Shimano BH-59 vs BH-90 brake hose

[Ballmead]

I just picked up a front and rear Deore M6100 lever and caliper set to replace the MT200 brake set currently on my flat bar road bike.
The existing brakes have BH-59 hoses and the new ones come with BH-90 hoses.
Is it worthwhile going through the hassle of running the new BH-90 lines or can I just use the existing BH-59 lines instead?

[Duck!]

It will be a less messy project if you run the new hoses, and you will get better braking in high-demand situations. I would only retain the existing BH59 hose for the rear if it's routed through the frame, because running new internal ones can be right pain (but there are tricks to reduce the pain)

The 6100s come as a pre-bled system, and it is possible to fit the brake & trim hoses with virtually no fluid loss (except for what's in the discarded length of hose, which still is very little). Swapping both caliper and lever onto an existing hose adds another potential air entry point to each brake, then you have the oil-filled full length discarded hose that will want to dribble everywhere once it's disconnected.

Under normal use, you won't notice any difference in performance between the two hoses, but when you *really* need the brakes, the BH90 will give you more power (as long as the tyre-ground grip isn't overloaded!) - it's a stiffer hose, so when you're really reefing on the lever, more that effort is going into the caliper, The thinner-walled BH59 will tend to expand a bit under high pressure, which takes away some of the brake's power when you really want it.

[Ballmead]

It will be a less messy project if you run the new hoses, and you will get better braking in high-demand situations. I would only retain the existing BH59 hose for the rear if it's routed through the frame, because running new internal ones can be right pain (but there are tricks to reduce the pain)

The 6100s come as a pre-bled system, and it is possible to fit the brake & trim hoses with virtually no fluid loss (except for what's in the discarded length of hose, which still is very little). Swapping both caliper and lever onto an existing hose adds another potential air entry point to each brake, then you have the oil-filled full length discarded hose that will want to dribble everywhere once it's disconnected.

Under normal use, you won't notice any difference in performance between the two hoses, but when you *really* need the brakes, the BH90 will give you more power (as long as the tyre-ground grip isn't overloaded!) - it's a stiffer hose, so when you're really reefing on the lever, more that effort is going into the caliper, The thinner-walled BH59 will tend to expand a bit under high pressure, which takes away some of the brake's power when you really want it.

Thank you for your reply.
I've decided to take your advice and run the new hoses. The front is easy enough and the rear only runs internally from just below the top tube to just before the BB, so it probably won't be too difficult.
I'll need to buy some new barbs and olives though.

[Duck!]

The new brakes should include spare barbs & olives, because it is expected that the hoses will need to be sized to the bike they're going on.

[Ballmead]

All sorted with the brake line replacement, installation and bleeding of my Deore M6100 brakes. It was much easier than anticipated.

I used a piece of plastic coated coat hanger wedged between the old and the new hose and was easily able to push and pull it through the frame.

[familyguy]

I used a piece of plastic coated coat hanger wedged between the old and the new hose and was easily able to push and pull it through the frame.

QFT because I think is a great tip. I'm about to re-hose a bike with full internal routing, so I reckon you've just saved me hours of angst. Thanks!

[Ballmead]

I used a piece of plastic coated coat hanger wedged between the old and the new hose and was easily able to push and pull it through the frame.

QFT because I think is a great tip. I'm about to re-hose a bike with full internal routing, so I reckon you've just saved me hours of angst. Thanks!

No problem. While my coat hanger trick worked ok, one of these would be even better:
https://www.mtbdirect.com.au/products/r ... uting-tool

You can screw it into both ends for a really secure bond between old and new hoses.

[OnTrackZeD]

I used a piece of plastic coated coat hanger wedged between the old and the new hose and was easily able to push and pull it through the frame.

QFT because I think is a great tip. I'm about to re-hose a bike with full internal routing, so I reckon you've just saved me hours of angst. Thanks!

No problem. While my coat hanger trick worked ok, one of these would be even better:
https://www.mtbdirect.com.au/products/r ... uting-tool

You can screw it into both ends for a really secure bond between old and new hoses.

I've done it with a long thin screw by chopping the head off.
Hard to get off so just trim it off.