Availability of Ultegra Di2 11 speed (R8070) in the Future

I am wondering whether equipping a new bike with an Ultegra Di2 11 Speed Hydro Groupset makes sense today? I currently have the rim brake Ultegra Di2 8050 and would only need to find some Brifters and Hydro Calipers for my new disc brake bike, however I am concerned about the long term availability of spare parts. In particular, I was wondering if anyone had any information about how long Shimano will continue to produce spare parts, and beyond that, how long I can expect to find spare parts in shops (without having to scour ebay etc).

I would love to go for the new 12 speed Ultegra Di2 Hydro, however the price is astronomical and the availability thin on the ground right now.

Basic maintenance/consumables (i.e. chains, cassettes and pads) should be around for quite a while, not least because 105 is still 11 speed, and there are plenty of generics around. As regards shifters and derailleurs, it’s harder to say. A lot will depend on whether or not the new 12sp units are made backwards compatible (as SRAM have done, for example). The pandemic/shortage will have used up a lot of inventory that might ordinarily have been held as spares. I’d still buy 11sp Di2 in your situation I think, though a complete new groupset would be a doubtful choice IMO.

1 Like

According to the Di2 E-TUBE compatibility chart, it’s rather flexible (at least 11-speed amongst itself). I would really love for the 12 speed shifters to be backwards compatible at least… time will tell

Im building a bike with r8070 as we speak. Not at all worried about lack of consumable parts with a mix of used, 11spd 105, older gen. 11 speed and grx. I guess the shifters are the only thing that is difficult to replace, but I’ve imagine that single parts will be available as leftovers in at lot of shops when 12 spd. arrive in numbers.

1 Like

Why not use the ST-RX815 which are the (ergonomically and functionally) better brifters anyway and their BR-RX810 calipers which are identical to the BR-R8070?
If you prefer to ride your road bike without gloves and don’t like the structure of the ST-RX815 rubber covers just grind them smooth. It took me maybe 20 minutes in total.

1 Like

That is an excellent suggestion, thank you. I see that some of the lever ergonomics have been changed, probably for the better, but how are they functionally different?
Unfortunately the looks of the levers don’t agree with me that well for a road bike, I prefer the shape of the R8070 here.

The big difference with regards to function is that the pivot at which the brake lever turns sits much higher than with the “old” and even the very new Ultegra and Dura Ace brifters. Braking with your hands on the hoods your two strongest and most skilled fingers, the index and the middle finger, touch the lever of an Ultegra brifter with only a very small distance to that pivot thus generating a rather small momentum and therefore a small braking force. You’ve got to exert a lot of force in order to produce some serious deceleration. The stronger you pull the more difficult it becomes to modulate that force which, for obvious reasons, is not desirable when trying to brake hard.

With the GRX brifters Shimano has basically eliminated the need to grip the handelbars in the drops if you don’t like that position. You can comfortably generate the same braking force from the hoods as in the drops.

The extended height of their hump also forms some sort of a hand lock making it nearly impossible to loose grip off the hood while descending on a bumpy road.

Furthermore riders with rather large hands like their longer bodies as it allows for three fingers to grasp the brifter’s body while the index finger is slung around the brake lever. For riders with large hands (glove size 10 = XL) the Ultegra and Dura Ace brifters just feel too small.

Interestingly even riders with small hands like most women prefer the ST-RX815 over the Ultegra or Dura-Ace levers when we let them ride different demo bikes. So the additional length of the brifter’s body doesn’t seem to be a problem for them whereas the body’s girth, the more crucial dimension with regards to hand comfort and safety, is nearly identical.


Thank you for your comprehensive reply. I’m starting to lean in favour of the GRX! I’ve got XL hands and am primarily switching to disc brakes for improved safety, so I shouldn’t stop short and compromise on brake lever ergonomics. I also like that the hidden button has been relocated to the side which makes it easier to reach. I’ll need to take a closer look at these levers in person, they could really be the ticket.

Could you say anything regarding the hydro brake calipers? I was considering using after-market Hope RX4+ calipers in a funky colour, however from what I’ve heard they are not entirely trouble-free either.

I’ve never had a problem with Shimano disc brake calipers either off the road or on the road. Great stopping power although to be honest I feel that pad choice would actually be a bigger factor than how many pistons the caliper has. Well on the road/gravel anyway…

I’ve seen that the Hope calipers can be a pain to set up:

In comparison I’ve set up R7020, R8020 and GRX brakes and each time it’s been really easy and not too time consuming.

I’d only get the Hope calipers and rotors if the lovely anodised colours would really make the bike look that much better.

1 Like

Having ridden both setups, I’d have the GRX levers given a choice. I don’t love the ridges on the hoods, but that aside, they’re ergonomically great.

1 Like

While well designed 4-piston calipers make a huge difference with regards to performance - which you’ll only believe after you have tested them - I’d advise against using the Hope RX4. Our experience is related to their first version - not the RX4y they’re now offering - but those were nearly impossible to set up so that even a perfectly trued rotor would not rub against the pads with the slightest movement of the frame / fork.
For whatever reason Hope chose to minimize the pad clearance on those. Their unibody design with a much to slender brace connecting the two “halves” of the caliper also means the caliper isn’t stiff enough to deal with all the force those four pistons generate. There’s considerable bending (“breathing”) going on in that caliper contrary to what their marketing guys want us to believe.

On two of my own bikes - road and gravel - I run the ST-RX815 with Shimano’s BR-M9120 4-piston calipers which offer more than double the pad clearance of the Hope RX4. That does NOT mean though that I’d have to pull the brake lever a long way before the pads engage with the rotor. It’s as close to perfection as bicycle disc brakes have come in my more than twenty years of testing and tinkering with them.
On this setup I only have rotor rub occasionally in the rain / mud when particles stick to the rotor.

If you don’t want to run those Post-Mount calipers on your probably sleek looking road bike I’d therefore go with the Shimano BR-RX810 Flat-Mount calipers. You’ll most probably be content with their performance as long as you don’t test ride a bike with 4-piston calipers in direct comparison. Two of my friends did that and then felt the need to upgrade all their bikes to 4-piston calipers at least at the fork ;-).

1 Like

Thanks again for the great reply and your experience with the Hopes. They’re just damn pretty, that’s all, but I won’t sacrifice that much performance and hassle just for pretty looks.

I’m a tall and heavy rider (mid 80 kgs) and live in the alps, so fast and long descents are a big reason why I’m switching to disc brakes. While the roads are so well maintained here that 25 mm tires are absolutely fine from a comfort standpoint, I was considering going to 28s also for the improved grip and braking performance which a larger contact patch will afford.

What are your experiences in this regard? For example, would it make sense to run 4-piston brake calipers on the front with only 25 mm tires? Or would that only make sense with a switch to 28 mm tires?

How does tire pressure play a role here? I was thinking about also making the switch to road tubeless, however I like the feeling of firmer tires (e.g. 85 PSI on 25 mm), so I’m a bit put off by the low pressures recommended for road tubeless.

So I suppose you’re living in Switzerland. :wink:

I’m 1,90m and 82 - 83 kg and living on the other side of the border in the Black Forest. And I absolutely love descending as fast as reasonably possible. (At least I think it’s reasonable, riders I pass might disagree.) I’d say our road riding experiences are therefore probably similar.

I rarely ride tires wider than 25 mm labelled width (measured with between 27 and 28 mm) on my road bikes. Sometimes when testing tires I install tires labeled as 28s (measured width up to 30 mm). Even when riding in Provence where many roads still feature a chip seal surface which are sometimes in a really bad state I get along well with that tire dimension. I just ride them with considerably less pressure there.

My usual pressures are 5 to 5.2 bar in front and 5.8 to 6.0 bar in the rear tire (25mm tires) for rides on mostly good tarmac. While I never ride higher pressures than those I ride the same tires with 3.5 and 4.2 bars in Provence without bottoming out those tires. I always run tubeless tires.

To answer your question: No, on the road I’ve never experienced the need for a bigger contact patch in order to transfer all that braking power to the ground. Not even on wet roads. The limit to how much you can decelerate - when riding in a straight line - is always formed by the dynamic wheel load transfer which happens while braking. At some point your rear wheel will come up. And that’s even true on a very wet road provided your running good tires and at reasonable pressure and the road is just wet and not also covered in oil or other grime.

I’m noticing that many riders still falsely believe that they will have more comfort if they just install wider tires while the truth is that you have to run a considerably lower pressure in those wider tires in order to increase their ability to absorb road shocks. Wider tires offer a bigger potential for “suspension travel” and therefore increased comfort but only if you’re ready to run them with way less pressure. At some point they will feel too soft especially in turns. And that’s when the internal width of the rim becomes crucial. The wider the rim the lower you can go with the tire pressure without experiencing that disadvantage of a comfortably low tire pressure.

As you mention the size of the contact patch I just want to make sure that you understand that the size of the tire’s contact patch is not directly related to the stiffness of the spring which the tire forms. The contact patch of a 25 mm tire (measured width) at 5 bar is 25 percent smaller than the contact patch of a 30 mm tire at 4 bar. But their spring rates, the vertical stiffness of the tire, will be very close to identical at those pressures.


Bang on, Switzerland it is. I’ve been into the Black Forest and it’s a lovely area to ride.

I’ve got a gravel bike which uses post-mount brakes and I admit that on the front it just doesn’t look as sleek as aflatmount would, though for a gravel bike which has more of a rugged appearance that suits it just fine.

For my planned road bike, however, I’d like to see what the braking performance is like before deciding whether I should upgrade to the XTR 4-piston. I see that there’s also XTR 2-piston calipers which, from what I’ve read, are identical to the Dura Ace, however the fundamental build of all of Shimanos upper end disc calipers seems to be more or less identical, so I’m not sure what, if any, benefit the XTR 2 piston would have over the GRX.

I’m also curious which rotors and pads you would run. I’m leaning towards XTR rotors, however I’m unsure about the pads. My priorities are braking performance > longevity > noise while braking. On my gravel bike I have some semi-metallic ones which I’m happy with so far, but I would be interested in hearing your opinion.

For the wheels, I’m thinking of going for Lightbicycle AR46 rims, laced 24h/24h to some Bitex 312 hubs. Carbon-Ti hubs would be pimp but I can’t justify the extra cost. I’d like to try road tubeless in 25mm with conti 5k tr s or even the new veloflex corsa evo tlr which seems to be very good and also much more affordable.

All Shimano Flat-Mount calipers are technically the same.
Post-Mount two piston calipers though feature longer pads. Which means they don’t get as hot as quickly.
As long as I ran Shimano two piston Post-Mount calipers on my road bike I needed to run metallic pads in the summer. The organic pads regularly got too hot after around 300, maximum 400 metres elevation loss of full gas descending (brake late and hard, sprint out of any switchback, get into an aero tuck at around 70 kph, and then repeat for the next switchback). The brakes then started to howl and fade, rotors (180 mm front, 160 mm rear) turned brown.

With the four piston calipers and their longer pads I don’t need to swap pads anymore. I can run the organic pads (Shimano N03A) all year round. They are less loud, cause less rotor wear and are not as allergic to salt as the metallic ones. Once those came into contact with salt water they’re spent. I couldn’t make them stop squealing after that.

So, if you go for Flat-Mount calipers be prepared to run metaillic pads with cooling fins (L04C) in the summer. And if you can grab a fork which allows a 180-mm-rotor buy it. Doesn’t OPEN offer such a road bike fork?

So far my favourite rotors are TRP TR-25 for Centerlock hubs. There is also an identical version for 6-bolt-hubs. Very silent even in the rain. Sram’s Centerline X rotors have also always worked very well for me for a very long time and still do. But the TRPs even better and much quieter performance in the rain made me replace the Srams on more and more wheels.

Shimano Freeza or Ice-Tech rotors though perform badly under my braking demands. They don’t stay true, they squeal like crazy and will eventually even fail terribly if you ignore the fading and continue to charge them. From a safety point of view the aluminum layer in their sandwich design is just a terrible idea IMHO.

Those rims are great and 24/24 spokes are sufficient, but I would recommend to be patriotic when it comes to choosing hubs and go with DT Swiss 350s Straight Pull. You can of course spend much more money on hubs, but that won’t buy you any more performance or reliability.

1 Like

Thanks for the further information, particularly regarding the rotors and pads. I don’t plan on hitting such speeds regularly, but I’m also very fond of braking late and hard so I’ll make sure to have proper equipment just in case the mood strikes me. I’ve only ever hit 80 kph once, that was descending the Brunnigpass down to Meiringen, there’s a long and sheltered straight bit of road. The high alpine passes often have unexpected gusts of wind which lead me to be more cautious as my old bike had narrow 60mm deep wheels.

I plan on building my bike up around the Time Alpe D’Huez 21 frame, and I think it can only take 160 mm rotors.

If you have the time, would you mind taking a photo of your bike, especially the front wheel? I’m having a bit of trouble visualizing how the beefy XTR brake looks. I want to strike a balance between looks and usability (hence the Time frame which isn’t the lightest or most integrated, but is solidly built with no proprietary forks, headsets or seatposts etc.).

I’m torn on the hubs, my second choice would be the DT350s, I like their freehub mechanism but they’re both heavier and more expensive than the Bitex 312s and spare parts are also more expensive from what I’ve read. I like the look of the DT350s though, they would complement the rest of the build very nicely.

Personally I’m a big fan of Bitex 312’s and have two wheelesets built with them. You can’t do better than them if you want good value hubs.

Also they come in a range of anodised colours if you want to match them up with those nice, shiny Hope components.

If you’re going to be slamming the brakes on quite late I’d deffo use 28mm tyres to increase your contact patch and not get the tyres skidding out from you.

I’m 70kg and use a 160mm rotor on the front and 140mm rotor at the rear and it’s all the braking I need on the road on long descents. A 180mm rotor on the road is unnecessary IMO unless it’s on a tandem or a heavily loaded bike.

1 Like