# 23c or 25C



## rave81 (Mar 20, 2016)

What tire size do you use in your front wheel 23c or 25C and why? 

is the benefit of wider tires super pass the benefit of aero 23C tires?


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## SauronHimself (Nov 21, 2012)

rave81 said:


> What tire size do you use in your front wheel 23c or 25C and why?


I use a 25c because I can run a slightly lower pressure for comfort without a speed penalty. It also corners slightly better than a 23c.



rave81 said:


> is the benefit of wider tires super pass the benefit of aero 23C tires?


That depends. Do you cruise at 25+ mph? If not, stick with a 25c. If yes, the 23c might benefit you more.


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## cxwrench (Nov 9, 2004)

rave81 said:


> What tire size do you use in your front wheel 23c or 25C and why?
> 
> is the benefit of wider tires super pass the *benefit of aero 23C tires?*


Seriously? Do you _have a need to be aero_? Is it actually something you'll benefit from? Do you consistently ride to work but leave 30 seconds late and need to make the time up on the road by riding a tiny bit faster? And your job is so hard that you can't expend the extra energy required to move a 25mm tire at that speed? And how do you know your 23mm tire/wheel combo are more efficient than your wheel w/ a 25mm tire? Do you know for sure?


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## craiger_ny (Jun 24, 2014)

I run the same tire up front as I do in the back because eventually the one in the front is going to end up in the back.

If I'm slow/slower than I want to be I blame myself not the bike.


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## Blue CheeseHead (Jul 14, 2008)

craiger_ny said:


> I run the same tire up front as I do in the back because eventually the one in the front is going to end up in the back.
> 
> If I'm slow/slower than I want to be I blame myself not the bike.



^^^This. I am not sure I could ever wear out a tire on the front before it dries out and deteriorates from age.


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## Lombard (May 8, 2014)

I use 28c front and rear. Believe me, I did not notice they were any slower than 25c or 23c. The improvement in ride is well worth it.

If you are racing on a closed track with perfect conditions, the narrower tires MAY be a tiny bit faster. On real imperfect road conditions, the narrower tires may indeed slow you down as they require more pressure which will bounce you around more.


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## crit_boy (Aug 6, 2013)

Lombard said:


> On real imperfect road conditions, the narrower tires may indeed slow you down as they require more pressure which will bounce you around more.


That is a backwards way of saying it. 

The new wide tire popularity is based on the mantra that wider tires are faster when run at the same pressure as the narrower version of the tire. 

Be aware that most people leave off the "at the same pressure" qualifier. 

So, it boils down to wider may be faster when pumped to the same pressure as the narrower tire. 

OTOH a wider tire allows one to use lower pressure, which may provide a more comfortable ride. 

I currently ride 25c pumped to 100 psi F and R. For years, I rode 23c pumped to 100 psi. I think the 25c in the same make/model feel a bit different. But, I don't think they are noticeably faster.


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## Lombard (May 8, 2014)

crit_boy said:


> That is a backwards way of saying it.
> 
> The new wide tire popularity is based on the mantra that wider tires are faster when run at the same pressure as the narrower version of the tire.
> 
> ...


I'm not sure I agree that what I said is backwards. Yes, it is true that in theory, wider tires have less rolling resistance than narrower tires. And in theory, this is offset by the extra rolling weight and wind resistance of the wider tires. So in theory, you could say that these issues cancel each other out.

But enter the world of real road conditions. Wider tires let you run less pressure which smooths the ride. Having to use more pressure in the narrower tire means on rougher roads, the tire will lose contact more often and not roll as well and therefore slow you down.

So at the end of the day, the net result is a more comfortable ride and no noticeable difference in my speed. I can tell you that I have run 23s, 25s and 28s at appropriate pressures for their width and have noticed no difference in my speed/performance. I am now running 65 front/95 rear on my 28s. It is comfort heaven and I can climb as well as ever.


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## crit_boy (Aug 6, 2013)

Lombard said:


> I'm not sure I agree that what I said is backwards. Yes, it is true that in theory, wider tires have less rolling resistance than narrower tires. And in theory, this is offset by the extra rolling weight and wind resistance of the wider tires. So in theory, you could say that these issues cancel each other out.
> 
> But enter the world of real road conditions. Wider tires let you run less pressure which smooths the ride. Having to use more pressure in the narrower tire means on rougher roads, the tire will lose contact more often and not roll as well and therefore slow you down.
> 
> So at the end of the day, the net result is a more comfortable ride and no noticeable difference in my speed. I can tell you that I have run 23s, 25s and 28s at appropriate pressures for their width and have noticed no difference in my speed/performance. I am now running 65 front/95 rear on my 28s. It is comfort heaven and I can climb as well as ever.


You can't have your cake and eat it too. 

Wider tires have lower rolling resistance at the same pressure. 
Wider tires are more comfortable at lower pressures. 

From everything I have read, you don't get both decreased rolling resistance and more comfort. 

You have made this argument before. http://forums.roadbikereview.com/wheels-tires/why-not-28mm-tires-264656-6.html Feel free to review the citations in post #127.


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## cobra_kai (Jul 22, 2014)

This test is probably relevant: Continental Grand Prix 4000S II 23 25 28 mm Comparison. Just pulling the round numbers off their chart on the bottom, if you run 23s at 100 PSI, 25s at 80 PSI, and 28s at 60 PSI you will see a small increase in rolling resistance at each step, but most likely a large increase in comfort. You'll have to decide where your sweet spot is.


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## Blue CheeseHead (Jul 14, 2008)

crit_boy said:


> You can't have your cake and eat it too.
> 
> Wider tires have lower rolling resistance at the same pressure.
> Wider tires are more comfortable at lower pressures.


These are not mutually exclusive. The key is at what pressure reduction does the rolling resistance of a 25 equal a 23? For sake of argument say that is 10 psi. So if one were to run their 25 9 psi lower than a 23 they still would have lower rolling resistance, BUT it does not necessarily mean it will be more comfortable.

A 25 run at the SAME pressure as a 23 will experience LESS tire drop when loaded, and thus less cushion via tire sidewall deflection, thus a firmer ride.

If the 25 tire theorized above experiences MORE tire drop with 9 psi less than the 23 then one could expect more comfort AND less rolling resistance.

While that window exists, it is pretty small. More often when one optimizes for comfort they sacrifice some rolling resistance and visa versa.


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## changingleaf (Aug 20, 2009)

There's a general consensus that that a 25mm tire is better for most condition. But, not all 25's measure 25 and not all 23's measure 23, and the width of the rim can affect the tire width. So, if you're choosing a 25, it will be safe to make sure your frame and fork can handle at least a 26mm tire. I've seen some frames and forks that rub with 25mm tires on them. One the other hand some come in undersize.


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## rave81 (Mar 20, 2016)

I'm currently running 25c on my Mavic r-sys I has plenty of clearance. However I order a 45mm lb wheelset which is wider than Mavic-says. I run my tires 80-120 psi however 95psi is the sweet spot between rolling resistance and comfortable. 


I cruise between 40-50kph. 

Im new to road biking. I normally ride my mtb bike with 40mm wide wheelset and maxxis DHf 650bx2.5. Wider tire and low pressure in mtb is better in terms of traction and speed.


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## crit_boy (Aug 6, 2013)

More interesting: 
So when should I mount a bigger tire? Only when you need more comfort and your tire 'bottoms out' on bumps. Aero resistance and weight will increase. Rolling resistance will increase even more because a bigger tire needs an even lower tire pressure to offer the same comfort level, which in turn increases rolling resistance. Link

For me - I see the take away as selecting a wide enough tire to not pinch flat at the pressure you run. I personally don't understand "comfort heaven" on the bike. My couch is comfortable. I am not on my bike for physical comfort. 

However, I don't think the available information supports the common statement that you get more comfort and lower rolling resistance with wider tires.


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## Lombard (May 8, 2014)

crit_boy said:


> You can't have your cake and eat it too.
> 
> Wider tires have lower rolling resistance at the same pressure.
> Wider tires are more comfortable at lower pressures.
> ...



Your black and white logic is astounding and you seem to be hung up on the phrase "*at the same pressure*". Yes, that part is true.

However, how much do you really think reducing pressure in the wider tire by 10-20 PSI will increase your rolling resistance? Or let's put it another way. How many PSI would you have to reduce the wider tire to make the rolling resistance equal to that of the narrower tire? Has anybody explored this, or are we just throwing out talking points for the sake of argument?

My point is more that in our real world of riding conditions, it really doesn't make that much of a difference. You are getting more comfort without any noticeable losses.


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## crit_boy (Aug 6, 2013)

Lombard said:


> Your black and white logic is astounding and you seem to be hung up on the phrase "*at the same pressure*". Yes, that part is true.
> 
> However, how much do you really think reducing pressure in the wider tire by 10-20 PSI will increase your rolling resistance?


Yes, decreasing pressure increases rolling resistance. Look at the data in the links.


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## Lombard (May 8, 2014)

crit_boy said:


> For me - I see the take away as selecting a wide enough tire to not pinch flat at the pressure you run. I personally don't understand "comfort heaven" on the bike. My couch is comfortable. I am not on my bike for physical comfort.



If you are a crit rider as your moniker implies, comfort is probably not high on your list. However, if you are an endurance rider who normally does 50-70 mile rides, your hands and arse will thank you for the little bit of extra comfort.


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## crit_boy (Aug 6, 2013)

Lombard said:


> If you are a crit rider as your moniker implies, comfort is probably not high on your list. However, if you are an endurance rider who normally does 50-70 mile rides, your hands and arse will thank you for the little bit of extra comfort.


I do two or three 50+ mile rides per week and at least one ride over 80 miles per week. 

However, distance ridden does not change the facts.

It seems you have decided to abandon logical discussion about the merits of your position. As such, it appears your argument has run its course. So, I think we are done.


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## Lombard (May 8, 2014)

crit_boy said:


> Yes, decreasing pressure increases rolling resistance. Look at the data in the links.



But by how much? Significantly for me to even notice?

Something else in the Velonews link you posted that you may want to re-read. As I said before, this is not the black or white world you seem to be clinging to:

_"On rough surfaces, however, a tire at lower pressure is able to absorb more of the bumps than a tire at higher pressure, with less deflection of the bike and its rider. This is the same “sprung vs. un-sprung weight” argument that demonstrates why suspension makes a bicycle faster on rough terrain — it takes less energy to keep the bike rolling if only a small amount of weight is lifted (like a small section of the tire) than if the entire bike and rider is lifted by the bump."

Resistance is futile: How tire pressure and width affect rolling resistance - VeloNews.com 


_


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## November Dave (Dec 7, 2011)

changingleaf said:


> There's a general consensus that that a 25mm tire is better for most condition. But, not all 25's measure 25 and not all 23's measure 23, and the width of the rim can affect the tire width. So, if you're choosing a 25, it will be safe to make sure your frame and fork can handle at least a 26mm tire. I've seen some frames and forks that rub with 25mm tires on them. One the other hand some come in undersize.


This. 

I regularly see various tires that are called "25" that inflate to between 25 and 28.5mm wide at the same pressure on the same tire. Which of them are 25s? A Continental GP4000 23 is 25.25 or so mm wide on most wide-ish rims. Does that make it a 25? Current Michelin 25s are over 28mm wide, and Conti GP4000 25s are just a hair under 28 on 18mm bead seat rims. 

The effect of inflation pressure on rolling resistance is not predictable from tire to tire. The only correlation that seems dependable there is that the better a tire's rolling resistance, the less impact inflation pressure has on that tire's rolling resistance. 

Aerodynamics and crosswind handling both suffer with wider tires (we confirmed this in the wind tunnel with a range of wheels) but the magnitude of these effects would be negligible for a large majority of people. 

There are no hard and fast (pun unintended) rules on this.


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## Lombard (May 8, 2014)

November Dave said:


> There are no hard and fast (pun unintended) rules on this.


Hear that, Crit Boy?


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## cobra_kai (Jul 22, 2014)

rave81 said:


> I'm currently running 25c on my Mavic r-sys I has plenty of clearance. However I order a 45mm lb wheelset which is wider than Mavic-says. I run my tires 80-120 psi however 95psi is the sweet spot between rolling resistance and comfortable.
> 
> 
> *I cruise between 40-50kph. *
> ...






Lombard said:


> But by how much? Significantly for me to even notice?
> 
> Something else in the Velonews link you posted that you may want to re-read. As I said before, this is not the black or white world you seem to be clinging to:
> 
> ...


If you read the bicycle rolling resistance links for the popular GP4000s II, which is what I use on my 'fast' bike, you'll see that a low pressure (60 PSI) 28mm tire loses about 1.5 watts to a high pressure (100 PSI) 23mm tire. You'll also notice the test corroborates what Dave says in that a 23 measures nearly 25, a 25 measures nearly 28, and a 28 measures nearly 32.


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## Lombard (May 8, 2014)

cobra_kai said:


> If you read the bicycle rolling resistance links for the popular GP4000s II, which is what I use on my 'fast' bike, you'll see that a low pressure (60 PSI) 28mm tire loses about 1.5 watts to a high pressure (100 PSI) 23mm tire. You'll also notice the test corroborates what Dave says in that a 23 measures nearly 25, a 25 measures nearly 28, and a 28 measures nearly 32.



1.5 watts?? Damn, I can't lose that very precious energy! I must go back to 23s right now and pump them up to 120 PSI so I can possibly get another 0.5 watt gain!  I might even qualify for the Tour de France then!


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## pmf (Feb 23, 2004)

I always thought the measurement was height, not width. Albeit, a taller tire is probably wider.

As November Dave points out, labeling isn't really very accurate. I find Conti 4000s tires to be a lot bigger than Michelin Pro4's. 

I'm lucky. All my bike frames are old. Tires labelled 25 that I've tried don't clear the fork on the bikes I own. I had to give them away.


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## cxwrench (Nov 9, 2004)

Lombard said:


> 1.5 watts?? Damn, I can't lose that very precious energy! I must go back to 23s right now and pump them up to 120 PSI so I can possibly get another 0.5 watt gain!  I might even qualify for the Tour de France then!


One does not 'qualify' for the TdF.


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## November Dave (Dec 7, 2011)

cxwrench said:


> One does not 'qualify' for the TdF.


Especially if one is losing all them watts with the under inflated tires!


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## Mr645 (Jun 14, 2013)

Once I tried 25c tires, I'll never go back to 23. Smoother ride for sure. 25mm was also the most common tire size used for the last Tour de France. 
"Most teams are using 25mm tires—up to 30mm for stage four’s cobblestones—at this year’s Tour, mirroring the general trend toward wider tires for all bikes. The extra girth provides a bit more suspension for a smoother ride, and some more traction. There are exceptions: Trek Factory Racing continues to use 23mm tires because, according to its data, narrower tires are faster after you account for rolling resistance and aerodynamics."


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## Mr645 (Jun 14, 2013)

Also Continental sponsored teams got a special 28c tubular not sold to the public


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## November Dave (Dec 7, 2011)

That 28mm tubular is probably just about the same size as a Continental GP4000 "25" clincher, and smaller than a new "25mm" Michelin Power clincher. Tubulars generally run true to stated size and don't vary depending on which rim they're used with. Neither of these is true of clinchers. 

So just be aware that the 25mm tubular your favorite pro team is riding may be a heck of a lot closer in size to a 23mm clincher.


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## Kerry Irons (Feb 25, 2002)

crit_boy said:


> Yes, decreasing pressure increases rolling resistance. Look at the data in the links.


You're only looking at hysteresis losses, not suspension losses. Hysteresis losses are from the flex of the tire casing and tread rubber. They decrease as pressure increases. Suspension losses are created when the tire does not compliantly overcome road roughness and transmits energy into the rider's body, where it is lost. Suspension losses increase with increasing pressure.

Bicycle Quarterly has done extensive testing on this and shown that compliant wider tires are no slower but provide much more comfort and better traction.


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## Trek_5200 (Apr 21, 2013)

I use 23's on both the front and back. The bike was spec'd for23's and 25's would be tight. 23's work great for me(the trick was finding the optimal tire pressure which for me is 90 psi). As far as aero, the effect if any is going to be so minimal i doubt anyone would notice. Just remember the width of a nickel is 1.95 mm vs the 2 mm in tire width your debating. Body position is what drives aero more than anything else. The supposed benefit of 25's is you can run them with lower pressure to gain comfort but I did that on my 23's. I do have another bike where i'm seeing huge impact of wider tire running lower pressure but that's my gravel bike running 32's.


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## Lombard (May 8, 2014)

Trek_5200 said:


> As far as aero, the effect if any is going to be so minimal i doubt anyone would notice.


Exactly! There is theory, and then there is reality. And that difference will be even less if you are riding less than 20mph.



Trek_5200 said:


> The supposed benefit of 25's is you can run them with lower pressure to gain comfort but I did that on my 23's.


If you're not too heavy, you can certainly do this with 23s. If you're not getting any pinch flats, you're golden. And you could also run at least 20 PSI lower in the front without problems. You would certainly notice an even greater advantage with 25s, but since they don't fit in your frame, it's a non-issue.


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## sneakyracer (Dec 1, 2007)

rave81 said:


> What tire size do you use in your front wheel 23c or 25C and why?
> 
> is the benefit of wider tires super pass the benefit of aero 23C tires?


I currently use 25 front and rear and have for almost 2 years. It just provides the best combination of speed and comfort. 

I still do think that generally (given equal tire designs) that the 23's are faster on rides with sustained higher speeds (25mph and above) on good roads. But if the rolling surface is anything but smooth the 25's are the best choice.


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## wgscott (Jul 14, 2013)

rave81 said:


> What tire size do you use in your front wheel 23c or 25C and why?
> 
> is the benefit of wider tires super pass the benefit of aero 23C tires?


40 mm. Same as the rear.

WTF "super pass"?


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## Notvintage (May 19, 2013)

crit_boy said:


> I do two or three 50+ mile rides per week and at least one ride over 80 miles per week.


oooh, look out gang. Alpha male in the hood. Lol.


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## TmB123 (Feb 8, 2013)

Just throwing this out there as trying to get my head around it as it's not something I ever thought of before until buying different sized tyres lately.

A bigger tyre is usually wider and taller. I recently went from a Roubaix Pro 25/28 to a Conti CX speed 35 on my Gravel bike. The Conti's added about 6mm to both the width and height when mounted on the same rims. 

So the question is, how does this effect gear ratios on the bike? Is there a point where going bigger actually loses you one gear for instance, and what point is that? I'm really not sure how much matters, but at some point it must make a noticeable difference?


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## Lombard (May 8, 2014)

TmB123 said:


> Just throwing this out there as trying to get my head around it as it's not something I ever thought of before until buying different sized tyres lately.
> 
> A bigger tyre is usually wider and taller. I recently went from a Roubaix Pro 25/28 to a Conti CX speed 35 on my Gravel bike. The Conti's added about 6mm to both the width and height when mounted on the same rims.
> 
> So the question is, how does this effect gear ratios on the bike? Is there a point where going bigger actually loses you one gear for instance, and what point is that? I'm really not sure how much matters, but at some point it must make a noticeable difference?


Your answer is here:

Mike Sherman's Bicycle Gear Calculator


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## Lombard (May 8, 2014)

sneakyracer said:


> I still do think that generally (given equal tire designs) that the 23's are faster on rides with sustained higher speeds (25mph and above) on good roads.



And then I pinched myself and woke up out of that dream.


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## TmB123 (Feb 8, 2013)

Lombard said:


> Your answer is here:
> 
> Mike Sherman's Bicycle Gear Calculator


Ah cool, thanks, so there is a difference (obviously) but not much :thumbsup:


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## Lombard (May 8, 2014)

TmB123 said:


> Ah cool, thanks, so there is a difference (obviously) but not much :thumbsup:



Exactly. A difference, but not significant. Less than the difference of one less tooth in the largest cog!


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## Jay Strongbow (May 8, 2010)

TmB123 said:


> Just throwing this out there as trying to get my head around it as it's not something I ever thought of before until buying different sized tyres lately.
> 
> A bigger tyre is usually wider and taller. I recently went from a Roubaix Pro 25/28 to a Conti CX speed 35 on my Gravel bike. The Conti's added about 6mm to both the width and height when mounted on the same rims.
> 
> So the question is, how does this effect gear ratios on the bike? Is there a point where going bigger actually loses you one gear for instance, and what point is that? I'm really not sure how much matters, but at some point it must make a noticeable difference?


I 'think' I notice the difference with 33mm tires compared to 25mm. There's a really steep that I can get up fairly easy with 34x25 and 25mm tires but it seems a lot harder to keep a decent cadence with 33mm tires. Only done it a once with 33s though so might have just been having a bad day. I also use 28mm sometimes and can't notice any difference from 25's.

I'd say it's not something to be concerned about unless you're already on the verge of walking up hills and are making a big jump in tire size.


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## Lombard (May 8, 2014)

Jay Strongbow said:


> There's a really steep that I can get up fairly easy with 34x25 and 25mm tires but it seems a lot harder to keep a decent cadence with 33mm tires. Only done it a once with 33s though so might have just been having a bad day.


Possibly a bad day. Or maybe a headwind, or possibly other factors we can't explain. I would not consider an experiment like this conclusive until you have done it numerous times.


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## TmB123 (Feb 8, 2013)

Jay Strongbow said:


> I 'think' I notice the difference with 33mm tires compared to 25mm. There's a really steep that I can get up fairly easy with 34x25 and 25mm tires but it seems a lot harder to keep a decent cadence with 33mm tires. Only done it a once with 33s though so might have just been having a bad day. I also use 28mm sometimes and can't notice any difference from 25's.
> 
> I'd say it's not something to be concerned about unless you're already on the verge of walking up hills and are making a big jump in tire size.


If the 33mm tyres are CX tyres (Challenge Chicane?) it's possible that rolling resistance may also be a factor in making things feel harder on top of the slight shift in gearing. There is a definite difference for me pushing a mainly slick 25/28 Roubaix Pro pumped at 60/70 and the Conti or Challenge CX tyres pumped at 50/55. It all adds up.


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## Lombard (May 8, 2014)

TmB123 said:


> If the 33mm tyres are CX tyres (Challenge Chicane?) it's possible that rolling resistance may also be a factor in making things feel harder on top of the slight shift in gearing. There is a definite difference for me pushing a mainly slick 25/28 Roubaix Pro pumped at 60/70 and the Conti or Challenge CX tyres pumped at 50/55. It all adds up.



Tread slows you down MUCH more than width, weight or wind resistance.


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## bigjohnla (Mar 29, 2010)

I ride 25mm Maxxis Refuse on 23mm Velocity A23 rims at 90PSI front 100PSI back. On these rims the width of the tire is close to the width my wife's 28mm tires on her hybrid. I am 271 pounds. I ride 15-16 mph average on a metric century which is my favorite distance. They ride good.


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## Jay Strongbow (May 8, 2010)

TmB123 said:


> If the 33mm tyres are CX tyres (Challenge Chicane?) it's possible that rolling resistance may also be a factor in making things feel harder on top of the slight shift in gearing. There is a definite difference for me pushing a mainly slick 25/28 Roubaix Pro pumped at 60/70 and the Conti or Challenge CX tyres pumped at 50/55. It all adds up.


Given that I'm pretty much just as fast down hill and ordinary riding I doubt the change in rolling resistance when doing like 4mph on a steep hill is a factor.


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## wpwoodjr (Aug 3, 2011)

I did some roll-down tests between a Specialized Roubaix running 25mm Conti 4 Seasons in front at ~80psi and a 28 mm Conti 4 Seasons at the rear at ~90 psi, vs a Specialized Diverge running Compass Barlow Pass 38s at ~50 psi front and ~60 psi rear. The course was 0.53 miles on a smooth downhill asphalt trail. The results over 3 runs for the Roubaix averaged 116.03 secs and for the Diverge 117.03 secs, a small difference of about 2 secs/mile. Unless you’re doing a time trial you wouldn’t notice this.

Running parallel to the asphalt trail is a gravel trail. On this, the Roubaix took 163.1 secs vs 150.5 for the fat tired Diverge. That's 26 secs faster per mile, an 8% improvement for the wider tires!

If your roads aren’t perfect, the advantage of thin tires on smooth asphalt can evaporate quickly due to suspension losses. And there is a huge increase in comfort with the fatter tires.


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