Tire size
 

I know this has probably been asked on here before. I am thinking about buying new tires before my first century ride in september. My bike, Specialized Allez Sport, came with 25c tires. I asked one of my friends who has been riding longer and he seems to think that there is plenty of room for adjustment to run 28c tires if I took it to my LBS. Anyone have any experience with this transition??

Tire labels are sometimes Incorrect.

Try one and see.

Not quite sure what sort of "adjustment" your friend is talking about. You either have enough frame/fork/brake clearance for the wider tires or you don't. Rim width can make a small difference in the shape of the cross section of the tires, but changing wheels might would be an expensive proposition

Many bikes can run 28c tires. You'll only know if you try. It's not the width that's typically the problem. It's the height of the tire. It'll run close to the brake bridge in the rear.

On my specialized Secteur I normally use 25mm or 28mm tires. About 6 months ago I mounted a Specialized, I think they called it a Gripon, nominally 28mm. This tire is mounted in a Velocity A23 rim and measures 29.5mm and is noticibly bigger than a typical 28mm tire. It fits fine but that is the maximum tire that will fit with about 2-3 mm clearance each side. If you can't judge by eye how much larger of a tire will fit, fashion a wooden wedge and slide it in between the tire and frame and mark how far in goes. Then measure the wedge at that point. Likely left and right sides will be slightly different and but add the two sides together. My guess is a 28mmm tire will fit fine. With bigger tires you will be able to drop the pressure several pounds for a more comfy ride.

You are taking the bike to the LBS to change tires?

50 miles is a long walk if you can't repair your own punctures.

Worth considering IMO.

Look at how much room you have around the tire as it passes through different regions of the bike; brakes, rear brake bridge, chain stays, and so on. Every 1mm of added tire width will reduce each clearance by around half a millimeter. Note that there's a lot of slop in tire sizes, they can vary by a millimeter or two from manufacturing tolerances and whatnot, so if you don't have much room, you might need to mount a tire before you know if it'll work. I personally also like to leave at least a couple millimeters of clearance everywhere to be on the safe side.

BUT, also.

25->28 isn't that huge of a difference, and there are other ways to squeeze extra plush out of tires.
Even if you can't go to 28mm, you could try out a high-performance racing-style tire in 25mm. And if you do go to 28mm, make sure to not get a harsh-riding tire, because that could easily more than cancel out any gains you get from the added size.

Also crucial is selecting tire pressure well. Don't err high.

not your model but ... verdict here was affirmative


other threads of interest

https://www.cyclechat.net/threads/70...it-fit.147556/

http://forums.roadbikereview.com/spe...ld-352289.html

http://www.bikeforums.net/commuting/...zed-allez.html

http://forums.roadcyclinguk.com/show...cialized-Allez

https://www.******.com/r/Velo/commen..._conti_gp4kii/

I bought a specialized allez sport (I'm pretty sure that's the exact model) for my son, it's black and red, I can look up later exactly which year. But just two days ago I put a conti 700x28 ultra sport on the rear wheel for that and it fit fine. I ordered another, and expect no problems putting onto the front.

Do you "need" 28's to ride a century? I put 28's onto my bike and it's nicer, but I wouldn't say dramatically better than 25's. Maybe I have too much psi? When I ran the 25's it was not uncommon for me to pump up only when they had gotten down to 60psi; and they rode pretty good at 60psi. And more importantly, I did not flat on them.

I did find it annoying last night to have to let all the air out so I could pull the wheel to do some work. Ok on the rear, but if I had to pull the front on a regular basis (say to put the bike into a car) that might get old fast.

If the tire isn't kaput I'd err towards leaving as-is. If it's gone, or a known "poor rider" then sure why not try a 28. But I'd learn how to do tires at home. Then you can always switch around at will once you have the skill.

28 mm tires will probably fit. "Probably" means they might not.

The way to tell for sure is to test fit. Somebody already mentioned clearance to the seat stay bridge and chain stay bridge. Assuming you have caliper brakes, I'd check that clearance (with the QR open) too.

Tire sizes are nominal and can vary quite a bit from spec. If you see some tires you're interested in, Google around for user comments. Often users will say whether the tires seemed to run small or larger than nominal, fit problems with rims, etc.

Any particular reason you'd want to try larger tires? I'm asking because I just got my first road bike in 30+ years and was surprised to find the adjustment so easy from the 700x40 tires I run on my hybrids to the 700x23 shoes on the road bike. I really thought the skinny minnie tires would be a huge adjustment in terms of comfort and handling but so far, so good.

Yeah, I can feel the chip seal and striated concrete chatter more. But I've tried the tires at 80 psi to 110 psi and can't say I notice a huge difference. I weigh 165 so I'm not too worried about pinch flats at lower pressure. The tires are inexpensive Vittoria Zaffiro. Nothing special but I didn't want to spend much until I'd become re-accustomed to a lightweight drop bar bike.

Most of the comfort issues come from the handlebar/stem height, reach to rest on the hoods, etc. -- stuff that will come with experience and conditioning. And the bar tape is thin, no padding at all, so I'll probably get some padding to reduce vibration a bit -- after three rides this week my wrists are a bit achy.

But the tire size? Not a big deal overall, at least not what I'd expected.

Referring to adjusting the rim breaks. I know how to change a tire and tube

Comfort is not that big an issue for me. I'm more or less seeking opinions. I've done some reading about 28's having less rolling resistance due to having a wider contact surface with the ground. Just think that by the time the race comes around I might be looking at replacing the tires anyway. If not eventually...

IDK what good Opinions will do you , its your bike not mine..

I just fix things in front of me ..



Race bikes are not about comfort , you just make the other guy suffer more, trying to match your pace..





....

Yep, that's the main reason I might eventually consider wider tires after these 700x23 Vittoria Ziffiros wear out. By then I might be in good enough shape and adapted to the bike to get some good from better tires. These old Araya rims and narrow Suntour GPX brakes will probably limit me to 700x25, but that opens up some options.

Ain't THAT the truth!!!!

Not sure how that is harder than changing a tire... I mean, I think changing a tire is more physical labor than adjusting the brakes. Have you taken a look at various videos on youtube and/or looked at websites? Usually it's just a few minutes with some Allen keys to get them right. Worse case, you don't get the toe quite right, they squeal--and you then have to stop and adjust the toe slightly (depending upon what the setup is).

The rim size and width would not change, no need to adjust brakes. No idea why you would think that brake adjustments would be necessary when switching to wider tires