I have some (non flatmount) RX4 paired with road 4700 hydraulic sti levers, on a frame that is being retired.

Basically will these work with the hope Tech 3 V4 Levers?

Since the brakes seem to be the same thing, they use the same pistons (14mm and 16mm) and parts, so i’d assume the brakes are set to push the same amount of fluid into the calipers?

I’m trying to do a bit of swapping because I have some flatmount grx calipers that will fit well with the 4700 sti’s on a new frame. Which leaves me with the rx4 calipers, but i’d like to put them on a mountain bike since it has regular old school mounts.

Is this mad?

Don’t Hope usually use dot brake fluid – in which case the tech 3 levers will have seals for that….the RX4 calipers have mineral oil compatible seals for road shimano brake levers?

Why not just sell the grx and fit the rx4 with flat-postmount adapters. The shimano will only leak 😜.

Why not just sell the grx and fit the rx4 with flat-postmount adapters. The shimano will only leak 😜.

Nope, not gonna work For the reason mentioned above. The seals won’t take Dot oil, which is what the levers work with. You might be able to run them with some Shimano MTB brake levers though…

Edit stupid gateway error double post.

Hope sell dot and mineral oil compatible versions of the RX4. I assume the only difference is the seals, which means you probably just need two dot fluid seal kits from Hope

The other thing to double-check with Hope is whether the hydraulic ratio is the same ie does a Tech 3 lever push the same amt of fluid as a Shimano STI lever

The dot Vs mineral RX4 calipers are quite different in that they even use different pads. I have two pairs of RX4s with SLX levers and they work very nicely.

Even ignoring the hassle factor I just can’t see it making sense. Unless you just happened to have levers already and even then you’d be better with the proper dot x2 or e4 calipers for them.

Oh pm me as im after a set of Hope Tech 3 levers!

Haha, i woke up this morning and totally realised the DOT mineral problem, is was so focussed on the piston, bore and stroke length i was ignoring the obvious problem 😀

Yeah i’ll just put them on adapters no problem really, they are quite overspecced for this frame/bike was thinking i could retire them to a slightly bigger hardtail!

singletrackworld.com/forum/topic/hope-rx4-vs-tech-3-v4/#post-11289794

Oh right this has actually interested me GeForce Junky, so the regular SLX/XT shimano levers (since they are mineral) are compatible with the RX4? That could work for me, I already have the levers kicking about. That means i can just swap a few things about between bikes.

Bit of a faff, i’d just like to know someone might have tried it first before i have all three bikes with brakes in bits attached to things that werent designed, and mineral fluid everywhere 😀

Yeah it’s a straight fit, cut the bango off the SLX hose, insert the hope olive and fittings, bolt up and bleed. Gives a more progressive feeling brake than SLX with a good amount of power. Lever travel is good and I haven’t had any wondering bite points which I was getting with one of the slx calipers. Looks great and they use normal E4 brake pads.

Sweet, i think this is exactly what i want, i’ll give it all a whirl, i just assumed the stroke/bore and whatever in the hydro system wouldn’t be compatible with the mtb levers. Or at least that’s probably what they want you to think.

Oh wait i’m out of the right barbs and olives, this has to wait for now anyway it seems.