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Looking for a decent seat post for my mk1 Blue Pig so its a 27.2mm post. Had a couple but they keep bending thus not letting me drop my saddle down when I feel the need. Both have been 400mm but when in use not anywhere near the minimum insertion point. So recommendations please!
What posts did you bend? (Just to get a feel for your "bending capacity")
Race Face Atlas and a Superstar one. Certainly capacity for bending the ss one was high as its fairly new!
Thompson? I'll be impressed if you bend one of them
I've bent Thomson!
Try Blackspire. One of mine is 6 or 7 years old and still perfectly straight.
easton Vice? not bent mine, and thats a miracle for me. Also Race Face evolve DH?
Both great clamp systems too, and not too expensive.
Dont buy a ragley spike, first one bent, second the bonding between head and post broke so now head swivels. Should've just got the thomson in the first place.
I've been through 2seats on my the same thompson post .....they were Ti railed Bel Air ones. Now I'm using chromoly bel air. So far so good! I do think Thompson very strong versus their weight. I use the straight base model Thompson not the curvy ones.
bending seatposts? maybe your frame is too small or you've been at the pies once too often?
2nd the Blackspire.
My ragley spike has started swiveling as well. Although it did get stuffed up my arse on a very poor landing the other week!! Up till then it was fine....
-1 for the Ragley spike, the head of mine has started swivelling after 2 months.
The best post I've used is the Nukeproof Warhead. Never bent mine (27.2 on an Inbred) and I'm 18st !
Lay off the pies and stand up more
I was going to say Nukeproof Warhead too - definely very solid for the money
alaric, how the hell does one bend a Thomson?!?! Fair play, that's some abuse you must've given it... I've bent a fair few cheaper seatposts in ths past, but never a Thomson which is why they're always a default fit for me on any bike, even if they're not the lightest or the most pimp etc.
I've currently got a Hope Eternity, can't fault it. Anodizing is very tough, its well made, looks good, and its very easy to adjust.
mboy - Memberalaric, how the hell does one bend a Thomson?!?!
Seems to be pretty common, I've had 2 used ones and both were slightly bent, known it happen to a couple as well- albeit one on a dh bike and one under a fat lad. Maybe a lesser seatpost would have snapped, or maybe they're just overrated, who knows?
The latter.
Thomson every time for me. Didn't bend mine even when I was an 18-19 stone biffer riding sat down too much. And that's a 26.8mm one with loads of post out the frame. I bent both a DMR one and an NC17 empire pro, which apparently has similar construction to a thomson with the oval shaped innard.
Oh look GW taking the opposing view once more. How predictable.
I've bent a number of posts in the last 22 years. The only ones that haven't were an original syncros and 2 Thomson's.
Oh, look... "Bigyinn" still bearing his long term grudge over being proven wrong in another discussion on the inrerwebz, how pre.... 😉
FWIW I'm not taking an opposing view, I'm simply being realistic. Heralding any seatpost as "un-bendable" is "overrating" it! and in this respect Thomson seatposts are one of the most overrated products on the market, doesn't mean they are not a good product, they are indeed both strong and fairly light but most (even cheap) seatposts of around the same weight will also bend before they snap.
I've seen a few Thomsons bend and break, they are not unbreakable.
[i]Give me a lever long enough and a fulcrum on which to place it, and I shall move the world.[/i] Archimedes
So with a chubby lad on a long seatpost sticking out of a tiny frame, because it's more 'chuckable' and bending will occur.
I have cracked a thomson post and and so has my racing snake friend who weighs 62kg - I weigh 72kg - we have used seatpost mounted racks on them so maybe that caused the failure...
however I would agree thomson is over rated - nice products but they do have a lifespan....
paul
So with a chubby lad on a long seatpost sticking out of a tiny frame, because it's more 'chuckable' and bending will occur.
Gotta love that "I bought a size smaller because its more chuckable"
BS!
Double post
varying between 17 and 18 stone on a long travel hardtail have bent seat rails-touch wood- still not bent or snapped my Thomson seat post. Been running them ever since I bought a £20 replacement on a new bike and it bent first ride. I can only suggest that some folk that are managing to break Thomson posts are landing really heavy on them or are not out the saddle as much as perhaps they should be on really rough sections or the posts are getting fatigued being dropped and extended using a mud grinding paste.
skywalkerDouble post
Well., it'd be stronger
had a truvativ stylo race 27.2 400mm. not a bad post. replaced due to swapping from +20mm to inline.
inline thompson is 410mm and therefore more tube in the frame.
like its design a lot!
so far no problems on same bike
I'm 6'2 with fairly long legs, and weigh 120kg.
Since I can't afford a custom frame, even the biggest stock frames need a 400mm+ seatpost to get the saddle in the right place.
That's a lot of leverage and a good test of a seatpost.
I've just snapped an Eternity, 27.2. Hope replaced it under warranty but only with a 350mm - when I queried it they said they'd had problems with 400mm at the smaller diameter, so have discontinued it...
Blackspire have it right, though...
GW - MemberOh, look... "Bigyinn" still bearing his long term grudge over being proven wrong in another discussion on the inrerwebz, how pre....
There's no grudge, I just think you could be a little less arrogant and condescending in your postings. 😉
Here is my Blackspire as it was in my Balfa Minuteman... surprisingly the frame died before the seatpost did 
[img] 
[/img]
Well one or both would have died eventually!
Controltech team issue
I'm 6'2 with fairly long legs, and weigh 120kg.
That might have something to do with it!
Heralding any seatpost as "un-bendable" is "overrating" it! and in this respect Thomson seatposts are one of the most overrated products on the market, doesn't mean they are not a good product, they are indeed both strong and fairly light but most (even cheap) seatposts of around the same weight will also bend before they snap.
I don't think anyone mentioned them being unbendable, a couple of us have mentioned how we'd be impressed to see someone managed to bend one agreed. At 75ish kg, and not a particularly hardcore rider, I've bent a few seatposts and saddle rails in the past, but like I said, never a Thomson. Nothing is perfect, but they're one of the strongest offerings out there, and the weight is still pretty good, whilst also not being silly expensive, which means they're popular.
messiah's Balfa was asking for trouble! That is one small frame, and one long seatpost! Haha. Expect it was fun to ride though...
Messiahs seatpost is longer than the seat tube!
Im 6'5" tall and im no lightweight at 16.5st. Broke kalloy, bent xlite, bent control tech.
Only syncros and thomson have remained fully functional! The syncros lasted 10 years before being sold on!
Thread resurrection.
I've just broken the front bolt of my On-one post for the 2nd time in 12 months.
Its probably is my fault this time cause I replaced both bolts with ones I bought from the hardware store after it broke the first time.
The On-one post has a similar front and back bolt like the Thomsons do.
Has anybody had the bolts break on a Thomson?
I'm not worried about the remote chance of it bending cause I think that will probably not lead to a crash, but when the bolt goes, your arse comes down hard on the rear wheel and that could easily end very badly.
Any other ideas for a very strong post?
[img] http://www.rotorburn.com/forums/attachment.php?attachmentid=232725&d=1334960204 [/img]
At the moment I weigh 99kg, done over 2k miles since I have had a 27.2 Thompson. Done around 10 full trails on the post and not bent it (6ft rider), even after having a few "mishaps"
I've just broken the front bolt of my On-one post for the 2nd time in 12 months.
Torque wrenches are awesome..
I'm impressed with the controltech one I've got.. Similar construction as the Thomson I've got, but beefier.
Torque wrenches are awesome..
Do you think its due to over tightening?
You might be right which is why I'm asking.
I replaced the bolts probably 2 months ago then I read a comment by Brant in [url= http://singletrackworld.com/forum/topic/on-one-twelfty-seatposts-are-they-tough-enough ]this thread[/url] so I snugged them up tighter.
I have no problem with buying a new post but I was wondering if this front/rear bolt design was prone to failure compared to other mechanisms of securing the saddle.
You have to remember at most a seat post uses a M6 thread bolt, they can only take so much tightening, if they are "posh" stainless steel they can shear easier than a steel bolt.
Do you think its due to over tightening?
Most probably.. I think the torque on a thompson is something like 4Nm.. Just enough to stop it coming undone with the flex in the clamp, which will be very little. It's nothing like a single bolt M6 design, where the levering force on the ends of the rail clamps is multiplied onto a single bolt, so the bolt has to be very tight so the clamp doesn't move.. Hence why it's an M6 bolt. In the 2 bolt design, the force through the bolts is lower than the ends of the rail clamp, as they're further out from the leverage fulcrum, so they're smaller M4 with a much lower torque setting.
Also worth checking out the Acros A-SP seatpost. I've got a couple and they're beautifully made, certainly on a par with Thomson which I've used before and come in 400mm.
The post and head are all machined from one so no bonded head to come loose. Morewood use them on their Makulu downhill bikes so they must be pretty tough.
They got 9/10 from MBR and were well rated by Dirt. Because they are not such a well known brand they go for peanuts on Ebay. They're £75 RRP but I recently bought another brand new one on Ebay for £11 inc postage!!
Thomson posts are apparently built to bend, rather than fail catastrophically:
.The Thomson seatpost design incorporates a bending fuse to prevent catastrophic failure. All competitive seatposts we tested failed catastrophically with the seat and clamp components, and sometimes pieces of the tube and head flying off in all directions.
Are far as tightening the saddle rail bolts goes, the torque is pretty low, just 6.8Nm for an Elite and 5.1Nm for a Masterpiece ([url= http://www.bikethomson.com/blog/wp-content/uploads/SeatpostFull.pdf ]Instructions[/url]). One of the problems of overtightening that I have seen listed on the internet isn't so much snapping the bolt, but breaking the head assembly (would the bolt perhaps be desinged to fail before the post?):
[url= http://1.bp.blogspot.com/_urSQl6wUA5g/ScGvE5AOTuI/AAAAAAAAGTw/Pb2MZLt2Z_M/s400/6a00e398aeb836000401101810a04c860f-500pi.jp g" target="_blank">
Thomson do say that their posts are strong but the selling point is also that they're supposed to have double the fatigue life of other posts. I don't know much about fatigue life but presumably any post made of aluminium, with a finite fatigue life, will break at some point so presumably a snapped post may not necessarily be the result of a flaw,misuse or inherent weakness.