Shimano Hydro Brake > Post Mount Fork (RS785 Questions)

[pakora]

Soooo long story short I'm annoyed as heck that through a series of miscommunications, ambiguous spec sheets and me shooting first and asking questions later, I find myself in possession of a groupset with flat mount brakes and a frameset with a post mount fork.

It turns out their builds with new Ultegra and DA employ the older RS785 calipers with the newer R8020 and R9120 levers.

I'm 99% sure my only alternative is to run a RS785 caliper. Questions:

1) Is it compatible with the hoses and the rest of the fittings? Shimano's compatibility sheet lists RS785 as compatible, but it lists only the lever and caliper. Does it need any other parts?

2) Does it actually work? Sometimes compatible means "won't explode" and not necessarily "works well" or "works as intended."

3) I assume the compatibility extends to the new Freeza rotors is fine as well?

4) Are there any long term consequences?

[tigoat]

I do not use Shimano hydraulic levers so I cannot confirm the compatibility of this specific configuration. However, I have a bike where I use RS805 (flat-mount) at the rear and RS785 (post-mount) at the front and can confirm that both use the same hose fittings and I have not been able to detect any performance difference between the two after ridden this bike more than 10K miles. The RS785 caliper uses a much larger set of pads/heat-sinks and these pads lasted much longer than those smaller pads/heat-sinks of the RS805. I am on the third set of pads on the RS805 while the RS785 still on the second set. Basically, I think Shimano tried to make those road specific flat-mount calipers smaller and more compact, as RS785 is basically a MTB caliper. I just wish they would make a post-mount Dura Ace caliper, as there are still a lot of bikes out there with a post-mount setup that is not changeable.

[zank]

It's A level compatibility if you use the BH90 hose that comes with the R9120/R8020 levers. You will use the olive and connector that comes in the kit for the caliper end. Yes, you can use any Shimano Freeza rotor with the RS785 caliper. No long term consequences.

https://i.imgur.com/6uk2Zly.png

[sales guy]

Soooo long story short I'm annoyed as heck that through a series of miscommunications, incorrect spec sheets and me shooting first and asking questions later, I find myself in possession of a groupset with flat mount brakes and a frameset with a post mount fork.

It turns out for their builds with new Ultegra and DA employ the older RS785 calipers with the newer R8020 and R9120 levers.

I'm 99% sure my only alternative is to run a RS785 caliper. Questions:

1) Is it compatible with the hoses and the rest of the fittings? Shimano's compatibility sheet lists RS785 as compatible, but it lists only the lever and caliper. Does it need any other parts?

2) Does it actually work? Sometimes compatible means "won't explode" and not necessarily "works well" or "works as intended."

3) I assume the compatibility extends to the new Freeza rotors is fine as well?

4) Are there any long term consequences?

I just built up a bike for NAHBS that has R8020 levers and BR785 calipers. They work perfectly fine. Stock hoses, olives and barb fittings from the R8020 levers. Just make sure you don't lose the new R8020 compression nut that screws into the lever body. You can't buy them separately. ONLY with the levers OR with a hose kit for $50.

But yes, they work perfect together.

[oldpotatoe]

It's A level compatibility if you use the BH90 hose that comes with the R9120/R8020 levers. You will use the olive and connector that comes in the kit for the caliper end. Yes, you can use any Shimano Freeza rotor with the RS785 caliper. No long term consequences.

https://i.imgur.com/6uk2Zly.png

:eek:

[zank]

Eek what?

[pakora]

yay, thanks zank. I have the full lever/brake/hose kit so it looks like the best case scenario - I only need a different caliper.

[pakora]

Whelp, complications. I shared this information with my friendly neighborhood wrench and they said they would order a RS785 caliper.

I just got a voice mail that they installed a M785 caliper because they had one in the shop already and it works fine.

Does it? Googles sez yes and that side from a couple of grams it's a cosmetic difference except for how they secure the pads, and they ship with different pads, but all are interchangeable between these two models.

Is that true? Will it blow up? Do I get to ride a new bike this weekend?

[zank]

Yes, it's totally fine.

[pakora]

Thanks again!