# 25mm tires 2 days before century?



## reg32 (Jul 21, 2008)

Would there be any benefit by switching to 25mm tires 2 days before century? Or silly? 
Current setup is Mavic Ksyrium SLS with 23mm mavic tires on cannondale supersix.

Thanks


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## Silentfoe (Aug 22, 2009)

I am not an expert here but the new school of thought (with evidence) is that wider tires with slightly lower pressures are actually faster (and more comfortable) than skinnier tires with higher pressure. I'm actually interested in putting 28's on my bike for the Lotoja next weekend. If I am way off base here, I hope someone will sound off.


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## Jay Strongbow (May 8, 2010)

reg32 said:


> Would there be any benefit by switching to 25mm tires 2 days before century? Or silly?
> Current setup is Mavic Ksyrium SLS with 23mm mavic tires on cannondale supersix.
> 
> Thanks


There's more to tires than width but when comparing similar quality tires bigger will always be more plush which is something sane people view as a positive on a century ride. Let's not get into the speed thing because 2mm won't change anything in a meainingful way.


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## ericm979 (Jun 26, 2005)

The rolling resistance difference between two different sizes of the same tire is very small. And it's not always the larger tire that is lower. What's surprising is that larger does not always have higher RR as had previously been the dogma. However aerodynamics also play a part and there larger tires would be a disadvantage unless on rims made for them.

25s at a lower pressure might provide a better ride but no noticeable speed difference.


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## Srode (Aug 19, 2012)

I wouldn't call it silly. Really depends on how comfortable you are on your current tires. If you can ride them for a metric comfortably, no need to change IMHO. Of course the pavement where you are riding may not make it apples to apples either, could be better or worse than what you are used to. Net, hard to say.


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## NJBiker72 (Jul 9, 2011)

I would have said don't change before a big ride. Until I switched. I noticed the difference immediately. Comfort is one thing but confidence and stability is more noticeable for me. I just feel more stable when I go really hard. 

The drawback is not the aero or rolling resistance I MO but the weight. Still that is relatively minor.


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## kjdhawkhill (Jan 29, 2011)

Maybe a little late, but changing to a 25mm tire, as long as you're capable of installing them yourself and inflating them, shouldn't cause any negative reactions. I usually wait to switch tires until one is worn out, and switching from a worn-out 23 to a new 25 would be a good idea for handling and reliability's sake.


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## woodys737 (Dec 31, 2005)

I've done a lot of switching back and forth from 23 to 25's as the tire wears. Basically, I buy one brand/model of tire now and whichever size is selling for a better price I buy that one. Sometimes I end up with a 25 on one wheel and a 23 on the other. Sometimes both 23, or both 25. I'm in the minority of riders that hate running lower psi on the 25's. I found they roll better at the same psi as the 23's fwiw. I thought I would love they way they feel at the lower psi like damn near everyone else seems to find but, to me they were slow as mud and it pissed me off. Why work harder/longer to have a "plush ride"?


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## Trek_5200 (Apr 21, 2013)

reg32 said:


> Would there be any benefit by switching to 25mm tires 2 days before century? Or silly?
> Current setup is Mavic Ksyrium SLS with 23mm mavic tires on cannondale supersix.
> 
> Thanks


I've done dozens of centuries, this year alone, all on 23 mm tires. I would not switch, especially two days before a long ride. If you are planning on doing a lot of riding on not the best roads, you might consider wider tires, but then you'd probably want something larger than 25 maybe 27.


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## woodys737 (Dec 31, 2005)

Trek_5200 said:


> I've done dozens of centuries, this year alone, all on 23 mm tires. *I would not switch, especially two days before a long ride*. If you are planning on doing a lot of riding on not the best roads, you might consider wider tires, but then you'd probably want something larger than 25 maybe 27.


I don't get it. I guess I'm not in tune with details or I don't ride enough to know. I'd friggin switch 10 minutes before the start and not even think twice about it. About as important of a decision as what color bar tape to run.


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## Trek_5200 (Apr 21, 2013)

woodys737 said:


> I don't get it. I guess I'm not in tune with details or I don't ride enough to know. I'd friggin switch 10 minutes before the start and not even think twice about it. About as important of a decision as what color bar tape to run.



If the bike felt different, I would not push it to the limit as much. That's just me.


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## woodys737 (Dec 31, 2005)

Trek_5200 said:


> If the bike felt different, I would not push it to the limit as much. That's just me.


That's cool. Honestly I can't tell the diff


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## blitespeed (Mar 2, 2013)

I wouldn't hesitate to switch, except for the matter of tire clearance. I would find the discovery of tire rub very annoying on my event ride, especially as everything was probably fine before the switch.


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## kps88 (Dec 3, 2013)

me neither. 25mm is much more comfortable. speed and handling not much different, but much better feel. I wont ever ride 23mm again. Don't the Pro's sometimes have different tires if they have a puncture? Their sag wagons aren't always there for them...right? That's mid ride..not 10 minutes before.



woodys737 said:


> I don't get it. I guess I'm not in tune with details or I don't ride enough to know. I'd friggin switch 10 minutes before the start and not even think twice about it. About as important of a decision as what color bar tape to run.


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## ziscwg (Apr 19, 2010)

You don't run 25 mm tires already??

You must have shocks in your elbows.

It's just all better on 25 mm tires.

The only consideration is your frame.


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## bayAreaDude (Apr 13, 2012)

It will almost certainly be more comfortable. I'd just question the timing. Might want to give it a week or at least a couple long rides to make sure there's not an issue with a tube or having gotten the new tires on.


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## Local Hero (Jul 8, 2010)

Do it, especially if your old tires are showing signs of wear. You'll have less chance of flats on new tires. What's the big deal with timing? This is only a concern if you cannot successfully change a tire. We're talking about a five minute swap, not open heart surgery.


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## Silentfoe (Aug 22, 2009)

I'll follow up here. I threw 28's on my bike the day before the Lotoja (204+ miles). I took off 25's to do it. Very nice upgrade. It didn't change the handling of the bike at all but I could tell I had a slight comfort upgrade. I guess it did feel a bit more stable at speed and I didn't feel like it slowed me down at all. Plus I was able to lower my PSI to about 100.


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## duriel (Oct 10, 2013)

28's & 100psi, you must be HEAVY. I run 90 in my 25's. with 28's I could run about 70.


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## ericm979 (Jun 26, 2005)

I run 85/90 in 23s for extra bumpy road races.


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## Silentfoe (Aug 22, 2009)

duriel said:


> 28's & 100psi, you must be HEAVY. I run 90 in my 25's. with 28's I could run about 70.


Thanks for calling me fat!  I'm 200.


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## Michael L (Dec 27, 2008)

Most important bit of advice found here- make sure the larger tire doesn't have a rub issue or harder to get on and off the frame (especially if the bike is older). I'm also 200 and recently went from 23s to 25s. The improvement is not major but worth doing. I run them at 95psi. The biggest advantage is psychological. When I'm going downhill I like the idea of just a little more rubber between me and the pavement.


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## DasBoost (Aug 15, 2013)

Silentfoe said:


> Thanks for calling me fat!  I'm 200.


Eh, I'm right there with you. For my 25 Gatorskins, I'm at 95-100F/105-110 rear and it's a pretty nice ride. I could probably drop the rears lower, but anything below 105 makes it feel like I'm starting to get a flat. :lol: For 28s, I'm at the max of the ThickSlicks (~85psi IIRC) and those with the steel frame feel like an old Cadillac. :thumbsup:


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## sbradleyhall (Sep 8, 2014)

Total newb here but I've got some experience under my belt now with this subject...
Just completed my first century this past weekend. 
I switched from 23's to 25's a week before the ride (new tires are the 25 Gatorskins) and I couldn't be happier that I did. 
Unexpectedly, 3 miles of the century route was in the process of being repaved and had been grated prior to resurfacing. At the absolute maximum speeds were only about 13mph through that section and I would have been miserable with the 23's that were on my bike. It was pretty bad as it was, even with the 25's. We had to hit that section twice so 6miles and I was never happier to see crappy shoulder debris on a paved road in my life.
Also, no flats *knocking on wood* so far. I am a big guy (but getting smaller) at 235lbs and 6' and I run the fronts at 100 and the rears at 120.


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## jkc (Jun 23, 2014)

I switch to 28s after during my third year of collegiate racing (some 25 years ago) and haven't look back. Here is some information on tire inflation. I still tend to over inflate the front than what's recommended (my floor pump su$% and just can't seem to leave the pressure that low, 60 psi front & 93 psi rear; I'm at ~100 psi even).

Optimal Tire Pressure for bicycles | Bike Tinker
Can I just have a bit more air in these tyres?
http://www.bikequarterly.com/images/TireDrop.pdf
https://docs.google.com/spreadsheet...idFp6OWpxRHpGdGVXbHQzYy1pX3BMVGc&hl=en#gid=20 (Copy of Imperial tab)
http://bit.ly/tiredemo


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