41ants

Currently riding mich krylion 700x23 on my steel frame roadie and was wanting to move to a 700x25 tire. The move is to improve ride quality and I also just wanted to try a different tire than the krylions, so I was leaning towards the Conti GrandPrix4000s'.

I went to my LBS and asked to see what they had in 700x25, but learned from the gentleman working there they do not carry much in that size. He then asked me why would I want a tire that is just going to make me slower? What???? I explained to him that I was hoping that the tire would improve overall ride quality (I'm 6'1" 208 lbs currently). He then told me that I need to toughen up a bit and he chuckled a bit when he said that to me. I couldn't believe this statment was coming out of the mouth of a guy that had an obvious beer gut. Granted he was probably joking, but what about the 700x25 making me slower?

I thought I did enough due diligence on making the change....to improve quality of ride and possibly grip?

brian416

25c tires won't make you slower and will ride quite a bit nicer that 23c tires. The store probably stocked mostly 23s and wanted to sell you those rather than have to order tires.

RT

His response is more suited for the fare you would expect in this forum. Find another LBS.

Beaker

Not the best response in the world, but he's probably also making the point that the difference may be more subtle than you think. The speed difference comment is bogus though. Plenty of posts here actually claiming that 25s roll a little faster due to less deformation of the tire.

Bob Dopolina 

You're talking about deflection and it depends on whose tire you're talking about.

OP: You're a big guy. Go 25's but buy them from a different LBS.

caloso

https://www.wiggle.co.uk/continental-...paign=products

Biketiresdirect.com and probikekit.com seem to be out of stock on the 25mm size, but Wiggle has them. They're great tires and you'll feel like you're floating over bad pavement, especially with a nice 531 frame. (The guy at the LBS is an idiot, but you knew that.)

Beaker

Yup.

SoreFeet

You need to try to get a 28MM tire in your frame. If you can go 28 why bother with 25? More width really helps soak up the bumps.

41ants

I am golden with fitting a 28: https://salsacycles.com/bikes/la_raza/

hhnngg1

Going to 25cs make more of a difference than your fork, in my experience. It's like getting a front shock - pretty impressive how noticeable the smoothed out ride is.

I actually don't believe the hype that 25s are as fast as 23cs. You don't get something for free, ever. I immediately notice a slightly decreased acceleration and heaviness on climbing when I slap on a 25, and I'm not one for subtlety - it's very obvious. On flats, the inertia cancels the weight effect out, but there's definitely more rotating weight that is quite noticeable.

I was riding a Cervelo for 2 years only with 23cs, and I bought a Giant Defy3 that happened to come with 25c, but I had no idea, and assumed they were 23s. My first time on the bike, I immediately thought - 'wow, plush, smooth ride that's an incredible alloy fork!' but also "why does this feel 'clunky and a bit slow on the pickup?' Fortunately, I'm experienced enough to know that it wasn't the bike geometry or even the Sora groupset - and when I checked the tires, voila - 25cs. Rode them for 4 months, killed them, and swapped back to 23cs, and everything is as fast as I'm used to. Unfortunately, I didn't do any 25c vs 23cs time trials to test the actual times; for sure, the timed speed difference is probably marginal, but the difference in the feel on the acceleration is pretty dramatic for me.

I've seen that data on 25cs being as fast as 23cs, which might be true averaged over a typical ride, but the loss in pickup and acceleration is enough for me to avoid using them. I also am used to ridng a super-stiff Cervelo, so I feel disconnected with the 25s which absorb too much road vibration for my feedback.

FactVord

Snobbery and elitism at its best. The moment the LBS gentleman chose to ignore the empirical rule of "the customer is always right," he lost you as a potential sale. In hindsight, you did yourself right by finding a new LBS.

achoo

So, but you do believe the hype/groupthink that 23s are faster than 25s?

Cycling - the only wheeled sport in human history where there's a belief that narrower tires go faster. Even open-wheeled cars like F1 or Indy have big FAT tires sticking right out there in the 200+ mph wind.

bmulls

screw that guy, hit up another LBS. the difference between 23 and 25 is going to be subtle but you'll probably notice it if you ride a lot. Because of the riding pressure of 25's they do make for a slightly smoother ride and you also get away with less pinch flats (technically) though that means a little bit more rolling resistance. get the 25's.

datlas 

I have found more stupidity in my LBS than even on BF....I know, hard to believe.

You are a GREAT candidate for 25's. Get some from wiggle, PBK, or ribble. +1 for Conti GP4000s.

I am sticking with the 23's but I am a skinny-ass 142 pounds...if I weighed more than say 180 I would certainly go for 25's.

Fiery

Yeah, the traction demands on a bicycle tire are so similar to those used in car sports...'

Bikes are light enough and go slow enough that it's all about efficiency. So let's compare to other wheeled sports where it's all about efficiency, say supermileage competition...



Well, well, what do you know... They actually use narrow tires for some reason. Not all of them as narrow as road bicycle tires, but then they don't need the acceleration so rotational mass is not as important.

41ants

I don't know if this matters, but the 25's that I am looking at are not any heavier than the current 23's that I am riding. So hopefully that will help minimize going to the larger tire... No? And as far as finding a new LBS, I did.... Amazon.com and I didn't even have to leave my house.

jamesdak 

Well, I'm just a simple rider but I switched to 25c tires from 23C on two of my road bikes. Never saw any decrease in speed but did feel more comfort on my rides which are primarily of rough chip seal roads. Fact is I just set a PR today on my 53 mile route using the Madone 5.9 with GP 4000S 25 c tires mounted. Of course I only averaged a measly 19.6 mph for the ride so maybe a real rider that is so much faster would notice the difference.

hhnngg1

Dude - we have severely limited horsepower compared to a motorcar.

Fat tires are ABSOLUTELY slower on a bike - no contest. If you doubt this, get on a mtn bike with slicks and compare to a road bike in the upright similar body position on a flat. Get up to speed so the bike weight/acceleration isn't a factor, and just see if you can hold within 3mph on your mtn bike compared to the road bike. It's also not the suspension - touring rigs with wide tires and no suspension are also slower. It's even worse when talking acceleration, as well.

patentcad

They race on 25c tires in some of the spring classics in northern Europe. Anybody who makes a big deal about them slowing you down is utterly clueless.

Quote me on that when you talk to this imbecile again.

Vicelord

I find it hard to imagine 2CM would make a hell of a lot of difference.

Regardless, the guy sounds like a ******.

Beaker

How about 2mm?

FactVord

Insert sexual innuendo retort.

fordmanvt

I am 6' 200 pounds and have settled on a 23 in front and a 25 in back. Using the calculations Psimet posted previously, it puts me at the same pressure in each tire (110psi).

dahut

I went from 23's to 28's and never looked back. I didn't really notice a difference in speed, either. I reckon the trick is to pump them babies up to full pressure.

Now, if this thread is like most others, somebody will soon offer some exotic formula, showing how much speed you're losing. They'll figure out wattage and energy expended, factoring in the amount of tire contacting the road and so on. The end result? You may drop a tiny bit of speed - BFD

Its kinda relative, anyway.
You're not a TdF racer and I gather from your comments your not really in it for competition, anyway.
So "Ride It and Like It," that's my motto. If you don't have bugs in your teeth, you aren't trying hard enough to have fun.

As for the dude at the LBS. Well, the experience jibes with much of the 'boutique elite' crap I've both heard from others and which I get from my own area shops.
He wasn't listening to what you were really after - a more moderate ride.

Gonna turn down your money, so he could be right? Dayum! I guess it's true when people say bikes ARE overpriced. The guy has so much money - he don't need yours.

gregf83 

The difference in weight between 23 and 25mm tires is about 25g/tire or 50g for two tires. You might be feeling something but it's not a difference in acceleration. Any difference in acceleration would not be measurable.