Mtbr's 2016 Winter Biking GearReviews and Roundups

FAT BIKES

WINTER APPAREL

TRAINERS

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  1. #1
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    Are my rims too narrow?

    Hi,

    I've flatted again, this time by cutting the side of my valve stem by the rim, probably during hard braking. I've figured out that I have to stop using the cheap Schräder-valve tubes and get something with a metal valve stem. Now I can either spend about 200 Kč ($8) on two tubes, or about $12 for a set of tubeless valves (I already have a bottle of cheap sealant and my rim tape looks like it could work, and if not, Gorilla tape is cheap) and go tubeless. However, there's a problem: I have 18 mm rims, can't afford wider ones, and I use a 2.35" Kenda Kadre on my front wheel and a 2.1" one on the rear wheel, inflated to 18-30/23-35 psi (F/R) depending on where I want to ride. I'm worried this could lead to burping at the low pressures, which is something I'd prefer to avoid.

    So, should I ditch the tubes or not?


    Also, does anyone have any experience with Joe's No Flats tubeless Schräder valves (I'd prefer those because my pressure gauge doesn't work on Prestas and the one on my floor pump sucks)?


    Thanks.

  2. #2
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    Reputation: J.B. Weld's Avatar
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    Old tires are the primary cause of broken valve stems IME, and I've seen plenty of presta valves cut at the base due to that as well.

    I'm not sure about the ghetto conversion, except that I know I wouldn't do it.

  3. #3
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    Mine was cut exactly at the point where it met the rim while being pushed against it by the tire. The tire is almost new.l

  4. #4
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    Old tires are the most common culprit but some rim/tire combinations result in loose fitting tires, which is what causes the problem you describe.

  5. #5
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    Go tubeless to save weight, re-invest your savings in tougher sidewall tires.
    I like Sand - I don't like Witches


  6. #6
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    I'm not going to buy new tires now because these are still usable (only a few hundred km on them) and I also have another pair ready to use. And they aren't super tight but also not super loose (like the Smart Sams on my other bike - I can remove those without even using a tire lever).

    So it should be possible?

  7. #7
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    If the tire slips on the rim and breaks the tube at the stem, just glue the tire bead to the rim. There are glues that dont't stick that hard, so you can still easily disassemble things later, just stopping the slips is the goal. It's an old BMX trick.

    2.35" tires could use a bit more inner width. I went from 19 to 21 mm inner width and that made all the difference I wanted: things work as they should even at 16/19 psi (F/R). I do run 19 mm rims with 2.3" tires on my JYD, but it's a street bike so pressures are around 30 psi and the Geax Tattoos I have on it are very stiff at the sides.

  8. #8
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    I'd not be running a 2.35" tyre on a 18mm rim, not internal width and if that's actually the external measurement, then that's just plain crazy. As has been said, the tyre rotating on the rim is what's causing the valve stem cuts and if you go to a steel stem it'll just tear as it moves further and puts too much strain on the valve. Tubeless is an option to help alleviate that, but again, as I said, wouldn't be risking that with such narrow rims and the fact that the tyre is rotating on the rim wouldn't most likely give a good seal, so you'd need to take Saul's advice and glue the tyre to the rim.
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  9. #9
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    The tires actually also say "56-584" and are indeed 56 mm wide, the rims are internal width. I'd like to switch to 25mm ZTRs in the future but now it's, sadly, far outside of my budget :-( The valve was NOT cut at the base (even though I've done that too, but that was at an even lower pressure), it was cut by the inside edge of the rim, like this:

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    I've now realized that it could actually be caused by me not being careful enough with the pump and pressing the valve stem against the rim while inflating the tube.

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