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  1. #26
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    Quote Originally Posted by JSR View Post
    It wants me to inflate 23mm tires to 232 psi.
    Quote Originally Posted by kapusta View Post
    Unless you are 400 lbs, you are using it wrong.
    And if you weigh 400 lbs, you definitely should NOT be using 23mm tires.

    So let me repeat what I wrote in post #23. Pay close attention to the bold face:

    Here is a good starting point for tire pressure. Enter tire width and total weight of rider and bike into the 2nd box here:

    Bicycle tire pressure calculator

    As I said, a starting point. Most people use way more pressure in front than they need to.
    “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



  2. #27
    JSR
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    Oh. The 2nd box. Got it.

    I'm down to 195 lbs rider weight today. The calculator gives me f/r = 88/136 for 23mm. I'm intrigued with the theory that I use too much pressure in front. But 136 in the rear? Too radical for my brain.

  3. #28
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    Quote Originally Posted by oct3 View Post
    The back pain is normal to an extent: if you're trained for a certain distance/time, then doing more will tax the endurance of the back muscles.
    I've only experienced back pain on my bike once. I took my temperature then went to the clinic. I had a infection in an organ back there.
    I don't sit like anybody whizzing by in the wheelman club. I can go 4 hours without back pain, neck pain, only some gluteal pain and numb hands.
    Below 50 psi my front rim hits the back edge of potholes, so I keep pressure above that. I'm using 55 mm tires. I weigh 170. With 30 lb of lard around my middle, getting the bike weight below 40 lb seems silly to me. More bike miles!
    The OP might gain some benefit from less bike weight.
    Last edited by indianajo; 06-06-2017 at 07:05 AM.

  4. #29
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    Quote Originally Posted by JSR View Post
    Oh. The 2nd box. Got it.

    I'm down to 195 lbs rider weight today. The calculator gives me f/r = 88/136 for 23mm. I'm intrigued with the theory that I use too much pressure in front. But 136 in the rear? Too radical for my brain.
    As I said, it's a starting point. If your rear is coming up with 136 PSI, that's a good sign 23mm is too narrow for your weight and you should go to a 25mm if your bike frame will allow it.

    If you really want to keep the 23mm tires, I would start with 90 front/120 rear and adjust from there. If you start getting pinch flats in the rear, 23mm tires are definitely too narrow. Unless you ride a glass smooth velodrome, anything over 120 PSI will be a nightmare to your arse.
    “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



  5. #30
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    Quote Originally Posted by JSR View Post
    Oh. The 2nd box. Got it.

    I'm down to 195 lbs rider weight today. The calculator gives me f/r = 88/136 for 23mm. I'm intrigued with the theory that I use too much pressure in front. But 136 in the rear? Too radical for my brain.
    The first time I got turned on to the "15% drop" theory behind that calculator, I was 185 lbs and running 23s. Recommended pressure in the rear was higher than the max pressure listed for my tire.

    That was my first big clue that I was running tires that were too small.

  6. #31
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    So did you get one? Sounds like a trek 920 or 720 may fit the bill for your gravel/commuter needs. Nice and stable but still fun. It's a tank but fun. It does not care about crappy roads at all. Check it out, can't hurt.

  7. #32
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    Quote Originally Posted by indianajo View Post
    I've only experienced back pain on my bike once. I took my temperature then went to the clinic. I had a infection in an organ back there.
    I don't sit like anybody whizzing by in the wheelman club. I can go 4 hours without back pain, neck pain, only some gluteal pain and numb hands.
    Below 50 psi my front rim hits the back edge of potholes, so I keep pressure above that. I'm using 55 mm tires. I weigh 170. With 30 lb of lard around my middle, getting the bike weight below 40 lb seems silly to me. More bike miles!
    The OP might gain some benefit from less bike weight.
    My bike is pretty light as it is. It's a carbon frame, size 47cm, so it's pretty light. I get back pain regardless of whether I have the bike loaded up, or if it's free of everything (including rack). I can condition myself a bit and slowly work up to being able to go for longer without my lower back literally cramping up, but there comes a point where I just can't my back to be pain-free.

    Stop and go (routes with lots of lights or stop signs) puts a lot of strain on my lower back and kills me a lot faster. Gravel paths strain it faster too and I fatigue a lot sooner. Getting off the bike and standing up and letting my back ease out only works for as long as I'm off the bike--once I get back on and start riding, the burning and then cramping happens right away (unless I'm starting from completely fresh).

    I'm 29 years old, and my lower back muscles have bothered me like this since I was in high school. I do a lot of stretching, but that doesn't seem to help.

  8. #33
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    Quote Originally Posted by seventh77 View Post
    I'm 29 years old, and my lower back muscles have bothered me like this since I was in high school. I do a lot of stretching, but that doesn't seem to help.
    You would probably benefit from some core strengthening exercises. You may want to try doing some planks:

    https://www.youtube.com/results?sear...plank+exercise

    The stronger your core is, the less strain there will be on your back.
    “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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