lugged bikes and dropper posts
10-16-21, 03:52 PM
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lugged bikes and dropper posts
I was wondering if anyone ever looked into getting a dropper post into a lugged bike -- other than 27.2, which seems to work fairly well nowadays. I have reasons to go bigger. It seems like I could ream out the seat lug and bb and possibly grind off an external butt on a seat tube if required.
Yes, I'm being lazy right now, it's pretty tedious to look at tube specs. So I'm hoping someone has this figured out.
Yes, I'm being lazy right now, it's pretty tedious to look at tube specs. So I'm hoping someone has this figured out.
10-17-21, 04:54 AM
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Besides 27.2, there are only 2 other sizes of dropper posts, 30.9 and 31.6. The tubes for the 30.9 post are 33.5-33.7 at the top and 32.7 at the bottom bracket. The 31.6 post fits in a 34.9 seat tube. I think you'd be fabricating a seat lug and you might be able to grind away enough to fit that 32.7 tube in a 31.7 socket. Seems like a lot of work to keep the lugged frame look.
10-17-21, 05:18 AM
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Looks like I would have to take .5mm off of the lug/bb wall, which is probably too much. People fabricate lugs all the time, it's not too scary. I don't think I would want to do it with a bb shell though.
10-17-21, 07:26 AM
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I've been wondering about "printed" lugs for applications like this... Have you considered doing anything like that, unterhausen ? I haven't investigated pricing yet... Might be more expensive than a bike! But, maybe not... Could make some interesting geo and parts selections this way.
10-17-21, 07:54 AM
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Yes, I even have an unfinished design. I think it's pretty expensive though. Especially the bb shell.
I was looking at the pictures from Bespoke UK and someone had a 3d printed head tube, which I thought was a horrible idea.
I was looking at the pictures from Bespoke UK and someone had a 3d printed head tube, which I thought was a horrible idea.
10-17-21, 10:26 AM
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I don't know the details but I believe I remember reading somewhere (is that vague enough?) that Serotta put their tapered ST around the outside of the ST socket and did a fillet braze until they could get appropriate castings. You may be able to do that or grind off the 27.2 socket and fillet braze the big ST to the shell. Maybe David Kirk or one of the builders was talking about it...
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10-17-21, 11:07 AM
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I thought of just brazing the tube to the bb shell, but maybe it would fit a little better aesthetically to braze a bigger tube to the shell and then braze the seat tube inside. I have to go measure some lugs.
This whole thought process got started when I found out nobody makes a seat post to fit OS lugged seat tubes. I think you can get NOS
This whole thought process got started when I found out nobody makes a seat post to fit OS lugged seat tubes. I think you can get NOS
