Hydro - shimano or sram

[TurboKoo]

Which brakes you have to compare? Zee brake pads are almost double the size and that’s why also last longer. Better to compare BR-RS785 and BR-R8070 than 4-pot brakes.

In my opinion that’s a good indication that bigger pads last longer but it’s not really scientific as conditions can vary a lot

[seahuston]

I have bikes with Shimano and Sram road stuff and I would definitely go Shimano for anything in the future. I like shimano hoods and lever feel and appreciate the pretty good adjustability in the new kit.

However, it's mainly for the bleeding and maintence. I personally hate bleeding Sram/Avid brakes.

The shimano bleed process is dead simple and it's mineral oil.

[mattr]

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.

Funny, DOT works perfectly in all the hopes i've dealt with (lots) generally better than the mineral oil, at least, it comes out clean and the ones i've got *tend* to perform better, but that might just be that the hope brakes/design suit my type of riding.
I think the degassing was more a feature of SRAMs brake designs than any inherent problem with the fluid. (And AFAIK they took that part of the process out of the manual a couple of years ago for some/all of their models)

Disclaimer, I've yet to use a SRAM/Avid brake for more than a handful of rides, just about every one i've ever had has failed almost immediately out of the showroom. These days i swap immediately, even the bottom of the range, non-series shimanos are more reliable than the last set of SRAMs i used.

[bm0p700f]

My comment is the address the problems some have with overheating brakes or warping rotors. For many 140mm is fine but not all. Being able to lock the rear wheel is irrelevant. Given the weight difference between a 140mm and 160 mm rotor there is simply no point them. Bigger rotors are a bigger heat sink. I have warped 160mm rotors in the lake District. A 140mm rotor would have been in worse shape.

[TobinHatesYou]

What exactly is difficult about bleeding SRAM brakes? You attach to syringes and slosh the fluid back and forth until there’s no bubbles, optionally agitating more bubbles out slightly pulling/pushing on the plunger before pressurizing it again. The only real faff is that DOT fluid is a pretty strong acid and eats paint.

[jeanjacques]

What exactly is difficult about bleeding SRAM brakes? You attach to syringes and slosh the fluid back and forth until there’s no bubbles, optionally agitating more bubbles out slightly pulling/pushing on the plunger before pressurizing it again. The only real faff is that DOT fluid is a pretty strong acid and eats paint.

+1
No problem at all with Sram, very quick to bleed. Even bubbles isn't a real deal, the piston can handle a lot of them before the lever feel spongy.

[bm0p700f]

It takes longer to get right with SRAM bleed pro redirect than on a Shimano brake set. However now everything is internally routed that's no less nger the case. Everything is a bit of a pain to bleed as getting all the air out involves contouring your bike or caliper into funny positions not need just 5 years ago.

[MichaelB]

Which brakes you have to compare? Zee brake pads are almost double the size and that’s why also last longer. Better to compare BR-RS785 and BR-R8070 than 4-pot brakes.

In my opinion that’s a good indication that bigger pads last longer but it’s not really scientific as conditions can vary a lot

Had all three side by side.

Either way, was VERY surprised that given the caliper piston size is the same (AFAIK), that the pad is that much smaller on the 785 calipers vs the 505/805 versions.

[youngs_modulus]

What exactly is difficult about bleeding SRAM brakes? You attach to syringes and slosh the fluid back and forth until there’s no bubbles, optionally agitating more bubbles out slightly pulling/pushing on the plunger before pressurizing it again. The only real faff is that DOT fluid is a pretty strong acid and eats paint.

Technically, DOT 5.1 fluid isn't acidic; it's usually close to neutral. Here's a link to a Finish Line safety data sheet that calls out a pH of 7 (neutral, just like water):
http://www.finishlineusa.com/files/Brak ... 202015.pdf

But I think we all knew what you meant: DOT 5.1 is a strong solvent and totally eats paint. And this is my primary complaint about using DOT 5.1 for bicycles: the consequence of getting a little fluid on the bike's paint are pretty major, whereas getting mineral oil on your bike's paint isn't a big deal. On mountain bikes, you run the risk of stripping paint away from your fork lowers, which are often made of corrosion-prone magnesium. Even on a road bike, it's pretty easy to get fluid on the paint at either the lever or the caliper. Sure, you can use rags to protect your paint, but DOT 5.1 is nasty stuff and (IMHO) a pain to use.

I like ETap better than Di2 but strongly prefer brakes that use mineral oil, so I find myself idly wishing that someone would make an alternative set of brake seals that would allow the use of mineral oil in SRAM road brakes. But the potential liability there would be huge, so I can't imagine anyone will do that. I also don't see SRAM changing--ever--because then you'd have to know which model year your brakes are to know which kind of fluid to use with them. Getting it wrong could easily mean an ugly, ugly injury (or worse). So SRAM brakes will likely use DOT 5.1 for the foreseeable future. Sigh.

[TobinHatesYou]

Technically, DOT 5.1 fluid isn't acidic; it's usually close to neutral. Here's a link to a Finish Line safety data sheet that calls out a pH of 7 (neutral, just like water):
http://www.finishlineusa.com/files/Brak ... 202015.pdf

I actually meant basic rather than acidic.

Looks like DOT fluid is spec anywhere between pH 7 and 11.5. I've definitely seen a datasheet of one brand with pH 10. Maybe it was DOT 5.1 specifically though.

[dvq]

I've been perfectly happy with sram hrd -- they're easy to get install, bleed, and set piston advance. They've been noise free and low on dust with organics, metallics and even some of the swiss stops. Brake fluid doesn't bother me at all, it won't strip your paint off if you get a some on your bike unless you leave it on there for a while. I usually just bleed, spray it down with isoproypl alcohol and I'm good. Whenever I bleed my track car's brakes I also bleed the bicycle's brakes -- usually gets some left over Castrol SRF DOT 4 -- the good stuff.

[youngs_modulus]

Technically, DOT 5.1 fluid isn't acidic; it's usually close to neutral. Here's a link to a Finish Line safety data sheet that calls out a pH of 7 (neutral, just like water):
http://www.finishlineusa.com/files/Brak ... 202015.pdf

I actually meant basic rather than acidic.

Looks like DOT fluid is spec anywhere between pH 7 and 11.5. I've definitely seen a datasheet of one brand with pH 10. Maybe it was DOT 5.1 specifically though.

Yeah, I follow. 11.5 is pretty strongly basic. But 7 is neutral, so even though some DOT 5.1 is basic, much of it is neutral or only weakly basic. All DOT 5.1 varieties are solvents, though, and that's my objection to using it on bikes.

To be clear, DOT 5.1 and mineral oil both seem to work just fine in bikes; I just think that bleeding SRAM brakes is a hassle because I have to protect my bike's paint.

Another factor that might be worth mentioning: I own what I need to bleed Shimano brakes, but I don't own the equivalent tools for SRAM brakes. I don't want to mix bleed kit components because I don't want to mix these incompatible fluids.

I hear a lot of disc-brake skeptics complain that "hydraulic disc brakes are a pain to maintain" when what they mean is "I own the tools to work on mechanical rim brakes, but not those for hydraulic disc brakes." Part of my irritation with DOT 5.1 is driven by the fact that I don't currently own the tools to work on hydraulic brakes that use anything but mineral oil. I don't think "I don't own the right tools" is a reasonable argument against hydraulic disc brakes, so it's also not a reasonable argument against a particular hydraulic fluid.

[mattr]

TBH, i've been using hopes with DoT fluid for near enough 20 years (and worked in a few hope dealers doing service work etc) and i've yet to see any of my bikes (or the bikes i work on) suffer any paint or finish damage from spilt DoT fluid. And i HAVE spilt DoT on fork lowers more than once. 10 seconds with a rag, and/or a bit of brake cleaner. Or even hot soapy water

Even the forks and stays on my old retro race bike (mid 90's vintage) which ran hope discs for ~10 years has no signs of paint damage, or damage to the drop outs or carbon fork legs.

(i have seperate boxes for DoT and mineral bleeding stuff, IKEA can be useful.)

[onemanpeloton]

I've had numerous problems with leaky RS685 calipers so I wouldn't buy those again.

I like shimanos shifting though so I've just ordered a set of hope RX4s. Not fitted them yet.