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  1. #1
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    New question here. 700x38 tires that aren't too thick

    Hi all,

    I just bought a set of fenders that would fit fine on my bicycle except the bolt above the rear wheel is too close to the wheel -- there's nothing I can do about it since the frame is designed poorly like that.

    It works fine but the clearance between the fender and tire is only about 1 mm.

    Now it's also about time for a tire change on my rear tire, and I was wondering if you all have any suggestions on a tire that isn't too fat, or else it won't clear!

  2. #2
    Fat-tired Roadie
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    Yeah.

    Road tires.

    700x38 is a size. You want thinner, try 700x35, 700x28, etc.
    "Don't buy upgrades; ride up grades." -Eddy Merckx

  3. #3
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    My concern is actually not about clearing on the side, but clearing above the tire. Clearing on the sides are fine since the fender is designed for this size, the only problem is the fender sits too close (almost pressed against) the wheel. It can't go further up since that piece of my frame is built that close to the wheel (without fenders, that bar would already have only 3-4mm clearance, with fenders only 1mm).

    So when I said less fat tire, I actually meant vertical fat, not horizontal fat

    (By the way, if I put a 700x35 tire in a rim meant for 700x38, won't it pop out when inflated?)
    (Excuse my ignorance, I haven't tried and don't have spare x35 tires lying around)

  4. #4
    Fat-tired Roadie
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    No.

    http://www.sheldonbrown.com/tire-sizing.html

    Unless you're looking at wildly different widths, the only important measurement is the bead seat diameter. That has to match on the rim and the tire for the tire to stay on. To my knowledge, all tires marketed as 700C or 29er have a 622 mm BSD. So while you might have trouble putting a 700x20 tire on a 21mm 29er rim, a small difference like 3mm is not a big deal.

    There are some ways you can get yourself into trouble. Read the link and you'll see what I mean. But there should be no problem with the swap you're asking about.
    "Don't buy upgrades; ride up grades." -Eddy Merckx

  5. #5
    weirdo
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    "Unless you're looking at wildly different widths, the only important measurement is the bead seat diameter."
    The only important measurement as far as the rim is concerned- you can still end up with a tire that doesn`t clear the rest of the bike. Just to be clear

    Yeah, Andrew is right about the widths. Some models might be a little bit lower in profile, but you aren`t going to find a big difference there. If the 38 is bordering on being too tall, I`d try a 35- there are lots of 35s available.

    Another thing to keep in mind (so that it stays confusing) is that different manufacturers don`t all measure their tires the same way, as Sheldon Brown explains in the link Andrew gave you. So, in theory, you COULD end up with a 35 that`s actually bigger than your 38, but that isn`t very likely. Also, don`t be too critical about the fact that your bike barely fits the 700 x 38 with fenders- that`s actually very good. Most bikes using 700c wheels would have you down to a much smaller tire. Codwater had to go through a lot of trouble just to get 32s to fit, and that was without fenders. Good luck with your tire decision and let us know how it goes for you.

  6. #6
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    ONLY IF you are pushing the limits of tire clearance do small effects on tire size matter.

    Tires can squat with miles and can get a mm or two shorter (beyond wear) and about the same wider. I suspect that is more in the thick walled tires as the thin walled ones balloon pretty well from new.

    The widest tire Sheldon recommeds for Deep Vees on one bike is slightly pinched ( an bit narrower but taller that they are on a slightly wider rim..

    The slightly narrow for the rim Michelin City 35 mm are about 2.5 mm shorter that specified and only about 0.5 mm wider. So a slightly wider rim seems to have made them squatter but I think they are slightly oval in cross section.

    The '32 mm' studded tires are actually 30 mm high and wide on the 19 mm rims but they have stiff nearly vertical sidewalls allowing lower pressures. They may balloon more with age.

    Note that a number of mfr's tire sizes are not 'true size'. Swalbe tires are often 2 mm or more smaller than listed. See rivbike.com for actual sizes on some rims of some of their lineup. Someone was compiling rim/tire size numbers for Swalbe tires I came across on a Google search, FYI.

    Mud clearance for some is important. Not for most commuters unless the bike is multi-purpose. It is suggested by some, to have about 1 cm of fender tire clearance at the brake bridge and fork crown to clear small stones and debris that might ride the tires to those points. This seems to be common on built up bikes aimed at commuters and for city or country bikes.

    The lawyers are right, there is risk with closer fender tolerances. Depends on the surfaces you ride and the debris you encounter. I got by with about 2.5 mm with some flintkote chips riding and scouring the inside of the fenders at crown and bridge. No jamb ups, though, other than fallen leaves which grind away until they clear through. I suspect larger tires and lower pressures helped get stone chips through So we are dealing with a risk. A rear jamb is a manageable slide but a sudden and firm front jamb-up is a likely OTB.

  7. #7
    weirdo
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    Quote Originally Posted by BrianMc
    Note that a number of mfr's tire sizes are not 'true size'. Swalbe tires are often 2 mm or more smaller than listed. See rivbike.com for actual sizes on some rims of some of their lineup.
    Hey, Brian- that information sounded pretty handy to me (I`ve often wished for it), so I went looking in Riv`s site. I DID find some juicy articles about tires and rims that I didn`t realize were there, but no tire/rim width combo listing. Do I misunderstand your post? If there is a reference for actual tire widths or diameters on his site, would you mind digging it up and linking it? Thanks.

    Oh, and if not, thanks for the convenient misdirection, anyway. I`m going right back there and read through those tire and rim articles to try and pick out the real world info from the whacko GPisms. Either way, it`s good- one way is good for entertainment value and the other way is good for cycling value

  8. #8
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    Thanks all for the suggestions! I'll do some shopping around online, probably for a 700x35 tire and report after I get it

  9. #9
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    Bontrager makes the Select k in 700x35. Fairly thin tread. No flats yet. They also make an inverted select- thick and heavy.

  10. #10
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    Quote Originally Posted by rodar y rodar
    that information sounded pretty handy to me (I`ve often wished for it), so I went looking in Riv`s site. ..... Do I misunderstand your post? If there is a reference for actual tire widths or diameters on his site, would you mind digging it up and linking it? Thanks.
    Rivendell's data is not tabular. THAT would be MUCH too easy! Since you appear to like their copy, you can enjoy even MORE of it by looking up each tire of interest under the purchase side of their interface, and reading their take on it! Bon Apetit!

    The other site I stumbled on googling something like 'Schwalbe tire size mounted rim size' it may be a few pages deep, I think it was a bike shop's blog. It WAS a table or listing some from the shop but they incuded a form to list your combinations for submission.

  11. #11
    weirdo
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    Thanks, Brian. Nothin easy in this world, eh? Well, there IS Papa Murphy`s Pizza.

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