, but all manufacturers I know of use a similar system). https://jagwire.com/products/hydraulic-hose/mountain-pro-hydraulic-hose

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