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After riding for about 300km, I'm looking at adjusting some parts to fit me.

First adjustment: Because I feel that I'm stretching a little too forward, causing my back to ache, I've decided I would decrease my stem from 110 to 90.

Second adjustment: Because I feel that the saddle is too small for me, causing the sensitive area to compress, I've decided to change my seat to swork power (OEM).

Right now I'm looking at my leg reach to the pedals. Currently I feel that I have to stretch a bit more than I feel comfortable to, while pedaling, so I'm considering if I should shorten my seat post or change my crank length from 172.5 to 165. HOWEVER my seat post is integrated to the frame, I feel like I shouldn't cut it (plus its risky as it is carbon).

165 cranks are rare: I only found Dura-Ace 7950 that would cost me $275, but it would be a upgrade from the current Ultegra. Also my friend is saying that changing my Ultegra BB to a Dura Ace BB would make my ride much smoother.

Please advise me if all these changes I'm doing are advisable. Also crank change vs seat tube cutting!!

Thank you for your reading time!

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    Could you clarify what you mean by "seat post is integrated to the frame"? Would you be able to simply buy a shorter seat post? I once had a similar problem when installing a dropper post on a MTB: the post was too long by about a cm and you can't shorten dropper posts. So I actually had to shorten the seat tube of the frame, which thankfully wasn't a problem due to it being an aluminium frame. This is not a good idea with carbon frames, but shortening the seatpost might be fine (can't give a qualified answer to that). – anderas Aug 14 at 7:54
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    There is no point whatsoever changing the bottom bracket. Bottom brackets are bottom brackets and they're all as "smooth" as you need. The only advantage of a more expensive bottom bracket is that it's likely to be slightly lighter; if weight's such an issue, you could save more by going for a pee before you ride... – David Richerby Aug 14 at 7:59
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    @anderas it means that there is no separate seatpost, but it is a part of the frame. The only way to adjust it is to cut it shorter. This doesn't encourage experiments with saddle height. – ojs Aug 14 at 8:09
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    @anderas They're called integrated seat masts (also "integrated seat post"). Thankfully, they're mostly dead. – Andrew Henle Aug 14 at 10:44
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    The other question is: Who sold you a bike that doesn't seem to fit your size? Or didn't adapt the integrated seatpost correctly? You normally find these in the upper price segment and the shop who sold it should have fitted it properly, at least. – Carel Aug 14 at 19:21
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Because I feel that I'm stretching a little too forward, causing my back to ache, I've decided I would decrease my stem from 110 to 90.

You can help this by also moving your saddle forward. If you combine that with raising your handlebars some by changing the stem angle, you'll shift your torso to be more upright, too. That will also shift your weight back a bit, putting a bit less pressure on your hands and a bit more on your bottom.

Moving the saddle forward would also slightly shorten the reach to the pedals.

165 cranks are rare

They sure don't seem to be. A simple Google search returns many examples of Shimano 165 mm cranksets that would likely all be compatible with your bicycle.

Also my friend is saying that changing my Ultegra BB to a Dura Ace BB would make my ride much smoother.

Hogwash. You wouldn't be able to tell. You'd probably be surprised at how many amateur road racers use things like Sora or Tiagra cranksets, or won't bother paying more for Ultegra - much less DuraAce - over 105 or today's Tiagra. (Wheels are what gets the money - good aero wheels can save 40 or 50 watts - maybe more - at 30+ mph...) Pros and higher-level amateurs ride high-end bikes because they get them for free - it's marketing aimed at getting you to pay a premium for bling. DuraAce doesn't make your bike faster. All it really does is make your bike a little bit lighter and a lot more expensive. How much better is a $275 DuraAce crankset than a $65 Sora crankset anyway? IMO, don't worry about the grams until you get down to 2% body fat.

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    Moving the saddle to deal with reach to the bars is the wrong thing to do. The saddle should be adjusted to the right position relative to the bottom bracket for the riders legs, then the bars adjusted. – Argenti Apparatus Aug 14 at 11:38
  • @ArgentiApparatus I don't think there is a single "right position" for a saddle. No one bicycle fit item exists in isolation from any of the others. Saddle position also impacts weight distribution, and the desired posture also can require different saddle positions. A more upright posture will likely fit better with a saddle set more forward, while a more aggressive aero posture will likely work better with a saddle set further aft. See peterwhitecycles.com/fitting.php for a better description than I can do. – Andrew Henle Aug 14 at 12:01
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    @ArgentiApparatus While in principle true, we can't know whether the current saddle position is the "right" one - it might also be set too far back, thus moving it forward may even improve two things at once. – Marjan Aug 14 at 12:08
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    'I don't think there is a single "right position" for a saddle': I agree. 'more upright posture will likely fit better with a saddle set more forward': that's the wrong way around. Bikes with more upright positions generally have the saddle a little further back. – Argenti Apparatus Aug 14 at 12:10
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    Two things mean changing the bottom bracket will make the ride smoother. The lump from the wallet full of cash in the rear pocket will significantly reduced, meaning its interfere less with the pedaling motion, and Placebo effect. – mattnz Aug 14 at 21:46
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Reducing the reach with a shorter stem is reasonable if you think you are leant too far forward. You can also experiment with raising the bars a little by flipping the stem over.

Dropping the saddle is reasonable if your legs are too extended. The standard rule of thumb is your knee should be slightly bent at the bottom of the pedal stroke, with your feet level.

Changing to shorter cranks to effectively reduce the seat to pedal distance is inadvisable, I think. The point of shorter (or longer) cranks is to match the cranks arm length to the riders leg length. With shorter cranks you may find that you introduce other problems.

Depending on the design of your seat-mast, you probably can cut it even if it is carbon fiber composite. Presumably you have a short seat post that fits into the longer mast. If you are confident that the post will go lower into the mast and the clamping mechanism will not be affected the mast can be shortened. Cutting down a CFC tube does not affect it structurally, if you cut is correctly. See this Park Tool video that shows how to trim a CFC handlebar. A special CFC hacksaw blade is used with a cutting guide.

Before cutting the mast, have at least one knowledgeable person look at your saddle height, just to make sure you are not doing it needlessly.

About the Dura Ace BB, yeah, that's BS. Does your friend have one he's trying to sell you?

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Thank you all for your participation and advise. I'm new to this forum so i might be using the wrong method to reply to your answers. From the answers I've concluded that

  1. it is pointless to change BB

  2. It is fine to change crank length but not an Orthodox method.

  3. Shifting saddle forward aids in finding the comfort position too

  4. Maybe get a professional to see if cutting seat tube (seat mast) is the right thing to do.

To answer some of your questions:

  • no, my friend is not trying to sell me his bb

  • maybe 165mm cranks are rare only in my area.

  • i bought the bike second hand cause i thought that would be the best way to learn

    Below is a picture of my integrated seat mast enter image description here

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    I would think you could safely cut that mast, so long as the cutting is done carefully with an abrasive blade, and the top of the cutoff is visible in the cutout of the clamp. No stresses would be placed on the cut end, so there would be very little danger of it splitting. (I'm guessing that the mast is designed to be trimmed as needed.) – Daniel R Hicks Aug 15 at 1:10
  • I'd start by measuring another bike on which you feel comfortable. Even if you have to borrow someone else's bike for a couple days. Get it all dialed in, raise and lower the saddle height till it feels right, and compare that BB/saddle-top distance to your frame before cutting. Most of those integrated seatposts have some adjust, but its often as little as 10mm and achieved with rubber shims/blocks. – Criggie Aug 15 at 3:17
  • Not relevant to your question, but get some real lights. The ones you have might look bright but the problem is that they contain no reflectors or lenses so all you have is one or two tiny points of light. Those are extremely easy to miss in an urban environment where there are lots of lights all over the place. – David Richerby Aug 15 at 8:10
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    When you want to add more information you can and should edit your question instead of adding the information as an answer. – Tooniis Aug 15 at 12:48

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