Gravel / Gravé / Gnarmac / Groad / ATB

my bladder bursts frequently, but not because someone has spread my pistons, nor touched my bleed port

Narrator: he burst his bladders.

I only do this when the pistons won't stay back, but it's good advice for home mechanics

I've never opened the bleed port to spread Shimano pistons and I've never burst my or a brakes bladder.

This. I have a 'very filled' system (bleed it with something skinnier installed) because I like the minimal lever throw and I've lost count of the times I've pushed the new pads apart to fit the wheel in. Zero problems.

Yeah, if they've been overfilled or whatever and they don't retract fully I'll let some escape at the lever, but it's never caused a problem on the hundred of brakes I've done that haven't needed that.

it's never caused a problem on the hundred of brakes I've done that haven't needed that.

You’re definitely lucky, even Shimano themselves specifically said to open bleed port before spreading piston.

It’s very common on the later Shimano shifter from R7000/8000 etc.

People; don’t open up piston on Shimano levers without taking the bleed port out, it’s seriously a thing and will cause it to leak from the hood if bursted.

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Is that only on road levers or on mtb too?

Very common on road, less so on MTB.

Are you sure about that? Just a random manual on their site and they don't mention opening bleed ports at all https://si.shimano.com/en/dm/RADBR10/replace_brake_pads

Shimano themselves specifically said

They say lots of stuff. Most of it can be ignored if you kinda know what you're doing.

don’t open up piston on Shimano levers without taking the bleed port out

Are you talking about the a piston in the levers or the pistons at the calipers?

So if I'm going from one pair of wheels to another, should I realistically expect problems? Would wiping the rotors with rubbing alcohol between swaps cover me? The use case you've described is exactly what I'd planned to do. 700x32 slicks for road, 700x45 knobblies for gravel. I only have the one bike!

should I realistically expect problems?

No

Literally spent the last 3 pages explaining that we've been doing wheel swaps for years now with no issues.

No, if you swap wheels, everyone in your house will all die horribly.

Ive a several days training with Shimano whom explicitly said this, and in their training module too (Shimano T.E.C.), it also what I teach other mechanics, including one who was a bit too giddy with a Ribble and made an audible pop sound when spreading a completely worn out pads with exposed piston much to my dismayed.

Shimano being Shimano don’t mention it on their website, despite them telling us not to spread piston without taking the bleed port out and in their training video.

@hippy the bladder in the levers, not the calipers.

Several years ago Shimano don’t sell the bladder on its own until recently due to so many warranty from the bladder bursting on their levers, we send a lots because we simply couldn’t get the bladder at the time to repair it, especially during the pandemics.

We have to find old broken levers to take the bladder out and fit it in the bursted one, now a new bladder is about £9-10.

This what happened when the bladder burst (incidentally show that the person couldn’t get that part at the time).

I’m not kidding when I said some of you are incredibly lucky not to burst them, I did a couple times before realising.

I liked it more when I thought it was like a Grand Crus than a problem solver…
That said it’s a wicked bike

@hippy the bladder in the levers, not the calipers.

I knew it.

Happy Friday people!

Misunderstood; I meant don’t open up the piston of the caliper without taking the bleed port out.

That's good to know, I've burst the bladder of my GRX Di2 lever when I fell, it has long been replaced but I still have the old one, I will see if it's repairable.

On the topic of Di2 (from a few pages ago), I must be one of the few people who has downgraded from GRX Di2 to 105 R7000 while still having no regrets.

Shifting quality is not the argument to differentiate the two I believe. As long as there's a significant price gap between the two ( which seems to be reducing, in part due the increase in price of mechanical groupset unfortunately), I'd much rather put the ~ 400£ difference in clothing and luggage, it'll make a way bigger impact for my enjoyment of the bike, imo.

.

I’m going to throw my 2p in and say;
I too have pushed the pistons back in Shimano brakes and never had this problem, but have seen it happen to someone. The difference between us? They boshed a screwdriver between the pistons and turned it quickly the spread them. I on the other hand have always done it slowly and carefully. Makes a difference or just lucky?

You may need to shim your rotors if they're not exactly in the same place.

Lucky, I did have a customer who tried that (so they claimed).

On averages I’ve bled maybe 10 Shimano hydraulic a weeks in my current workshop, the keys difference I think between my workshop and on here, is that on here people are a little more savvy with their home mechanic skill.

So if I'm going from one pair of wheels to another, should I realistically expect problems?

You won’t, but I would be amiss to not highlight potential issues you may have if something doesn’t feel/sound/look quite right when
Swapping wheels like Pokémon.