Tires Tire help needed badly!!!!

Discussion in 'Bicycle Repair' started by HGaither, Apr 27, 2008.

  1. HGaither

    HGaither New Member

    OK I give up, I have searched and searched but got no answers. I need a rear tire to work with my friction drive Honda engine that will last more than an hour. I know I need a kevlar one but which kevlar one?
     

  2. WELCOME! Please introduce yourself in our introduce yourself forum.
    What bike? What size tire? These are questions we need to know.
     
  3. HGaither

    HGaither New Member

    Tire size is a 26 by 2.125, bike is a Hermosa, looks kinda like a Schwin.
     
  4. Where are you located? Are you near a Wal Mart? They have Kelvar tires pretty cheap too.
     
  5. HGaither

    HGaither New Member

    I live about three miles from a Wal-Mart but I just assumed that they would not have kevlar tires , I'll give them a try.
     
  6. They have them all wrapped up funny like it's on a roll. But it unrolls pretty well.
     
  7. loquin

    loquin Active Member

    Kevlar's not going to help tread life much. It'll help against flats, but not tread life. (I bought one of those wally world kevlar cruiser tires for the front wheel on my bike but haven;t installed it yet - I'm waiting for the original to get worn out...)

    NOTE: ANY tire should last longer than an hour. I got about a thousand miles out of the original tire on my bike. I would guess that you have your friction drive either misaligned, or not pressing down on the tire enough to get good friction between the roller and the tire.

    The friction roller MUST be at 90 degrees to the tire, when viewed from the top (critical,) and from the rear (not so critical.) Any misalignment will reduce the tire life. And, the greater the misalignment, the greater the tire wear.

    Now. As far as pressure. Your rear tire should be (if it's a standard cruiser tire) at about 50 psi. Then, lock the roller down when it deflects the rear tire enough to avoid slippage when driving. I put my weight into the frame when locking. Probably around 50 pounds of force. The trick is to have enough tire surface in contact with the roller to avoid just grinding the rubber away. For a starting point, I would go for a center of tire deflection of a quarter of an inch, or maybe a bit more. Make a point of noting the deflection each time, and the pressure, until you get a good feel for it. And, every time you change the tire, check it again a few times.

    Finally. When driving and the tire gets wet - let up on the gas if you hear or feel the tire slipping. If you keep revving the motor, you'll wear a hole in the tire.

    BTW - I just put an Innova Swiftor 26x2.0 on my Staton friction drive cruiser, and I'm VERY happy with it so far. With the almost slick inverted tread, it's a MUCH smoother ride, as the roller vibration is completely gone. And the rolling friction is quite a bit less - I'm noticing between 1 & 2 MPH higher top end.
     
    Last edited: Apr 28, 2008
  8. HGaither

    HGaither New Member

    Hey thanks for the info all.
     
  9. Zev0

    Zev0 Member

    I have a giant mtn bike with a robin/subaru friction drive with the original tires on the bike. I now have over 600 miles on it with the friction drive and over 2400 miles total and the tire hardly looks worn at all. I can't say the same for the roller tho. It's really getting worn.
     
    Last edited: Apr 28, 2008
  10. fetor56

    fetor56 Guest

    Cog shape.

    To my way of thinking it also helps if u have the drive cog concave for max surface area against the tyre.
    P1010012.JPG
     
    Last edited by a moderator: Apr 29, 2008
  11. Esteban

    Esteban Active Member

    You are doing something VERY wrong. My tires last a very long time & they are only $10 each.
     
  12. HGaither

    HGaither New Member

    I ordered some inova swifters last night and when I get them on I'm going to redo the tension. I thought I was in spec but obviously not.
     
  13. loquin

    loquin Active Member

    Nope.

    If the roller is concave, the narrow part has a lower linear speed then the wider part.

    Think about it. The roller has the same RPM at all points.

    For each rotation of the roller, the speed of a point on the circumference determines how fast your bike will move, and the distance that the bike moves in that one revolution is the length of the circumference of the roller. The length of the circumference is pi * the diameter.

    But, with a concave roller... which diameter???

    Lets assume 7000 RPM and a concave roller, 1 inch diameter at the narrowest point, and 1.25 inch in diameter at the widest point, and pressed down so that the full range of diameter is in contact with the tire.

    The small circumference of the roller is 3.14 inches, the large portion circumference is 3.93 inches.

    7000 RPM times 3.14 inches is 21,980 inches per minute, or 20.8 MPH for the narrow part of the roller,
    but, with the same RPM...
    7000 RPM times 3.93 inches is 27,510 inches per minute, or 26.1 MPH for the large part of the roller...

    Your concave roller is trying to make the outer part of the tire spin over 5 miles an hour FASTER then the crown of the tire!

    The tire is going to wear out quite a bit faster if there's that kind of difference in speed between the two portions of the roller - there will be a LOT of slippage, resulting in a lot of friction, a lot of heat, and a lot of wear, not to mention wasted fuel. Essentially, that roller will be grinding on the tire, all the time.

    If you get better friction at the crown, the shoulders of the tire will wear out faster; if you get better friction at the shoulders, you're crown will wear out faster.
     
    Last edited: Apr 29, 2008
  14. loquin

    loquin Active Member

    Also, make sure that the roller is aligned per the attached diagram...
     

    Attached Files:

  15. loquin

    loquin Active Member

    Heads-up re the Innova Swiftor tire...

    I really like the tire - it grips very well, and is really a smooth ride. However, it's made from a very soft rubber compound. Because if this, if you skid the tire, the asphalt or concrete WILL grind the tire flat in spots. I had an emergency stop last week, and the road ground right through to the fabric!

    FYI: A plastic water bottle, cut into a couple of "U" shaped sections three inches long or so, will make a temporary 'liner' to keep your patched tube from blowing out again at the same spot.
     
  16. Esteban

    Esteban Active Member

    A few tips on friction drive. They WILL eat a tire if you are not operating them correctly. NEVER,, over-rev engine,,, over-rev when tire/roller is wet,,, rev while sitting still ,,, start from a stop using only motor,,,apply full throttle quickly. Always gradually accelerate. I always have to change tires because of dry-rot.
     
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