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  1. #26
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    Quote Originally Posted by skhan007 View Post
    Are you guys stating I'm having too much pressure at 110 psi? I don't know any better and I was told this was the pressure. I'm 6'1" and about 163 lbs. What pressure would you suggest for 25mm and what pressure for 23 mm? Guidance is most appreciated!
    i'm about the same weight and ride at 90-95 front and 100 rear on 23s. go a little less on 25s.
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  2. #27
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    hairline ? I wonder what you call a proper cut then. Stop riding on that thing asap..

  3. #28
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    Quote Originally Posted by skhan007 View Post
    Are you guys stating I'm having too much pressure at 110 psi? I don't know any better and I was told this was the pressure. I'm 6'1" and about 163 lbs. What pressure would you suggest for 25mm and what pressure for 23 mm? Guidance is most appreciated!
    You were told old school thinking. Lower pressures give you a smoother ride and are actually faster. Rock hard tires are only faster on velodrome smooth surfaces.

    I'm about your weight. On 25's I run 65-70psi front and 80-85psi rear.
    On 23's I run 80psi front and 90-95psi rear.
    I never pinch flat.
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  4. #29
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    Replace that pronto, protisimo!!!! And throw it away if you don't want a catastrophic failure. Gp4000s have weak sidewalls. Seen it a lot of times.


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  5. #30
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    Quote Originally Posted by skhan007 View Post
    Hi Guys- I was out for a ride today and had a rear flat. When changing the inner tube, I noted that there was a hairline split on the sidewall of the rear tire (pic below). The inner tube suffered a puncture at this location. I put on my spare inner tube, pumped up to about 70% of my normal 110 PSI, noted that it was not bulging through too badly, and safely finished my ride back home.

    A couple of questions:

    1) Is the side wall hairline split something I can somehow fix (no ideas here, except I read that I could fold a dollar bill on the inner wall to prevent the inner tube from protruding).

    2) If replacing is required, I'm certain I should replace both front and rear tires. Any recommendations for brands/models? Current tires are Continental Grand Prix 4000 25 mm and I've got about 4500-5K miles on them thus far. I'd likely like to go back to 23mm, if replacement is recommended.

    Cheers!

    Attachment 319523
    Gp4000s are great tires. I use them myself for everything. Now they have some setbacks. The sidewalls are weaker than other tires. I used to run at 90psi 23s and I was destroying the sidewalls on the back. I'm 205lbs. I did some research and they recommend 110-120psi for the 23s. If you go 25 then you can do lower. 90-95psi.
    After a flat or running them at low air after a slow leak I usually have to toss them out or move it to the front. The problem is the same as with car tires and a flat. The rim border cuts into the tire and destroys the side wall. You will start noticing strands of thread falling and getting stuck in your hubs. What happens next is that the weak sidewall will separate when the bead meets the tire and you will have a catastrophic failure that will send you home walking. Happened to me 2 times after I learn my lesson.the tire was ran at low pressure because it was a slow puncture. So I didn't noticed after a while when I was probably at 60psi or so. Next ride I went out my front tire blew from under me. If I would have been going fast it would have been a messed up move.
    So when this happens you either move the tire to the front and risk getting a blown tire or throw it out. The key here is the amount of time you run at low psi. To prevent these things from happening I installed Mr tuffy light and my flats decreased significantly although the gp4000s are really good with flat protection. You start getting flats when they are worn out. Mr tuffy allows me to ride them a couple more months w/o flats.
    Good luck.


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  6. #31
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    Quote Originally Posted by charlitin View Post
    ...Next ride I went out my front tire blew from under me. If I would have been going fast it would have been a messed up move.
    So when this happens you either move the tire to the front and risk getting a blown tire or throw it out....
    I personally would never put a damaged tire on the front. A front blowout at speed can be a heck of a lot more risky to deal with than a rear blowout. You seem to even acknowledge that prior to recommending moving a damaged tire to the front. If a tire is unsafe to use as a rear tire, then time to toss it.

  7. #32
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    Quote Originally Posted by charlitin View Post
    After a flat or running them at low air after a slow leak I usually have to toss them out or move it to the front.
    So when this happens you either move the tire to the front and risk getting a blown tire or throw it out.
    This is terrible advice. Do not follow it.
    You never want a tire with known issues as your front tire. A blow out on the front can be extremely dangerous. Blowouts on the rear are much easier to maintain control of the bike.

    When a rear tire is no longer usable, dispose of it. Move the front tire to the rear. Install a new tire on the front.
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  8. #33
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    Quote Originally Posted by tlg View Post
    You were told old school thinking. Lower pressures give you a smoother ride and are actually faster. Rock hard tires are only faster on velodrome smooth surfaces.

    I'm about your weight. On 25's I run 65-70psi front and 80-85psi rear.
    On 23's I run 80psi front and 90-95psi rear.
    I never pinch flat.
    Similar weight, I run 100 psi in 25s. I have to handicap myself with "high pressure" slowness, else I'd get kicked out of my group rides for being too fast.

  9. #34
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    Quote Originally Posted by tlg View Post
    This is terrible advice. Do not follow it.
    You never want a tire with known issues as your front tire. A blow out on the front can be extremely dangerous. Blowouts on the rear are much easier to maintain control of the bike.

    When a rear tire is no longer usable, dispose of it. Move the front tire to the rear. Install a new tire on the front.
    You are correct. I'm giving him options. Didn't I explained that it was dangerous? Read te whole thing before picking on a particular part. If you leave the tire on the back due to the constant deflection it would blow up faster. Yes the tire on the front blowing up is a higher risk for control.
    The bottom line is that he needs to get rid of that tire. It is dangerous period and will leave him stranded.
    I explained what I used to do and what I learned. For 35-40 bucks is not worth it. Toss the tire and get a new one.


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  10. #35
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    Quote Originally Posted by charlitin View Post
    You are correct. I'm giving him options. Didn't I explained that it was dangerous? Read te whole thing before picking on a particular part.
    Meh. I did read the whole confusing paragraph.
    And yea.. I pointed out the dangerous part. As did RHankey too.

    If you know something is dangerous, you really shouldn't be offering that as "options".
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  11. #36
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    Quote Originally Posted by tlg View Post
    If you know something is dangerous, you really shouldn't be offering that as "options".
    This.
    “Statistics are like bikinis. What they reveal is suggestive, but what they conceal is vital.” -- Aaron Levenstein

    "Beware of geeks bearing formulas."
    -- Warren Buffett

    "Education is what you get when you read the fine print. Experience is what you get when you don't. -- Pete Seeger



  12. #37
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    Quote Originally Posted by tlg View Post
    Meh. I did read the whole confusing paragraph.
    And yea.. I pointed out the dangerous part. As did RHankey too.

    If you know something is dangerous, you really shouldn't be offering that as "options".
    Really?!?
    Hey don't join the army...you could get shot!
    Hey don't jump out of a plane skydiving...you could splat!!!!
    Hey don't go Mountain biking you are going to break your neck!

    Do I need to keep going with examples of dangerous things that people still do regardless. It Is called choice and the power to have it.


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  13. #38
    tlg
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    Quote Originally Posted by charlitin View Post
    Really?!?
    Hey don't join the army...you could get shot!
    Hey don't jump out of a plane skydiving...you could splat!!!!
    Hey don't go Mountain biking you are going to break your neck!

    Do I need to keep going with examples of dangerous things that people still do regardless. It Is called choice and the power to have it.
    Sorry you're all butthurt over this.

    But this is the wrenching forum of RBR. Generally people aren't coming here for bad advice on how to get hurt.
    If someone asks for advice on tires and you advise them to join the Army, it'll be pointed out as bad advice too.
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  14. #39
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    Quote Originally Posted by charlitin View Post
    Really?!?
    Hey don't join the army...you could get shot!
    Hey don't jump out of a plane skydiving...you could splat!!!!
    Hey don't go Mountain biking you are going to break your neck!

    Do I need to keep going with examples of dangerous things that people still do regardless. It Is called choice and the power to have it.


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    That doesn't mean you should be giving out dangerous advice. Weak analogies.
    “Statistics are like bikinis. What they reveal is suggestive, but what they conceal is vital.” -- Aaron Levenstein

    "Beware of geeks bearing formulas."
    -- Warren Buffett

    "Education is what you get when you read the fine print. Experience is what you get when you don't. -- Pete Seeger



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