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From: Frank Krygowski <frkrygow@sbcglobal.net>
Newsgroups: rec.bicycles.tech
Subject: Re: RE: Re: DeRosa Merak Rear Brake Problem
Date: Wed, 1 Jan 2025 19:20:00 -0500
Organization: A noiseless patient Spider
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On 1/1/2025 6:20 PM, cyclintom wrote:
> On Wed Jan 1 16:14:05 2025 AMuzi  wrote:
>> On 1/1/2025 2:46 PM, cyclintom wrote:
>>> I discovered why I got the Merak for nearly nothing.
>>>
>>> When it came time to install the rear brake I found a bolt somehow installed in the rear B-stay brake hole that has a 5 mm threaded hole in it. It is aluminum so the forward end of the device (between the B-stay and seat tube) which appears to be a normal brake lock, is stripped.
>>>
>>> Since the B-stay is carbon fiber I don't think that it is screwed in. I would think that it is a slight interference fit which would explain the stripped allen end. I suppose I could thread in the 5 mm allen bolt and using a puller, push the fitting out. Hopefully that would leave the original brake hole in original condition.
>>>
>>> I have never seen a rear brake attachment of this sort so I am asking if anyone has ever seen anything like this and if they have any comments on it and if they could suggest a removal technique that would leave the hole in original condition?
>>
>> There is something inside your rear brake mount?
>> And that is a bolt? Or a sleeve with a 5mm threaded bore?
>> What is a B stay?
>> What is a normal brake lock?
>>
>> Could it be a stuck/corroded brake mounting nut? That would
>> be M6 not M5.  An aluminum nut may well be corroded in
>> place. Clean as well as possible, examine in a good light
>> with a magnifier if needed to see what it is an dhow it's
>> held in place.
> 
> 1. https://www.ebay.com/itm/387414175414?_skw=B-stay&itmmeta=01JGJ1SMVC3X64P451Y7V26RDP&hash=item5a33af2eb6:g:ojsAAOSwapJm8SeY&itmprp=enc%3AAQAJAAAA4HoV3kP08IDx%2BKZ9MfhVJKkKk%2BT%2BCfPB1NFw1gIOhTDcX5INzW7ZyWXx6ymLMxxUkrjgqEbMjg7byxSVBbnUf1OSX%2Fvcil1p15XMnhKWGWTb3w6SI%2BSogBVxH8U3lJYJ9cCu1IHbjcweuReuInwNEbjWdSN0YS743SYts0ZqnTbaXTlvuKSY6sywZQureWu4x4wfDXgFkt0cutCbAuWgNrXUrAyZ0kHi9fGa9FDktoHBJ2Ou5RhYYeJpFZojnp7qCmg2u61ElYwc8ZHbrzANgaQ2bBquUYm9q0wd1ExtoN%2Bp%7Ctkp%3ABk9SR-bN5sGEZQ
> 
> 2.  https://www.ebay.com/itm/183751311056?_skw=Ultegra+rim++brake+fixing+nut&itmmeta=01JGJ1RGGSH2W5TD4WMQXC1WN8&hash=item2ac86e7ed0:g:SLAAAOSw5cNYbIi8&itmprp=enc%3AAQAJAAABAHoV3kP08IDx%2BKZ9MfhVJKmDXGrXXDIzZaBH8%2FV8tvPcg9OmXd%2BLSGTrZ0E3ttBzz91TsnLw5frOpgp5%2BaLgKnsVuajVdLQlissnahvLQ1s%2B8jjBW5Zwe9gx3ufmUqMQbR28s5kmllEA6TneV3nRuIyCrBZ3w2AHL8T%2Fum15FGCrgWW3lJa5poIsouZTt3cjjMZUTQ6ChkB5U0JDjSSF6K8J4s9R1YtMY9twloP2CvPnXPEA01h2at9kiWlAko%2BecP%2FnrsuiewDvsK2lC1HohuyheFliyzVpmmF1v9KImGbXMTdMZt7gyFMor%2B%2BtTLFBurUsXqzG0OeVxPKt3VXc9zg%3D%7Ctkp%3ABk9SR7yI4sGEZQ
> 
> 3 No chance at all. The threads start at juust below the surface of the brake hole.

The answers to Andrew's questions are still not clear to me, except that 
a "B stay" seems to be a proprietary term for an odd frame configuration.

I don't recall seeing any brake mounting hardware that took an M5 
fastener. I think M6 is normal.

The photos of the bike are helpful, but can you post and link to a 
closeup photo of the object(s) you're asking about? That, and/or a good 
engineering drawing of the relevant part might allow some of us to help.

-- 
- Frank Krygowski