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Bicycle Mechanics Broken bottom bracket? Tacoed wheel? If you're having problems with your bicycle, or just need help fixing a flat, drop in here for the latest on bicycle mechanics & bicycle maintenance.

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Old 07-22-09, 09:12 PM   #1
gerboa
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Constant Flats, Tried Everything...Overweight Rider

Hi, I have a Mountain Bike, and a road bike.
EVERY time I go out on the road bike I get a flat on the rear.very rarely the front.Tyre pressures 90-100 psi.

I inflate with a standing pump with a guage at home and CO2 on the road.

I have tried neoprene tyres, anti puncture strips, new rim tape et al.

I don't repair tubes, I always fit new..it's getting very expensive.

The roads I cycle are good

I have been mending punctures and fixing my own bikes for 60 years and never had this type of problem.

I am a toolmaker so know tools.

I have put KY on the rims so that no danger of pinches. Never use tools to replace tyre.

My bike repair shop have fitted new tyres and tubes,(they have been listening to my woes a long time, so were meticulous), just in case I have been kidding myself on my abilities. I got a flat 30 mins after leaving the shop.

I still get flats, they appear as pin ******.

I replace tubes at roadside and at home.

have had guys bring tubes from Europe, thinking it may have been quality, all they get are made in taiwan.

I am beginning to believe that it may be my weight..95 kg, when I consider the tiny contact with the road.

I don't get many punctures on my mountain bike.

Should I give up road biking..is there something else I could buy..expense no object ?

Yours in Desperation
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Old 07-22-09, 09:22 PM   #2
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It's not your weight.

Might be the rim. If the rim tape doesn't completely cover the spoke holes, you will get flats like this. Could also be a rough metal burr on the rim. If I was you at this point, I'd consider a new wheel and a new shop.

For a rider of your weight you should be running more like 105-110 psi, but I doubt that's your problem.

Good luck

BL
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Old 07-22-09, 09:28 PM   #3
gerboa
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Thanks a lot..be easier to buy a newwheel than lose weight, can you pleasespecify a high quality make ?

In th meantime I'm going to lightly stone and polish the rims.

The tape looks and feels perfect.

Thanks again.
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Old 07-22-09, 10:34 PM   #4
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If you are getting new wheels, custom made wheels might be the better choice, as most factory made wheels are not really suitable for heavy riders (riders weighing around 100+ kg or 220+ lb).

I weigh over 100 kg and I use custom made wheels with 32 spokes per wheel. Higher spoke counts help wheels deal with extra loads imposed by heavier riders.

Several good rim manufacturers are DT swiss, Mavic, and Velocity. DT Swiss spokes are very good. And Shimano Ultegra and Dura Ace hubs are also very durable and reliable.

The flats due to pin ******, are they located on the outer side of tubes? If so, that suggests the flats are due to road debris, although there's the possibility of debris trapped inside the tire opposite the tread. A thorough inspection of the inside and outside of the tire under a strong light and using high magnification magnifying glass or reading glasses should be done. Be sure to check the inside of any cuts and nicks for any trapped debris (glass, wire etc), and remove any debris using tweezers or a needle.

Or are the flats located on the inner side of tubes? If so, this suggests a problem with the rim tape or some debris on or around the rim tape. Again thoroughly inspect the rim tape area for problems under a strong light and using magnification.

If the flats occur around the side of tubes, then this suggests either a problem with the rim (burrs etc), or again flats due to road debris. Thoroughly inspect the rim for any sharp edges and remove them using emery cloth or fine file.

If it is determined that road debris is the cause of the flats, then you may wish to consider using more puncture resistant tires such as - Specialized All Condition Armadillo, Michelin Krylion Carbon, Maxxis Refuse, Continental Ultra Gatorskin, Schwalbe Marathon, or Serfas Seca.

Good Luck!
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Old 07-22-09, 10:37 PM   #5
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Check the rim for any spokes poking through the rim-tape. I highly recommend using Velox rim-tape for all rims. And check the inside of this tire. I'm suspecting it may have something sharp stuck in it. Check it by eye and - carefully - with your fingers.
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Old 07-22-09, 11:30 PM   #6
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This might help you cut down your flat expenses. I've had very good success patching my own tubes with the inexpensive ($2.00) patch kits sold in dept. stores (not the "glueless" patches, I use the kits with the tube of glue included). I've never counted, but one patch kit can be used to fix dozens of flats, and a patched tube is literally as good as new (often a pin-hole puncture only requires a round patch that is a centimeter in diameter). I carry a good tube with me when I ride. If I flat I change-out the flatted tube for the good one and fix the flatted tube at home, then repeat as needed. When I've had to buy tubes (maybe one or two a year for the last three years) it's usually been because I've damaged the tube around the valve stem from bad pumping technique (at which I'm improving).

Which leads me (less enthusiastically, I admit) to recommending a frame pump to eliminate your CO2 expenses. I use a very basic Beto brand pump that I got for less than $15 from a seller on ebay. It has two holes in the head (one for shrader, one for presta) and it is okay to get the tire pumped up enough to get home. Many on BF recommend the Topeak Morph pumps (they come in different varietys: road, mountain bike, with gauge, without gauge, mini, etc.) The Topeak Morph pumps uses a hose like a regular floor pump and thus eliminates a lot of the stress one might put on the stem with a regular mini/frame pump. Since flats have become less and less a problem for me, and I've had mostly good success with the system/tools I already have, I've never gotten around to spending the aprox. $30-$35 for a Topeak Morph yet.

Along with making sure that your flat problem is not coming from the rim/wheel itself I recommend (what might be) the obvious, especially if you've read much on BF, a thicker-walled tire on the rear wheel. I've got a bike with a Marathon Plus in 700 X 25 size on the rear wheel and have great confidence that it won't flat. The downside is its quite heavy (I think around 580 grams). I haven't ridden this bike a lot since I put the tire on it so I can't say I've gotten x amount of flat-free miles on it. I've had more experience with Panaracer Pasela TourGuard tires in 27 X 1 1/8 size, never had a flat in (at least) 600 plus miles on those. They are plenty light for me (under 300 grams). I've looked at 700 X 25 Armadillos in a store before and they looked/felt quite tough (I think I've read they are around 400 grams). I've also found less expensive tires that seem pretty tough. I am riding a recently-installed Hutchinson Basic Flash tire on the back wheel of a road bike that is a thicker-walled tire (around 400 grams I believe) that seems fine so far. I weigh around 210 lbs. 80% of my flats are on the back wheel. I can use about any thin-walled tire on the front wheel, but found I need a beefier tire on the back wheel.
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Old 07-23-09, 01:12 AM   #7
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flats

Thanks so much for all the input, it is pleasure to find a forum with such constructive people.

I have rubbed down the minute (salt grain size) defects and if the present condition of the wheel,rim,rim tape, tube and tyre still fails, I'm going to get a stronger wheel and wider rim.

Unfortunately here in Thailand there will be little or no selection of any of the excellent products recommended, and if there were they would probably be fakes.

Since my Bluemels bicycle pump was stolen in 1947 (the police have still not found it), all my experiences with the new fangled pumps have not been happy, but I'm always trying.

Surprisingly the tiny CO2 is as effective as a hand pump as all the others.

Will keep you posted.

Best Regards
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Old 07-23-09, 06:14 AM   #8
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Switch to Road Tubeless and your flats will significantly diminish. No chance of pinch flats or spokes pushing through a tube.
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Old 07-23-09, 06:35 AM   #9
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I'm 95kg. I pump to 120psi, but let them go down to about 90psi over the course of a week (the ride quality improves as the week drags on). My stocked alexrim da16 were fine, but i upgraded to mavic aksium. I've never needed to true them since installing a year ago. And I bunny hop off kerbs. I use velox rim tape, specialized tubes, gatorskin tires and have not had a flat for 7 months (and even when I did get a flat, it's coz I sidewalled the tire against a kerb).

Before commuting, I used mich krylion tires and got flats every 4 months, but that's when I was doing training rides on good roads. now I commute to city and have to go on crappy roads.
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Old 07-23-09, 06:50 AM   #10
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Try some continental ultra gator skins

I ride a recumbent so all the weight is over the back tyre. I kept getting flats in the back, never the front - like every ride. I thing what was happening was that i'd get a bit of glass or road debris stuck in the tyre but not going through to puncture it. Then i'd go down a kerb or over a bump/pothole and because my bike isnt suspended the weight of myself and the bike would force the debris/glass shard through the tyre and cause a puncture.

Fitted a gator skin on the back - havent had a flat since.

Maxxis Re-fuse are supposed to be good too
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Old 07-23-09, 08:28 AM   #11
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i had a similar problem. every ride I would get a flat.
sounds like you already tried the things that fixed mine, but underpressure was the underlying root cause for me.
i switched to a new pump and havent had a flat in about 2k miles since the change.

are you checking if the location of the hole is in a simialr spot as the previous hole?

also, if you ride the bike home on a flat, then make sure to replace the tire.
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Old 07-23-09, 09:12 AM   #12
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Quote:
Originally Posted by gerboa View Post
I still get flats, they appear as pin ******.
Inside or outside circumference of the tube.

If it's the inside circumference, check your rim strip all of the way around. The tiniest little arc of exposed spoke hole will cause repeated flats.

If it's the outside circumference, proper diagnosis might take a little planning. If you have made a habit of installing the tire with the label adjacent to the valve stem, you can check to see if the pin ****** are in the same place relative to the tire. If that's the case, you have a little piece of wire or something stuck in your tire. If you can't find it (and I've had that happen), throw the tire away. It isn't worth the aggrivation.
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Old 07-23-09, 09:48 AM   #13
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it sounds like the rim tape needs to be re-done. i had the same issue on the front and the tape looked fine but after very close inspection the spoke holes were just enough to cause pinch flats. if you're finding tiny little hole(s) on the inner side of your tube that don't cause the tire to deflate all the way this might be your situation, too.

find a tire that will hold more than 100psi, too. that could also help. when i'm over 200lbs i will push conti's gp's and tubes to 130psi.
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Old 07-23-09, 10:16 AM   #14
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I'll first blame the tires. Then I'll blame your PSI.
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Old 07-23-09, 11:15 AM   #15
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When you flat and remove the tube, carefully mark it to some standard reference point on the rim. Likewise the tire always should be installed in a fixed orientation (e.g. letter of the label directly over the valve).

Then when you find the hole in the tube you can match it to the exact spot inside the rim or tire and the cause should become obvious.




If the spot moves around try an exorcism.


And please put your location in your profile.
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Old 07-23-09, 03:26 PM   #16
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This is sort of out in left field but I found that just looking at and feeling a tire (while it is off the bike) and comparing tires in this way has told me a lot about how puncture-resistant a tire would eventually prove to be. I avoid using practically "paperthin" side-walled tires on my back wheel. These types of tires are often (I believe) designed for those heavily concerned about light-weight and speed (low rolling resistance) over puncture resistance (one exception I've found is the Panaracer Pasela TourGuards I mentioned). Some of the most inexpensive tires I've found have been made out of relatively thick nylon and have been very good at preventing flats (I ran a 27 inch Cheng Shin tire on the back wheel of my '86 Schwinn Traveler that worked fine).
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Old 07-23-09, 03:36 PM   #17
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So far I have not seen an answer to the question "where on the tubes do the holes occur?". To properly diagnose your problem we need to know if the punctures are on the tread side, rim side or sidewall.

Also increase the pressure and fully inflate before each ride.

Al
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Old 07-23-09, 03:47 PM   #18
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Alright, not 210lbs right now, but have been and didn't have nearly so much trouble with flats.

General tips

1) At your weight, you should be inflating to max pressure indicated on the tire sidewall. For most road bike tires, this is going to be around 120psi not 100.

2) Watch where you're going. Avoid glass, gravel and holes and debris on the road to the best of your ability.

3) When you do flat, find out what caused it before just slapping in another tube and continuing on your way. Otherwise, the sharp object may still be stuck in tire and you will flat again very soon.

4) snake/vampire bite looking holes on the inside of the tube are from hitting something too hard. Either don't do that, or go to higher tire pressure if possible.

5) Single holes on the inside are from debris in the tire or some kind of sharp or rough spot on the rim. Fix it.

6) Holes on the sidewalls and treads are "legitimate" punctures and you just have to fix them. Try watching where you're going more, but you're going to get these no matter what. You can't see everything that's going to flat you at 20mph.

Good luck.
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Old 07-23-09, 04:37 PM   #19
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CO2 will leak out of the tubes rapidly. It's okay for an on-road emergency, but should be removed and replaced with air ASAP.
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Old 07-24-09, 12:12 AM   #20
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Urban legend .. sort of.

Yes tubes are more permeable to CO2 than to air, but not all that much. Since you have to inflate every time you ride it hardly makes a difference.
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Old 07-24-09, 12:43 AM   #21
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Quote:
Originally Posted by gerboa View Post
I have put KY on the rims so that no danger of pinches. Never use tools to replace tyre.

KY, like most petroleum products, can damage the rubber used in tubes and tires. You'd probably be better off using talcum powder to "lubricate" the tube. There's a place for KY, for sure, but it ain't in your wheels.

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Old 07-24-09, 01:14 AM   #22
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once you've determined if your flats are "inside" or "outside" -- if inside, next time apply a wider rim strip. Don't use the rubber stretch-to-fit kind, use the Velox stick-on type to be sure to cover the spoke hole drillings / burrs.
If you're riding 23 mm wide tires, go for a 25 on the rear, or even 28, if your rim is wide enough
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Old 07-24-09, 06:17 AM   #23
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KY, like most petroleum products, can damage the rubber used in tubes and tires. You'd probably be better off using talcum powder to "lubricate" the tube. There's a place for KY, for sure, but it ain't in your wheels.

bumper
Not. KY has no petroleum in it. It is completely harmless to the rubber. Often, when fitting new rubber suspension parts to an older car, KY is great to lubricate the metal to get the parts on.

Guess you've never used KY for anything, eh?
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Old 07-24-09, 07:44 AM   #24
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Urban legend .. sort of.

Yes tubes are more permeable to CO2 than to air, but not all that much. Since you have to inflate every time you ride it hardly makes a difference.
I actually conducted an experiment on this. A tube/tire inflated to 100psi with CO2 - it was down to 68psi in 18 hours. No riding involved, just standing.
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Old 07-24-09, 12:15 PM   #25
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When I've had successive flats, it's always been something in the wheel or tire causing it: a worn or off-center rim strip, a burr in the metal, a tiny piece of glass in the tire, etc. Unless you find the problem and remove it you'll keep getting flats.

Here's a tip. Whenever you put a new tube in, always align the valve stem with the most notable label on the tire. There's usually some bright logo on only one side of the tire. I use that.

Then, when you get a flat, pull out the tube, locate the puncture, see how far from the valve stem it is, and check wheel at about the same distance from the valve hole, and the tire at about the same distance from the label. Instead of having to check the entire wheel/tire, you can focus in on two fairly small areas and give them a really thorough check. (Heck, if you're really good you might be able to remember the orientation of the tire on the rim and only have to check one small area, but I can't ever seem to do that.)

I always install my tube this way, and when I get a flat I always check carefully to determine what caused the flat. It usually doesn't take me long to find the sliver of metal, shard of glass, etc., or the sharp edge on the rim.
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