Air

So, I'm riding my new folding bike with an al seat post and tonight when I tried to put the seat down it got stuck. Looks like the post is bent

Should still be under warranty so once I get [out the bfh and use it to get] the seatpost out I should be able to send away for a new one. It has me wondering if a new one will do the same over time. I probably have less than 60 miles on the bike.

So, any thoughts on a beefier seatpost? Weight is irrelevant to me (well the weight of the bike anyway!). The post was not near the warning mark though a lot of it was out of the tube.

If this should be in mechanics someone can move it - figured this would be a good starting point.

Thanks!

Mr. Beanz

Well what brand and model was it? I' ve had no problems with Thomson. But paid $80 bux!

markhr

I use a Deda Metalstick which seems plenty strong so far - you may also want to try downhill specific seatposts that have internal reinforcement

Wellsack

I have had good luck also with Thomson, but they are expensive. I figure it will outlast the rest of the bike.

hammond9705

+1 on Thomson. I still have the original after 8,000+ miles. In that time I've broken rails on 2 different saddles.

Bob

FarHorizon

Seatpost DIAMETER is more critical in avoiding bending than brand, IMHO. The larger the post diameter, the more resistant to bending. "Cruiser" bikes with 22.2mm diameter seat posts are sure "benders" when I rode on them. That's why I sold my cruiser!

In my experience any seatposts that are 27.2mm diameter or larger handle my 275# weight without bending.

There's another consideration to be taken into account with seatposts other than bending - what happens with really large impact-stresses? In early June of this year, a rear rim blew on me. I was thrown into the air a foot or so and come down on my 31.6mm seat post. The post didn't bend. The one-bolt seat-holder, though, snapped that single bolt into two pieces! The seat came completely off the post and dumped me (and the seat) onto the pavement at high speed. I was lucky I wasn't impaled on the remains of the seat post itself!

I now use a two-bolt seat post (Thompson), and I've spent some time bouncing up and down on it to make sure I get no surprises. So far, zero failures. I don't plan to ever use a one-bolt seat post again.

Nightshade

Call Worksman cycle about one their SOLID STEEL seat post.

www.worksman.com

FarHorizon

Tightwad is right - steel seatposts are more durable than aluminum ones for bending resistance! When I had my cruiser, though, the stock one-inch steel seatpost bent when I extended it high enough to fit me. I then got a stainless-steel, heavy-ga. pipe from the plant, cut it to length, and used that for a few months when it began bending too! I then went to larger-diameter aluminum posts and have had no bending problem since.

The Worksman posts, however, ARE significantly thicker and stronger (but not significantly larger in diameter) than the average cruiser bike seat post. Thick enough to resist my bending them? I don't know - I haven't tried them.

schnee

Thompson. They're amazingly strong, first and foremost. Every serious mountain biker I know swears by them, so that should say something about durability. There are seat posts that are just as good, I'm sure, but Thompson has the best rep and great service.

PopCycleKen

+1. In my case, it wasn't a particularly big impact, maybe just the straw that broke the camel's back. And mine was in the middle of the woods. Likewise, I was lucky on the impaling. I'm still looking for a decent, inexpensive two-bolt seat.

Ken

a2psyklnut

+100 on Thomson. I've used their Elite seatpost on all my bikes in the last 8 years without one problem.

Although expensive, you can usually find a deal on Ebay or even used.

The thing I really like about Thomson and any others I've considered buying (but haven't) is the double bolt design. Single bolt designs will strip out. Especially for us heavier riders.

Hambone

I have a seatpost on my MTB which has reinforcement ribs inside. (Viewed from the base it looks like a Mercedes logo...)

I used to bend posts on that bike all the time. That one is ten years old and from the college days, so it couldn't have been too expensive. If you want me to check brand, just let me know.

Air

Thanks Hambone - I appreciate it! I like the idea of something reinforced. The solid steel design sounds like a good idea too. Is this the Thompson?

Hambone

T "brand" on it looks like T3 System. On the post is said TAHOMA. I googled it and it looks like Tahoma made psots for Trek. (I could be wrong on this.)

There is a ton of NOS stuff like this on ebay for like $15. But I couldn't tell if it was the kind I have with the rib/reinforcement inside. I'll leave that research to you...

IM me if you want me to look for serial/model numbers tonight.

a2psyklnut

That's it. No "P" in Thomson.

You can usually find them on ebay for around $60.

I picked one up used for $40 that was still in great shape!

Alox

There's no single rule about which material is better for a seatpost. Steel has a higher breaking strength and greater resistance to fatigue than aluminium, but if the steel is not processed properly (wrong microstructure) it won't work for us clydes. I remember trying a ZOOM post in the early 90's; it was ultra-light steel but within a week of commuting, it was bent back like a banana. Replaced it with an aluminium Syncros post that was still straight, true and on the bike when I sold it ten years later.

Air

Update: After a while with a plastic rod and my hammer I finally got it out. It's funny, was keeping that around just in case I had a use for it. Turns out it was the perfect size and hardness to fit inside the tube and be able to wack it out from the bottom. Now that it's out I can tell how bent it is; couldn't tell as much when it was on the bike. Oh well.

Needs to be 27.2 in diameter and have at least 340 mm from the top of the frame (or the min line) to the seat rails. Thomson has one 27.2 but only 410mm long. I can't find on their site how much of the post has to be in the frame but I'll assume at least 100mm? A little too short

Anyone have any history with Thudbusters? They have an extra long suspension seatpost (look halfway down). While I don't like the idea of a suspension seatpost my seat (with springs) on my mtb is quite comfy plus the Thudbuster is adjustable to a fairly firm setting. I fired off an email to see what the weight threshold is.

Also checked out Worksman. Very, very helpful - though what they carry won't work. What he suggested though was to take a tube that will fit inside and tack weld the bottom to give it extra strength. I'm hearing that 25.4 will fit inside a 27.2 Thudbuster but am trying to find some more information on that. Ideally I'm thinking a steel rod inside will corrode a bit and basically fuse to make one superstrong post. Thoughts?

Hambone: Looked up the Tahomas - as far as I can tell they don't come that long but if you think yours is than I'd love to know the model number!

Man, wouldn't think this would be such a process! Thanks all!

Hambone

I'll take a look tonight after I fix the GD radiator.

Keep in mind, many seatposts are not cylindrical on the inside. They "ovalize" them to make them stronger... You need 13.6 inches of post? I've never measured my MTB but that seems like a lot.

I'm no engineer but I was going to tack weld something inside, I'd try and go with angle iron first. That would be even stronger. Keeping in mind that you really need protection from bending in primarily one direction.

Air

Thanks Hamone! It is a lot - but it's a folding bike so it's meant to be long so the bike can fold up.

Dubbayoo

Ritchey Comp.

Hambone

gotcha... by the time I moved all the tools away from the furnace; cleaned the wood chips, and other crap; fixed the radiator; broke the other radiator; fired up the furnace; you get the idea. I totally forgot about you.

I'll check tonight.

Air

I'm not the most important thing in your life? I'm insulted! Glad to hear you got that fixed!

When you get a chance, I've resigned the fact that that bike will sit for 2 weeks - another day isn't going to hurt

Air

Seems too short - how much minimum has to be in the frame?

v1k1ng1001

Thompson Elite - I've been riding it for 8 yrs.

I just got a new bike that came with a carbon seatpost and I immediately replaced it with my Thompson.

Air

Do you know what the minimum has to be inside the frame?