Hot answers tagged

17

Before you take any more forceful measures, it may be a good idea to think a little about chemistry: 'Rust' is typically the name put on any type of corrosion, but technically & specifically, it is the corrosion of iron (or steel) to form iron-oxides. Although your bicycle is most definitely steel, your seatpost is not -- it's aluminum-alloy, which ...


14

You might find a suspension seatpost to be comfortable, but a suspension seatpost is not a substitute for a full suspension bike. The purpose of a suspension seatpost is purely comfort (though as mikes mentions, not everyone agrees that they achieve this goal), where as the purpose of a full suspension bike is first and foremost control. Suspension on the ...


13

Phil Wood, the owner of the bicycle tool and components company of the same name, once commented that his number one requirement when he was buying barrels of grease for his company, was that it be the exact same green color shade as the previous batch, so that he didn't get too many phone calls asking what he'd changed. Point is that the "bike specific" ...


12

There are generally two types of dropper seatposts, mechanical (e.g. GravityDropper) and hydraulic (e.g. RockShox Reverb). Mechanical dropper seatposts use a spring to move the seatpost and a bolt to keep it in place. This is a very simple design and there are few things that can break or jam, and the weight is also kept very reasonable since there are few ...


11

On old steel bikes a good reason would be to prevent the seatpost from rusting onto the frame, thus preventing saddle height adjustment. More recently I understand from my LBS that you do it to prevent water from seeping into the frame along the (imperfectly sealed) seatpost. Depending on your frame you could end up carrying one or more kilo's of water with ...


11

To crudely simplify things, a triathlon/TT bike position is much the same as a road position, but basically "rotated forward", so your arms rest atop the very-low-set bars. A consequence of this is, the seat ends up further forward. (source) Using Chris Froome's TT position as an example, noting the hip position versus the bottom-bracket position: (...


10

Greasing your seatpost will prevent problems like this: "Removing Seat Post rusted into downtube". Don't use chain oil, grease is what you want. As whatsisname pointed out, all fasteners on your bike should be lightly greased. This is what keeps them from corroding and seizing over time, becoming a real pain to remove. If you have trouble with a ...


10

Yes. However, it varies by type of riding and conditions. All Mountain is probably the extreme example of this (and the main market for dropper seatposts). All Mountain bikes are designed to be able to climb and for that generally one would want the seat in a "high" position to be efficient. During a technical descent, however, the seat is generally ...


9

As the person who made that claim, the reason is that allegedly some greases can attack the epoxies found in some carbon fiber applications, causing a breakdown of the CF structure, and causing expansion which will jam the post in place. The epoxy will otherwise not corrode, so it's not necessary for that purpose. The manufacturers also recommend you do not ...


9

This is a tough one. It's not impossible but you really need mechanical advantage. If you can clamp the seatpost, you will get the best chance at freeing this. You will probably damage/lose the seatpost with this method. Make sure the seatpost is free of grease and oil on the outside. Turn the frame upside down and clamp the seatpost into a bench vise....


9

The problem is that there is only one bolt holding the seat at the angle you want. Put enough torque on the back of the saddle and can overcome the friction that's holding the seat in place. A few options: Tighten up that bolt as much as you dare (but you've already tried that). Increase the friction between the seat post and the bottom of the seat clamp ...


9

There are seatpost shims available for a few dollars. You should get them easily in your local shop or online. I use an aluminum shim in one of my bikes with exactly the dimensions you need, it works flawlessly and looks very clean. I got it for about 3.50 € (5$).


9

Most seat posts have a "minimum" insert of 3 to 4 inches. But this varies with the material and the thickness of the post, and the weight of the rider means the minimum might still be too little. As a tall rider I frequently have my seatposts up to maximum, and have bent several over time, and have fractured one frame. Now I always buy a 450 mm or 500 mm ...


8

You should absolutely grease your seatpost (unless it is carbon fiber). It won't slip around if your seatpost clamp is properly tightened. Get a thing of grease from the bike shop, like the park tool grease. Better yet, get the big tub. Then, generously apply it all over inside your seattube. When you think you have enough, add some more. Then put the ...


8

Carbon parts will cause aluminum to oxidize, as a chemical reaction which is why seat posts wind up stuck in frames. But that isn't why this is necessary. "Carbon grease" is not actually grease. It's a friction compound which increases the friction between your fancy carbon seat post and your frame. Increasing the friction allows a lower torque on the ...


8

The best grease is the grease with the least amount of contaminants. Everything else is secondary to that. Naturally grease does not come with contaminants in it, but, in the workshop it attracts any dirt going, as if it were some huge magnet. Therefore, packaging is important. The large tub that you have for the car/motorbike/boat/unicorn cage might not ...


7

While it's true that your hips rocking indicates that the seat is too high, there is a different rule of thumb for knee pain related to the fore and aft position of the saddle. It's easy to remember: If your knee hurts in front, your seat is too far forward. If your knee hurts in the back, your seat is to far backward. The most important thing to ...


7

I present you with evidence that seatposts can, in fact, seize! Alloy and steel seatposts are both perfectly capable of seizing to both alloy and steel frames. IIRC, carbon seatpost/frame combinations may need carbon assembly paste for almost the opposite reason: to increase friction and reduce the torque required for a good grip.


7

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.


6

In general, you've hit the high points yourself. The benefits (and issues) will vary by post model, manufacturer, and design. Carbon fiber is a very versatile material engineering wise. Storck makes 2 carbon posts, which are externally identical. But one is a comfort post, which focuses solely on smoothing out your ride, and the other focuses on being ...


6

You can probably use a small wire brush to get the rust out of the frame and for the future use JP Weigle Frame Saver spray. It acts as a rust inhibitor so should slow down/stop any rust forming on the inside of the frame. You can get frame saver at JensenUSA (I'm sure there are lots of other spots too).


6

Unfortunately, this is a common issue with more basic seat posts. There are 2 options: Use sandpaper or a Dremel to remove the teeth which fix the angles of the seat post. If you make it completely smooth, then you can use grip tape like that designed for a skateboard deck to add friction without locking you in to specific angles. This approach has ...


6

Seat post suspension is not designed for efficiency. It is designed to add comfort to a hard tail mountain bike frame. There are only a few really good suspension seat posts, and they are rarely used on hybrid bikes. Almost always, you will find that the suspension post on a basic hybrid is just a spring in a tube. Occasionally, they add the ability to ...


6

After some more searching, it looks like I'm looking for a layback seatpost, and they're available for purchase on eBay.


6

There isn't always one size frame which fits a person well in a given model line of bikes (there may be 2 or more - probably 2 if someones on the border of sizes). In some cases, you can get multiple models to fit by swapping out stems and seatposts and saddle and handlebar adjustments or swaps. However, this is highly dependent on the particular model of ...


6

Any frame can support a range of rider sizes by adjusting (among other things) the seat post and stem. However, as you might suspect, there are compromises to be made. And, there are limits to how big of a rider can fit on a given frame. I'll explain a bit more below to illustrate these points. You can adjust the seat post by making it higher (may ...


6

This article, The Four and a Half Rules of Road Saddles, from Cervélo Cycles has been really helpful to me when pondering saddles. I think the key points are: The saddle needs to be wide enough to support your "sit bones" but not so wide that it chafes on your thighs. The saddle has to be flat enough that the part between your sit bones doesn't press up on ...


6

The manufacturer of the seat post would have really answered this with the minimum mark. You should really maintain at least the same length within the frame. Aside from stability, if the seat post is too short, then you risk damaging the frame of the bike, because there is a higher force within the frame due to the same torque being required, but at a ...


6

I had an exactly same problem: Ritchey WCS seatpost, Merida frame (both alu alloy) and a lightweight clamp, like in @Frisbee's answer. What I tried: Beefy clamp with various torque settings. Didn't help at all. PVC tape. Helped, but didn't last long. More torque on a lightweight clamp. I snapped it in half with only 6Nm. Hair spray. To my surprise, it ...



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