Tire size mixing okay?

Discussion in 'Cycling Equipment' started by Steve Sloan, Feb 20, 2003.

Thread Status:
Not open for further replies.
  1. Steve Sloan

    Steve Sloan Guest

    I have a bike I'd like to mix tire sizes on. I can't imagine why this would cause any problem at
    all. Here's what I want to do:

    I commute about 22 miles a day into downtown San Jose, CA. The transit agency, streets and traffic,
    sewer, power and telecom folks seem to be competing with each other trying to see who can tear up
    the streets the most! There are potholes and patches on patches. I cross six railroad tracks. I
    carry a computer, books in my panniers plus my weight (total about 250 lbs) over this, the roughest
    ride I do.

    I have broken 2 frames, so far, please see:

    http://homepage.mac.com/s_sloan/Show7/12.htm

    A couple of weeks ago I hit a pothole and bent a rim (and it was a stout rim!) The rim was a Mavic
    T220 with 36 14 straight gauge spokes and Top Touring 700x32 tires.

    I replaced the bent rim with a bigger Mavic 520 with 36 14 straight gauge spokes. I am thinking
    maybe if I increase the rear to 700 x 37 it will give me more of a cushion of air to protect my rim
    and frame and support the weight better. My front tire/rim are in fine shape and have less of a
    load. Is there a problem if I run a700 x 32 on the front with the bigger tire in the back?

    --Steve Sloan [email protected]
     
    Tags:


  2. Steve Sloan wrote:

    > I have a bike I'd like to mix tire sizes on. I can't imagine why this would cause any problem at
    > all. Here's what I want to do:
    >
    > I commute about 22 miles a day into downtown San Jose, CA. The transit agency, streets and
    > traffic, sewer, power and telecom folks seem to be competing with each other trying to see who can
    > tear up the streets the most! There are potholes and patches on patches. I cross six railroad
    > tracks. I carry a computer, books in my panniers plus my weight (total about 250 lbs) over this,
    > the roughest ride I do.
    >
    > A couple of weeks ago I hit a pothole and bent a rim (and it was a stout rim!) The rim was a Mavic
    > T220 with 36 14 straight gauge spokes and Top Touring 700x32 tires.
    >
    > I replaced the bent rim with a bigger Mavic 520 with 36 14 straight gauge spokes.

    It was a false economy to use the cheap spokes. You would have been better to spring for butted
    spokes--they're not that much more expensive, and result in a sturdier wheel.

    > I am thinking maybe if I increase the rear to 700 x 37 it will give me more of a cushion of air to
    > protect my rim and frame and support the weight better.

    That sounds like a good idea.

    > My front tire/rim are in fine shape and have less of a load. Is there a problem if I run a700 x 32
    > on the front with the bigger tire in the back?

    Nope. Theoretically it will raise the rear end of the bike by 2.5 mm, but that's insignificant.

    I address the issue of mixing tires on one of my Websites, see:

    http://sheldonbrown.com/tires.html#mixing

    Sheldon "Insert Nickname Here" Brown +-------------------------------------------------------------+
    | Is the only reason you are virtuous because that's your | ticket to heaven? Is the only reason
    | you don't beat your | children to death because you don't want to go to hell? | It seems to me
    | that it's insulting to human beings to | imply that only a system of rewards and punishments
    | can | keep you a decent human being. Isn't it conceivable that | a person wants to be a decent
    | human being because that | way he feels better? Because that way the world is better? | --Isaac
    | Asimov |
    +-------------------------------------------------------------+ Harris Cyclery, West Newton,
    Massachusetts Phone 617-244-9772 FAX 617-244-1041 http://harriscyclery.com Hard-to-find parts
    shipped Worldwide http://captainbike.com http://sheldonbrown.com
     
  3. Paul Kopit

    Paul Kopit Guest

    On Thu, 20 Feb 2003 10:56:19 -0800, "Steve Sloan" <[email protected]> wrote:

    >I replaced the bent rim with a bigger Mavic 520 with 36 14 straight gauge spokes. I am thinking
    >maybe if I increase the rear to 700 x 37 it will give me more of a cushion of air to protect my rim
    >and frame and support the weight better. My front tire/rim are in fine shape and have less of a
    >load. Is there a problem if I run a700 x 32 on the front with the bigger tire in the back?

    I don't think you'll have any problem unless the tire doesn't clear brakes or chainstays. I do it on
    the tandem all the time and frequently on singles.

    What's marked on the tires frequently doesn't mean much. My Panaracer Pasela 700x35 measures
    700x31. My 700x28 Specialized measures 700x32.

    If I were breaking stuff as much as you have, I'd consider a more rugged bicycle like a MTB with
    some suspension.
     
  4. David Ornee

    David Ornee Guest

    "Paul Kopit" <[email protected]> wrote in message
    news:[email protected]...
    > On Thu, 20 Feb 2003 10:56:19 -0800, "Steve Sloan" <[email protected]> wrote:
    >
    > >I replaced the bent rim with a bigger Mavic 520 with 36 14 straight gauge spokes. I am thinking
    > >maybe if I increase the rear to 700 x 37 it will
    give
    > >me more of a cushion of air to protect my rim and frame and support the weight better. My front
    > >tire/rim are in fine shape and have less of a
    load.
    > >Is there a problem if I run a700 x 32 on the front with the bigger tire
    in
    > >the back?
    >
    > I don't think you'll have any problem unless the tire doesn't clear brakes or chainstays. I do it
    > on the tandem all the time and frequently on singles.
    >
    > What's marked on the tires frequently doesn't mean much. My Panaracer Pasela 700x35 measures
    > 700x31. My 700x28 Specialized measures 700x32.
    >
    > If I were breaking stuff as much as you have, I'd consider a more rugged bicycle like a MTB with
    > some suspension.

    I agree with both Sheldon and Paul. I would add that a quality suspension seatpost and front rack
    with front low riding bags can help balance the load.

    David Ornee, Western Springs, IL (riding with potholes, RR tracks, and other road hazards)
     
  5. Jim Adney

    Jim Adney Guest

    On Thu, 20 Feb 2003 14:42:29 -0500 Sheldon Brown <[email protected]> wrote:

    >Steve Sloan wrote:

    >> My front tire/rim are in fine shape and have less of a load. Is there a problem if I run a700 x
    >> 32 on the front with the bigger tire in the back?
    >
    >Nope. Theoretically it will raise the rear end of the bike by 2.5 mm, but that's insignificant.

    Don't forget that the extra weight in the rear will remove at least some of this. He's actually more
    likely to come out level this way. Not that it matters at all....

    -
    -----------------------------------------------
    Jim Adney [email protected] Madison, WI 53711 USA
    -----------------------------------------------
     
Loading...
Thread Status:
Not open for further replies.
Loading...