I am replacing a tire that is 700x23c. The store only has a 700x25c in stock, and the guy tells me such a small change in width won’t matter.
Is he right, or just trying to sell me a tire?
This is for a 1999 Specialized Allez with original stock wheels.
Depends on the width of you wheels and frame, but that little difference should be fine. Might be able to to 28,
.
Brian
Not an expert
No problem, especially with those 1999 wide cantilevers.
The Allez is a road bike with side-pull caliper brakes, not cantilevers.
25mm will be fine with the rims and brakes. The only possible issue is if the frame doesn’t have clearance for 25mm at the fork, seatstays, and chainstays, which doesn’t seem terribly likely. But road bikes back then were all about the skinny tires, so I can’t be sure.
Ah, sure enough. I worked at a bike shop until about 1997 and road bikes were very much out of style at the time. ‘Hybrids’ that used the 700c rims were super popular, though.
I’m sure he’s right. It’s not much of a difference.
It doesn’t seem at all likely to me. 25mm is pretty much a standard size for road bikes. I bet the OP could go to 28mm, actually, if he/she wanted to. 32mm might be pushing it.
No issue. Even 32 is likely OK
Thanks for the help. I decided to order 700x23 tires from an Amazon seller, to be delivered tomorrow. My local shop sells them for $80; I ordered two for $100, free shipping.
By the way, just a piece of advice. Never mount your tires inside out.
He/him/his
Whenever I’ve bought new tires, I’ve just pointed to my bike and said “this size”, and the bike shop guy has never once felt the need to measure the width.
They are marked on the tyre so no need to measure. Plus to a practiced eye it’s pretty obvious because there are only a limited array of sizes.
A couple of times, the bike shop guy has double-checked the wheel diameter measurement (even though that’s also pretty obvious to a practiced eye), but even then, they never double-checked the width.
Your Local Bike Shop (LBS) is paying rent to be near you, has invested in tools & knowledge to do all sorts of repairs that you may not be able to do at home. While you unit price was cheaper you actually spent more total dollars for something you don’t need now & by not contributing to keep that LBS there, they may not be when you do need a repair that you can’t do.
I appreciate the lecture but there are some other factors not germane to the thread about why I chose not to patronize the shop I mentioned. Price was a factor but not the only one. I had a negative experience there and won’t be going back for tires, repair, or anything else.
There are at least three other bike shops in my area and what I wanted is not stocked at any of them. One could have ordered it (for $64) but it would have taken a week, and I had the tire on my bike by noon today instead of waiting a week.
Tangential to the OP…I think road bikes used to come stock with 23mm tires (my Allez Sport did in 2004), but I think most, if not all of them are now sold with 25mm tires stock (the new Specialized Allez line has 26mm). Somewhere in the last 10-15 years this switch was made - I guess most recreation/fitness riders were finding the ride is better with no real sacrifices by switching-up to 25mm (that’s my experience, FWIW). As long as your bike frame and fork can accommodate the slightly wider tire, why not?
A narrower tire will take a higher pressure, and a higher pressure means less rolling resistance. If you’re really serious about cycling, and you have good roads, that matters.
If you’re not so serious, then there are a lot of other factors that’ll be more significant.
Right Now, bicycle shops are having problems but lack of local customers is not one of them. If anything, they have too many customers, since there’s been a big surge in people wanting bikes during the pandemic. Their main problem is difficulty in getting new bikes, parts, and accessories from their suppliers. So even if someone wants to support their local bike shop, it’s often impossible to do so because that shop doesn’t have they need.
Personal example: I recently needed new cycling jerseys. There are three shops in this area, but two don’t carry cycling clothes. The other one apparently has not had a shipment of clothes is several months and their stock is really low. Most of what they have is either too large or too small. So I ended up amazoning[*] them which I really did not want to do. Not terribly efficient, since the four jerseys came in three different shipments.
[*] I’m sure I’m not the first person to verb “Amazon”, but I can’t recall seeing it done before.
That’s used to be cycling doctrine, but current thinking is that wider tires at lower pressures (still pretty high mind you) are actually lower in rolling resistance on real roads with imperfect surfaces. Pro racing is largely done on 25mm now, when it used to be all 21mm. This is because the slightly lower tire pressure results minor road imperfections being absorbed rather than transmitted into the frame. Or, it takes less energy for a pebble to deflect a tire than to push a bicycle frame upwards.
That’s what I thought, too. Someone on a bike forum provided this in response:
Well, Poertner knows his stuff (mostly). But Heine, in my opinion, is an unredeemed charlatan. His experimental methods would have mortified Aristotle. Like, it’s really bad.
Heine postulates unfalsifiable hypotheses and then challenges others to falsify them. It’s not subtle. It’s definitely not science.
I mean, it’s cargo cult science, but that’s not an improvement.
As far as I can tell, Heine has a Ph.D. in paleoclimatology. His father was a prominent paleoclimatologist, and while Heine published a few papers with his dad, he’s never held a research position—not even a postdoc—as far as I can tell.
People leave scientific academia for all sorts of legit reasons. They also leave because they’re not good at science. Heine expressly rejects a method called “virtual elevation,” AKA “the Chung method.” I do engineering simulation for a living, and the Chung method is solid. By “solid” I mean “the best research method available to cycling short of a low-speed wind tunnel.”
Heine, in my opinion, enjoys being a contrarian. He doesn’t enjoy physics or engineering. How could he? He’s never sincerely engaged in either, as far as I can tell.
But I don’t have an axe to grind. 
Possibly because there is only an 8mm difference between what are known as 700c and 27" wheels, which is not detectible by eye but is critical. Contrastingly, even if the bike shop guy got the width wrong, (and they aren’t going to get it very wrong) it wouldn’t really matter.