[IMeasure]

OK

So my son's bike is fitted with (10s) BR-MT410 Shimano Deore - 2-piston - Calipers that use the BH59 Hose and the corresponding (very large) lever.

I have a spare set of Shimano Deore BL-M6100 (12s) levers that would normally attach to a BH90 Hose.

Can I just swap out the current lever attached to the BR-MT410 with the Deore BL-M6100 (12s) levers using the existing BH59 Hose?

Can this be done?

Are there any issues with this setup?

I think both the BH59 and BH90 use the same olive and different insert (correct me if I'm wrong). I have plenty of spare bolts for the M6100 levers.

Thanks again

Dan

 

[FlaMtnBkr]

I don't know the technical differences in the hoses, but I think they have the same outside diameter but a different inside diameter. Don't know why they changed but if you have the olive and insert that fits the hose then I don't see a problem. In fact, if the hose already has an olive and insert you can try it as is and just replace if it leaks.

What I'm not sure about is how much fluid the levers push compared to the levers that go with the calipers. But there shouldn't be a problem with trying if you're willing to do the work. There is a chance that the levers don't push as much fluid, so that the calipers don't squeeze the rotors hard enough or that it grabs too hard and there's no modulation. I think most likely they will work fine but it's a possibility if you're going to try. Once hooked up you'll know immediately how they feel and that shouldn't change or explode mid ride.

Hopefully someone will come along that has a better answer for you or that has tried it, but hydraulics are hydraulics.

 

[Kiwibaconator]

Yes you're fine - technically you can simply remove the hose from your 410 levers and plug them into your 6100 levers, followed by a bleed.

The BH59 hose has a larger internal diameter for the same outer diameter - the thinner wall expands more as it's pressurized. The end result of this extra expansion of BH59 vs BH90 is less brake force at the caliper and a "squishier" lever feel when you use BH59 vs BH90.

BH59 uses the same olive as BH90 but a larger diameter (gold coloured) barb, the BH90 uses a thinner silver barb.

There is a chance that the levers don't push as much fluid, so that the calipers don't squeeze the rotors hard enough or that it grabs too hard and there's no modulation

All current Shimano levers have the same master cylinder diameter. The hydraulic leverage ratio (ratio of master piston diameter in lever to slave piston diameter in the caliper) remains unchanged if you swap levers. But the 6100's servowave cam increases the lever's mechanical leverage (i.e. your finger's effective force on the lever is increased compared to the 410 lever's direct engagement).

Brakes don't function like a flushing toilet - the bigger the hole doesn't mean the more fluid gushes down it and the more braking power you get. Your finger, via a mechanical lever, exerts force on the master cylinder piston in the lever. This force pressurizes the brake fluid (the smaller the diameter of the piston in the lever, the higher the pressure - mathematically pressure = force / area). If there is no pressure losses between the lever and the caliper (for example through expansion of the hose, splaying of the caliper itself, compression of air trapped along the way, etc) the same brake fluid pressure in the caliper translates into force applied on the pistons in the caliper (the larger the diameter of the pistons in the caliper, the greater the force - mathematically force = pressure x area).

 

[Sparticus]

I know it'll work cuz I recently did the opposite -- put some SLX 2-piston levers on my Deore 4-piston brakes. Works a charm.
=sParty

 

[IMeasure]

Thanks everyone for your responses!

That clears up everything and I will do the swap tonight after work.

Regards

Dan

 

[IMeasure]

New levers went on without a hitch. Bled the system and the new levers are a big upgrade on the originals.

Happy days!

 

[emerik]

hi, I would like to do the same upgrade. So did you use the bh90 fittings into your bh59 hose?

 

[IMeasure]

No, you leave on the originally BH59 fittings on the BH59 hose.

Just pull if the original lever and install the new one.

You will then need to bleed the system.

 

[FlaMtnBkr]

If you push the pistons out some you can switch levers without losing much if any fluid. Then push the pistons back in and fluid will be pushed thru the hose giving a mini bleed. Might need to top off fluid in master cylinder if it was low to begin with, but shouldn't need an actual bleed.

When pushing the pistons back in, it's best if they are on cleaner side so maybe clean them if filthy. Then it comes down to which you want to do less, cleaning pistons off with a handful of q tips or bleeding the brakes.

 

[wolfeno]

Hi,

Just found this thread with same idea in mind to replace my break levers with M6100.
Have BH59 hose and have question: do I need to purchase fixing flange bolts from BH90 set (black ones), or the BH59 ones will screw in fine into Deore levers?

Talking about these in the middle: