Fifty Plus (50+) - Tire question
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08-10-07, 09:01 AM
The rubber on my Miyata is pretty old. I intend to replace the tires ASAP. They are currently 700C28's. Would there be any real advantage/disadvantage to going with 700C25's? The ride is quite comfy with the 28's. Will it be harsher with 25"s?
08-10-07, 09:19 AM
The general rule of thumb is..the smaller the tire, the lower the air volumn will be and the less flexable the sidewall will be. This equates to less comfort. The other half of the "general" rule is...smaller is faster due to less rolling resistance (not always absolutely true) and less air drag.
Unless you are in a position to do an A-B comparison on the same bike you have to make some assumptions based on the general rules.
The link above has an interesting short analysis of rolling resistance and some possible myths in the paragraph about tire pressure.
08-10-07, 09:33 AM
I doubt you will notice a lot of difference for the same tire, but give it a try and find out. I have found that the make and model of the particular tire makes for more variation (i.e., Conti 2000 ultra vs. Specialized Armadillo, etc.).
08-10-07, 11:16 AM
A lot of the comfort issue also has to do with the amount of weight the tires are carrying. Someone weighing 130 lbs is going to be much less concerned with 25s vs. 28s than someone weighing 220 lbs. I hover around the 195 to 205 range. I have a touring bike with 28s, two road bikes with 23s and one road bike with 25s. The 25s seem just as comfortable to me as the 28s on all but the most rough road surfaces.
08-10-07, 11:31 AM
Maybe it's all in my head, but for most riding I prefer the 25s to 28s. Seems a little less cushy a little more speedy.
08-10-07, 12:22 PM
Don't think there will be a great deal of difference from a 28 to a 25 but down to a 23 and WOW. Get a Michelin or Conti in 23 and pump em up to 120 psi and ride. Rolling resistance wil be less, speed will be up but Comfort might be a bit lacking.
Or failing that- Just put 140 psi into the 28's.
08-10-07, 12:23 PM
Rivendell usually has interesting opinions on bicycle topics, and tires are no exception.
08-10-07, 08:04 PM
Thanks for the input everyone!
I wanted something with puncture resistance to replace the 18 yr old tires on the bike. An LBs had some Bontrager Race Lite Hardcase tires for $10 off. I went with the 25s. While not as smooth riding as the original tires I feel a lot better with the new rubber between me and the road. They are only a little harsher than the originals.
08-10-07, 08:37 PM
Now that I won't be influencing you, I can reveal that I just ordered a set of Continental Ultra Gatorskins in 700 x 25 for my Coda Elite, to replace the worn out in 1300 miles 700 x 28 Vittoria Zaffiros that came on it. From LBS for $30.00 each!!
08-10-07, 09:55 PM
The next time I need tires, I am going to look at the Armadillo 25/23[or23/25?] It has a 25 casing and 23 tread and the Armadillo flat resistance.
You asked this just to cause controversy on this forum didn't you?
I find 700x23's are worlds faster than the original equipment 28 inch x 1.25's on my Peugeot U08. I even noticed a speed difference vis 700x25's. Other's here have not.
Remember, though, and I don't think there would be any controversy over this point, that even with tires with the same published measurements, there are actual differences in the size. AND, even if they are the same size, some of the 'racing-type" tires are much faster than the all-weather or more puncture resistant tires.
Play around with several different types. In the big scheme of things, tires are not all that expensive.
08-11-07, 04:36 AM
Racing tire manufacturers tend to fudge the numbers slightly to gain the impression of additional performance over rivals. Racers tend to pay a lot of attention to weight and perceived rolling resistance. My favorite Kenda Kalliente Iron Cloak 23mm road tires are in no way as wide as most other 23's so because there is less tire there, they are lighter. Marketing or just another way to make a measurement......you make the call.
There are almost as many different tires out there as there are saddles. Everyone likes one of them.
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