Correct seat post bolt size 1979 Motobecane?
09-17-20, 11:04 AM
#1
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Correct seat post bolt size 1979 Motobecane?
Anyone know the correct size seat post bolt for a 1979 Motobecane off the top of their heads? Tried 17mm - too big.
Thanks. - Pat.
Thanks. - Pat.
09-17-20, 11:20 AM
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Better off asking IN Clasic & Vintage or asking mods to move this there.
09-17-20, 11:44 AM
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I tried there a few days ago, no luck, but thanks.
09-17-20, 01:12 PM
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Bolts can be cut shorter. I am assuming that the 17mm quoted was the length.
09-17-20, 09:55 PM
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I assume that measuring is not on the table. Andy
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09-17-20, 10:43 PM
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So, what threading would the French use for a binder bolt?
Is there unique French threading on the entire bike?
That is probably a type of C&V question, as few people will know the exact size, but they may know the thread type.
I have no clue.
John
Is there unique French threading on the entire bike?
That is probably a type of C&V question, as few people will know the exact size, but they may know the thread type.
I have no clue.
John
09-18-20, 05:25 AM
#7
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09-18-20, 08:16 AM
#8
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6mm is what I've seen.
Buy the correct length to suit.
1/4-20 is SLIGHTLY larger dia.
Buy the correct length to suit.
1/4-20 is SLIGHTLY larger dia.
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09-18-20, 09:07 AM
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[QUOTE=renrub;21700198]I just picked up some digital calipers. It looks like 7 x 18.5mm, but the hole also seems a little oblong.
Trial and error it is then.[/QUOTE]
In your first post you stated that the 17mm was too big, but measuring up the area gives you 18.5mm;
are you sure that bolt was 17mm? If it was, and it is indeed too long/"big", go to it with a grinder or file, taking off equal amounts on the bolt and captive nut, and call it a day. Good luck.
Trial and error it is then.[/QUOTE]
In your first post you stated that the 17mm was too big, but measuring up the area gives you 18.5mm;
are you sure that bolt was 17mm? If it was, and it is indeed too long/"big", go to it with a grinder or file, taking off equal amounts on the bolt and captive nut, and call it a day. Good luck.
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09-18-20, 12:48 PM
#10
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09-18-20, 05:17 PM
#11
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1979 Super Mirage seat post bolt size
OK, just for anyone referencing this thread in the future, I persuaded the seat post bolt that I bought on Amazon (that I couldn't get to fit initially), to work by using a large screwdriver to round the hole from oval, and a dead blow hammer to tap it in. Sounds bad, but pretty sure I didn't do any damage. The bolt is a sleeved and keyed Sugino Seatpost clamp bolt, 17mm - chrome. The diameter of the sleeve is 7.9 - 8mm. Amazon has jacked the price up by $7 since I bought it, so I would look elsewhere. But that's the size. Thank you to everyone who replied.
