Technical & Reference Section > Tech and Restoration

loop tail ripper seat tube replacement (warning lots of pics)

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Donker:
Sawzall, excellent job mate it makes my day to see another saved.

S&M Alex, if you did find stock material with a 13/16" bore, it would be a poor finish inside and there would be enough variation in size (batch to batch) giving a potential poor fit with the seat post tube, this would probably lead to cracking again. do a google for stockists and if you find some please let me know as itll save a load of time drilling that stuff out. i have 2 of these tubes left if anybody needs one.
 :Great_Britain:

SaMAlex:
I can see that a stock tube might not be as good as one made to measure, and Im sure that your tubes are way way better because you make them, but I thought that THE reason most bike, esp ones from the 80s, chose its tubing size was because it was a stock size. Its def the case for most Cro-mo frames, forks, seat posts, ect. That is partly why oversizes seatposts and headsets, and one piece fork stear tubes took so long to be avalable, cos no-one could aford to custom make tubes. Maybe PK seat tubes were an easy size to get in the 80s, in the US? and they were probably still a bit crappy too.

Can you give me the OD and ID of the tube, and the ally grade, cos I talk to tubing and metal suppliers quite a bit and it might be worth asking a few of them.

lazychubs:
i reckon they welded a seat post into em bitd
instead of a seat tube lol

Donker:
From the ones ive measured the O.D. is usually 1" plus a few thou.  obviously its a stock 13/16" bore. 6061 spec material which can the be heat treated to t6 spec if you can! the last batch i made were a 7000 series. as im sure you will know its difficult to but in small qty for fair prices so maybe you can find some at a good price with your contacts, this will save the time/cost to drill out the 13/16. we can only try!

kdw712:
amazing job
and balls of steel to start chopping a ripper up

def worth it in the end though  :daumenhoch:

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