25 or 28cc tyre?

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Dethagorf
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25 or 28cc tyre?

Postby Dethagorf » Fri May 17, 2019 11:40 am

Hello everyone, we want to buy tyre to our roadbikes do you recommend 25 or 28cc tyre to us?
We are not racing, we ride to enjoy.
Also we think buying the continental gatorskin? Is there anyone use it or should we look for anything else?

keef66
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Re: 25 or 28cc tyre?

Postby keef66 » Fri May 17, 2019 12:00 pm

If your frame will take them, choose the 28 mm tyre every time. Gatorskins have the reputation of being tough, but slippy in the wet.

Depends on what you want / how much you want to spend.

mamil314
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Re: 25 or 28cc tyre?

Postby mamil314 » Fri May 17, 2019 14:44 pm

Hello, your Highness. Would you kindly use the ******* search function. Thank you
28mm Durano

NitrousOxide
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Re: 25 or 28cc tyre?

Postby NitrousOxide » Fri May 17, 2019 15:38 pm

Wider for comfort, just be aware that tyre width sizing varies between manufacturers and even brands, for example 28mm Continental 4 Seasons and GP4000S IIs are ~29/31mm wide respectively in the real world.

Supposedly a tyre that meets the rim of the front tyre with less bulge has good aero benefits, so some might use a 25mm (or even 23mm in Conti GP40000S II case) up front and 28mm on the rear.
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plymouthsteve
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Re: 25 or 28cc tyre?

Postby plymouthsteve » Fri May 17, 2019 23:09 pm

28.
No question

Dethagorf
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Re: 25 or 28cc tyre?

Postby Dethagorf » Sat May 18, 2019 07:45 am

NitrousOxide wrote:Wider for comfort, just be aware that tyre width sizing varies between manufacturers and even brands, for example 28mm Continental 4 Seasons and GP4000S IIs are ~29/31mm wide respectively in the real world.

Supposedly a tyre that meets the rim of the front tyre with less bulge has good aero benefits, so some might use a 25mm (or even 23mm in Conti GP40000S II case) up front and 28mm on the rear.


I wasnt know that until that.
Our bikes are : KTM Strada 2000 (2015) and B'TWIN ULTRA 900 AF
I am not sure that I can use 28" with these bikes. What do you think?

Zest28
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Re: 25 or 28cc tyre?

Postby Zest28 » Wed May 22, 2019 08:43 am

As already mentioned, if you frame takes it, go for the 28mm.

keef66
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Re: 25 or 28cc tyre?

Postby keef66 » Wed May 22, 2019 09:03 am

Dethagorf wrote:
NitrousOxide wrote:Wider for comfort, just be aware that tyre width sizing varies between manufacturers and even brands, for example 28mm Continental 4 Seasons and GP4000S IIs are ~29/31mm wide respectively in the real world.

Supposedly a tyre that meets the rim of the front tyre with less bulge has good aero benefits, so some might use a 25mm (or even 23mm in Conti GP40000S II case) up front and 28mm on the rear.


I wasnt know that until that.
Our bikes are : KTM Strada 2000 (2015) and B'TWIN ULTRA 900 AF
I am not sure that I can use 28" with these bikes. What do you think?


Measure how much extra space you have around the 25mm tyre?

Under brake calipers
Under the fork crown
Inside seatstays
Inside chainstays

Think I'd want to have at least 5mm space round a 25 to comfortably run a 28mm tyre

plymouthsteve
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Re: 25 or 28cc tyre?

Postby plymouthsteve » Thu Aug 15, 2019 23:15 pm

At last someone has explained the science to me in a way that I can understand. . Hopefully it'll help you too..

The only part of the tyre that can affect momentum is the part that is in contact with the ground. On a 28c, there is more contact, so more momentum. Yes there is increased drag but. If drag from 1 inch of contact outweighs momentum from your 3ft legs then I'm afraid you are pretty weak.
You wouldn't expect an Olympic runner to wear trainers that have tread which is narrower than their feet.

thecycleclinic
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Re: 25 or 28cc tyre?

Postby thecycleclinic » Fri Aug 16, 2019 07:40 am

Some 25mm tyre size like 28's so actually it the real width and height your interested in on the rims you are using. Whats on the sidewall does not tell you how big the tyre will be. It turns out is just a number and if your clearance is tight a meaningless one.

The above post is using faulty physics. wider tyres are faster on rougher roads because you can run lower pressures/you have a bigger air cushion which result in slower vertical accelerations and and therefore less energy loss from the rider bike system. On smooth tarmac a narrower tyre is faster as vertical accelerations are not a problem and a narrower tyre can be run at higher pressures reducing rolling resistance and more importantly aerodynamic drag is lower. In the real world though you will struggle to notice a difference in speed between 25mm and 28mm tyres but the 28mm tyres are more comfortable on real roads and therefore overall are a tad faster.

Psuedo physics annoys me. I cant help correct it.
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Imposter
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Re: 25 or 28cc tyre?

Postby Imposter » Fri Aug 16, 2019 08:55 am

plymouthsteve wrote:At last someone has explained the science to me in a way that I can understand. . Hopefully it'll help you too..

The only part of the tyre that can affect momentum is the part that is in contact with the ground. On a 28c, there is more contact, so more momentum. Yes there is increased drag but. If drag from 1 inch of contact outweighs momentum from your 3ft legs then I'm afraid you are pretty weak.
You wouldn't expect an Olympic runner to wear trainers that have tread which is narrower than their feet.


Either they didn't do a very good job of explaining, or you must have misheard them...

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meursault
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Re: 25 or 28cc tyre?

Postby meursault » Sat Aug 17, 2019 01:43 am

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Def Defyr
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Re: 25 or 28cc tyre?

Postby Def Defyr » Sat Aug 17, 2019 07:39 am

It's funny how just 10-15 years ago you could buy 21 mm tires because they were "faster" than fat 23s...

I was a late convert to 25s, but they're just so much more comfortable -- and for me comfort equals a better, longer rider. I'd run 28s if I had the clearance on my old steel frame.

Simon E
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Re: 25 or 28cc tyre?

Postby Simon E » Sat Aug 17, 2019 08:11 am

keef66 wrote:If your frame will take them, choose the 28 mm tyre every time. Gatorskins have the reputation of being tough, but slippy in the wet.

Depends on what you want / how much you want to spend.

Agree on all 3 points. Schwalbe Durano and Michelin Endurance/Krylion get my vote.

I've gone from 25mm to 28mm Schwalbe Durano and there is a definite improvement in comfort. I run about 10 psi less now (50 F, 60 R, I weigh 60kg). May even try 32s next time...
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CookeeeMonster
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Re: 25 or 28cc tyre?

Postby CookeeeMonster » Sat Aug 17, 2019 10:27 am

Genuinely I find 28's harder work that 25's....but for the OP's question, 28 is the answer

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First Aspect
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Re: 25 or 28cc tyre?

Postby First Aspect » Sun Aug 18, 2019 08:37 am

plymouthsteve wrote:At last someone has explained the science to me in a way that I can understand. . Hopefully it'll help you too..

The only part of the tyre that can affect momentum is the part that is in contact with the ground. On a 28c, there is more contact, so more momentum. Yes there is increased drag but. If drag from 1 inch of contact outweighs momentum from your 3ft legs then I'm afraid you are pretty weak.
You wouldn't expect an Olympic runner to wear trainers that have tread which is narrower than their feet.
Conversation bots are much better than they used to be, but you can still tell this isn't a real person.

PhotoNic69
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Re: 25 or 28cc tyre?

Postby PhotoNic69 » Sun Aug 18, 2019 11:27 am

plymouthsteve wrote:At last someone has explained the science to me in a way that I can understand. . Hopefully it'll help you too..

The only part of the tyre that can affect momentum is the part that is in contact with the ground. On a 28c, there is more contact, so more momentum. Yes there is increased drag but. If drag from 1 inch of contact outweighs momentum from your 3ft legs then I'm afraid you are pretty weak.
You wouldn't expect an Olympic runner to wear trainers that have tread which is narrower than their feet.



WTAF????

mrobbie
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Re: 25 or 28cc tyre?

Postby mrobbie » Mon Aug 19, 2019 15:30 pm

I swapped 23 Bontrager tyres to 25 Continental GP4000 on my old Trek. My Cannondale came with Mavic 25 and I swapped them to 28 Continental 4000... on both occasions bigger was definitely better...

Going back to 25 while I experiment with Mavic UST in my new wheelset. Will see how that goes.
Quite addicted to cycling now....

neeb
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Re: 25 or 28cc tyre?

Postby neeb » Mon Aug 19, 2019 17:24 pm

It's amazing how these threads repeatedly spring up and always completely miss the point, which is that the answer COMPLETELY depends on your particular situation, most importantly 1) the surfaces you ride on most often, 2) your weight, 3) your priorities.

I still prefer 23mm, but the roads where I ride are above UK-average smoothness, I'm light, and I prioritise speed and ride feel over "comfort". While I can detect/appreciate the difference in comfort with wider tyres run at lower pressures it's a minor variable for me personally, I don't like the more sluggish road feel, and they are definitely not any faster.


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