Sunday, May 31, 2009

fixing disc brake tab

i received jasons frame on thursday. i built it so he could do a trip from South America to Alaska. this frame has really taken a beating. he made it to alaska, but his rear disc mount didnt.
upon arrival, it seems like its in part due to the thin walled seat stays. i know of others builders using the same stays with good results, never the less...lesson learned. thicker stays next time.
i decided to replace it with some comotion disc drops from pacenti cycles. they are designed for tandems and mountain frames. they are so burly, its not even funny.
i thought that the tab for the seat stay would be long enough when i cut off the damaged portion of the stay, but no dice. i had to do an internal sleeve and extend the tube to meet the tab. i then replaced the brace from the seatstay to chainstay. this may not be necessary with the disc tab being part of the dropouts and the things being so stout , but i did it anyway for good measure. plus its adds to the strengh of the internal gussetting. all brazing was done with brass and i left the ends of the stays square in order to have as much bulk at the joints as possible.

tab ripped off of tube.

damaged disc brake tab.

old drops removed.

old drops removed

mocking up dropouts.

after fillet brazing

finished repair

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