First Look – Shimano Flat Mount hydraulic road disc brakes debut, new 11-speed 105 Level hydro shifter & more!

Written by Zach Overholt Mar 31, 2015 2:36 p.m. ET

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Shimano BR-RS805 flat mount hydraulic road bike disc brake caliper

There has been a lot of speculation since Shimano first announced a new brake mount specific to road, but little in the way of details. Ironically coming on April 1st in Japan, Shimano is finally showing their hand and introducing two new hydraulic road disc brakes built specifically for the Flat Mount fitment. Announced along with a new 10 speed Tiagra group and WH-RX010 road disc wheelset, the new BR-RS505 and BR-RS805 disc brakes are non-series components at the 105 and Ultegra level respectively.

We have a feeling we’ll be learning more about these new brakes come Sea Otter, but the preliminary details are after the break…

Beneficial to both the frame and the caliper design, Flat Mount uses an all new caliper that bolts up from the bottom instead of through the top like most calipers. On the rear brake that results in a true “Flat Mount” with the caliper sitting directly on the chainstay. Caliper mounting bolts are inserted through the bottom of the chainstay and thread into the caliper making a very tidy rear triangle of the frame. While the mounting and shape of the caliper changes, the brakes still use one-way bleeding with a bleed nipple at the highest point in the caliper’s hydraulic workings.

Due to the fact that the caliper bolts up through the bottom, the front brake will still need an adapter which is then bolted to the back side of the fork leg. Shimano tells us that you can still use additional adapters to run larger rotors while the brakes are capable of running 140mm.

Visually, there is little difference between the BR-RS505 (105 level) and BR-RS805 (Utlegra Level), other than the finish. We wouldn’t be surprised to find that there is more to it beneath the surface though. Both calipers will use new brake pads which are not mountain bike compatible, likely meant for much higher heat applications.

Completing the RS-505 level hydraulic system is the new ST-RS505 hydraulic/mechanical shift lever which brings Shimano’s hydraulic road performance down to the most affordable level yet. Compatible with either of the new Flat Mount disc calipers or even previous Shimano hydraulic road calipers, the 11 speed mechanical shift lever with Vivid Indexing includes reach and free stroke adjustments as well.

As promised, frames equipped with the new Flat Mount standard will still be able to run standard road brake calipers with one of the Shimano adapters. That means frames will be backwards compatible, but the new Flat Mount brakes will not be since they can only be mounted to frames with the Flat Mount provisions.

Along with the ST-RS505 brake levers, the RS505 system includes a new 105 level Centerlock hubset to facilitate custom wheel builds that are 11 speed road disc compatible.

The Flat Mount brakes will continue to use the current Shimano Centerlock rotors with the SM-RT81 and SM-RT99 Freeza rotors available down to 140mm.

Updates on availability: The Ultegra level flat mounts will be available in July. The 105 level calipers and 105 hydro/mechanical shifters will come out in October 2015.

We’ll update the story as pricing and weights become available.

Bike.Shimano.com

Zach Overholt

5,630 articles

Zach Overholt is the Editor in Chief of Bikerumor. He has been writing about what’s new in the bicycle world for 12+ years. Prior to that, Zach spent many years in the back of a bicycle shop building and repairing nearly every type of bike, while figuring out how to (occasionally) ride them.

Based in Ohio, Zach is now slowly introducing a new generation to cycling and still trying to figure out how to fit the most rides into a busy schedule as a new dad.

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62 Comments

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What goes Around

9 years ago

Wow Hayes tried to do a flat mount years ago. They were ahead of their time.

9 years ago

Why all shima calipers have this fugly black plastic on top of the pads??? I just don’t buy because of that, Life is too short to ride bike with fugly black plastic on top of the pads.

bikertidy

9 years ago

It’s not plastic, it’s the pad backing extended into a heating to help keep the brakes cool. It’s literally a very cool feature.

gabe b.

9 years ago

Didn’t hayes come up with this in the 90’s with their 22mm direct mount caliper?

Andrew

9 years ago

@me they are heat fins. They serve a purpose and look badass!

Mike

9 years ago

@me
They are anodized aluminum cooling fins.

It’s one of the reasons why Shimano brakes operate at a much cooler temperature.

Kerry

9 years ago

@me

If you haven’t been following along with Shimano moutain tech, those are cooling fins that dramatically increase heat dissipation over non-finned pads. Read: You modulate speed better and experience less brake fade. This makes for a happier ride, where you might spend more time looking ahead on the trail/road/gravel than looking down at your brake caliper.

satisFACTORYrider

9 years ago

me was jokin. me thinks…

Graham

9 years ago

So with a flat mount frame, and the new flat mount brakes, you’re restricted one rotor size in the back? Hmm. Also those levers looks very interesting…….

Smitty

9 years ago

@me, also life’s too short to care THAT much about how little bits on the brakes look.

jeffnbose

9 years ago

So, which companies are on-board to produce disc compatible frames? Is carbon fiber still a frame material option?

em2

9 years ago

So they solve the big problem of the ”now” standard mount which was that everybody liked it … #cute

MikeC

9 years ago

If the bleed nipple on the rear caliper is at the highest point, to facilitate bleeding, it’s at the lowest point on the fork, to ________ bleeding.

Glenngineer

9 years ago

“me” is why I don’t miss working in consumer product design…there are consumers at the other end of your work.

Hansen

9 years ago

Does this affect the standard on disc brake spacing?

9 years ago

yeah I was jokin. Smitty…common, lets be honest…cycling is all about how things look…still not buying.

9 years ago

Oh Shimano, you tease. Those hubs aren’t 15/12mm axle compliant! It is a good business model, changing the disc standards from mountain.

anonymous

9 years ago

Make a new standard, and only release a brake that requires an adapter for it. Good job Shimano.

Also, that shifter/brake unit almost made me throw up a little.

gibbon

9 years ago

Err…..How do you align the caliper? The mounts are’nt slotted……

swmmo

9 years ago

That rear mount location is nothing new… I had a Hayes hydro. Disc mounted there on my 1999 trek 8900… My first ever disc brake equipped bike…

I don’t know why they ever moved the mount from there in the first place. Makes perfect sense to be inside the rear triangle rather than mounted up top above the axle… Structurally sound in the frame and concealed well.

http://forums.mtbr.com/trek/1999-trek-8900-build-800492.html

anonymous

9 years ago

Also, it’s a shame the hubs aren’t thru axle. If the industry is going to settle on standards for the future of road disc brakes, it really should do it now, all at once.

Ripnshread

9 years ago

Sure, but are they BOOST compatible?

Frippolini

9 years ago

What’s the advantage except the looks for this new standard? Does the disadvantage include the change of “squeezing” the chain stay tube if not properly using a torque wrench? What was wrong with what is in place today? In general I’m all for evolution and technological innovation, but come’on are there no limits to how many variations of “standards” that the bike industry needs to adapt to? An interesting topic in itself, how many variations of frame affection variables are required until the frame producers says enough no-more? OR is the total market value of sold “adapters” sufficiently profitable to offset the disadvantage of 1000’s of possible variations?

As for the looks of the brifter… I’ll rather stick with rim brakes until something nicer looking comes out from the great S-factories.

jesse

9 years ago

That bolt on right side looks amazingly irritating to get in or out, but maybe I’m missing somethign.

JBikes

9 years ago

@ Graham – not technically. If a larger rotor fits in the frame, an adapter could be used to move the caliper toward the crank and upward.

@ Frippolini – I’d think most manufacturers would place tubes spanning vertically across, thereby eliminating any clamping of the chainstay. All bolt clamping forces will be applied directly to the tubes, be they metal or composite, leaving the chainstay wall to remain as thin as desired. At least that is the way I’d do it.

anonymous

9 years ago

@Jesse
That’s the bleed nipple

These calipers bolt in from the bottom.

Gunnstein

9 years ago

So, on the front brake the cooling fins are parallell to the airflow. In the rear they are more or less perpendicular. Would like to know what guided that decision.

PeteG

9 years ago

I like the idea of the flat mount. Esp if it means theres a lack of thread in the frame for people to screw up. Replacement caliper a lot cheaper than a frame.

JBikes

9 years ago

@ Gunnstein,
There is certainly enough turbulent flow around the cooling fins to displace any heated air, which is all that is needed. They just act as a heat sink. There is no reason to have f/r specific pads with “aligned” cooling fins.

Ride With Mee

9 years ago

@gunnstein, it’s the same caliper front and rear, same pads, same alignment.

Gunnstein

9 years ago

@JBikes Sure, but then it would at least look better if they where rotated 45 degrees, aligned semi-radially. But perhaps the logic is that efficient cooling is more important at the front, which does most of the braking, so even if the difference is marginal they would optimise for the front.

@MikeC seems to have a good point about bleeding the front.

fast foreward freddy

9 years ago

as long as the bleed nipple is at the very top or bottom, you’re fine. The front probably bleeds nicer. just open the valve and let gravity do the work for you.

Nico

9 years ago

Why do you think thru axle will we the new “standard” for road bikes? At best it will be the second standard.
They way thru axle works now, it will be impossible to use in the protour. Try changing a flat wheel/tyre in sub 15sek, like they do today, with a thru axle.

Gunnstein

9 years ago

@fast foreward freddy Ok. I know little about this oily stuff. Something new learned today then.

Dude

9 years ago

What is up with that new lever? Huge bulbous knob and either a long body or skinny blades – looks totally out of sync with the rest of the Shimano line up. On the one hand, I’m dying for Deore-level hydros for the CX/gravel machine, on the other, it’s got to at least have familiar ergonomics.

JBikes

9 years ago

Gunnstein,
You just need some cooling pins!
https://bikerumor.com/2014/05/21/stop-components-kool-stop-bring-peg-finned-brake-pads-to-north-america/

imalittlegurl

9 years ago

@swmmo totally agree. my trek 8900 is the greatest bike ever, still blowin’ past all the h8’ers on the trail. the 22mm mount for the rear caliper was the shiznit. also, thru axles are for the nerds who cant get their wheel in str8. open dropouts forever!

pdxfixed

9 years ago

@fffreddy, that’s not how one-way bleeding works. If you look at the front caliper, any bubbles on the non-drive side will be trapped at the top of the piston, up and to the left of the “S” in the logo, where the shape draws to a point.

Also, I second the question of “How am I supposed to line these things up??”

mike

9 years ago

is the new one can squeze the brake from booth side? or the same like ultegra, from one side only?
in from one side only like ultegra, better buy trp brakes

Ilya

9 years ago

Any info on the weight compared to RS685 shifters?

Mike

9 years ago

I just want to know, will the revisions be called BR-RS506 or BR-RS505-B?

muf

9 years ago

im not sure to see what the new standards in this one bring to the table (except being incompatible)
ive riding a disk brake bike for hours downhill and braking all along.. on a road bike.. because im a chicken.. sure it ran hot but nothing happened. my mtb appears to run around as hot eventually …

as for the flat mount, meh ive had such brakes, its the same really. I feel like all this is just to be incompatible with MTB and thus have a different price range/buy twice/etc.

John

9 years ago

@Nico: The RAT thru axle system developed by Focus Bicycles is easily as fast as a QR wheel change.

Rob

9 years ago

@pdxfixed and @gibbon – Looks like the frame needs to be slotted to line up the brakes rather than the calipers as we are use to. Makes sense to me.

gringo

9 years ago

One point worth noting for anyone who asks ‘why?’ Any performance or maintenance benefits touted here are the bait to get OEM’s on board.

With this new interface, if shimano can sell OEM’s a certain amount of spec in a given model year, this interface will ensure that all bikes from said model year will always be shimano equipped as SRAM et al. do not produce brakes to fit this interface. After riding the bike for a few years, the consumer wants to upgrade or refresh some parts, goes online or to their LBS and is either bound to Shimano, or will need to add a (heavy) adaptor to their light and fast road bike.

This will result in a fairly nice chunk of additional aftermarket revenue for Shimano simply by selling OEM’s on a (for now) proprietary interface.

Shimano makes amazing components, but also has some savvy minds driving the business.

anonymous

9 years ago

Not seeing where Shimano has exclusive rights to flat mount standard.

gumby

9 years ago

@fast foreward freddy I think you’re optimistic expecting to bleed it with the bleeder at the bottom of the calliper unless it’s water you’re removing.

9 years ago

The reason for the new mounting pattern is cosmetic. Shimano have so much as said so in the past. The reason they are pursuing a new brake mount for mostly cosmetic reasons can be found in about half the comments on this and most any other post about how ugly something is, and that’s all that matters to a large percentage of riders… er, people that buy bike stuff (if you’re that worried about how your brakes look, I have doubts about how much you actually ride).

9 years ago

One of the beauties of the old system was that if the customer screwed up a thread the adaptor was the only part that got ruined, cheap and easy to replace. Now with threads in the caliper any thread damage is going to be very expensive.
I also wonder how the front is supposed to work, how do you align it when the bolts are trapped behind the adaptor, and as already mentioned the bleeding just seems to have got as bad as it could be…

gringo

9 years ago

@ Anonymous.

If you think Shimano is going to spend development time on a new interface then promptly give it away to SRAM or Hayes then I got bridge in Brooklyn with your name on it!