1. The most important thing about buying a new bike is to make sure it fits. The only way you'll know if the bike is right for you is to size up the bike and make sure that the bike's geometry matches your body's geometry. Ask questions and do some research.
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2. If possible, try to find a shop that will let you demo the bike on real dirt. Five minutes in a parking lot won't cut it. You wouldn't buy a car without a real world test drive, and a bike should be no different.
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  1. #1
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    Tube Problem and True question

    I've noticed over the course of the last two weeks maybe that my front tire is a little low ( i always check before I ride) I'm on a trek marlin 29er with WTB tires. I usually ride the tires at 33-35psi and i noticed the front had been dipping down to 15ish and the back was fine. So after my ride the other night I came down to check on my bike, stored in the basement so a pretty consist temperature, and the front tire was completely flat. I can't find any puncture in the tube and nothing inside the tire I noticed. I pumped the tube back up out of the tire and couldn't find a leak at all but this has happened before and I knew it would lose air. I let it sit overnight and low and behold its flat in the morning but still enough air in it to hold its shape.

    I know its not a pinch flat because it would have pinched during my ride and there would be puncture and I wouldn't be able to reinflate it. Same with a thorn. I'm using schraders btw and they have been different tubes. This one in particular was a forte.

    This has happened to me at least two other times over the past year. Any idea what is going on? I thought maybe the valve stems had gone bad? I got a new pump recently incase my old one was damaging stems.

    might be time to bite the bullet and go tubeless

    Second Question.

    I think my front wheel is out of true but I wanted to make sure I understand exactly what that means. I've always just assumed it means the rim is uneven due to spoke tension. After removing the tube I put the bare rim back on the bike (on workstand of course) and spun the rim. Side to side the rim looks ok but it does seem like it lost its shape a little bit. Hard to explain but I think it might have a slight bulge top to bottom. I'm really at a loss for words on how to describe this but basically if i spun the rim and put something flat just above it as a point of reference it looks like the distance changes slightly.

    I'm rambling but I guess my question is can a wheel being out of true be the distance between the rim and the overall shape of the wheel?

    ps. Also when i had the bike suspended and lit the bare rim spin it always stopped with the same part of the rim ending at the bottom. So if the rim was coming to a stop and that are went past the bottom (6o'clock) it would spin itself backward until that part was resting at 6.

  2. #2
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    As far a the tube issue, IDK for it to be happening on multiple different tubes there must be something small inside the tire from a previous flat (run a shop rag inside the tire and feel for it to snag on something)or rim itself may have something puncturing the tube slightly.
    Yes a wheel can be out of round as you describe (sort of egg shaped) and may even have a flat spot from a spill or hard landing.
    The rim stopping at the same spot just means that is the heaviest spot on the wheel and gravity is doing its job. It doesn't take much at all to get the action you describe.

  3. #3
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    If your tire is losing pressure then there is a hole somewhere, and if it's losing pressure very slowly then the hole will be very small and hard to detect. Take the tube out of the tire, over-inflate it so it's nice and tight and submerge it in water- you will find the hole. It could also be the valve core leaking which can usually be fixed by tightening it, water will reveal that too.

    A perfectly true wheel is just that- no deviations side to side or up and down when you spin it, very few wheels are perfectly true. Minor flaws can be corrected with spoke tension, but having even spoke tension is more important.

  4. #4
    R.I.P. DogFriend
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    Be sure to inspect the rim tape too. Any exposed spoke holes or even bunched up rim tape are trouble.

  5. #5
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    Could be a bad valve on the tube too. Fill up the bathtub, air up the tube and hold it under water. You will find the leak.

    Take your rim to the bike shop and let them have a look for the trueness if it is in question.

  6. #6
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    I think there is a spot where the rim tape is slightly off. Never though of that being an issue.

    Thanks

  7. #7
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    About the trueness, check the wheel at the rim with the tire removed. It is possible, in fact very easy on my tubeless setup, for the tire to not be seated evenly all around, making it look untrue when in fact it is -- or more accurately the rim is true, but the tire is not. Spraying some soapwater on the bead before mounting it will help.

    You can true your rim using your bike and some zip ties for pointers (although a truing stand is money well-spent). Read up on truing -- it isn't that difficult. Just don't get anal about it --- a few mm off is OK.

  8. #8
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    I just took the wheel to a shop near my office (not a lbs I use regularly) and they replaced the rim tape and said the rim was so slightly out of true they didn't even want to take my money to do it.

    Should i use soapy water when applying the tire with tubes? I've seen it done in the stans video but its never occurred to me to do it regularly

  9. #9
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    Just fill up the sink or bathtub with clean water and submerge the tube that should allow you to find the leak. Some are a tiny stream of bubbles. Once you find the leak note its position with respect to the valve and go looking for anything that might re-puncture the tub after you patch it.

  10. #10
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    Bathtub worked. So now i have a question about patches. Is it best to put the patch on with the tube somewhat inflated? I would think if you tried to patch it when it was totally flat the patch would stretch when the tube was inflated?

  11. #11
    turtles make me hot
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    Quote Originally Posted by hankscorpio View Post
    Bathtub worked. So now i have a question about patches. Is it best to put the patch on with the tube somewhat inflated? I would think if you tried to patch it when it was totally flat the patch would stretch when the tube was inflated?
    Yes.
    I like turtles

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