Questions tagged [seatpost]

Questions referring to the part of a bike that extends upward from the seat tube on the frame to the saddle.

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3 votes
2 answers
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How to calculate how strong is seat post?

Is 27.2mm seat post stronger than 25.4mm because it has bigger diameter? How to mathematically calculate how much 27.2mm stronger than 25.4mm provided both seat posts have same length, wall thickness ...
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  • 424
2 votes
1 answer
94 views

Is there a way to add offset to Rockshox Reverb AXS dropper seatpost?

Does anyone have any suggestions on how to add offset to a Rockshox Reverb AXS seatpost? I saw a company called FAIR Bicycle that developed hardware to add offset (+ or -) to a Reverb, but it's not ...
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2 votes
2 answers
197 views

Cutting back seatpost binder slot

I've got a tandem with brazed on seatpost binder ears. The slot between them is so narrow that I can't clamp the seatpost with sufficient force: with the two sides bottomed out, the stoker can apply ...
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  • 24.1k
3 votes
2 answers
100 views

Loosening up an over-tightened seatpost clamp

I recently purchased a used tandem. The stoker's seatpost is 27.2 mm diameter, and I'm not having any trouble with that. The captain's seatpost is a weird suspension seatpost that is less than 27.2 mm,...
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  • 24.1k
6 votes
2 answers
259 views

Seatpost/saddle moving down when riding

I noticed that that my saddle started moving down when riding (maybe 1cm/hour). When cleaning the inside of the seattube I noticed that the part at the height of the clamp became smooth, compared to ...
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  • 6,805
1 vote
1 answer
57 views

Seat Post Compatibility

I have a Kona Stinkey Deluxe and someone recently stole the seat post. I remember the seat post and it was called the RaceFace Evolve DH. Was wondering if there were any other types of seat posts that ...
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  • 223
1 vote
2 answers
196 views

Dropper Seat Post Compatibility - Kona Mahuna 2021

I have a medium Kona Mahuna 2021 (Seat tube length 420mm and seat post diameter 31.6mm) which I would like to fit a dropper post on. The bike is 'dropper ready' with internal routing. I've never had a ...
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  • 113
14 votes
3 answers
6k views

Why are all road bike frames now squashed parallelograms?

I am currently shopping for a road bike and have questions about current frame designs. My height is 6'3" and decade(s) ago I always liked frame designs for which the top of the seatstays joined ...
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2 votes
1 answer
309 views

Adjusting the saddle angle on a single bolt saddle clamp without grooves

I am about to buy a new seat post on the Internet. Looking at the pictures, the saddle clamp has a single bolt, but I can not understand how it could adjust the saddle angle. The seat post I ...
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  • 157
2 votes
2 answers
268 views

Has anyone experience in using a Thomson Elite Setback Seatpost in the forward position?

Background: 54cm Cervelo R5 2013 with original UO Carbon seatpost. Seat is set as forward as possible and I'm using a shorter handle stem. Problem: Bike fitter stated I've got the body of someone 5'4&...
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1 vote
0 answers
102 views

How to remove loose seat post stuck down inside tube, without saddle to grip? [closed]

I was reading this forum the other day to see how I could get the seat post out of the frame. I was putting a new bike together and had never done so before. I messed up and let the post go into the ...
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  • 11
1 vote
1 answer
78 views

Trying to tighten a saddle clamp but nothing seems to give

I'm first trying to remove a stuck seat post through brute force. I've removed the wheels, fork, and chain so that it can more easily be worked with upside down. I began to turn the frame in a ...
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  • 11
3 votes
3 answers
1k views

How to install a saddle on a seatpost with a top facing bolt

I recently purchased a new bike and I am trying to swap the original saddle for my own. On my previous bike both bolts holding the seat clamp together are down facing, i.e. accessible from below the ...
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5 votes
1 answer
318 views

Seat post clamp bracket failure - how to repair?

I have a Jamis TAXI beach cruiser needing repair. Part of the bracket that is welded for holding the seat post clamp in place has come loose. The frame says T6 6061 aluminum. I am having trouble ...
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4 votes
1 answer
90 views

Saddle / Seat slowly creeps backwards

So, over the course of several months, I notice that my saddle has been creeping backwards on the seat post. Road bike. Fizik seat post (two screws, one manual, one hex head.) Ti rail saddle. I tend ...
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1 vote
0 answers
127 views

Specialized Roubaix Seat Post Rubber Seal Loose

On my Specialized Roubaix Comp, the rubber seal where the seat post enters the frame works loose and slides up the seat post a little. The seat post itself is not loose and stays put, the issue is ...
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  • 11
2 votes
1 answer
855 views

Torque of the rails or torque of the post?

I am building a bike and I am using a saddle with carbon rails on an alloy seatpost. I read that it's not an issue as long as the shape of the clamps is compatible with the shape of the rails, and in ...
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2 votes
4 answers
177 views

Can I attach a rear cargo rack directly to the seat clamp?

I'd like to install a rear cargo rack on a bike that doesn't have eyelets for the top attachment. Would it be a bad idea to attach the rear rack stays to this seat clamp that's welded onto the frame, ...
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  • 121
1 vote
1 answer
248 views

Can I run an internal dropper post on a small size 2014 Giant XTC Advanced 2 (2014)?

The specific bike model is this one: https://www.giant-bicycles.com/au/xtc-advanced-27dot5-2-2014 The dropper post I am looking at is this one: Brand-X Ascend CX Dropper 105mm I was thinking I could ...
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  • 27
6 votes
2 answers
271 views

I'd like to fit a suspension seatpost but have only 9 cm between saddle and frame - is this enough?

I'm 5'3" tall and ride an XS size gravel bike. I have only 9 cm of seatpost between the saddle and the frame, and you can see there's no possibility of extending that! I find the aluminium frame ...
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  • 61
1 vote
1 answer
276 views

How to determine my bike's seat post clamp size?

My mountain bike came with a quick release clamp that reads '34' on its side (embossed or debossed, am forgetting. Reading online there are about 3 sizes for seat post clamps I went with i believe '...
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14 votes
4 answers
3k views

How to stop bike renters overextending seatposts?

A friend and I have been operating a bike rental shop for about a year, and just recently we've started to notice more and more customers extending the seatpost well beyond the maximum line. So far we ...
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  • 159
7 votes
3 answers
2k views

How do I place the seat back 20 cm with a full suspension bike?

Here are 2 ideas for a makeshift design. The first one is no not that good. The second idea seems more doable using 2 heavy duty seatpost attached luggage racks. The seatpost is 33mm diameter, dunno ...
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4 votes
2 answers
582 views

Seat post nominal and actual size

If seatpost has nominal size of lets say 27.2, what is its actual size? Or other way around, if frame nominally accepts post of 27.2 what is the actual size of the bore in the frame? Obviously both ...
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0 votes
1 answer
71 views

seat post bolts won't fasten + spares?

got into a slight accident at home and my saddle has slid off my seat post. It looks like the rear bolt is now bent out of shape and the front bolt won't tighten at all into the nut. I wasn't sure ...
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2 votes
1 answer
236 views

How do you tighten a Hope seat post quick release?

I have a couple of these Hope seat post quick release, but I realised I don't know how to tighten it. I am referring to the adjustment on the bolt (not the qr lever).
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  • 2,890
6 votes
4 answers
821 views

Will grooves on seatpost cause rusting inside frame?

My bike has grooves in the seatpost as shown in the picture. The grooves do stop slightly further down the post, but the best saddle height for me is when the grooves partially go down into the seat ...
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  • 501
4 votes
1 answer
314 views

Skipping bolts on seatpost , please help?

Couple weeks back I bought this aluminium single-bolt seatpost . Now, just 20 days later, the nut that tightens the the mechanism to fasten the saddle rails to the seatpost is skipping around and not ...
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  • 312
9 votes
4 answers
2k views

How to make old bike's seatpost slide smoothly when it needs adjustment again?

I've several old bikes with a common problem, the seatpost is a bit too much hard to slide just to adjust the height (sometimes the frame scratch the seatpost), which might be ok on a road bike, but ...
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  • 460
4 votes
2 answers
450 views

How do I fix the comfort of my bike?

On a folding ebike with no suspension what’s the best addition to help with uneven roads bumpy surfaces etc? Whats the best/valued part I could add for comfort please?
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  • 96
0 votes
1 answer
117 views

25.4-27.2mm seat post shim on a seat tube with 26.8mm inner diameter

From where I live (Philippines) , there seems to be no stock for 26.8mm seat posts. All other sizes are available except for 26.8mm; they don't even sell shims for that size. Currently I am forced to ...
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  • 113
5 votes
1 answer
861 views

Bike seat tube is messed up

I was testing my seat and as I was sitting on the bike on the highest level of the seat post. My seat post came off and bent my seat post, so I ordered another, but now my seat tube doesn't allow my ...
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7 votes
2 answers
571 views

Before re-inserting a stuck seat post what should I do to the steel/alloy surfaces?

After several days and great effort I've succeeded in removing a stuck seat post (alloy post in a steel frame). It's actually in a reusable condition. Before trying to re-insert it, what should I do ...
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0 votes
1 answer
361 views

Seatpost clamp arrow and too wide saddle rails

I have two questions in one: :) The first would be what direction does this arrow on the seatpost's top clamp indicate? Is it towards the front or rear of the bike? Second would be what should I do if ...
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  • 241
10 votes
3 answers
737 views

Seat post bolt sheared off - twice

I use a BMC TM02 on CycleOps Magnus. The seat bolt has sheared off twice while riding on the trainer. The seat is attached to the post by a single stainless steel bolt. KSFC 12.9 appears on the head ...
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1 vote
0 answers
103 views

Size of clamp for Fizik Vento Argo R1 saddle on Specialized CG-R seat post

I have a 2015 Specialized Roubaix SL4 Disc with a CG-R seatpost, and recently bought a Fizik Vento Argo R1 short-nose saddle for it. Knowing it has ovalised carbon rails and not the standard 7 mm ...
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8 votes
3 answers
2k views

Why the small difference between common sizes of handlebars (31.8mm) and MTB seatposts (31.6mm)?

Many handlebars have a 31.8mm clamp section, and a common MTB seatpost size is 31.6mm. I know these are both around 1 1/4 inches. Why the 0.2mm difference though?
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  • 10.9k
3 votes
4 answers
382 views

What's the better option to buy? [closed]

I am about to get myself a hybrid bike, but being tight on budget (~ 200USD). I didn't really have many options to choose from. I'd initially thought of buying this particular bike, Mach City Munich ...
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  • 87
5 votes
1 answer
209 views

Saddle Position

I am a newbie to biking. I got my bike fitted in a local bike shop. I feel comfortable riding it. However, I feel (by looking at it) that the saddle is fitted way too back. It looks as if the back ...
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5 votes
2 answers
604 views

Are bike saddles always removable from the saddle post?

I want to buy a mountain bike soon and I’ve been doing a bunch or research. I noticed that some bike saddles can detach from the top of the saddle post, while others get removed with the whole post. ...
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  • 75
2 votes
1 answer
3k views

Is my dropper post too long?

I got a bicycle with a dropper post. As you know, there is currently a bicycle shortage, which is why I ended up getting it online instead of in a local shop (none of which had in stock what I was ...
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  • 141
-1 votes
1 answer
2k views

Canyon Endurace CF SL Disc: 7.0 vs 8.0 [closed]

Mission: On the market for a new road bicycle. Since May 2020 I stepped up my cycling and will probably at least triple the yearly kilometres (3k?). So I want to treat myself and I decided to invest a ...
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5 votes
3 answers
269 views

Reversible but not symmetrical lower plate in seatpost

I have an old seatpost that was removed from its original bike quite some time ago, now I want to use it in another bike, but I don't know if the lower plate should be positioned so it extends behind ...
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  • 265
4 votes
2 answers
2k views

Compatible seatpost for Brooks C13 saddle with 7x9 oval carbon rails?

I just purchased a Brooks C13 saddle (7x9 oval carbon rails, the more recent version with no tape) and was hoping it would fit on my existing post (2016 Jamis Coda Sport - it's a top/bottom clamp with ...
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6 votes
4 answers
2k views

What do I need to change to avoid 'bouncing' in my bike seat at high RPM?

I've noticed while cycling on my road bike that, when I try to pedal very quickly, I start to 'bounce' a little in my seat. As in I'm lifting off the seat a little with each pedal, so feel I'm not ...
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3 votes
0 answers
88 views

Need help understanding the components of a carbon fiber seat tube to properly unseize it

I recently picked up my first carbon fiber bike which has a carbon fiber seat post that seized to the frame due to rust. I did not initially think that was possible but after looking at it, I believe ...
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3 votes
1 answer
191 views

Direction of saddle clamps on seatpost

I have a seatpost from a Canyon Dndurace AL 7.0 from 2016. The seatpost has a saddle clamp consisting of two parts. The lower part has one long end and a shorter one. I can rotate both parts of the ...
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  • 215
2 votes
1 answer
195 views

Magura Vyron dropper seatpost internal shaft can be easily twisted

I had a very light crash (in fact just rode into a bush) after which I noticed I twisted magura vyron seat post. Apparently my seat post clamp was too tight.. Now it can be twisted when some force is ...
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  • 257
1 vote
1 answer
675 views

Increasing length of seatpost on a foldable bike

One of my bike is this little Dohiker 14" electric bike, but I actually pedal a lot when riding it, and the seatpost is a bit too short. It is about 50cm long, and I would need a few more centimeters. ...
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5 votes
1 answer
397 views

Seat rail clamp spins in the seat post

When I last got on my Specialized Stumpjumper the seat wanted to spin freely. The seat post was firmly clamped in the frame. With further inspection the seat is spinning where the seat clamp goes into ...
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