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  1. #1
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    Using Rain-X on carbon wheels

    Hello, Guys. I hope you're doing well and I thank you for any assistance you can provide.

    I recently got into road cycling (I ride MTBs with disc brakes), and I couldn't get an aero bike with disc brakes locally. My first experience trying to brake in the rain was terrible. Is it safe and effective to apply something like Rain-X to carbon wheels? I'd expect this to help the wheels repel water and give me better braking power, but I fear it could damage the carbon's composition or reduce friction.

    Have an awesome day!

  2. #2
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    No. It's not safe.

    If you ride in the rain, maybe you should use aluminum rims.

    Or maybe get a normal road bike with disc brakes.
    use a torque wrench

  3. #3
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    Thank you for your comments, MMsRepBike! I'll try to save up for some aluminum wheels, then. Buying a bike with disc brakes would not be possible for me right now, but it's definitely going to be a consideration for the next one.

  4. #4
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    For now, if in the rain with carbon rims, you'll have to brake quite early.

    It will take the brake pads a few revolutions to clear the water from the wheels before they begin to bite in. Have to plan for that.
    use a torque wrench

  5. #5
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    Thank you for the advice! I'll do my best to keep that in mind, and I'll also be riding at lower speeds.

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  6. #6
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    Quote Originally Posted by Renzo7 View Post
    Hello, Guys. I hope you're doing well and I thank you for any assistance you can provide.

    I recently got into road cycling (I ride MTBs with disc brakes), and I couldn't get an aero bike with disc brakes locally. My first experience trying to brake in the rain was terrible. Is it safe and effective to apply something like Rain-X to carbon wheels? I'd expect this to help the wheels repel water and give me better braking power, but I fear it could damage the carbon's composition or reduce friction.

    Have an awesome day!
    Wait...read your post again. How do those 2 things make any sense at all?
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  7. #7
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    Quote Originally Posted by cxwrench View Post
    Wait...read your post again. How do those 2 things make any sense at all?
    Which two things are you referring to, cxwrench? Edit: just noticed the two parts in bold. I hope the explanation I'd written helps clear it up.

    My thoughts were that either:

    1. Rain-X will help the water into beads and off the wheel with the centrifugal force, allowing it to start off drier and dry faster when braking. A dry track will have higher friction, so it will brake better.

    Or

    2. Rain-X, being silicone - based (if I'm not mistaken) will create a surface that's too slippery and will reduce the friction between the track and pads regardless of whether or not the wheels are wet. This would be a recipe for disaster.

    I was also wondering if the chemicals in Rain-X could interact negatively with the carbon wheels, reducing their hardness, ruining the resin, or any other harmful effect. This would also be something that I want to avoid.

    Does this explain what I meant more clearly? I had lots of ideas on possible consequences and wanted to know if anyone could point me in the right direction.

    If I'm still not getting my point across, I'd appreciate it if you could help me understand what isn't clear, or what's contradicting.

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  8. #8
    'brifter' is a lame word.
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    You wrote, and I'll quote...

    "I'd expect this to help the wheels repel water and give me better braking power, but I fear it could damage the carbon's composition or reduce friction.

    You're expecting to get better braking power while at the same time fearing you'll have reduced friction. You can't have both...braking power and friction the way you're talking about them are the same thing.

    I'm not how anyone could reasonably expect something that works like Rain-X to do anything but pretty much destroy the braking performance of anything it's applied to. It's like a polish or wax...it makes the surface slippery. Not going to help you slow down.

    The only good thing is that there isn't a chance it would damage your rims in any way.
    I work for some bike racers
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  9. #9
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    Quote Originally Posted by cxwrench View Post
    You wrote, and I'll quote...

    "I'd expect this to help the wheels repel water and give me better braking power, but I fear it could damage the carbon's composition or reduce friction.

    You're expecting to get better braking power while at the same time fearing you'll have reduced friction. You can't have both...braking power and friction the way you're talking about them are the same thing.

    I'm not how anyone could reasonably expect something that works like Rain-X to do anything but pretty much destroy the braking performance of anything it's applied to. It's like a polish or wax...it makes the surface slippery. Not going to help you slow down.

    The only good thing is that there isn't a chance it would damage your rims in any way.
    Thank you for your insight, cxwrench! I see how my statement was confusing.

    Have a nice rest of the weekend 👍

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  10. #10
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    Quote Originally Posted by cxwrench View Post
    You wrote, and I'll quote...

    "I'd expect this to help the wheels repel water and give me better braking power, but I fear it could damage the carbon's composition or reduce friction.

    You're expecting to get better braking power while at the same time fearing you'll have reduced friction. You can't have both...braking power and friction the way you're talking about them are the same thing.

    .

    WTF dude. It's perfectly reasonable and logical to expect one thing to happen but fear another 'could' happen.

    You'd think on a site dedicated to riding bikes on roads with cars of all places that would be fairly obvious.

  11. #11
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    Quote Originally Posted by Jay Strongbow View Post
    WTF dude. It's perfectly reasonable and logical to expect one thing to happen but fear another 'could' happen.

    You'd think on a site dedicated to riding bikes on roads with cars of all places that would be fairly obvious.
    Thanks for your comment, Jay. I thought the same thing thing you did.

    It's like when we post on forums, expecting to find people who will be understanding and helpful, but fearing we may find a troll or a bully.

    Still, it was a risk worth taking, and I got some answers

    Have a great week!

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  12. #12
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    I would err on the safe side and say that no chemicals or additives should be put on any braking surface. On my aluminum rims, I will clean them with soapy water and a nylon brush, rinse thoroughly, dry immediately, and sometimes even swab the rims with alcohol to remove any possible contaminants. I also check my brake pads for any debris and will take a fine grit sandpaper to them to remove any glazing or surface contaminants on the pads. I've always had good braking and have never had a reason to change how I do things. Anybody have another way of ensuring optimal braking performance?

  13. #13
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    Quote Originally Posted by TDFbound View Post
    I would err on the safe side and say that no chemicals or additives should be put on any braking surface. On my aluminum rims, I will clean them with soapy water and a nylon brush, rinse thoroughly, dry immediately, and sometimes even swab the rims with alcohol to remove any possible contaminants. I also check my brake pads for any debris and will take a fine grit sandpaper to them to remove any glazing or surface contaminants on the pads. I've always had good braking and have never had a reason to change how I do things. Anybody have another way of ensuring optimal braking performance?
    Thank you for your response and for sharing your maintenance tips with us, TDFbound! That sounds like a thorough and effective procedure.

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  14. #14
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    FWIW, Rain-X will make water bead, just like if you applied grease to your windshield, so I would assume this would classify Rain-X as a lubricant. Therefore, applying it would make as little sense as that guy a month or so ago who applied WD-40 to his discs (thereby ruining his pads..), albeit not quite as dumb a move.

    CF is hardly the best material for wheels in the rain, between having poor stopping power, and the possibility of the fibers getting water-logged and delaminating, possibly leading to an "asplosion".
    I'm upping my standards;
    Up yours!

  15. #15
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    Quote Originally Posted by No Time Toulouse View Post
    FWIW, Rain-X will make water bead, just like if you applied grease to your windshield, so I would assume this would classify Rain-X as a lubricant. Therefore, applying it would make as little sense as that guy a month or so ago who applied WD-40 to his discs (thereby ruining his pads..), albeit not quite as dumb a move.

    CF is hardly the best material for wheels in the rain, between having poor stopping power, and the possibility of the fibers getting water-logged and delaminating, possibly leading to an "asplosion".
    Thank you for your contribution, No Time Toulouse.

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  16. #16
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    Quote Originally Posted by No Time Toulouse View Post
    the possibility of the fibers getting water-logged and delaminating, possibly leading to an "asplosion".
    Yeah, that's not a thing.

  17. #17
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    I wouldn't ride carbon in the rain, go to a bike shop and see if they have any wheels they got off a new bike at discount, maybe the place you got your bike from.
    BANNED

  18. #18
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    Quote Originally Posted by duriel View Post
    I wouldn't ride carbon in the rain, go to a bike shop and see if they have any wheels they got off a new bike at discount, maybe the place you got your bike from.
    Thank you for the advice, Duriel. I'll be on the lookout for some aluminum wheels 👍

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  19. #19
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    Quote Originally Posted by cobra_kai View Post
    Yeah, that's not a thing.
    Well it's on the internet now, so it's basically true.

  20. #20
    'brifter' is a lame word.
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    Quote Originally Posted by Renzo7 View Post
    Thank you for your response and for sharing your maintenance tips with us, TDFbound! That sounds like a thorough and effective procedure.

    Sent from my SM-G900M using Tapatalk
    His advice sounds good to me. If you have any brake pad residue that won't come off w/ soap, and won't come off w/ alcolhol, you can always use lacquer thinner. It's what we normally use to remove any excess tubular glue and it seems to work well on those black streaks of pad material that sometimes get deposited on rims. Won't hurt cured carbon at all.
    I work for some bike racers
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  21. #21
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    Quote Originally Posted by cxwrench View Post
    His advice sounds good to me. If you have any brake pad residue that won't come off w/ soap, and won't come off w/ alcolhol, you can always use lacquer thinner. It's what we normally use to remove any excess tubular glue and it seems to work well on those black streaks of pad material that sometimes get deposited on rims. Won't hurt cured carbon at all.
    Thanks, man. At this time I'm having no issues, but I'll keep this in mind if I ever see these symptoms 👍

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  22. #22
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    Quote Originally Posted by No Time Toulouse View Post
    CF is hardly the best material for wheels in the rain, between having poor stopping power, and the possibility of the fibers getting water-logged and delaminating, possibly leading to an "asplosion".
    I hate when that happens.
    In reference to the Assault on Mt Mitchell...
    Quote Originally Posted by merckx56
    The easier solution is to find a biker bar in Spartanburg the night before, go in and pick a fight. The ass-whipping you'll get will be far less painful than the one Mitchell will give you the next day!

  23. #23
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    I suggest just buying a fork and front wheel with disc brake. The front brake does about 70% of the work anyway.

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