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From: AMuzi <am@yellowjersey.org>
Newsgroups: rec.bicycles.tech
Subject: Re: RE: Re: Disc Compatibility?
Date: Wed, 5 Mar 2025 14:29:06 -0600
Organization: Yellow Jersey, Ltd.
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On 3/5/2025 2:17 PM, cyclintom wrote:
> On Tue Mar 4 21:55:28 2025 Roger Merriman  wrote:
>> cyclintom <cyclintom@yahoo.com> wrote:
>>> Andrew, I have GRX levers and Ultegra  actuators. It acts as if these are
>>> not compatible. The levers on both front and rear will not "pump" the
>>> brake pades close enough to the discs so that they actuate with almost no
>>> pull. Instead they pull almost all of the way to the bar.
>>>
>>> The pads are hardly worn and there are no leaks from the connections.
>>>
>> Should be, uses same pads/hose fitting kit and so on, and appears to be
>> same calipers broadly from Tiagra to Dura Ace, though Cues is I believe
>> doing its own thing! Aka less performance more simple design.
> 
> 
> 
> 
> What I was trying to discover was if the 10 speed GRX levers didn't have the capacity of the 11 speed Ultegra actuators. That occurred to me in a dream. But since they are compatible it must be air in the system. The thing that bothers me is that all of my previous disk bikes had hard front and back brakes. This setup has the same pull on front and back and the front is a straight shot up and bled without a problem.

Because the rear caliper line entry is at an unusual angle. 
The front points straight up.

Need to remove the rear caliper form the frame so it can be 
at the lowest point in the system, line pointing up.  Rap 
the caliper with a tool handle while purging the fluid. It 
has air in the nooks and crannies of the caliper.

-- 
Andrew Muzi
am@yellowjersey.org
Open every day since 1 April, 1971