School me on 4-pistons

[sethschmautz]

Looking for info on 4-piston brakes. I'm finding that I'm starting to outrun my 2-pistons a bit and doing bigger descents (3000-4000+ vert) so looking to upgrade to 4-pistons. I have Shimano on just about everything that I own currently so there is a lot of value (for me) in staying with something I can use the same mineral oil and bleed kit to fix.

I actually have a set of the TRP Slates but the last time I pulled them out of the parts bin the metal pistons fell out of the caliper which made me concerned about their viability. If anybody has much experience with these, I'd love to know whether this is normal or something to be concerned about. They (pistons) seem to be very loose in the calipers.

However, I'm open to other options from magura, etc. also. Anybody have any recommendations or a set to sell?

Seth

[Falcon3]

I upgraded about a year ago to Deore 6120 4-pots. There’s really no reason to go higher grade, even the XT is only a couple grams lighter. MT520 is the same as the 6120.

I got mine from Taiwan on eBay for under $200/set.

[rod9301]

I had magura mt7 on two bikes and nothing but problems, pistons not retracting, do really noisy.

Went to Hayes dominion, 4 pistons, great brakes

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[SKIP IN7RO]

My stock Sram Code R's have been fine so far.

[nickwm21]

What size rotors do you have? What compound pads?

You can possibly save yourself $500 by bumping up to 200mm rotors and metallic pads….

Brake wise - I like Magura MT7s. I have had them on two bikes and none of the issues Rod had… Brakes definitely fall into the “choose a brand and be a dick about it” category. It’s really about what annoys you the least..


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[sethschmautz]

203 up front and 180 out back. Metallic pads.

[dannynoonan]

Did you say that the *pistons* fell out? Did you mean pads? If the pistons came out, those are basically just trash.... Not that you were gonna use em anyway

[rod9301]

Mt7s are great when they work.

When i had them, 4 years ago, i couldn't believe how much braking power they had, and how good the modulation was.

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[detrusor]

My xt 4 pots have been outstanding….


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[sethschmautz]

Pistons, yes. I'll try to upload a picture later this evening.

[mooseknuckle]

I upgraded about a year ago to Deore 6120 4-pots. There’s really no reason to go higher grade, even the XT is only a couple grams lighter. MT520 is the same as the 6120.

I got mine from Taiwan on eBay for under $200/set.

Got bit by some Taiwanese xt m8000 pedals. They sucked. Hoping brake experience is better. The price was right.

[SJG]

I like the stopping power of 4pot calipers, BUT they are not perfect. I run 203/203mm, Clydesdale with long/fast descents (2-3k').

My biggest complaint with 4pots are they are more prone to issues if a piston sticks. In a 2pot it's not nearly as big a deal, but on a 4pot it causes binding and pad drag on the rotor. I have seen it with Shimano, Hope, and SRAM. I only have 1 buddy with TRPs and his are only a month old, and he hasn't had any issues (yet).

But 4pot are a huge upgrade over 2pot brakes. If you do any gravity or lift-serve riding they are strongly recommended IMO.

[toast2266]

Shimano: more power than the equivalent sram options. Relatively cheap. 70% chance that your lever will randomly pull to the bar with no warning. This can be fixed with an involved bleed procedure, which will make the brakes work great until the next time they randomly stop working.

Sram: better modulation, but the least power of any of the common brake options (although they're still much more powerful than a 2 piston). If you leave them in the sun for too long, there's a chance the lever will seize. Bleeding is easy, but you need their special bleed kit.

Magura: good modulation, great power. The plastic lever will fail at some point.

TRP: everyone I know either loves them more than any other brake or utterly despises them. There is no in between. I haven't ridden then enough to give any opinion beyond that.

Hayes: the new crop actually sounds really good, but I haven't tried them.

[HAB]

Those Slates are basically the least powerful 4 piston brake out there anyway. They're actually pretty good in most other respects (or at least the newer, updated ones are) but if you're after more power they're not the answer.

I haven't tried the more powerful TRP options enough to have an opinion on those, but the rest of the stuff Toast said is right. Hayes Dominion A4s are my favorite.

[skizix]

Current Saints w/ 203/180 are fkn super strong and have never ever even slightly faded on me. Modulation is great (vs e.g. XT). Not the lightest but one-stop shopping for bombproof stoppers. These things kick ass.

Bleed process is simple enough (I just do the gravity thing and then a quick lever bleed - no syringe involved, no mess) and I’ve never needed it until pads were on their very last leg (at which point completely replacing oil is the right call anyhow).

[justcuz]

I had magura mt7 on two bikes and nothing but problems, pistons not retracting, do really noisy.

Went to Hayes dominion, 4 pistons, great brakes

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This.


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[Beaver]

Have you tried finned brake pads? That and a 203mm rotor on the rear will help, that was my solution for the 3000' decent I rode often on my Reign.

[SKIP IN7RO]

My dentist says Trickstuff Maximas are worth the 18 month wait.

[sethschmautz]

Finned pads - yes. 203 rotor on the back - not yet. In the overall stopping power percentages I have been assuming that rear braking power is significantly less effective than front. It has been a while since physics and no doubt somebody can (and will) set me straight, but here is my thought process - rear brake accounts for ~30% of total stopping power and the increase from 180mm to 203mm rotor is approximately a 13% increase in size (how does that translate to power?). 30% of 13% is about 4%.

On the surface, it looks like this upgrade in rotor size would give me approximately 4% increase of total stopping power. Even as much as 13% is something, but not sure it's going to be all that much.

[toast2266]

Putting aside all of the front vs rear power calculations (which are valid, but not static unless you're just on flat ground), a bigger rotor will dissipate heat better and run cooler. Which matters, especially on a long steep descent where you end up dragging the rear brake a lot.

[sethschmautz]

Additional thought - haven't I read on here that all shimano levers are essentially the same? I.e. can I just install a 4 piston caliper with my existing levers? Is there value in upgrading the lever at the same time as long as the current levers seem to be fairly solid?

[meter-man]

203 up front and 180 out back. Metallic pads.

Check out this article. https://enduro-mtb.com/en/rotor-size-myth/ I found it surprising and counterintuitive, but also persuasive.

I run 200/200 with Code RSC. Maybe try the 200-203 rear rotor first as that is the cheapest upgrade and will work with any brakes.

If that doesn't do it, go with a 4-piston.

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[Beaver]

Like toast said, its all about heat dissipation. Fancy schmancy ice tech rotors would help too.

[jm2e]

You're already using Shimano brakes.
And you said you want to keep using Shimano brakes.
So not much point in the whole brand vs brand tangent.
Going from 2 piston Shimano to 4 piston Shimano will make a big difference. Especially on big fast steep descents. The levers will also have a similar ergonomic feel. Similar braking style, just better in every situation.

Probably not worth messing around with just swapping the calipers. Get a Zee brakeset and call it good.

That Enduro-mtb article is intriguing. Not scientific, but a provocative viewpoint. I don't know anyone outside of DH racing who's using 220mm rotors front or back. I can see their point with warping (which the article doesn't really address directly). To that end, I put 2.0mm thick Magura rotors on one of the DH bikes this season and so far no warping which is soooooo nice. Cheaper and working as good/better than overpriced IceTech.

[sethschmautz]

All good thoughts. The current XT 2 pistons are going to go on my wife's bike and I got word back from TRP that the pistons can go right back in without issue. I'm going to give them a shot (since I have them and why not?) and also try upsizing the rear rotor. If it works it's just the cost of the rotor. If it doesn't, I'll look at the shimano 4 pistons.