Brake piston spreaders

So, it doesn’t “really” say that.

Eh? It quite literally says in a highlighted section “Do not apply DOT brake fluid or grease to caliper pistons”.  Clarified further by saying it may cause rotor rub. It repeats this elsewhere in the manual and a SRAM video I’ve seen explains that the piston isn’t supposed to move in and out past the seal during braking but rather the seal itself flexes in order to draw the caliper away from the rotor.

This is a technical manual not ham fisted amateur guidance so I very much doubt they say that just to prevent overspill.

Anyway, you do what you think is best obv. I’ll follow the manual.

@oceanskipper you are 100% right

The Sumart one is in this week's Fresh Goods Friday which links to a UK seller, which looks like it's a website of the Cornish Bike Mechanic.

I went right through to checkout with one of those Sumart tools (clicking the link for STW goodness) but then pulled out as it’s a lot of money (for me), if I was still working as a bike mechanic I would buy one, however, now I’ve got time to work more slowly and only on my own bikes I’ll stick with the Shimano tool I have. I’m not saying that I will never buy one, it’s a desirable tool in my “cheer myself up” wish list!

The Sumart one is in this week’s Fresh Goods Friday which links to a UK seller, which looks like it’s a website of the Cornish Bike Mechanic

It says its designed specifically for 2 piston calipers so will be of limited use for most brakes these days

Wouldn't you just push back two at a time?

Wouldn’t you just push back two at a time?

It's a bleed block as well so if it only works on 2 pistons its no use for any of my brakes, definitely not worth £40 when a tyre lever will push the pistons back perfectly well and I already have some

Okay, I wasn't intending to use it as a bleed block, just wanted something to push pistons back evenly without damaging anything. Tyre levers ain't up to the job sometimes.

Ok. Thanks. I stand corrected. I'll still continue to pump out the pistons and clean with dot fluid before pushing them back in. I'd rather have the pistons clean and smooth rather than dragging dirt into the seals. But I hadn't considered that the seals flex to return the piston during use. In reality, the way I do them probably leaves very little lubrication on the piston as I push them (easily) all the way in this the clean and flexible seal wipes the fluid away. Then I wipe again.

Again, thanks for explaining. Excellent stuff ?

That question mark is supposed to be a thumbs up

Another thumbs up emoji…. ?

The trick is to clean with isopropyl alcohol rather than DOT fluid/mineral oil/ silicon etc I think, as DOT etc will actually do what you are trying to prevent ie dragging dirt past the seals…

So my Sram brake spreader tool arrived... And it's flippin' ace!!

TBF, I was a bit disappointed when it arrived; the threaded lead-screw wasn't very smooth to wind in or out. I pulled it apart, cleaned the threads and applied a very light coat of lube. That transformed it.

I've used it on Sram 2-pot and 4-pot brakes, and also on the latest Hope 4-pots (Tech 4 / E4). It's worked beautifully on all of them.

Thanks to @oceanskipper for putting me right, I'm now removing the old pads, pumping the pistons out a bit, a quick clean with IPA before diving in with the new tool. The tool makes pushing the pistons back an absolute doddle. Even easier if you give the lever the occasional light squeeze.

No more fannying about with screwdrivers or tyre levers 🙂

I got a Sram knockoff (or maybe Sram is the knockoff) from AliExpress. Think it was about £16 delivered. Does what it says on the tin. I take back what I said about it pushing the pistons at an angle. Now it's in my hands I can see both surfaces remain flat to the pistons as they slide by each other.

Didn't intend to end up with two but I've also got the Sumart one. Probably stick whichever one I like less on ebay, but not tried it yet. It's tiny next to the Sram one, but looks like it should work. I'm not convinced it looks like 40 squids worth of tool.

I've got one of the alexpress sram copies and it is great.

https://www.aliexpress.com/item/1005008170570977.html?spm=a2g0o.order_list.order_list_main.5.21ef1802ceKMJA

If you buy one they aren't supposed to fall apart, but they do. What you need to do is take the head off and screw it in a few turns then put the head back on so it'll top out before coming apart.

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^ Where did you get the 1"AF Knipex, I could only get metric 😉

^ Where did you get the 1″AF Knipex, I could only get metric

Lol... another great tool that I was sceptical about at first. Think I have 3 or 4 plier/wrenches in various sizes now. I got the genuine Knipex... one tool does metric AND imperial 😉

I really want to know if that  Aliexpress one is for a 4 piston pineapple

That one you bought it does it spread the piston by pushing down from the top like pushing a wedge in?

Where as something like this https://www.aliexpress.com/item/1005005610286620.html? pushes them back square in rather than top down

Hey guys, Jack from Beaut Bike here.

Just wanted to clear up a few questions I saw about our Beaut Bike Mini Piston Press / Sumart UBB-20

Sumart aren't the original designer of the Piston Press, as far as I am aware the aren't the designer or manufacturer of any of the products in their catalogue. They're jacking up prices now and trying to charge a lot more than they are worth imo.

I saw a few people asking if we ship internationally and we do, it's a flat AU$19 worldwide. If you're in South America or Africa, you'll need to contact me so I can process the shipping manually, but if you're in Australia, Europe, North America etc. you can just checkout like normal.

Please let me know if you guys have any other questions 🙂

Ordered a SRAM tool yesterday from Bikeinn for £59.98.I’ve never regretted buying decent tools which generally last forever

Thread resurrection. After a pad change on my G2 4-pots took an exorbitant amount of time ovr the weekend, I'm looking at getting either an official SRAM tool, Aliexpress copy, or one of the new Sumart 4-pot tools. A few quick Qs for the forum:

1. SRAM tool works on both 2 and 4-pot brakes - correct? The design / width looks like it might not push 4-pot pistons back evenly though?

2. Sumart tool users - how is the general quality? easy to turn and retract pistons by hand, or are you always reaching for the 3mm hex?

1. I've used my Sram tool on Sram 2-piston (road) and 4-piston brakes (G2 RSC ). Also used on Hope Tech4 brakes. All good: it doesn't completely cover the full surface area of all 4 pistons but it covers enough of them that the pistons are pushed back smoothly and evenly with little effort. Tried it on some cheapo Shimano 2-piston brakes (BR4xx?) but it would not fit in the calliper. Going back to the plastic tyre-lever method felt terrible!

I've got the Park Tool thing linked above, but rarely, if ever use it now.

Cush Core Bead Dropper levers give a nice amount of leverage, have a wide plastic tip, and once you've used them to get the pistons back, then can be used as a brake block during the bleed. I guess you can also use them as a tyre lever.

https://www.sprocketscycles.com/products/cushcore-bead-dropper?variant=37915338047671&country=GB&currency=GBP&utm_medium=product_sync&utm_source=google&utm_content=sag_organic&utm_campaign=sag_organic&gad_source=1&gclid=Cj0KCQiAkoe9BhDYARIsAH85cDOIbnkCP9tHWOpv351RYPA6JxJlHXfB_WSP384oSPvPHpBdjWSgoEcaArReEALw_wcB

I got some of these after a recommendation on the escape collective site:

https://www.etsy.com/uk/listing/1554333966/bike-disk-brake-piston-spreader?click_key=b64c594f40ae64d4264f55306dd6ebd97d439ac1%3A1554333966&click_sum=cc2c5cef&ref=shop_home_feat_2&bes=1&sts=1

The postage is a lot but he does a few other useful bits that can soften the blow a bit.

Haven’t used them in anger but the narrow ones are designed such that you can use 2 sets on the weird magura 4 piston calipers on my cargo bike.