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Seatstay clearance for cassette- is modern different from vintage?

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Seatstay clearance for cassette- is modern different from vintage?

Old 05-13-21, 01:16 PM
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mstateglfr 
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Seatstay clearance for cassette- is modern different from vintage?

I just built up an old road frame I've had for years and the chain is rubbing on the seat stay.

I've had this frame set up with a couple different 9sp drivetrains, but its now 11sp.

Maybe the 9sp drivetrains had 12t cogs for the smallest one?...I don't think so, but there was no rub on those setups.

Question- does anyone who has been building since 126mm dropouts were used now angle the stays differently to accommodate an 11t cog?
I was surprised this is an issue since I've built probably 6 different 80s road frames with 11sp drivetrains and none have had this issue.


Guess I'll turn this into effectively a 10sp cassette and lock the small cog out?
Or save for a 12-28 duraace cassette that costs $285!! <--nope, not doing this.

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Old 05-13-21, 02:01 PM
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I just realized I have myself all sorts of confused. A 12t small cog would make things worse.
So if anything, gearing from back in the day would have made this worse since a 12t small cog would have been more common then, mated to a larger chainring.

The wheel is centered, so maybe ill add a small spacer on the driveside?
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Old 05-13-21, 02:30 PM
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the seat stay is blacksmithed back, but different mfg's did things differently. This was probably intended for 126mm 6 cogs, maybe 7 wit a touch more space, like 127.
That you stuffed in 9 is good, 11? more room.
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Old 05-13-21, 02:50 PM
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unterhausen
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I have been building since back when 6 speeds were new, and 9 speed needs a little more space at the seat stays. Really depends on the bike though, some of them used to have plenty of space BITD. The issue is that the first cog was further from the dropout. Typically a 6 speed would have a 13 tooth cog there, and 14 wasn't unheard of. In fact, for juniors racing, they were even bigger.
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Old 05-13-21, 04:03 PM
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What Eric said and know that as the cog counts increased the clearances are reduced. As Shimano became the 500 pound gorilla their dimensional requirements became the frame designer's (and builder's) standards. But for each change of drivetrain version those standards also changed. Additionally not every bike brand would follow those standards even as they existed for the bikes that were being made for the components that were speced on their new models.

I would want to have the bike in hand but a few file strokes will likely create more chain clearance. I'd want to be sure that only the stay end and the brass filler was being removed and no hole into the stay's interior was likely. Andy

Shimano Framebuilder Info - Pvdwiki (peterverdone.com) Here's an example of those standards from over a decade ago. Current stuff have "new and improved" guidelines
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