Hydro - shimano or sram

[Stueys]

Looking at a new bike build and disc groupsets. I've always preferred Sram mechanical and Shim electronic but there's now clear water in pricing between Etap Hydro and 9170, I'm seriously thinking about Etap.

Ignoring the fact that I think the Shim hydro hoods are better than Sram (and I prefer mineral oil) I've always had in my head that Shim ice tech has put them ahead in terms of heat management. I guess I could always run Shim rotors but the Sram calipers also don't have the cooling fins.

Have I just be suckered by the marketing or does anyone think there is an engineered advantage with Shim over Sram?

[XCProMD]

FWIW i have had nothing but problems with Shimano DA disc brakes: vibrations, leaking pistons, bleeding port bolts... to me it’s stay away.

Sram’s are nothing to write home about but they do what they are supposed to.

[Stueys]

FWIW i have had nothing but problems with Shimano DA disc brakes: vibrations, leaking pistons, bleeding port bolts... to me it’s stay away.

Sram’s are nothing to write home about but they do what they are supposed to.

Interesting, I heard that they had some early issues. I've had 8070 on my winter bike for a few months now and it's been bullet proof. Only thing I've had to do was clear some air bubbles on the front bike as it was getting spongy, not touched it otherwise.

[spdntrxi]

I have a mix of 8070/9170 on my allroad bike.. so far so good. I really dont like the look of the SRAM hoods and honestly would rather use mineral oil (+ for shimano) if given the choice. Etap v2 is immenent, if you could wait ?

[Hexsense]

Maybe Shimano levers and Hope RX4 calipers?

For disc rotors, sandwich construction (thin steel-alu- thin steel) of Ice tech Freeza rotors are more advanced and complicated.
Sure it up heat slower because more weight are in aluminum and less of steel (aluminum's heat capacity = 0.921 J/(g-°C) compare to carbon steel at 0.502).
It also shred heat better due to more surface area and the fan blade in the middle (which, could potentially cause extra drag and catch crosswind.)
However, thin steel wrapped aluminum could warp or fail at lower temperature too because of the different in thermal expansion of the material.

Sram Centerline X rotor, built with alu spider and steel outer perimeter, do not shred heat nearly as well but having lower frontal profile and side profile against the wind as well as having been prove reliable and quite quiet. It's not that worse of a deal unless extreme heat shredding is required.

[Lewn777]

IMHO, it's too early in the development of road disk brakes. They've been ported across from MTB with barely a thought.

If I had a gun to my head I would buy Shimano and probably TRP or Hope calipers with SRAM rotors but I'd prefer just to have direct mount or rim brakes, mostly because I prefer SRAM shifting and like to keep things simple. For example I've never understood why anyone needs a disk brake rear wheel. Why? Most road riders barely use a rear brake, and if they do feather it gently. You're just adding weight for asthetics essentially.

Shimano brakes leak and have problems but at least the mineral oil is easy to work with, SRAM on the other hand use DOT fluid which needs to be degassed before use. I'm really not sure that DOT fluid works well in such a small system which makes bleeding a real chore as air bubbles hide in system some old MTB brakes had bleed issues from new.

I'm certain that road disk brakes will go through a great deal of development in the next five years espcially if the UCI drops the bike weight limit, meaning that future evelotions of disk brakes probably won't be compatible with current brakes. Also that weight limit drop could seriously erode the market for disk brakes.

[bilwit]

Those massive hydro etap hoods were a huge turn off for me. The 9170 hoods are just about the same as the normal 9150/9070 hoods except wider where it interfaces with the bar (where the hose is). You can save quite a pretty penny with 9170 shifters+calipers and 9070 derailleurs btw..

[MichaelB]

OK, I'll chime in.

My current setup is RS685 levers with Zee capilers ona road bike. 160 F rotor (RT81) and 140 rear rotor (RT81). Weigh it at 95 - 98kg, and 6'. Do a lot of hills (but not mountains), but like descending fast.

Having had a mix of experience (TRP, SRAM and Shimano), I'd go Shimano hands down.

In the 8+ years of playing with road disk in various formats, I had issues with SRAM (bleeding & leaking, but great spares availability), TRP's had small pads and worked OK, but Shimano have been faultless. Yes, some people have reported faults with Shimano, but then again, they have by far the largest installed base.

The Shimano Icetech rotors work better when there is a high heat load - on the same descent at the same speeds, i've had the centreline and G3 rotors suffer from fade, but not the RT81/86.

One thing I did notice recently with a bike that I am testing with the Shimano flat mount calipers (RS505/805) is that the pads are MUCH smaller than the R785 versions - close to 30% smaller, so they'll wear much quicker. Mind you, this is WW

[TurboKoo]

One thing to remember is that less heat equals less pad wear. Flat mount brake pads are smaller but normally they are improved in heat management.

[XCProMD]

IMHO, it's too early in the development of road disk brakes. They've been ported across from MTB with barely a thought.

If I had a gun to my head I would buy Shimano and probably TRP or Hope calipers with SRAM rotors but I'd prefer just to have direct mount or rim brakes, mostly because I prefer SRAM shifting and like to keep things simple. For example I've never understood why anyone needs a disk brake rear wheel. Why? Most road riders barely use a rear brake, and if they do feather it gently. You're just adding weight for asthetics essentially.

Shimano brakes leak and have problems but at least the mineral oil is easy to work with, SRAM on the other hand use DOT fluid which needs to be degassed before use. I'm really not sure that DOT fluid works well in such a small system which makes bleeding a real chore as air bubbles hide in system some old MTB brakes had bleed issues from new.

I'm certain that road disk brakes will go through a great deal of development in the next five years espcially if the UCI drops the bike weight limit, meaning that future evelotions of disk brakes probably won't be compatible with current brakes. Also that weight limit drop could seriously erode the market for disk brakes.

Mineral oil and with interesting tweaks over mtb brakes, that’s Campag.

[Stueys]

Thanks, so looks as if my suspicion on heat management is probably right. Now to price up a mixed dura set...

[bm0p700f]

Mountain bikers use bigger rotors to shed heat and that tells you something about how much heat you can put into rotors off road. It's not fair to say disc brakes have been ported over from MTB without a thought. They have been ported over with little change because little change is needed. It's bike manufacturers that are making bikes for small rotors that's the problem. 140mm have no place anywhere on a bike. Shimano brake systems are very good as are campagnolo's. They are about as developed as they can be. Apart from making the hoods more compact there is not much scope for improvement on the horizon.

[spdntrxi]

I have 140mm on the rear of my Tri Bike... it's fine there and I dont need more.

[Miller]

Yep, 140mm rear is fine. I can lock the rear brake with my 140mm rotors, yay! (Remind me, is that good or bad?)

[MichaelB]

One thing to remember is that less heat equals less pad wear. Flat mount brake pads are smaller but normally they are improved in heat management.

From what I have seen, they are no different.

Have a Road/Gravel bike atm on review, and have worn out a set of pads after just 2,100km (22,000m ascent) with mainly road riding. They were finned resin pads.

My Zee pads lasted about 5,200km (55,000m ascent) and very similar riding.