GingerPrince

I have just started riding and currently use 700x25 tires. I notice that a lot of people use 700x23. Some questions:

• What benefits would I gain from a switch? I assume that 23s would provide a little more speed but be a little bit harder to control whilst cornering etc? If it makes a difference, I am 6ft2 and 180 pounds (although will hopefully drop another 5 or 10 soon!)
• How much of a speed difference would they give me?
• If I did change, do all 700 tires fit on the same rims? Would I need new rims?

Fat Hack

If you haven't been riding for long you might not notice a big difference unless you buy something like Vredesteins (most of which are rated to 145psi), and pump them up pretty hard.

However, if you ride on 23s for a period of time, then go back to 25s, you would probably notice a greater difference.

Some would argue that a 23mm tire might give you better cornering at high speed. A big squishy tire, such as a 28mm, is a bit spongey for cornering at high speeds (in my opinion), so a 25 might still be a bit squishy. But if you go down to a 20mm, then you definitely lose cornering capabilities. Back when I used to race in the 1980s, 20mm tires were all the rage, and guys with these tires would often crash on fast corners during criteriums because of the lack on traction.

Most of the "science" is saying that a 22 or 23mm clincher (maybe a 21) is the fastest tire, so, theoretically you'll be getting a speed advantage, and I think most people on the forum would aggree, but you'll be losing some comfort. I'm not sure how you would quantify the speed advantage, but the smaller tire should feel a little bit quicker to you.

You don't have to buy new rims, however, it's obvious to me that the narrower the tire is, the tighter it is to mount. Some narrow tires seem impossible to get on, so I've started buying light/thin tubes just to make puting them on much easier

ManBearPig

My first bike came with 23s, which I got used to. I just bought another bike with very similar components, except that it came with 25s. I feel slower on this new bike, to the tune of about 1-1.5 mph. The tires feel softer and heavier. I don't know -- the speed reduction could be due to other things, such as geometry, or the fact that I didn't ride much for a few weeks while in the process of changing bikes. But I like the idea of training with a heavier, fatter tire so that I will feel lighter and faster when I want to put on the skinnier tire.

Chad's Colnago

Wider tires will exhibit more compression effect, than the narrower tires. For example, a 25 size tire has the potential to exhibit more compression effect than a 23. A 23 size tire has the potential to exhibit more pillar effect than a 25 size tire. What does this mean? This means a 25 size tire has the potential for absorbing effort more so than the 23 size tire. Remember road bikes are all about getting every little drop of effort to the rear wheel.

PainTrain

My tires are 700x35, Trek 7100 hybrid. Easiest place to get tubes only carries American sizes.

Can someone tell me the closest conversion, i.e. 27x1.25?

late

Hi,
you would also need higher pressure with a smaller tire; which usually leads to a harder ride. If you have to have that last MPH, the 23c is for you. But I greatly prefer the comfort of a medium sized tire at a medium pressure. Sheldon Brown of Harris Cyclery has a good chart for determining tire pressure at his website. I run a little softer than what his chart says.

F1_Fan

27 x 1 1/4 would do. Basically the 27" and 700C tubes are interchanagable as long as you match the width.

Be careful... 1 1/4 and 1.25 have slightly different meanings in terms of tube sizing. Crazy but true... the 1.25 is usually a designation for MTB tubes as in 26 x 1.25. Road tubes are done as fractions.

The difference in width between a 1.25 and a 1 1/4 is significant. Bicycle tire sizing is a crazy thing. When in doubt the best option is the ETRTO number on the tire (usually something like 23-622) which gives nominal tire width and rim diameter.

All you ever wanted to know about tire sizing is here:

https://www.sheldonbrown.com/tire_sizing.html

PainTrain

wow, OK, thanks, this is actually 1/4 and seems to work fine.