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700X20..Alot diff.?(5 posts)

700X20..Alot diff.?James
May 23, 2001 12:23 AM
I just mounted a set of Vittoria 700X20 tires on my Vectors, Is there anything i should know about that small of a tire? My usual is conti GP 3000 700X23's. Anyone had problems with running 700X20's?
Pressure hypersensitivitybigdave
May 23, 2001 6:24 AM
All I can add is that I had some Conti GPs in 20s and if not at the recommended MAX pressure, they had a disturbing tendency to pinch flat. I had a marginal floor pump at the time, and if I couldn't get the pressures up to max (150 I believe) and only got it to 120-125, then pinch flats were a distinct probability. I went back to 23s, mainly for ease of use, but also because I don't think they're much slower if at all.

--Dave
Pressure hypersensitivityDINOSAUR
May 23, 2001 11:25 AM
The 23 is wider and you have more rubber on the ground. Depending on your body weight, 20's can pinch flat easier. Some guys run with 20's on the front and a 23 on the rear, as the rear is the tire that is prone to pinch flats. I run 23's on both and rear and I started to change my rim tape everytime I slapped on a new tire and I can't remember the last time I had a pinch flat. I also check my tire pressure before every ride. I think a lot of it depends on your body weight and the type of roads you ride. I guess like all of us, you have to experiment and see what works for you.
re: 700X20..Alot diff.?Steevo
May 23, 2001 10:45 AM
I have used 700-20's for years and never had any problems. It is true however, that you must be especially dilligent about maintaining the max. tire pressure.

The smaller size tires have smaller volumes of air inside and thus have greater loss in pressure with the same loss in air volume leaked out.
Higher Chance of Rim Damagegrz mnky
May 23, 2001 11:35 AM
You can do this even when at full pressure and may not even pinch flat. I used to run 20's and damaged some rims, but it really depends upon where you ride and your road surface.

I've also heard people make the statement that the more narrow tire has a smaller contact patch and thus doesn't tend to corner as well. However, I haven't seen any data on this.

Then there's always the slightly increased difficulty in getting a 20 on and off the rim. Not a show stopper, but just adds a little more insult to injury when you pinch flat.

I loved the feeling of a smaller lighter tire, but eventually felt it wasn't worth it unless you were doing a tri or time trial and the surface was clear.