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Discussion Starter · #1 · (Edited)
I have always used NOVA external butted seat tubes (.9/.7/1.2) but am going to build a little 26er for my 7 year old nephew.

What 4130 straight gauge tubing do you use for a 27.2 seat post? (will be purchasing from Aircraft Spruce) I have jacked this up once before so want to make sure I ask the question.

For example: 4130 STEEL TUBE 1-3/8X.065 for a 31.6 dropper seatpost. ".065" wall is a nice slip fit for a 31.6 seatpost." (OD 1-3/8, Wall Thickness .065, ID 1.245)=31.623

Thank you for your recommendation.

I also plan on sleeving it SS, TT, ST junction since my fillet brazing distorts that area (and I want to learn something new) "sleeve with a small piece of the next 1/8" larger diameter x .058" tubing"

Quotes are from posters on other threads.
 

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An 1 1/8" tube for 27.2 is 0.6mm wall if lugged or sleeved, which is about 0.023" wall. So if you could find it, your closest option would be to use 0.028" and ream it up. But it would be easier to go 0.035" and use a 26.6 post.

The other option would be to make a 1 1/8" x 0.058" sleeve that is turned down to slip fit into 0.035" and use a 1" seatpost.
 

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Columbus Gara is 28.6 in 0.8 wall which reams OK for 27.2. I usually add an outer sleeve but would be OK for a kids bike without provided you don't get it too hot / distorted. Comes in 635mm and 1500mm lengths that might be cheaper and more convenient than Aircraft Spruce.

Easy to get the tube and sleeve from Ceeway but guess you are USA so not sure who supplies over there.
 

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You can find over at Bikefabsupply.com that we stock a 29.2 x .95 x 330mm seat tube , its perfect fit for 27.2 , get in touch will me and I can give you a longer length if you need
 
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