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Old 06-25-12, 01:07 PM   #1
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First 2 flat ride in decades.

I've frequently mentioned that I'm generally only prepared for one flat tire but, fortunately for me, I happened to have a patch kit in the BIG bag that I carry on the recumbent.

The second flat was really my own fault. I didn't find the tiny little rock that caused the first one so it got me twice. After the second flat I looked harder until I found it. I figured as long as I had to wait for the glue to dry I might as well patch both inner tubes and rebuild my inventory for the ride home.

Here's a question for you smart guys. Since I've started riding recumbents I've had 4 flats - all on the 20" front tires. Is that a coincidence or is it something to do with recumbents. I'm used to about 75% of flats being on the rear wheel.
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Old 06-25-12, 01:51 PM   #2
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That wheel- being smaller -does more revolutions per mile than the back one. More mileage= more flats.
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Old 06-25-12, 03:01 PM   #3
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It may just be a matter of weight distribution. I think there's more weight riding on the front wheel of a recumbent than there is on the stand-up bike's front wheel. My opinion is completely uninformed and unproven by scientific methods!
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Old 06-25-12, 03:05 PM   #4
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That wheel- being smaller -does more revolutions per mile than the back one. More mileage= more flats.
True ^^^^^^^^^^^^^^^^^
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Old 06-25-12, 03:34 PM   #5
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When you think about it, revolutions have nothing to do with it, unless the flat is caused by the wedged rock being repeatedly hammered into the tire. Otherwise, it's a case of contact patch area times the number of miles ridden, which remains the same no matter what diameter the wheel is.

One other possibility is the angular approach of tire to flat-inducing-agent. A wider tire will come down to the contact at a much slower gentler pace than will a smaller tire. As a reference, it would be the difference between pressing a nail into wood with your thumb, and hitting it with a hammer...
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Old 06-25-12, 03:37 PM   #6
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zx@x^*(> is the probable cause!
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Old 06-25-12, 03:43 PM   #7
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When you think about it, revolutions have nothing to do with it, unless the flat is caused by the wedged rock being repeatedly hammered into the tire. Otherwise, it's a case of contact patch area times the number of miles ridden, which remains the same no matter what diameter the wheel is.
The more revs in comparison to the rear- the more "mileage" each 1" of tyre will do. Hence more usage on the front wheel. And more "mileage" means more chance of picking something up.

But a combination of things- weight distribution- "Mileage"= not being able to see what the front will will hit- so many things that can affect it--But many years ago--when Karting-- The 4" front tyres wore out quicker than the 5" and were more prone to punctures aswell. Problem was they handles better so we used the 4".
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Old 06-25-12, 04:05 PM   #8
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The more revs in comparison to the rear- the more "mileage" each 1" of tyre will do. Hence more usage on the front wheel. And more "mileage" means more chance of picking something up.
Huh? I think both tires go the same distance, covering the same length of road. If you pick up a tack 10 miles into a ride, it doesn't matter how many rotations your tire made before picking it up. You had to travel that ten miles to reach the tack regardless of the tire diameter or number of rotations.
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Old 06-25-12, 07:12 PM   #9
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I had 2 flats this week on my almost new Trek that I bought in May this year. Yesterday I when to ride it and the front tire was flat. I expected to find a puncture in tire. That is not what I found. The tube had a small 1/8 inch cut next to a spoke nipple. The rim tape was not cut and looked good. I was puzzled but I went ahead and patched the tube. This morning I went to go for a ride and the tire was flat again. The tube had another cut near the same spoke nipple. This time I removed rim tape and I found that this new rim had a tool mark gouge in it next to the nipple and a bur on the edge of gouge. This bike is less than 2 months old, so this gouge in the rim came from the factory. I did not want to put 2 patches on this tube. So I took the rim, tire and tube to the Trek shop where I bought the bike. The bike mechanic looked at the gouge in the rim and told me that it did not cause the flat. He said the rim tape would have protected the tube. However, he offered me no explanation of what cut the tube twice. He put in a new tube and told me to let him know if I had and more trouble.
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Old 06-25-12, 07:46 PM   #10
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The bike mechanic looked at the gouge in the rim and told me that it did not cause the flat. He said the rim tape would have protected the tube. However, he offered me no explanation of what cut the tube twice. He put in a new tube and told me to let him know if I had and more trouble.
What kind of rim strip?

I'm not big on those stretchy plastic bands. All too often they're on the too narrow side. If they slip over to one side and expose even the tiniest little crescent of spoke hole, you'll get repeated flats until you resolve the issue.
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Old 06-25-12, 08:08 PM   #11
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What kind of rim strip?

I'm not big on those stretchy plastic bands. All too often they're on the too narrow side. If they slip over to one side and expose even the tiniest little crescent of spoke hole, you'll get repeated flats until you resolve the issue.
Plastic band is exactly what this rim has. I even took a picture of it for my own record. One picture is the rim tape and the other is the gouge I was talking about.


Attached Images
File Type: jpg Rim tape03.jpg (85.5 KB, 8 views)
File Type: jpg Nipple rim damage New.jpg (85.8 KB, 9 views)
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Old 06-26-12, 06:40 AM   #12
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The 20" tyre/wheel has a smaller diameter and actually travels less distance than the rear wheel . Do the math, it will show you. Just think of your gears and the different sizes and how they work, your cadence has to change to get the different inch gears to work out and the different inch gears work because of their different diameters.

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Last edited by qcpmsame; 06-26-12 at 01:31 PM. Reason: Incorrect information on my part. My apologies.
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Old 06-26-12, 07:10 AM   #13
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The 20" tyre/wheel has a smaller diameter and actually travels faster than the rear wheel as well as traveling further. Do the math, it will show you. Just think of your gears and the different sizes and how they work, your cadence has to change to get the different inch gears to work out and the different inch gears work because of their different diameters.
Don't you mean "more revolutions" for the same speed and distance?

More revolutions mean the tire, assuming everything else is equal, should wear out sooner. Thinner tires also definitely puncture more easily. I don't think that's a factor yet on my bikes because the tires don't have a lot of miles on them.

On the other hand, rear tires on a DF road bike, for whatever reason, wear out roughly twice as fast as fronts. following the same reasoning, you'd expect rears to have more punctures which they do.

Maybe I need to find a helper and a couple of bathroom scales so I can check the F/R weight distribution of my SWB recumbent vs. a conventional road bike. Seems like a lot of trouble just to satisfy my curiosity. I wonder if any LWB recumbent riders have experienced the same F/R flat tire ratio.
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Old 06-26-12, 01:33 PM   #14
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RG,
I edited my post because part of what I said was actually backwards. My bad, I was in a hurry to make a doctor's appointment this morning. A smaller diameter tire covers less distance with a revolution than a larger diameter tire will in the one revolution and has to do more turning to cover the same distance is what I should have said. So what you said in you last post is correct.

Are the front tires on a recumbent wider than the rear? I have no idea what size or width they use. As to the weight bias I have no idea but from looking at a 'Bent I'd think the weight was rear concentrated with the seat back there. However the frame and crank being forward I am not in any way sure. Never weighed one and don't know how much they even weigh.
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