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5

Pull the post and hold it next to the seat tube to see how far it goes in. If it does not go in far enough to be into the seat tube below the top tube you are putting a LOT of stress on the top of the seat tube. Believe that maximum mark on the seat post. A seat post is not that expensive to risk damaging a frame. This is just one (not cheap) seat post ...


3

For road bikes of that age, showing just "a fistful of seat post" was considered good frame fit and style. Otherwise the frame was likely too small for the rider. Of course that was before the advent of sloping top tubes. If the bottom bracket is not too high, stand over height of the top tube should be no problem even with such small seat post extension.


3

When I've had bicycles shipped, its generally just been left empty (on a used bike), or had a little plastic plug in it (on a new bike). If you do want to plug it with something (say, you're storing it without the seatpost for some reason and don't want any critters in there), you could plug it with some news paper or something which you can easily remove or ...


3

On carbon frames I've used, they have had a single bolt clamp like this one, so it should be fine. Personally, I'd like to use a slightly bigger clamp and one of those rubber size-decreasing rings to avoid cracking the frame. If in doubt I'd phone up the manufacturer of the frame and ask!


3

Definitely alloy drink can or other thin sheet metal as it is not compressible and is not affected by water, oil or grease.


3

An up-down movement is perfectly fine – that's what suspension seat posts are designed for! For the side movement it's a bit more complicated. A suspension seat post is basically two tubes sliding into each other with some suspension mechanism. This requires two things: the tubes need a little clearance to move within each other and they need a mechanism ...


3

(this is more of a supplemental answer to Pete's one) The answer is somewhat different if you already have back pain vs if you don't. Simply, if you already have pain it's much easier to make it worse, but if you don't an upright bike is fairly unlikely to cause it. The main factor is likely to be how far forward you lean while stilling on the bike, with a ...


3

The number of comments to your question is becoming quite large, so I thought I'd roll my comments up into an answer (of sorts). You ask whether the seat postures could cause back pains, and whilst I have no specialist knowledge in this area, I'd have to say from a purely empirical viewpoint that the answer must be "no". A lot of people ride a lot of miles ...


3

Penetrating oil (Liquid Wrench). It may take a few days as it needs to work its way down. Or it may free it up in a few minutes. The risk you take with a lot of force with a pipe wrench is you bend the bike or brake off the post or get the post out of round. You should grease the seatpost to help prevent this. If you don't bend the post then I ...


3

What are you are tying to achieve? Is the bike too long for you? Bending a seatpost will weaken it. You can buy offset seatpost. Most people use them to move the seat back I cannot see why you could not use it to move the seat forward. But you are not going to pick up two inches. Two inches would put you almost straight over the pedals - are you sure ...


2

Nearly. The diameter does need to match, but you also need to consider the materials -- metal needs grease, carbon fiber doesn't, so combining the materials in the frame and seatpost shouldn't be done. Also, note that different seat posts have different levels of adjustability - saddle angle and position, height (which connects to minimum/maximum insertion ...


2

According to Sheldon Brown's site, there are 1987 Peugot Versailles with 23.8mm seatposts (and I have heard of other french bikes with 23.8 mm seatposts, so it is probable that you've measured correctly). The measurement should be done with calipers or a seat post measuring tool, though. One solution I've heard of is buying a 24 mm seatpost and sanding it ...


2

Yes, you can damage the frame if the seat post is too short. I have personally seen someone sit down on an overextended seatpost and fall off the bike as the seat post was wrenched out of the seat tube. The collar went flying and the top of his seat tube was mangled. His frame was titanium and he was able to bend it back. You probably wouldn't be able to ...


2

Sheldon Brown has a thorough article about stuck seat posts. http://sheldonbrown.com/stuck-seatposts.html Thick soled shoes might also work, if the saddle isn't that much too high.


2

I had a Peugeot bike once where the seatpost didn't have the usual clamp but a similar system to hold it in the seat-tube. The system was not very practical because if you wanted to adjust the saddle height you could only do so if the saddle was removed. The bolt was tightened from the top of the seatpost. There was a second draw-back: the seat-tube being ...


2

you can try to use caustic soda. It will melt down the aluminum. But you have to be very careful. Watch this video


2

Old thread.. But here's how I fixed it on my bike... Cut an old inner tube into strips that wrap around the rails. Wrap them around the rails and tighten down. It should last virtually forever this way and won't damage the rails like sandpaper will. It might also slightly lower vibrations in your seat.


1

Yes, on my 1975 Peugeot UO18, the brakes are located on the intermediate stays and the seat stays are used for the rack mount. The brake configuration is visible here. (photo source: http://oldtenspeedgallery.com/owner-submitted/joans-1975-peugeot-mixte-uo-18/#.VWFRtmDDz88)


1

Who says its the original seat post? (It likely isn't.) There are maximum amounts of insertion (determined by the frame; there may be things inside the frame or weird shaped tubes) and minimum lengths of insertion (determined by the seat post; if its not inserted enough, you can damage the seat tube or worse) -- it is unlikely, but someone may have needed ...


1

Soda cans do the trick, cf this tuto


1

Yes, it's ok and to be expected. Even expensive dropper posts, which work via the same basic principles as telescoping suspension seatposts, have a bit of side to side movement. For the suspension seatposts, just ensure that the collar at the top of the stationary (outer) portion of the seatpost is firmly hand tight.


1

No, flip up bicycle seats are not common. For (probably) less than $10US, you could get a quick-release seatpost collar so that it's easy to move the seat up or down. Just make sure to mark on the seat post what height you like it at. For over $100US, you could get a "dropper" seatpost (intended for mountain biking) and set one of the lower positions to be ...


1

Remove the seat and seat post from the bike, install the baby seat, reinsert the seat post, done If the seat post does not have a quick release, go to the local bike shop and buy one for $5.


1

Yes Of course it's possible, you just need to find a telescopic seat post on the market that is longer than the one you have. Your measurement of your post might be a bit off though, I'm guessing that from your 28.x measurement, and the fact that I don't think 34.2mm is a seatpost size... not one that I'm familiar with anyways. In which case chances are ...


1

I have used a couple of these seats over the years - the ones I had did have some movement - noticeable when riding. Although not ideal, you do get used to it. It comes down to cost - it would be more expensive to precision manufacture them with no movement, but at some point people would stop buying, and another point, might as well buy a full suspension ...


1

I'm not sure about structural problems, but the bigger problem is that bending it two inches forward will likely throw off the angle of the mounting clamp more than you can overcome by readjusting it. You'd probably want to put a z-bend in it: two inches forward and then two inches back to level off the mounting clamp. And you don't have enough seatpost to ...


1

I found this video, and decided to do like him. He puts some kind of extension on his power drill, and on the end he puts a tiny 1 inch steel wire wheel. He drives the wheel up and down in the seat tube for some time until the rust is gone. I tried hard but never found a wirewheel this small in my country, at least not one that would fit on an extension. ...


1

I had the same problem. I used vise grips and clamped down very tightly. I hit the vice grips with a hammer, repeatedly. This will jar it loose- it took me about 15 minutes. The bad news: when I did this with my bike, it left deep scratches on the post (the vice grips will come loose and need to be clamped down again).


1

You have to make sure that you're actually tightening the quick release down - it should leave an imprint on your hand when you close it down. If you put a product like frame saver in the frame, you'll need to tighten it down extra since that makes seat posts super slippery. See this thread as well.



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