Seat post is bending

[SirMike1983]

Chromoly 13/16" bicycle seat post with 7/8" seat mounting - 400mm

Chromoly 13/16" bicycle seat post with 7/8" seat mounting - 400mm

www.porkchopbmx.com

This is what I use. I’ve bought several and they are excellent. They actually are a better fit than the original seat posts. You usually have gently open up the top of the seat mast. I think I’ve used an old seat post to gently open the frame up. Then clean the the inside of the frame where the post goes in, very lightly grease the bottom section of the post and it makes for a really strong set up.

There’s many other options out there, usually associated with vintage BMX, but I can’t speak for those because I haven’t tried them.

I use those as well. Good posts and a good way to broaden your quality saddle options. They're also long enough to handle a variety of frame sizes.

 

[mrg]

I just pound a piece of solid rod into the hollow seat post, a little more weight be haven't bent one yet!

 

[ozzie]

I'm 210lbs, 6'2 and crank the posts high on all my bikes. I have used the solid 6061 alloy Atom post, Genuine bicycle products thick wall 4130 chromoly post and a steel lay back post with an alloy insert. They have all held up fine and are available on ebay.

A friend of mine used a MCS branded chromoly straight post and it bent quite easily.

They are all 7/8"at the top so you may need to buy a new seat clamp and use just the middle part of it which slides over the post to mount your seat.

Link to Genuine Bicycle Products post below,

13/16 4130 lay back and straight seatpost for schwinn klunker cruiser 26bmx reto | eBay

Find many great new & used options and get the best deals for 13/16 4130 lay back and straight seatpost for schwinn klunker cruiser 26bmx reto at the best online prices at eBay! Free shipping for many products!

www.ebay.com

Link to layback post with alloy insert.

Custom Bmx Schwinn H.D. Layback seatpost 13/16 chrome Beach Cruiser Strandie | eBay

Fits pre 1983 Chicago made Schwinn only. Schwinn size 13/16 (20.7mm) with 7/8 top.

www.ebay.com

Link to Atom post:

ATOM BIKES HARDASS SEATPOST 13/16" 20.6 MM SOLID 6061-T6 ALUMINUM OS BMX | eBay

Constructed of solid extruded 6061-T6 aircraft grade precisionaluminum rod. Hand polished to a high luster.

www.ebay.com

 

[mike cates]

Find an internal tube that presses into your existing seat post or one slightly undersized and fill the void as you are pushing in the internal reinforcing tube with JB WELD for steel and it will become very strong. Loctite also makes gap filling liquids and pastes used for setting ball bearing races in machinery that works fine.
Most seat posts are made from steel that has been EBW (Electron Beam Welded) and will have an internal protrusion of the weld bead, You can file a flat the length of your internal spacer to clear this weld bead protrusion when assembling.
Also remember "if" you are having problems with your seat pinch clamp not clamping tight enough and the seat post keeps slipping down, make an internal spacer out of steel, aluminum, copper or even PVC pipe which is not visible from the outside between the bottom of your seat post down to the crank bracket and you won't ever have slippage problems again. This also works on handlebar stems if the fork steering tube has an internal lip or step. If there is no lip or step, you can always drill and tap the steering tube and install a set screw and locktite it flush with the outside diameter to clear bearing cup races, etc so it protrudes internally for your internal spacer to stop against.
If you can't find the suitable OD pipe or tubing, you can always find or fashion a thick washer to just drop in the seat post tube, drop in you undersized OD tube or pipe and drop another thick washer in then push your seat post down to this stack of parts and you'll be good.
Mike Cates, CA.