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  1. #1
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    tire width vs. rim width

    Greetings,
    I just bought a beautiful pair of vintage Campy NR wheels with Mavic rims that I would love to run on an '84 Trek 520 touring bike I have, but I live in the Colorado Mtns. on dirt roads and I like to run 700c X 35 tires for both pavement & dirt. The inside diameter of the rims is 13.5 mm. (outside 19.5) The chart on Sheldon Browns site says that would be much too small a rim for this size of tire, but other sources like the Performance Bike site claim it would be no problem.
    Any thoughts out there on this subject?
    Thanks so much.....bumbliwa

  2. #2
    One Tough Cookie. Black Bud's Avatar
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    The concern with tire size v. rim width is based on the fact that a too-small rim and too wide a tire=stress on the side walls of the tire (because they splay out when inflated more than the designers likely allowed for) and poorer tire tread wear (too flat a contact patch, which also affects handling and may lead to a tire that is prone to flats). A too-narrow rim also creates the problem for the user who tries to mount the tire; it can be difficult to get the bead to seat properly when it has to be pinched too far inward to even fit inside the rim and can create problems with trying to fit a proper-sized tube in the tire.

    In short, you want to fit touring bike tires to your steed? You need wheels with a rim wide enough to handle them. If you don't or can't do that (the fork and stays are too narrow, for instance), you will have to make do the best you can with the widest tires you can find that also are designed fit the rims you have.

    No matter what the sales person (who wants to sell those wider tires!) might tell you "works".
    A bad day on the bike is better than a good day at work!!

    My discussion board, another resource for the "utility" and commuter cyclist: "Two Wheeled Commuter: The Everyday Cyclist"

  3. #3
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    Thanks so much Black Bud....I think I'll take your advice and err on the side of prudence in this case.....
    Bumbliwa

  4. #4
    Senior Member due ruote's Avatar
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  5. #5
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    You would have no problems with 28 mm wide tires, and 32s might work, but no way with 35s.

  6. #6
    Senior Member mechBgon's Avatar
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    Quote Originally Posted by AndrewP View Post
    You would have no problems with 28 mm wide tires, and 32s might work, but no way with 35s.
    Been there, done it, worked fine (Pasela 700 x 35 on Campy aero road-racing rims, to name one example). Heck, I used to run a variety of 1.7" to 2.2" mountain-bike tires on rims that narrow, namely the Matrix Mt. Aero, which used the same extrusion as the Matrix Aero II road-racing rim. Pundits notwithstanding, it worked fine.

  7. #7
    Senior Member Torchy McFlux's Avatar
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    As long as you don't inflate the tires to 100psi or something they should be fine.

  8. #8
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    Some people use whatever fits, but some people also don't care how their bike feels when riding it. For some, a bike is just a thing that moves when you pedal it, and for some it's a finely-tuned, responsive machine. A wide tire on a narrow racing rim is going to feel pretty mushy when cornering or descending on twisty roads. Even 28mm is pushing it as far as that goes, no matter what the websites and charts tell you.

  9. #9
    Senior Member mechBgon's Avatar
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    I guess we'll need to issue a recall on at least half of the world's nicer cyclocross bikes at this rate...

  10. #10
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    Greetings to one and all,
    Thanks so much for all of your input. I wound up consulting a local pundit with many years of experience who I respect (I found almost all young cycle nerds had no problem with large tires on small rims...I guess they grew up with mtn. bikes where a tire to rim width ratio of 2:1 is common) and he said he puts 700 x 32's on 20 mm rims for his customers all the time and it's no problem. So that's what I opted for...and keeping the tire pressure below 75 lbs. I realize that the cornering my be somewhat compromised on pavement but I have a Brooks saddle and a large leather saddlebag, as well as a rear rack and occasionally panniers, so this isn't exactly the lightest rig on the block, and I don't expect to be cornering or riding this particular steed at high speeds.
    thanks again!
    Bumbliwa

  11. #11
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    And by the way Black Bud, you were right, they were a pain in the ass to get on the rims.......

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