byrd48

Hi,
I bought a 90's mtn bike a few weeks back, which I believe to be all original (and in very good condition to boot). One thing I noticed was that when I opened the quick release skewer, the seatpost would slide straight down into the seattube. Again, I'm fairly certain it was factory stock, it had the seat clamp with the bolt that runs through it that requires an open end wrench for adjustment, etc. I've ridden 100 miles on the bike and have not had any problems, however I do make sure that I torque down the skewer before riding. On all the other bikes I have, when you release the binder, they stay where they are, and you have to wiggle the seat back and forth to adjust the height, some are tighter than others, but none just drop straight down to the bottom. The seatpost diameter is 26.2. It's not a huge issue I suppose, but it's in the back of my mind that I need to remember to check the seatpost before every ride to avoid a potential bad experience on the road.
Is it common, or even somewhat common to have a frame that allows the seatpost to drop so easily when the binder is released?
Thanks

Bill Kapaun

Not in my experience.
seat posts come in .2mm increments. (.008") Sounds like yours is one size too small?

byrd48

That is my thought also, but I would be very surprised if the seatpost that was in it was not original, it even had the original seat, same logo as the bike, but I suppose you never know, it could have been swapped out sometime over the past 25 years, but why just the seatpost? Somehow did the original one get damaged, but not the saddle? And to have that old style clamp for the seat, it's just odd. Maybe I'll stop by the co-op and see if they have any 26.4 posts and see how they fit before spending the $$ ordering a new one

cny-bikeman

Yes, try the next size up before ordering - some shops have a seatpost sizer (a graduated post with each size, you insert it until you get the right fit). But if the post holds well when tightened I would not worry about it - function is what counts. And yes, I have seen that before on bikes.

dsbrantjr

Never Fix A Running Piece AKA Don't Fix It If It Ain't Broke.

okane

1.Have seen this in other bikes. If it wobbles get replacement seat post....yours is a bit too small.

2.If it just slides up and down "too" easily, dump that QR binder and go back to bolt. I never liked the idea of someone being able to steal my seat with just a flick of the wrist and sometimes it's difficult to get them (QR's) to hold seat height properly.

3. No facts intended here, just my experiences

HillRider

Unless you adjust your saddle height frequently, I see no benefit to a quick release seatpost clamp. A bolt/nut will be more secure and more difficult to steal on a whim. Either use the standard two-piece seatpost clamp bolt or use a conventional bolt and a nylock nut.

byrd48

Thanks! Any recommendations on a binder bolt that fits on the qr clamps? I did a search but only found the recessed type. I totally agree that qr is not necessary unless you want to be totally safe and take your seat with you, which I don't ever do

byrd48

Actually, it looks like this one will work. https://m.jensonusa.com/!ep8WhsqRxheh...FfLm7Aod92gAJw

I can't find my calipers at the moment to measure the I.d. of the seat tube, so I will stop by the lbs and see what they say. Yes, it technically it's not broken, but if somehow someway it ever did release while riding...

FBinNY 

Don't look for problems where there are none.

It isn't all that rare for correct diameter posts to be free running, and slide down under the weight of the saddle. If we go back a few decades to the sixties, we remember that the steel pin type post supplied with Raleigh made 3-speeds (English Racers) was so free running, that it was common for mechanics to accidentally drop one down the seat tube where it would jam in the ID taper near the BB) If you've never done this you probably weren't wrenching bikes in that era.

A good test of whether you have the correct post is that it holds when clamped. A more precise test is o look at the top of the slot in the seat tube when clamped. Since the slot was cut with parallel sides, the amount it pinches together at the top is a good indicator of the diameter difference between the post and seat tube.

BTW- some time back, mtn bikers routinely adjusted their saddle height for climbing or descending. The rider released the clamp and used his weight to lower the saddle, and a spring gadget would lift the saddle when he took his weight off. This system required a free-running post like yours.

Reynolds 

I'd try another same size seatpost, not always a 26.2 is exactly 26.2.

FBinNY 

WHY is everyone suggesting that the OP fix what isn't broken?

Freerunning posts aren't an issue unless they cannot be clamped effectively, and the simple fact that there have been no problems in 100 miles is good evidence that the post fits.

A loose post would tend to creak since it's only clamped at the top, and is free to rock within the seat tube. The OP doesn't report a creaking. In fact the OP's only issue is that the post is free running when unclamped, which it would be if the prior owner used a spring loaded quick adjust system.

As I've said so often here on BF ---- Don't fix what ain't broke. And don't obsess over every minor meaningless detail on your bike.

BTW- my correctly fitted post doesn't slip down on it's own, but if I lift the rear wheel and bounce it from 6" or so, the post drops on impact. (when unclamped (duh)


To the OP, if it's a question of confidence, here's a link to Sheldon Brown's seat post dia database. Search for your bike and verify is 26.2 is the correct size (per spec.). If it is, understand that tolerance issues, and possibly someone having reamed your frame render this meaningless, but the amount of pinch at the top of the slot (see post 10) is a very reliable indicator of fit.

LesterOfPuppets

Which bike is it? One of the Hardrocks, Batavus or the Trek? Tell make/model/year and original seatpost size may be researchable online.

Does the seatpost head have a horizontal bolt or a vertical bolt?

If horizontal I'm guessing it's a replacement for those bikes, even though the Hardrocks might be cheap enough to have that style head. BTW, it's more of a cheap bike thing than an olde thing for bikes made after 1980. Horizontal bolt seatpost heads are de rigeur on Walmart bikes to this day.

I'm guessing orig got stolen and was replaced with nearest available size.

I'm kinda with the if it ain't broke don't fix it responses UNLESS the keyhole is closing up quite a bit and/or frame has ears that are touching when post is well clamped.

cny-bikeman

Well, not quite everybody, FB

FBinNY 

Yes, "everybody" is hyperbolic and doesn't actually mean everybody. But even you open your post with the suggestion that he visis a shop and have it checked before saying no sweat if it holds OK.

In fact the only post that says clearly not to fix what ain't broke is that by dsbrantjr.

We see many posts here where folks obsess over what is usually nothing, IMO the thing these folks need most is confidence rather than more things to consider.

I'm not saying that that I'm sure this is the correct post, it may well be under by 0.2mm, but there's nothing here to suggest that it is. So I posted a link to the SB database where he could look up the spec, and suggested using the slot as a guide. This will allow him to confirm whether the post is or isn't right without having to visit a shop.

BTW- I might add, that posts that are so tight that you need to twist back and forth to adjust the saddle are more of an issue than a free running fit. The perfect fit would allow the post to slide up and down with light force with the resistance coming mostly from the viscosity of the grease.

cny-bikeman

Well, I was mostly just tweaking you, FB. You did your usual thorough job. Honestly I wish I had that much time (next year!).

As for suggesting he visit a shop, that was because he said "Maybe I'll stop by the co-op and see if they have any 26.4 posts and see how they fit before spending the $$ ordering a new one." I wanted to encourage him to check before ordering something he did not need.

Reynolds 

I just said what I'd do. Never said it was a problem, but I think a snug fitting seatpost is better than a loose one. A loose fitting seatpost may not slip, but the seatpost clamp area might deform, and I've seen bulges in seat tubes caused by the bottom end of undersized seatposts.

FBinNY 

"Everyone" is hyperbolic, and not intended to mean each and every person. But your post along with many others carries the implication that a free running fit is likely an undersized post. Though that's always a possibility, it isn't necessarily so.

All a free running fit implies is that the fit is free running, which is not rare or problematic. A correctly fitted post in a tube that's round and free of burrs will often be free running, and that is preferable to the all too common situation where posts get marred when they have to be forced or twisted into position.

byrd48

I stopped by the lbs today (there are 5 within 8 miles - awesome). They put the measurement stick in the frame and confirmed my post is the right size. I did buy an Allen key binder bolt as I was having trouble torqueing the qr enough to keep the seat from sliding down while riding. the only thing I don't like about the binder bolt is that the bike goes all the way through the receiving bolt on one side and looks kinda ugly on that side :-) maybe I will saw it off so it's flush. Thanks again everyone

cny-bikeman

Isn't it strange that even with the magic, all-knowing Internet all it took was an old-fashioned visit to a bike shop to get the answer.

fietsbob

Buy a non QR seat post bolt. unless you worry about having the saddle stolen.
then you take seat and seatpost with you..

or buy like a Pitlock bolt with a security fitting mechanisim.

cny-bikeman

Then all you have to worry about is a sudden rainstorm or jokers pouring coke down your seat tube.

fietsbob

yea that happens.. personally I moved out to a town that seems OK for my simple needs.

only QR post is on My Brompton, I just Bring it, whole Bike, inside..