27.2 to 25.4 seatpost noticeable comfort

[beta_hat]

Anyone have expense with the two and can comment on the added comfort. I’m entertaining the idea of going down in size to a 25.4 seatpost for added comfort for longer rides. Is the idea of added comfort for the 25.4 observable or just a marketing tactic?

Thanks!

[FlashUNC]

You'll find more comfort taking 5 or 10 psi out of your tires than any seatpost diameter change.

[beta_hat]

You'll find more comfort taking 5 or 10 psi out of your tires than any seatpost diameter change.


Totally, ive already maxed my minimum tire pressure, wondering if the change to smaller diameter will add marginal benefits to longer rides

[palincss]

I'm having a lot of trouble understanding how this would work.

Put a 25.4 seatpost into a 27.2mm seat tube and the post is going to slide right down and bottom out. Is your point that a slammed seat feels more comfortable to you than a higher one?

Or am I missing something here?

[beta_hat]

I'm having a lot of trouble understanding how this would work.

Put a 25.4 seatpost into a 27.2mm seat tube and the post is going to slide right down and bottom out. Is your point that a slammed seat feels more comfortable to you than a higher one?

Or am I missing something here?


No I would use a shim.

[jtbadge]

Do you already have a carbon post? I feel like going from a stiff alloy post to a carbon post would make more of a difference than the diameter. The most common aftermarket 25.4 post I see is a Thomson, and those are about as stiff as it gets, although I know with Cannondale committing to this size that more companies are coming out with options. Also I wouldn't want to use a shim with a carbon post.

[prototoast]

I'm having a lot of trouble understanding how this would work.

Put a 25.4 seatpost into a 27.2mm seat tube and the post is going to slide right down and bottom out. Is your point that a slammed seat feels more comfortable to you than a higher one?

Or am I missing something here?

You can use a shim. Assuming you have a meaningful amount of seatpost exposed above the seattube, the 25.4 post will flex slightly more, which some may find to increase comfort.

I haven't gone from 27.2 to 25.4 but I have noticed a difference between 31.8 and 27.2. Not a lot, but does take the edge off ever so slightly.

[duff_duffy]

I think there are a few high flex carbon posts on the market id try first.

[KonaSS]

Not direct experience but, on my hardtail mountain bike with 2.3 tires running ~19lbs of pressure, I definitely noticed an increase in comfort going from a 31.8 seatpost to a 27.2 with a shim.

[hollowgram5]

Do you already have a carbon post? I feel like going from a stiff alloy post to a carbon post would make more of a difference than the diameter. The most common aftermarket 25.4 post I see is a Thomson, and those are about as stiff as it gets, although I know with Cannondale committing to this size that more companies are coming out with options. Also I wouldn't want to use a shim with a carbon post.Also, titanium posts offer more compliance than alloy posts. That compliance comes at a cost however.. I know my 31.6 ti post flexes quite a bit on my hardtail; helps take the edge off.

One could look at the eeSilk post Cane Creek is making. It's basically a 20mm travel thudbuster.. might be worth a look. Only available in 27.2.

[Dave]

Not worth the effort, according to this mechanical enngineer. Maybe a different saddle would help. As others mentioned lower tire pressure and maybe a wider tire.

[Mark McM]

The bending stiffness of a tube is:

Proportional to tube thickness;

Proportional to the cube of tube diameter;

Proportional to the cube of the length of the tube;

Propotional the elastic module of the material;

So, if you decreased the diameter of seatpost from 27.2 mm to 25.4 mm and left all else the same, the stiffness would decrease by 19% (i.e. you'd get 19% more flex in the seatpost). Since there isn't much flex in the seat tube to begin with, increasing that small amount of flex won't make much difference.

[jmoore]

Maybe a different saddle would help.

^this

[AngryScientist]

have you considered one of the handful of more compliant seatposts on the market that are specifically designed to do what it seems you're looking for?

maybe?

https://static.evanscycles.com/production/components/seatposts/product-image/484-319/specialized-cobl-gobl-r-carbon-seatpost-EV180943-8500-1.jpg

[OtayBW]

I'll take a different tack: If you're looking to improve the comfort of you saddle for longer rides by changing all these parameters, I'd say you need to find the right saddle....:eek:

[yinzerniner]

I used the following seatpost combinations to replace the stock 27.2 Cannondale C2 seatpost on my 2014 CAAD 10 a few years ago to try to eke out a bit more comfort, and the results were:

4 - FSA SLK 27.2 Carbon. Took a decent amount of the road "buzz" out, but didn't seem to appreciably help on bumps resulting from changes of level of more than 1/2"

3 - Focus Concept CPX 27.2 Carbon. Similar in feel to the above FSA SLK seatpost above, but better. Took more road buzz out, and the larger hits were damped more.

2 - Cannondale SAVE 25.4 Carbon with Shim. Very good with road buzz, maybe the Focus was a smidgen ahead, but where this really did work was the big hits. Tons more flex than the Focus and there was a noticeable but pleasant spring-like response to those larger hits, whereas my behind would bob up and down after big hits, but the hit was never transferred directly into my back. Road buzz mitigation is equivalent roughly to going down 15-20 psi vs the stock Alu post, but the big hits is where this shines.

1 - Ergon CF3 / Canyon VCLS 2.0. All the reviews are true, this thing is the real deal. Almost completely eliminates road buzz, and bit hits are dispersed incredibly well - better than even the 25.4 SAVE post. The only downside is that the post is flexy enough that you notice it when putting down the big watts, but otherwise I can't say enough great things. Have three of these now on my various rides. Also, because of the flex the post itself tends to get a bit more scarred at the clamp area, but that's to be expected since it flexes more and doesn't seem to really effect the structural integrity.

Never tried the Specialized CGR, but heard pretty good things about that as long as the weight and look doesn't scare you off.

[mhespenheide]

In fairness, Cannondale sized down to a 25.4mm seatpost and claimed that it offered an advantage, but I don't know how much they otherwise redesigned the seatpost at the same time. Echoing other opinions (and the calculations of Mark McM), it doesn't seem like it would make much of a difference.

Personally, I'd start by trying this second-hand thudbuster via eBay (https://www.ebay.com/itm/Cane-Creek-Thudbuster-Seatpost-27-2-Excellent-Condition/292864944243?hash=item44301c6873:g:Zf4AAOSwGBRcEag Y:rk:10:pf:0) or this titanium seatpost via eBay (https://www.ebay.com/itm/EasyTi-27-2x350mm-Offset-Setback-Layback-Titanium-Seatpost-for-MTB-XC-FR-Ti/223285090810?hash=item33fcd419fa:g:BIQAAOSwg2lb8YB A:rk:14:pf:0) and see how those work for you as proof-of-concept.

Or, like a lot of us, you can start looking at frames that use medium-reach brakes that let you go for larger tires...

[dem]

eeSilk is the way to go.. it really works, without a huge weight penalty over a normal post (although I suppose significant over a weenie post.)

I had an ergon CF3 knockoff, and the eeSilk is much better.

The flexy seatposts rely on having a lot of seatpost exposed, so if your frame doesn't have that, they won't be very effective. The eeSilk doesn't suffer that problem, so you get the full effect.

[mhespenheide]

...
1 - Ergon CF3 / Canyon VCLS 2.0. All the reviews are true, this thing is the real deal. Almost completely eliminates road buzz, and bit hits are dispersed incredibly well - better than even the 25.4 SAVE post. The only downside is that the post is flexy enough that you notice it when putting down the big watts, but otherwise I can't say enough great things. Have three of these now on my various rides. Also, because of the flex the post itself tends to get a bit more scarred at the clamp area, but that's to be expected since it flexes more and doesn't seem to really effect the structural integrity.
...

Thanks for that report. I'm so curious about these; the idea of a carbon-fiber leaf spring just makes sense to my wannabe-engineer brain. I'm going to have to bite the bullet and try one at some point soon.

[zap]

Anyone have expense with the two and can comment on the added comfort. I’m entertaining the idea of going down in size to a 25.4 seatpost for added comfort for longer rides. Is the idea of added comfort for the 25.4 observable or just a marketing tactic?

Thanks!

Road bicycle?

[mhespenheide]

Has anyone tried the Suntour NCX seatpost?

[beta_hat]

1 - Ergon CF3 / Canyon VCLS 2.0. All the reviews are true, this thing is the real deal. Almost completely eliminates road buzz, and bit hits are dispersed incredibly well - better than even the 25.4 SAVE post. The only downside is that the post is flexy enough that you notice it when putting down the big watts, but otherwise I can't say enough great things. Have three of these now on my various rides. Also, because of the flex the post itself tends to get a bit more scarred at the clamp area, but that's to be expected since it flexes more and doesn't seem to really effect the structural integrity.

Never tried the Specialized CGR, but heard pretty good things about that as long as the weight and look doesn't scare you off.[/QUOTE]


So I have the Ergon CF3 on my steel DeSalvo, mostly out of curiosity and I'd say it works well, although that bike is already plenty of compliant. I have been playing around with my Zanc Road bike and managed to squeeze 30s Schwalbe S-Ones for some mix-terrain rides (impressive for a bike with chain stay with 410mm). I have been taking this bike off road to some on mixed terrain with some light gravel. Was thinking I could swap over the Ergon CF3 or go with smaller diameter seatpost to cushion the ride further. I think the Ergon will stay for winter but was thinking of going 25.4 and leave it for the rest of year. The eeSilk does look appealing for winter riding!

[ghammer]

Yash, is that you? Gus here.

1 - Ergon CF3 / Canyon VCLS 2.0. All the reviews are true, this thing is the real deal. Almost completely eliminates road buzz, and bit hits are dispersed incredibly well - better than even the 25.4 SAVE post. The only downside is that the post is flexy enough that you notice it when putting down the big watts, but otherwise I can't say enough great things. Have three of these now on my various rides. Also, because of the flex the post itself tends to get a bit more scarred at the clamp area, but that's to be expected since it flexes more and doesn't seem to really effect the structural integrity.

Never tried the Specialized CGR, but heard pretty good things about that as long as the weight and look doesn't scare you off.


So I have the Ergon CF3 on my steel DeSalvo, mostly out of curiosity and I'd say it works well, although that bike is already plenty of compliant. I have been playing around with my Zanc Road bike and managed to squeeze 30s Schwalbe S-Ones for some mix-terrain rides (impressive for a bike with chain stay with 410mm). I have been taking this bike off road to some on mixed terrain with some light gravel. Was thinking I could swap over the Ergon CF3 or go with smaller diameter seatpost to cushion the ride further. I think the Ergon will stay for winter but was thinking of going 25.4 and leave it for the rest of year. The eeSilk does look appealing for winter riding![/QUOTE]

[oldpotatoe]

No I would use a shim.

A smaller diameter seat post of any material won't make any difference in comfort....as has been mentioned..tire pressure, tire size, tire construction..'tires'...

[beta_hat]

So I ended up switching from Enve 27.2 to a 30.9 Syntace P6 Carbon HiFlex seatpost (been using shims to go between different diameter posts), and I can say that is does make difference. I am not going to stretch the truth by saying it acts like a suspension post but it does dampen the medium-large imperfections on the roads of Chicago. Feels like I am riding on 32s instead of the current 28s.

Highly recommend this seatpost!