Adding strength to steel seat posts

[Wildcat]

When we raise the seat post pretty high, us bigger guys tend to bend the post. On most old cruiser frames, the 18" frame needs the seat post way up high.
If you can't get a heavier one, here's how I make them stronger. I got a length of 1/2" steel pipe to sleeve the seat post. I cut it to length of the seat post then made a couple small cuts vertically in the bottom of the post so I could make a tab that, when bent, holds the sleeve in place. I did two of them, one was already bent so I really had to hammer the sleeve in but the new stem needed the tab to hold it in.

 

[us56456712]

When we raise the seat post pretty high, us bigger guys tend to bend the post. On most old cruiser frames, the 18" frame needs the seat post way up high.
If you can't get a heavier one, here's how I make them stronger. I got a length of 1/2" steel pipe to sleeve the seat post. I cut it to length of the seat post then made a couple small cuts vertically in the bottom of the post so I could make a tab that, when bent, holds the sleeve in place. I did two of them, one was already bent so I really had to hammer the sleeve in but the new stem needed the tab to hold it in.

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I did almost the same thing. Years ago I got a replacement long seat post for my Chicago Schwinn. When it came in the mail it was way too thin to be up high. I got a piece of black water pipe and slowly ground it down by spinning it on my bench grinder. It ended out a tight fit, then I slobbered the whole black pipe with JB Weld and hammered the black pipe in. Won't bend but the post weighs more than a seat, ha ha.

 

[deorman]

Yeah, the newer 13/16" posts that look like the old Schwinn posts are definitely not as strong as the old ones. I'm using solid 5/8" carbon steel rod for my ORBO bike. Seems to be stiff enough. It is a 20" frame that came with a solid 5/8" "7" though. Your results may vary.

 

[us56456712]

Yeah, the newer 13/16" posts that look like the old Schwinn posts are definitely not as strong as the old ones. I'm using solid 5/8" carbon steel rod for my ORBO bike. Seems to be stiff enough. It is a 20" frame that came with a solid 5/8" "7" though. Your results may vary.

I bent two 5/8 carbon steel seat posts on my klunkers. I went with cold rolled 5/8 steel and no problem. Then I tried 5/8 inch 2024 aircraft grade aluminum alloy on another klunker and that has not bent either. I weigh 155 pounds. Prices vary on these on the net so you have to shop. A 250 pound guy will bend a carbon 5/8 post just sitting on it and going over a kids trail. I know this as I loaned a bike to such a person. The post bent right away.

 

[deorman]

Yeah, I'm not sure what grade or sort of treatment this is, I told the guy at the steel yard I wanted something that would hold up my 185 lbs, and he gave me this coated piece. I can't bend it, I tried. I used a diamond grinder blade cutting it down from a 3 foot piece.

 

[us56456712]

Yeah, I'm not sure what grade or sort of treatment this is, I told the guy at the steel yard I wanted something that would hold up my 185 lbs, and he gave me this coated piece. I can't bend it, I tried. I used a diamond grinder blade cutting it down from a 3 foot piece.

If you can't bend it it is probably cold rolled. Cold rolled is a true circle, and so shinny it looks polished when not coated. Hot rolled looks round and dull but the diameter it is not that precise. Anyway, if it bends get the cold rolled or aircraft grade aluminum and you will be OK.