Seat post question.



May 16, 2020
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Kankakee
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So...I had the wrong seatpost in my 1974 Huffy bike. The seat tube appears to be ALMOST 7/8". I have tried some different 7/8 posts, and all bind up 1-2" in. I already cleaned the inside of the seat tube, absolutely nothing in there. The inside of the tube is greased well. too. Well, I bought a new 13/16 15" long post and a shim from 13/16 to 7/8. That combo fit well, and tightened up properly. I am 6'2"& about 200lbs. The post is extended about 10". The post bent slightly my first time out. I am older, my ride hard days are over.
My new plan is to purchase a 16" piece of 7/8" 6061 Tempered to a T6511 standard ( whatever "T6511" means). Then turn it down a few thousandths, if necessary. Here's a link to the one i am talking about https://www.ebay.com/itm/7-8-ALUMIN...g-Solid-Extruded-Bar-Lathe-Stock/362849436168.
Think this will support my weight at the 10" post reveal required?
Or should I look for a 7075 piece instead? 7075 is substantially more costly.
Or, any other ideas.
Thanks for opinions.
 
May 16, 2020
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Kankakee
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54 views and no advice. I'm not looking for perfection, just new ideas. I think I might have overlooked something. Feel free to chime in.
 
Jan 21, 2009
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I've bolstered existing stems with wooden dowel rods and odd pieces of steel tubing. A friend used some square stock to line the inside of his existing stem on his bike. He had his extended about a foot above the 18" Schwinn frame and was always bending them until he added the reinforcement. But on mine it didn't need to be that high and I hammered a wooden rod into the post, then made a tab in the bottom of the post to hold it if it ever came loose. The extra support inside the post worked well and was strong enough. It was hidden so it could be wood or steel and not have to be pretty. And didn't cost much.
 
Jun 13, 2015
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I would be shocked if 6061 bar stock wasn't strong enough. On my Interrobang Spaceliner, I had a similar problem, so I hammered a 6061 rod into the cheap Wald 13/16 seat post and I have had no problems (at some point, there may end up being some galvanic corrosion, but I'll probably be dead before it's an issue). I'm not as big as you, but still much larger than a girl's Spaceliner was ever designed for at 5'11", 175 and with longish limbs so the seat post sticks up pretty high. Only issue I had was that I needed Grade 8 hardware for the seat post binder as it was so resistant to deformation that the original bolt stripped out before it could get tight enough to hold.
 

Captain Awesome

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Aug 9, 2012
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Tape one end, insert rebar or some reinforcement bar, fill the rest with epoxy making sure you tap or shake to avoid voids. I'm 6'2 and have been as heavy as 240 and this has worked many times
 
May 18, 2020
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My Huffman/Higgins clunker has a 5/8" seat post. I'm around 220 lbs so it needs to be strong. I purchased a 24" 304 stainless bar and a 1" long 7/8" bushing that I welded to the top for the seat clamp to bolt to. After getting my seat height set the bar was cut to length. For added security there is a 5/8" split collar on the post at the seat clamp. Won't bend, rust, corrode and under $25 for the whole shebang.


20210322_190742.jpg
 
Mar 26, 2021
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I just measured a Murray Westport seatpost, and it is .86 inch. That's slightly less than 7/8.
Personally, I wouldn't use 6061. If I were going to machine something, I would get a piece of 7/8" 4130 tubing with a heavy enough wall to allow for a bit of reduction. Aircraft Spruce has some in that size with a .188 wall thickness, which would be ample.
Aluminum fatigues.
 
Apr 4, 2021
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I'm having a heck of a time finding a 22.0mm lay back seat post for my schwinn. Anybody know where I can get one or anyone make them?
 
Jan 12, 2013
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Is a regular on the site who makes custom seat posts...
I have been in action for the last couple years and can't even remember his name! But solid steel bent to your request.
 
May 16, 2020
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Before someone says a i need a 22.2.....it says 22.0 on the current seat post. Bike is a schwinn cruiser six.
I am the originator of the post. What I ended up doing was to buy a piece of new 6061 7/8 x 18" aluminum solid rod from my local recycle place. it was $13 and change. To reduce the diameter, I used a file and rotated the rod in my hand. To save time, I only filed the part that would be inside the seat tube. I filed it to probably about the same diameter as you need. Only took about 20 min. I filed gently and checked for fit as I went. After it fit perfectly, I used some emory cloth to smooth the light file marks. After sanding, Scotch Bright gave it a nice sheen, apparent in direct sunlight. Much easier than I thought it would be. You can do it. BYW... I don't believe I will ever have trouble with my seat post again. One more thing. If you have a steel frame, grease the seat post and seat tube well. Aluminum, moisture and steel chemically react over time. Grease will dramatically slow that process.
 
Apr 4, 2021
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I am the originator of the post. What I ended up doing was to buy a piece of new 6061 7/8 x 18" aluminum solid rod from my local recycle place. it was $13 and change. To reduce the diameter, I used a file and rotated the rod in my hand. To save time, I only filed the part that would be inside the seat tube. I filed it to probably about the same diameter as you need. Only took about 20 min. I filed gently and checked for fit as I went. After it fit perfectly, I used some emory cloth to smooth the light file marks. After sanding, Scotch Bright gave it a nice sheen, apparent in direct sunlight. Much easier than I thought it would be. You can do it. BYW... I don't believe I will ever have trouble with my seat post again. One more thing. If you have a steel frame, grease the seat post and seat tube well. Aluminum, moisture and steel chemically react over time. Grease will dramatically slow that process.
How were you able to bend it? If at all? I'm trying to create a lay back set up.
 
May 16, 2020
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How were you able to bend it? If at all? I'm trying to create a lay back set up.
Sorry I did see you wanted a lay back post. Mine is straight. I wound not know how to bend an aluminum rod. A 7/8 Aluminum rod is super stiff.
You could always fit it, figure out where you want the finished top of post, cut the proper angle in the rod and have it TIG welded. Maybe add a gusset.