Shimano Rotor 160 mm to 140 mm conversion. Bolt lengths?

Discuss light weight issues concerning road bikes & parts.

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Eterna7m
Posts: 141
Joined: Thu Jan 07, 2021 11:25 pm

by Eterna7m

Hey,

I wanted to change the rear rotor on my Aeroad from 160 to 140 mm. it currently has the 8150 rear brake (Flatmount) with the appropriate adapter.
Checking the manual it says that I need both a C and C2 bolt, that protrude different lengths through the (20mm) frame.
Is this really necessary or can I use the same bolt lengths?
This has apparently also changed from 8050 to 8150, because for the 8050 you needed the same bolt with the same „overhang“.

Thanks :)Image

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Ritxis
Posts: 925
Joined: Fri Jun 01, 2012 3:00 pm
Location: San Sebastian

by Ritxis

Eterna7m wrote:
Wed Aug 10, 2022 12:54 pm
Hey,

I wanted to change the rear rotor on my Aeroad from 160 to 140 mm. it currently has the 8150 rear brake (Flatmount) with the appropriate adapter.
Checking the manual it says that I need both a C and C2 bolt, that protrude different lengths through the (20mm) frame.
Is this really necessary or can I use the same bolt lengths?
This has apparently also changed from 8050 to 8150, because for the 8050 you needed the same bolt with the same „overhang“.

Thanks :)Image
you still don't have to change the screws, the ones that go now to the adapter are worth it to hold the caliper directly

joejack951
Posts: 1105
Joined: Fri Feb 18, 2005 6:50 pm
Location: Wilmington, DE
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by joejack951

That’s a very narrow screw length spec so I highly doubt that the screws going through the adapter to the caliper will still tighten down properly without bottoming out when the adapter is removed. I would also not bother trying to make two of the same screw work. Perhaps buy the longer length and cut it down for the shorter size if you don’t feel like buying two different screws.

Eterna7m
Posts: 141
Joined: Thu Jan 07, 2021 11:25 pm

by Eterna7m

Thanks !
They’ve also used a ca 3-4 mm washer so without using these it might actually work.

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