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Where exactly does the brake adapter go ?

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Where exactly does the brake adapter go ?

Old 07-05-19, 05:40 AM
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Brocephus
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Where exactly does the brake adapter go ?

I just recently started delving into the whole disc brake adapter/mount issue, and it's a bit confusing. I may be installing a rear disc brake that's currently on a post mount, onto a frame with an IS mount, as seen (hopefully) in the photo below. But I'm not sure which of these 2 sets of holes are for the adapter to bolt to it, or which side it goes. I've seen a video (from Jensonusa) that showed the adapter inside the chain stays. But, in this pic, it looks like it goes on the outside. (but the adapters I'm looking at don't look like they fit in those upper two holes, because of that protruding rim underneath them).
Are both of those sets of holes for adapter mounts ? If not, what's the other set of holes for ??
BTW, my current rear rotor is a 140. Any specific suggestions on exactly what (economical) adapter would suffice, would also be appreciated. Right now, I'm looking around at Worldwide Cyclery, for their nice selection, and free shipping. (like this one.....https://www.worldwidecyclery.com/pro...per-51mm-frame )
A always, any good info is much appreciated....

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Old 07-05-19, 06:22 AM
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The brake adapter goes on the top side of the chain stay, the holes on the bottom side are for a stand.

The 2 holes above the dropout are for a rack or fender.
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Old 07-05-19, 06:31 AM
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Originally Posted by cobba View Post
The brake adapter goes on the top side of the chain stay.....
Thanks for the reply, that was my first guess. But, take a look at this adapter.....https://www.worldwidecyclery.com/pro...per-51mm-frame
I'm just not getting a sense that it's going to fit in that rimmed area just beneath the two holes. What do you think?
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Old 07-05-19, 06:55 AM
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It goes on the inside of the stay, so that rim won't effect it.
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Old 07-05-19, 07:06 AM
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Ah so, the plot thickens ! So, is that rim there to protect the bolt heads ? That's all I could guess, but that seems kind of excessive.
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Old 07-05-19, 07:52 AM
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Originally Posted by Brocephus View Post
So, is that rim there to protect the bolt heads ?
What's this rim you're talking about?

The adapter is attached like this........

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Old 07-05-19, 08:10 AM
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Think about it, the disc goes on the end of the hub, and the brake needs to be inside of the stay to reach the disc so the adapter has to go on the inside as well.
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Old 07-05-19, 09:22 AM
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Originally Posted by cobba View Post
What's this rim you're talking about?
There's a protruding "wall", or rim,(or even "tray") that's just beneath the two mounting holes (on the frame I posted). It kinda runs from the weld on the end of the chainstay, to the weld on the end of the seat stay?
See what I mean ? I was thinking the adapter nested right into it ( it looks like it should, not sure what else it's there for. Maybe just adding structural strength to the drop-out area?)
Anyway, I'm good, it's all clear now, thanks to all for chiming in.
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Old 07-05-19, 05:23 PM
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That "rim" is what many might call a reinforcing rib or a collar. It's there to strengthen/stiffen the construct. Andy
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