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Sram testing their brakes.

jonKranked

jonKranked

Detective Dookie
Nov 10, 2005
85,883
24,464
media blackout
'size said:
it was lumped in with the frankenbrake discussion. stoke level wasn't super high so i guess no separate thread.
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i looked (albeit briefly) and didn't catch any major discussion about it. but i did see someone posted a link for metal replacement pistons for shimano stuff.... anyone gonna have a go with those?`
 
Udi

Udi

RM Chief Ornithologist
Mar 14, 2005
4,915
1,200
jonKranked said:
i looked (albeit briefly) and didn't catch any major discussion about it. but i did see someone posted a link for metal replacement pistons for shimano stuff.... anyone gonna have a go with those?`
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I think @kidwoo fitted some so he can probably comment in time.
Loads of the factory-fitted ceramic pistons cause leaks, so this is just fixing a problem that Shimano created themselves (since they used to use alloy pistons anyway, eg. M800, M810).

The levers have had issues for ages too (unresolved) though so it depends which problem you're trying to fix - if any.

The XT 4-pot is just a Zee caliper painted black (I'm pretty sure) so nothing new there.
 
toodles

toodles

ridiculously corgi proportioned
Aug 24, 2004
5,502
4,752
Australia
The Shimano engineering department must be having a sabbatical or something. How are they rolling this out as "new" product?
 
Westy

Westy

the teste
Nov 22, 2002
54,408
20,197
Sleazattle
Bike product managers wanted a 4 piston caliper for their bikes but knew their dentists customers weren't going to be down with a product line for knuckle draggers.
 
Electric_City

Electric_City

Torture wrench
Apr 14, 2007
1,994
716
How does doubling the pistons (and piston area) and doubling the brake pads (close enough to doubling. Right?) lead to only a 20% increase in power?
 
Udi

Udi

RM Chief Ornithologist
Mar 14, 2005
4,915
1,200
Electric_City said:
How does doubling the pistons (and piston area) and doubling the brake pads (close enough to doubling. Right?) lead to only a 20% increase in power?
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It's because the piston area isn't doubled (nowhere near it), in fact if you check the spreadsheet Flo suggested, you'll see the total slave piston area increase for the 4-pot is pretty much bang-on 20% (which also confirms this caliper uses the same piston sizes as the Zee/Saint) - that's what generates the power difference. The MC piston diameter hasn't changed to my knowledge.

The lever throw will grow longer by a similar amount (not good), so Shimano haven't done much here apart from using up a little more black paint.

The pad size increase isn't relevant to the +20%, this number is only about leverage.
 
Flo33

Flo33

Turbo Monkey
Mar 3, 2015
2,065
1,304
Styria
Vital states this: The new caliper is based around the Zee and Saint 4-pot designs with some subtle tweaks like piston size to bring it in line with the XT family. Power-wise, it’s on par with zee but it’s likely to get fitted more frequently as part of OE spec, especially on e-bikes where trail / enduro brakes with extra power are appreciated.

I don't believe shit until somebody gets one in his hands and compares the pistons.
 
Udi

Udi

RM Chief Ornithologist
Mar 14, 2005
4,915
1,200
Flo33 said:
I don't believe shit until somebody gets one in his hands and compares the pistons.
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I agree and think that's smart, but the 20% force increase correlates with what they claimed for the Saint/Zee power increase over XT originally (from memory) and I kinda doubt Shimano went to the trouble of changing tooling to change the piston size and then redesign the servo-wave leverage curve to match the final power increase - esp since that'd be kinda pointless. Happy to eat my words if someone measures them though.

They can't be bothered to fix the leaky piston / varying throw dramas that have existed for years so I'm going to be impressed if they changed the piston diam. I think they are ~class-leading for power and miles ahead for heat management - what they needed to improve was the build quality and consistency / reliability. Jury's out.
 
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